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[emacs.git] / doc / misc / cc-mode.texi

\input texinfo
@c Notes to self regarding line handling:
@c
@c Empty lines are often significant before @end directives; avoid them.
@c
@c Empty lines before and after @example directives are significant in
@c info output but not in TeX.  Empty lines inside @example directives
@c are significant.

@c Conventions for formatting examples:
@c o  If the example contains empty lines then put the surrounding empty
@c    lines inside the @example directives.  Put them outside otherwise.
@c o  Use @group inside the example only if it shows indentation where
@c    the relation between lines inside is relevant.
@c o  Format line number columns like this:
@c     1: foo
@c     2: bar
@c       ^ one space
@c    ^^ two columns, right alignment
@c o  Check line lengths in TeX output; they can typically be no longer
@c    than 70 chars, 60 if the paragraph is indented.

@comment TBD: Document the finer details of statement anchoring?

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment %**start of header (This is for running Texinfo on a region)
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment How to make the various output formats:
@comment (Thanks to Robert Chassell for supplying this information.)
@comment Note that Texinfo 4.7 (or later) is needed.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@ignore
In each of the following pairs of commands, the first generates a
version with cross references pointing to the GNU Emacs manuals,
the second with them pointing to the XEmacs manuals.
    ## Info output
    makeinfo cc-mode.texi
    makeinfo -DXEMACS cc-mode.texi

    ## DVI output
    ## You may need to set up the environment variable TEXINPUTS so
    ## that tex can find the file texinfo.tex - See the tex
    ## manpage.
    texi2dvi cc-mode.texi
    texi2dvi -t "@set XEMACS " cc-mode.texi

    ## HTML output.  (The --no-split parameter is optional)
    makeinfo --html --no-split cc-mode.texi
    makeinfo --html --no-split -DXEMACS cc-mode.texi

    ## Plain text output
    makeinfo --fill-column=70 --no-split --paragraph-indent=0 \
      --no-headers --output=cc-mode.txt cc-mode.texi
    makeinfo --fill-column=70 --no-split --paragraph-indent=0 \
      --no-headers --output=cc-mode.txt -DXEMACS cc-mode.texi

    ## DocBook output
    makeinfo --docbook --no-split --paragraph-indent=0 \
      cc-mode.texi
    makeinfo --docbook --no-split --paragraph-indent=0 \
      -DXEMACS cc-mode.texi

    ## XML output
    makeinfo --xml --no-split --paragraph-indent=0 \
      cc-mode.texi
    makeinfo --xml --no-split --paragraph-indent=0 \
      -DXEMACS cc-mode.texi

    #### (You must be in the same directory as the viewed file.)

      ## View DVI output
      xdvi cc-mode.dvi &

      ## View HTML output
      mozilla cc-mode.html
@end ignore

@comment No overfull hbox marks in the dvi file.
@finalout

@setfilename  ../../info/ccmode
@settitle     CC Mode Manual
@footnotestyle end

@c The following four macros generate the filenames and titles of the
@c main (X)Emacs manual and the Elisp/Lispref manual.  Leave the
@c Texinfo variable `XEMACS' unset to generate a GNU Emacs version, set it
@c to generate an XEmacs version, e.g., with
@c "makeinfo -DXEMACS cc-mode.texi".
@ifset XEMACS
@macro emacsman
xemacs
@end macro
@macro emacsmantitle
XEmacs User's Manual
@end macro
@macro lispref
lispref
@end macro
@macro lispreftitle
XEmacs Lisp Reference Manual
@end macro
@end ifset

@ifclear XEMACS
@macro emacsman
emacs
@end macro
@macro emacsmantitle
GNU Emacs Manual
@end macro
@macro lispref
elisp
@end macro
@macro lispreftitle
GNU Emacs Lisp Reference Manual
@end macro
@end ifclear


@macro ccmode
CC Mode
@end macro

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment @setchapternewpage odd !! we don't want blank pages !!
@comment %**end of header (This is for running Texinfo on a region)
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment
@comment Texinfo manual for CC Mode
@comment Generated from the original README file by Krishna Padmasola
@comment <krishna@earth-gw.njit.edu>
@comment
@comment Authors:
@comment Barry A. Warsaw
@comment Martin Stjernholm
@comment Alan Mackenzie
@comment
@comment Maintained by Martin Stjernholm and Alan Mackenzie <bug-cc-mode@gnu.org>
@comment
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@comment Define an index for syntactic symbols.
@defindex ss

@comment Combine key, syntactic symbol and concept indices into one.
@syncodeindex ss cp
@syncodeindex ky cp

@copying
This manual is for CC Mode in Emacs.

Copyright @copyright{} 1995--2013 Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover texts being ``A GNU Manual'',
and with the Back-Cover Texts as in (a) below.  A copy of the license
is included in the section entitled ``GNU Free Documentation License''.

(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
modify this GNU manual.''
@end quotation
@end copying

@comment Info directory entry for use by install-info. The indentation
@comment here is by request from the FSF folks.
@dircategory Emacs editing modes
@direntry
* CC Mode: (ccmode).            Emacs mode for editing C, C++, Objective-C,
                                Java, Pike, AWK, and CORBA IDL code.
@end direntry

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment TeX title page
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@titlepage
@sp 10

@center @titlefont{CC Mode 5.32}
@sp 2
@center @subtitlefont{A GNU Emacs mode for editing C and C-like languages}
@sp 2
@center Barry A. Warsaw, Martin Stjernholm, Alan Mackenzie

@page
@vskip 0pt plus 1filll
@insertcopying

This manual was generated from cc-mode.texi, which is distributed with Emacs,
or can be downloaded from @url{http://savannah.gnu.org/projects/emacs/}.
@end titlepage

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment The Top node contains the master menu for the Info file.
@comment This appears only in the Info file, not the printed manual.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@summarycontents
@contents

@node    Top, Introduction, (dir), (dir)
@comment node-name, next, previous, up

@ifnottex
@top @ccmode{}

@ccmode{} is a GNU Emacs mode for editing files containing C, C++,
Objective-C, Java, CORBA IDL (and the variants PSDL and CIDL), Pike
and AWK code.  It provides syntax-based indentation, font locking, and
has several handy commands and some minor modes to make the editing
easier.  It does not provide tools to look up and navigate between
functions, classes, etc.; there are other packages for that.

@insertcopying
@end ifnottex

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@menu
* Introduction::
* Overview::
* Getting Started::
* Commands::
* Font Locking::
* Config Basics::
* Custom Filling and Breaking::
* Custom Auto-newlines::
* Clean-ups::
* Indentation Engine Basics::
* Customizing Indentation::
* Custom Macros::
* Odds and Ends::
* Sample .emacs File::
* Performance Issues::
* Limitations and Known Bugs::
* FAQ::
* Updating CC Mode::
* Mailing Lists and Bug Reports::
* GNU Free Documentation License::
* Command and Function Index::
* Variable Index::
* Concept and Key Index::

@detailmenu
 --- The Detailed Node Listing ---

Commands

* Indentation Commands::
* Comment Commands::
* Movement Commands::
* Filling and Breaking::
* Minor Modes::
* Electric Keys::
* Auto-newlines::
* Hungry WS Deletion::
* Subword Movement::
* Other Commands::

Font Locking

* Font Locking Preliminaries::
* Faces::
* Doc Comments::
* AWK Mode Font Locking::

Configuration Basics

* CC Hooks::
* Style Variables::
* Styles::

Styles

* Built-in Styles::
* Choosing a Style::
* Adding Styles::
* Guessing the Style::
* File Styles::

Customizing Auto-newlines

* Hanging Braces::
* Hanging Colons::
* Hanging Semicolons and Commas::

Hanging Braces

* Custom Braces::

Indentation Engine Basics

* Syntactic Analysis::
* Syntactic Symbols::
* Indentation Calculation::

Syntactic Symbols

* Function Symbols::
* Class Symbols::
* Conditional Construct Symbols::
* Switch Statement Symbols::
* Brace List Symbols::
* External Scope Symbols::
* Paren List Symbols::
* Literal Symbols::
* Multiline Macro Symbols::
* Objective-C Method Symbols::
* Java Symbols::
* Statement Block Symbols::
* K&R Symbols::

Customizing Indentation

* c-offsets-alist::
* Interactive Customization::
* Line-Up Functions::
* Custom Line-Up::
* Other Indentation::

Line-Up Functions

* Brace/Paren Line-Up::
* List Line-Up::
* Operator Line-Up::
* Comment Line-Up::
* Misc Line-Up::

Customizing Macros

* Macro Backslashes::
* Macros with ;::

@end detailmenu
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Introduction, Overview, Top, Top
@comment node-name, next, previous, up
@chapter Introduction
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex BOCM
@cindex history
@cindex awk-mode.el
@cindex c-mode.el
@cindex c++-mode.el

Welcome to @ccmode{}, a GNU Emacs mode for editing files containing C,
C++, Objective-C, Java, CORBA IDL (and the variants CORBA PSDL and
CIDL), Pike and AWK code.  This incarnation of the mode is descended
from @file{c-mode.el} (also called ``Boring Old C Mode'' or BOCM
@t{:-)}, @file{c++-mode.el} version 2, which Barry Warsaw had been
maintaining since 1992, and @file{awk-mode.el}, a long neglected mode
in the (X)Emacs base.

Late in 1997, Martin Stjernholm joined Barry on the @ccmode{}
Maintainers Team, and implemented the Pike support.  In 2000 Martin
took over as the sole maintainer.  In 2001 Alan Mackenzie joined the
team, implementing AWK support in version 5.30.  @ccmode{} did not
originally contain the font lock support for its languages; that
was added in version 5.30.

This manual describes @ccmode{}
@comment The following line must appear on its own, so that the
version 5.32.
@comment Release.py script can update the version number automatically

@ccmode{} supports the editing of K&R and ANSI C, C++, Objective-C,
Java, CORBA's Interface Definition Language, Pike@footnote{A C-like
scripting language with its roots in the LPC language used in some MUD
engines.  See @uref{http://pike.ida.liu.se/}.} and AWK files.  In this
way, you can easily set up consistent font locking and coding styles for
use in editing all of these languages, although AWK is not yet as
uniformly integrated as the other languages.

@findex c-mode
@findex c++-mode
@findex objc-mode
@findex java-mode
@findex idl-mode
@findex pike-mode
@findex awk-mode
Note that the name of this package is ``@ccmode{}'', but there is no top
level @code{cc-mode} entry point.  All of the variables, commands, and
functions in @ccmode{} are prefixed with @code{c-@var{thing}}, and
@code{c-mode}, @code{c++-mode}, @code{objc-mode}, @code{java-mode},
@code{idl-mode}, @code{pike-mode}, and @code{awk-mode} entry points are
provided.  This package is intended to be a replacement for
@file{c-mode.el}, @file{c++-mode.el} and @file{awk-mode.el}.

A special word of thanks goes to Krishna Padmasola for his work in
converting the original @file{README} file to Texinfo format.  I'd
also like to thank all the @ccmode{} victims who help enormously
during the early beta stages of @ccmode{}'s development.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Overview, Getting Started, Introduction, Top
@comment  node-name,  next,  previous,  up@cindex organization of the manual
@chapter Overview of the Manual
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@noindent
The manual starts with several introductory chapters (including this
one).

@noindent
The next chunk of the manual describes the day to day @emph{use} of
@ccmode{} (as contrasted with how to customize it).

@itemize @bullet
@item
The chapter ``Commands'' describes in detail how to use (nearly) all
of @ccmode{}'s features.  There are extensive cross-references from
here to the corresponding sections later in the manual which tell you
how to customize these features.

@item
``Font Locking'' describes how ``syntax highlighting'' is applied to
your buffers.  It is mainly background information and can be skipped
over at a first reading.
@end itemize

@noindent
The next chunk of the manual describes how to @emph{customize}
@ccmode{}.  Typically, an overview of a topic is given at the chapter
level, then the sections and subsections describe the material in
increasing detail.

@itemize @bullet
@item
The chapter ``Configuration Basics'' tells you @emph{how} to write
customizations: whether in hooks, in styles, in both, or in neither,
depending on your needs.  It describes the @ccmode{} style system and
lists the standard styles that @ccmode{} supplies.

@item
The next few chapters describe in detail how to customize the various
features of @ccmode{}.

@item
Finally, there is a sample @file{.emacs} fragment, which might help you
in creating your own customization.
@end itemize

@noindent
The manual ends with ``this and that'', things that don't fit cleanly
into any of the previous chunks.

@itemize @bullet
@item
Two chapters discuss the performance of @ccmode{} and known
bugs/limitations.

@item
The FAQ contains a list of common problems and questions.

@item
The next two chapters tell you how to get in touch with the @ccmode{}
project: whether for updating @ccmode{} or submitting bug reports.
@end itemize

@noindent
Finally, there are the customary indices.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Getting Started, Commands, Overview, Top
@comment node-name, next, previous, up
@chapter Getting Started
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If you got this version of @ccmode{} with Emacs or XEmacs, it should
work just fine right out of the box.  Note however that you might not
have the latest @ccmode{} release and might want to upgrade your copy
(see below).

You should probably start by skimming through the entire Commands chapter
(@pxref{Commands}) to get an overview of @ccmode{}'s capabilities.

After trying out some commands, you may dislike some aspects of
@ccmode{}'s default configuration.  Here is an outline of how to
change some of the settings that newcomers to @ccmode{} most often
want to change:

@table @asis
@item c-basic-offset
This Lisp variable holds an integer, the number of columns @ccmode{}
indents nested code.  To set this value to 6, customize
@code{c-basic-offset} or put this into your @file{.emacs}:

@example
(setq c-basic-offset 6)
@end example

@item The (indentation) style
The basic ``shape'' of indentation created by @ccmode{}---by default,
this is @code{gnu} style (except for Java and AWK buffers).  A list of
the available styles and their descriptions can be found in
@ref{Built-in Styles}.  A complete specification of the @ccmode{}
style system, including how to create your own style, can be found in
the chapter @ref{Styles}.  To set your style to @code{linux}, either
customize @code{c-default-style} or put this into your @file{.emacs}:

@example
(setq c-default-style '((java-mode . "java")
                        (awk-mode . "awk")
                        (other . "linux")))
@end example

@item Electric Indentation
Normally, when you type ``punctuation'' characters such as @samp{;} or
@samp{@{}, @ccmode{} instantly reindents the current line.  This can
be disconcerting until you get used to it.  To disable @dfn{electric
indentation} in the current buffer, type @kbd{C-c C-l}.  Type the same
thing to enable it again.  To have electric indentation disabled by
default, put the following into your @file{.emacs} file@footnote{There
is no ``easy customization'' facility for making this change.}:

@example
(setq-default c-electric-flag nil)
@end example

@noindent
Details of this and other similar ``Minor Modes'' appear in the
section @ref{Minor Modes}.

@item Making the @key{RET} key indent the new line
The standard Emacs binding for @key{RET} just adds a new line.  If you
want it to reindent the new line as well, rebind the key.  Note that
the action of rebinding would fail if the pertinent keymap didn't yet
exist---we thus need to delay the action until after @ccmode{} has
been loaded.  Put the following code into your @file{.emacs}:

@example
(defun my-make-CR-do-indent ()
  (define-key c-mode-base-map "\C-m" 'c-context-line-break))
(add-hook 'c-initialization-hook 'my-make-CR-do-indent)
@end example

@noindent
This example demonstrates the use of a very powerful @ccmode{} (and
Emacs) facility, the hook.  The use of @ccmode{}'s hooks is described
in @ref{CC Hooks}.
@end table

All these settings should occur in your @file{.emacs} @emph{before}
any @ccmode{} buffers get loaded---in particular, before any call of
@code{desktop-read}.

As you get to know the mode better, you may want to make more
ambitious changes to your configuration.  For this, you should start
reading the chapter @ref{Config Basics}.

If you are upgrading an existing @ccmode{} installation, please see
the @file{README} file for installation details.  In particular, if
you are going to be editing AWK files, @file{README} describes how to
configure your (X)Emacs so that @ccmode{} will supersede the obsolete
@code{awk-mode.el} which might have been supplied with your (X)Emacs.
@ccmode{} might not work with older versions of Emacs or XEmacs.  See
the @ccmode{} release notes at @uref{http://cc-mode.sourceforge.net}
for the latest information on Emacs version and package compatibility
(@pxref{Updating CC Mode}).

@deffn Command c-version
@findex version (c-)
You can find out what version of @ccmode{} you are using by visiting a C
file and entering @kbd{M-x c-version RET}.  You should see this message in
the echo area:

@example
Using CC Mode version 5.XX
@end example

@noindent
where @samp{XX} is the minor release number.
@end deffn

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Commands, Font Locking, Getting Started, Top
@comment node-name, next, previous, up
@chapter Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

This chapter specifies all of CC Mode's commands, and thus contains
nearly everything you need to know to @emph{use} @ccmode{} (as
contrasted with configuring it).  @dfn{Commands} here means both
control key sequences and @dfn{electric keys}, these being characters
such as @samp{;} which, as well as inserting themselves into the
buffer, also do other things.

You might well want to review
@ifset XEMACS
@ref{Lists,,,@emacsman{}, @emacsmantitle{}},
@end ifset
@ifclear XEMACS
@ref{Moving by Parens,,,@emacsman{}, @emacsmantitle{}},
@end ifclear
which describes commands for moving around brace and parenthesis
structures.


@menu
* Indentation Commands::
* Comment Commands::
* Movement Commands::
* Filling and Breaking::
* Minor Modes::
* Electric Keys::
* Auto-newlines::
* Hungry WS Deletion::
* Subword Movement::
* Other Commands::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Indentation Commands, Comment Commands, Commands, Commands
@comment node-name, next, previous,up
@section Indentation Commands
@cindex indentation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The following commands reindent C constructs.  Note that when you
change your coding style, either interactively or through some other
means, your file does @emph{not} automatically get reindented.  You
will need to execute one of the following commands to see the effects
of your changes.

@cindex GNU indent program
Also, variables like @code{c-hanging-*} and @code{c-cleanup-list}
(@pxref{Custom Auto-newlines}) only affect how on-the-fly code is
formatted.  Changing the ``hanginess'' of a brace and then
reindenting, will not move the brace to a different line.  For this,
you're better off getting an external program like GNU @code{indent},
which will rearrange brace location, amongst other things.

Preprocessor directives are handled as syntactic whitespace from other
code, i.e., they can be interspersed anywhere without affecting the
indentation of the surrounding code, just like comments.

The code inside macro definitions is, by default, still analyzed
syntactically so that you get relative indentation there just as you'd
get if the same code was outside a macro.  However, since there is no
hint about the syntactic context, i.e., whether the macro expands to an
expression, to some statements, or perhaps to whole functions, the
syntactic recognition can be wrong.  @ccmode{} manages to figure it
out correctly most of the time, though.

Some macros, when invoked, ''have their own semicolon''.  To get the
next line indented correctly, rather than as a continuation line,
@xref{Macros with ;}.

Reindenting large sections of code can take a long time.  When
@ccmode{} reindents a region of code, it is essentially equivalent to
hitting @key{TAB} on every line of the region.

These commands indent code:

@table @asis
@item @kbd{@key{TAB}} (@code{c-indent-command})
@kindex TAB
@findex c-indent-command
@findex indent-command (c-)
This command indents the current line.  That is all you need to know
about it for normal use.

@code{c-indent-command} does different things, depending on the
setting of @code{c-syntactic-indentation} (@pxref{Indentation Engine
Basics}):

@itemize @bullet
@item
When it's non-@code{nil} (which it normally is), the command indents
the line according to its syntactic context.  With a prefix argument
(@kbd{C-u @key{TAB}}), it will re-indent the entire
expression@footnote{this is only useful for a line starting with a
comment opener or an opening brace, parenthesis, or string quote.}
that begins at the line's left margin.

@item
When it's @code{nil}, the command indents the line by an extra
@code{c-basic-offset} columns.  A prefix argument acts as a
multiplier.  A bare prefix (@kbd{C-u @key{TAB}}) is equivalent to -1,
removing @code{c-basic-offset} columns from the indentation.
@end itemize

The precise behavior is modified by several variables: With
@code{c-tab-always-indent}, you can make @key{TAB} insert whitespace
in some circumstances---@code{c-insert-tab-function} then defines
precisely what sort of ``whitespace'' this will be.  Set the standard
Emacs variable @code{indent-tabs-mode} to @code{t} if you want real
@samp{tab} characters to be used in the indentation, to @code{nil} if
you want only spaces.  @xref{Just Spaces,,,@emacsman{},
@emacsmantitle{}}.

@defopt c-tab-always-indent
@vindex tab-always-indent (c-)
@cindex literal
This variable modifies how @key{TAB} operates.
@itemize @bullet
@item
When it is @code{t} (the default), @key{TAB} simply indents the
current line.
@item
When it is @code{nil}, @key{TAB} (re)indents the line only if point is
to the left of the first non-whitespace character on the line.
Otherwise it inserts some whitespace (a tab or an equivalent number of
spaces; see below) at point.
@item
With some other value, the line is reindented.  Additionally, if point
is within a string or comment, some whitespace is inserted.
@end itemize
@end defopt

@defopt c-insert-tab-function
@vindex insert-tab-function (c-)
@findex tab-to-tab-stop
When ``some whitespace'' is inserted as described above, what actually
happens is that the function stored in @code{c-insert-tab-function} is
called.  Normally, this is @code{insert-tab}, which inserts a real tab
character or the equivalent number of spaces (depending on
@code{indent-tabs-mode}).  Some people, however, set
@code{c-insert-tab-function} to @code{tab-to-tab-stop} so as to get
hard tab stops when indenting.
@end defopt
@end table

@noindent
The kind of indentation the next five commands do depends on the
setting of @code{c-syntactic-indentation} (@pxref{Indentation Engine
Basics}):
@itemize @bullet
@item
when it is non-@code{nil} (the default), the commands indent lines
according to their syntactic context;
@item
when it is @code{nil}, they just indent each line the same amount as
the previous non-blank line.  The commands that indent a region aren't
very useful in this case.
@end itemize

@table @asis
@item @kbd{C-j} (@code{newline-and-indent})
@kindex C-j
@findex newline-and-indent
Inserts a newline and indents the new blank line, ready to start
typing.  This is a standard (X)Emacs command.

@item @kbd{C-M-q} (@code{c-indent-exp})
@kindex C-M-q
@findex c-indent-exp
@findex indent-exp (c-)
Indents an entire balanced brace or parenthesis expression.  Note that
point must be on the opening brace or parenthesis of the expression
you want to indent.

@item @kbd{C-c C-q} (@code{c-indent-defun})
@kindex C-c C-q
@findex c-indent-defun
@findex indent-defun (c-)
Indents the entire top-level function, class or macro definition
encompassing point.  It leaves point unchanged.  This function can't be
used to reindent a nested brace construct, such as a nested class or
function, or a Java method.  The top-level construct being reindented
must be complete, i.e., it must have both a beginning brace and an ending
brace.

@item @kbd{C-M-\} (@code{indent-region})
@kindex C-M-\
@findex indent-region
Indents an arbitrary region of code.  This is a standard Emacs command,
tailored for C code in a @ccmode{} buffer.  Note, of course, that point
and mark must delineate the region you want to indent.

@item @kbd{C-M-h} (@code{c-mark-function})
@kindex C-M-h
@findex c-mark-function
@findex mark-function (c-)
While not strictly an indentation command, this is useful for marking
the current top-level function or class definition as the current
region.  As with @code{c-indent-defun}, this command operates on
top-level constructs, and can't be used to mark say, a Java method.
@end table

These variables are also useful when indenting code:

@defopt indent-tabs-mode
This is a standard Emacs variable that controls how line indentation
is composed.  When it's non-@code{nil}, tabs can be used in a line's
indentation, otherwise only spaces are used.
@end defopt

@defopt c-progress-interval
@vindex progress-interval (c-)
When indenting large regions of code, this variable controls how often a
progress message is displayed.  Set this variable to @code{nil} to
inhibit the progress messages, or set it to an integer which is how
often (in seconds) progress messages are to be displayed.
@end defopt

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Comment Commands, Movement Commands, Indentation Commands, Commands
@comment node-name, next, previous, up
@section Comment Commands
@cindex comments (insertion of)
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@table @asis
@item @kbd{C-c C-c} (@code{comment-region})
@kindex C-c C-c
@findex comment-region
This command comments out the lines that start in the region.  With a
negative argument, it does the opposite: it deletes the comment
delimiters from these lines.  @xref{Multi-Line Comments,,, emacs, GNU
Emacs Manual}, for fuller details.  @code{comment-region} isn't
actually part of @ccmode{}; it is given a @ccmode{} binding for
convenience.

@item @kbd{M-;} (@code{comment-dwim} or @code{indent-for-comment} @footnote{The name of this command varies between (X)Emacs versions.})
@kindex M-;
@findex comment-dwim
@findex indent-for-comment
Insert a comment at the end of the current line, if none is there
already.  Then reindent the comment according to @code{comment-column}
@ifclear XEMACS
(@pxref{Options for Comments,,, emacs, GNU Emacs Manual})
@end ifclear
@ifset XEMACS
(@pxref{Comments,,, xemacs, XEmacs User's Manual})
@end ifset
and the variables below.  Finally, position the point after the
comment starter.  @kbd{C-u M-;} kills any comment on the current line,
together with any whitespace before it.  This is a standard Emacs
command, but @ccmode{} enhances it a bit with two variables:

@defopt c-indent-comment-alist
@vindex indent-comment-alist (c-)
@vindex comment-column
This style variable allows you to vary the column that @kbd{M-;} puts
the comment at, depending on what sort of code is on the line, and
possibly the indentation of any similar comment on the preceding line.
It is an association list that maps different types of lines to
actions describing how they should be handled.  If a certain line type
isn't present on the list then the line is indented to the column
specified by @code{comment-column}.

See the documentation string for a full description of this
variable (use @kbd{C-h v c-indent-comment-alist}).
@end defopt

@defopt c-indent-comments-syntactically-p
@vindex indent-comments-syntactically-p (c-)
Normally, when this style variable is @code{nil}, @kbd{M-;} will
indent comment-only lines according to @code{c-indent-comment-alist},
just as it does with lines where other code precede the comments.
However, if you want it to act just like @key{TAB} for comment-only
lines you can get that by setting
@code{c-indent-comments-syntactically-p} to non-@code{nil}.

If @code{c-indent-comments-syntactically-p} is non-@code{nil} then
@code{c-indent-comment-alist} won't be consulted at all for comment-only
lines.
@end defopt
@end table

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Movement Commands, Filling and Breaking, Comment Commands, Commands
@comment node-name, next, previous, up
@section Movement Commands
@cindex movement
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ccmode{} contains some useful commands for moving around in C code.

@table @asis
@item @kbd{C-M-a} (@code{c-beginning-of-defun})
@itemx @kbd{C-M-e} (@code{c-end-of-defun})
@findex c-beginning-of-defun
@findex c-end-of-defun
@vindex c-defun-tactic
@vindex defun-tactic (c-)

Move to the beginning or end of the current or next function.  Other
constructs (such as a structs or classes) which have a brace block
also count as ``functions'' here.  To move over several functions, you
can give these commands a repeat count.

The start of a function is at its header.  The end of the function is
after its closing brace, or after the semicolon of a construct (such
as a @code{struct}) which doesn't end at the brace.  These two
commands try to leave point at the beginning of a line near the actual
start or end of the function.  This occasionally causes point not to
move at all.

By default, these commands will recognize functions contained within a
@dfn{declaration scope} such as a C++ @code{class} or @code{namespace}
construct, should the point start inside it.  If @ccmode fails to find
function beginnings or ends inside the current declaration scope, it
will search the enclosing scopes.  If you want @ccmode to recognize
functions only at the top level@footnote{this was @ccmode{}'s
behavior prior to version 5.32.}, set @code{c-defun-tactic} to
@code{t}.

These functions are analogous to the Emacs built-in commands
@code{beginning-of-defun} and @code{end-of-defun}, except they
eliminate the constraint that the top-level opening brace of the defun
must be in column zero.  See @ref{Defuns,,,@emacsman{},
@emacsmantitle{}}, for more information.

@item @kbd{C-M-a} (AWK Mode) (@code{c-awk-beginning-of-defun})
@itemx @kbd{C-M-e} (AWK Mode) (@code{c-awk-end-of-defun})
@kindex C-M-a (AWK Mode)
@kindex C-M-e (AWK Mode)
@findex c-awk-beginning-of-defun
@findex awk-beginning-of-defun (c-)
@findex c-awk-end-of-defun
@findex awk-end-of-defun (c-)
Move to the beginning or end of the current or next AWK defun.  These
commands can take prefix-arguments, their functionality being entirely
equivalent to @code{beginning-of-defun} and @code{end-of-defun}.

AWK Mode @dfn{defuns} are either pattern/action pairs (either of which
might be implicit) or user defined functions.  Having the @samp{@{} and
@samp{@}} (if there are any) in column zero, as is suggested for some
modes, is neither necessary nor helpful in AWK mode.

@item @kbd{M-a} (@code{c-beginning-of-statement})
@itemx @kbd{M-e} (@code{c-end-of-statement})
@kindex M-a
@kindex M-e
@findex c-beginning-of-statement
@findex c-end-of-statement
@findex beginning-of-statement (c-)
@findex end-of-statement (c-)
Move to the beginning or end of the innermost C statement.  If point
is already there, move to the next beginning or end of a statement,
even if that means moving into a block.  (Use @kbd{C-M-b} or
@kbd{C-M-f} to move over a balanced block.)  A prefix argument @var{n}
means move over @var{n} statements.

If point is within or next to a comment or a string which spans more
than one line, these commands move by sentences instead of statements.

When called from a program, these functions take three optional
arguments: the repetition count, a buffer position limit which is the
farthest back to search for the syntactic context, and a flag saying
whether to do sentence motion in or near comments and multiline
strings.

@item @kbd{C-c C-u} (@code{c-up-conditional})
@kindex C-c C-u
@findex c-up-conditional
@findex up-conditional (c-)
Move back to the containing preprocessor conditional, leaving the mark
behind.  A prefix argument acts as a repeat count.  With a negative
argument, move forward to the end of the containing preprocessor
conditional.

@samp{#elif} is treated like @samp{#else} followed by @samp{#if}, so the
function stops at them when going backward, but not when going
forward.

This key sequence is not bound in AWK Mode, which doesn't have
preprocessor statements.

@item @kbd{M-x c-up-conditional-with-else}
@findex c-up-conditional-with-else
@findex up-conditional-with-else (c-)
A variety of @code{c-up-conditional} that also stops at @samp{#else}
lines.  Normally those lines are ignored.

@item @kbd{M-x c-down-conditional}
@findex c-down-conditional
@findex down-conditional (c-)
Move forward into the next nested preprocessor conditional, leaving
the mark behind.  A prefix argument acts as a repeat count.  With a
negative argument, move backward into the previous nested preprocessor
conditional.

@samp{#elif} is treated like @samp{#else} followed by @samp{#if}, so the
function stops at them when going forward, but not when going backward.

@item @kbd{M-x c-down-conditional-with-else}
@findex c-down-conditional-with-else
@findex down-conditional-with-else (c-)
A variety of @code{c-down-conditional} that also stops at @samp{#else}
lines.  Normally those lines are ignored.

@item @kbd{C-c C-p} (@code{c-backward-conditional})
@itemx @kbd{C-c C-n} (@code{c-forward-conditional})
@kindex C-c C-p
@kindex C-c C-n
@findex c-backward-conditional
@findex c-forward-conditional
@findex backward-conditional (c-)
@findex forward-conditional (c-)
Move backward or forward across a preprocessor conditional, leaving
the mark behind.  A prefix argument acts as a repeat count.  With a
negative argument, move in the opposite direction.

These key sequences are not bound in AWK Mode, which doesn't have
preprocessor statements.

@item @kbd{M-x c-backward-into-nomenclature}
@itemx @kbd{M-x c-forward-into-nomenclature}
@findex c-backward-into-nomenclature
@findex c-forward-into-nomenclature
@findex backward-into-nomenclature (c-)
@findex forward-into-nomenclature (c-)
A popular programming style, especially for object-oriented languages
such as C++ is to write symbols in a mixed case format, where the
first letter of each word is capitalized, and not separated by
underscores.  E.g., @samp{SymbolsWithMixedCaseAndNoUnderlines}.

These commands move backward or forward to the beginning of the next
capitalized word.  With prefix argument @var{n}, move @var{n} times.
If @var{n} is negative, move in the opposite direction.

Note that these two commands have been superseded by
@code{subword-mode}, which you should use instead.  @xref{Subword
Movement}.  They might be removed from a future release of @ccmode{}.
@end table

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Filling and Breaking, Minor Modes, Movement Commands, Commands
@comment  node-name,  next,  previous,  up
@section Filling and Line Breaking Commands
@cindex text filling
@cindex line breaking
@cindex comment handling
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Since there's a lot of normal text in comments and string literals,
@ccmode{} provides features to edit these like in text mode.  The goal
is to do it seamlessly, i.e., you can use auto fill mode, sentence and
paragraph movement, paragraph filling, adaptive filling etc. wherever
there's a piece of normal text without having to think much about it.
@ccmode{} keeps the indentation, fixes suitable comment line prefixes,
and so on.

You can configure the exact way comments get filled and broken, and
where Emacs does auto-filling (see @pxref{Custom Filling and
Breaking}).  Typically, the style system (@pxref{Styles}) will have
set this up for you, so you probably won't have to bother.

@findex auto-fill-mode
@cindex Auto Fill mode
@cindex paragraph filling
Line breaks are by default handled (almost) the same regardless of
whether they are made by auto fill mode (@pxref{Auto
Fill,,,@emacsman{}, @emacsmantitle{}}), by paragraph filling (e.g., with
@kbd{M-q}), or explicitly with @kbd{M-j} or similar methods.  In
string literals, the new line gets the same indentation as the
previous nonempty line.@footnote{You can change this default by
setting the @code{string} syntactic symbol (@pxref{Syntactic Symbols}
and @pxref{Customizing Indentation})}.

@table @asis
@item @kbd{M-q} (@code{c-fill-paragraph})
@kindex M-q
@findex c-fill-paragraph
@findex fill-paragraph (c-)
@cindex Javadoc markup
@cindex Pike autodoc markup
This command fills multiline string literals and both block
and line style comments.  In Java buffers, the Javadoc markup words
are recognized as paragraph starters.  The line oriented Pike autodoc
markup words are recognized in the same way in Pike mode.

The formatting of the starters (@code{/*}) and enders (@code{*/}) of
block comments are kept as they were before the filling.  I.e., if
either the starter or ender were on a line of its own, then it stays
on its own line; conversely, if the delimiter has comment text on its
line, it keeps at least one word of that text with it on the line.

This command is the replacement for @code{fill-paragraph} in @ccmode{}
buffers.

@item @kbd{M-j} (@code{c-indent-new-comment-line})
@kindex M-j
@findex c-indent-new-comment-line
@findex indent-new-comment-line (c-)
This breaks the current line at point and indents the new line.  If
point was in a comment, the new line gets the proper comment line
prefix.  If point was inside a macro, a backslash is inserted before
the line break.  It is the replacement for
@code{indent-new-comment-line}.

@item @kbd{M-x c-context-line-break}
@findex c-context-line-break
@findex context-line-break (c-)
Insert a line break suitable to the context: If the point is inside a
comment, the new line gets the suitable indentation and comment line
prefix like @code{c-indent-new-comment-line}.  In normal code it's
indented like @code{newline-and-indent} would do.  In macros it acts
like @code{newline-and-indent} but additionally inserts and optionally
aligns the line ending backslash so that the macro remains unbroken.
@xref{Custom Macros}, for details about the backslash alignment.  In a
string, a backslash is inserted only if the string is within a
macro@footnote{In GCC, unescaped line breaks within strings are
valid.}.

This function is not bound to a key by default, but it's intended to be
used on the @kbd{RET} key.  If you like the behavior of
@code{newline-and-indent} on @kbd{RET}, you should consider switching to
this function.  @xref{Sample .emacs File}.

@item @kbd{M-x c-context-open-line}
@findex c-context-open-line
@findex context-open-line (c-)
This is to @kbd{C-o} (@kbd{M-x open-line}) as
@code{c-context-line-break} is to @kbd{RET}.  I.e., it works just like
@code{c-context-line-break} but leaves the point before the inserted
line break.
@end table


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Minor Modes, Electric Keys, Filling and Breaking, Commands
@comment node-name, next, previous, up
@section Minor Modes
@cindex Minor Modes
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ccmode{} contains several minor-mode-like features that you might
find useful while writing new code or editing old code:

@table @asis
@item electric mode
When this is enabled, certain visible characters cause reformatting as
they are typed.  This is normally helpful, but can be a nuisance when
editing chaotically formatted code.  It can also be disconcerting,
especially for users who are new to @ccmode{}.
@item auto-newline mode
This automatically inserts newlines where you'd probably want to type
them yourself, e.g., after typing @samp{@}}s.  Its action is suppressed
when electric mode is disabled.
@item hungry-delete mode
This lets you delete a contiguous block of whitespace with a single
key: for example, the newline and indentation just inserted by
auto-newline when you want to back up and write a comment after the
last statement.
@item subword mode
This mode makes basic word movement commands like @kbd{M-f}
(@code{forward-word}) and @kbd{M-b} (@code{backward-word}) treat the
parts of sillycapsed symbols as different words.
E.g., @samp{NSGraphicsContext} is treated as three words @samp{NS},
@samp{Graphics}, and @samp{Context}.
@item syntactic-indentation mode
When this is enabled (which it normally is), indentation commands such
as @kbd{C-j} indent lines of code according to their syntactic
structure.  Otherwise, a line is simply indented to the same level as
the previous one and @kbd{@key{TAB}} adjusts the indentation in steps
of `c-basic-offset'.
@end table

Full details on how these minor modes work are at @ref{Electric Keys},
@ref{Auto-newlines}, @ref{Hungry WS Deletion}, @ref{Subword Movement},
and @ref{Indentation Engine Basics}.

You can toggle each of these minor modes on and off, and you can
configure @ccmode{} so that it starts up with your favorite
combination of them (@pxref{Sample .emacs File}).  By default, when
you initialize a buffer, electric mode and syntactic-indentation mode
are enabled but the other two modes are disabled.

@ccmode{} displays the current state of the first four of these minor
modes on the modeline by appending letters to the major mode's name,
one letter for each enabled minor mode: @samp{l} for electric mode,
@samp{a} for auto-newline mode, @samp{h} for hungry delete mode, and
@samp{w} for subword mode.  If all these modes were enabled, you'd see
@samp{C/lahw}@footnote{The @samp{C} would be replaced with the name of
the language in question for the other languages @ccmode{} supports.}.

Here are the commands to toggle these modes:

@table @asis
@item @kbd{C-c C-l} (@code{c-toggle-electric-state})
@kindex C-c C-l
@findex c-toggle-electric-state
@findex toggle-electric-state (c-)
Toggle electric minor mode.  When the command turns the mode off, it
also suppresses auto-newline mode.

@item @kbd{C-c C-a} (@code{c-toggle-auto-newline})
@kindex C-c C-a
@findex c-toggle-auto-newline
@findex toggle-auto-newline (c-)
Toggle auto-newline minor mode.  When the command turns the mode on,
it also enables electric minor mode.

@item @kbd{M-x c-toggle-hungry-state}@footnote{Prior to @ccmode{} 5.31, this command was bound to @kbd{C-c C-d}.}
@findex c-toggle-hungry-state
@findex toggle-hungry-state (c-)
Toggle hungry-delete minor mode.

@item @kbd{M-x c-toggle-auto-hungry-state}@footnote{Prior to @ccmode{} 5.31, this command was bound to @kbd{C-c C-t}.}
@findex c-toggle-auto-hungry-state
@findex toggle-auto-hungry-state (c-)
Toggle both auto-newline and hungry delete minor modes.

@item @kbd{C-c C-w} (@code{M-x subword-mode})
@kindex C-c C-w
@findex subword-mode
Toggle subword mode.

@item @kbd{M-x c-toggle-syntactic-indentation}
@findex c-toggle-syntactic-indentation
@findex toggle-syntactic-indentation (c-)
Toggle syntactic-indentation mode.
@end table

Common to all the toggle functions above is that if they are called
programmatically, they take an optional numerical argument.  A
positive value will turn on the minor mode (or both of them in the
case of @code{c-toggle-auto-hungry-state}) and a negative value will
turn it (or them) off.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Electric Keys, Auto-newlines, Minor Modes, Commands
@comment node-name, next, previous, up
@section Electric Keys and Keywords
@cindex electric characters
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Most punctuation keys provide @dfn{electric} behavior: as well as
inserting themselves they perform some other action, such as
reindenting the line.  This reindentation saves you from having to
reindent a line manually after typing, say, a @samp{@}}.  A few
keywords, such as @code{else}, also trigger electric action.

You can inhibit the electric behavior described here by disabling
electric minor mode (@pxref{Minor Modes}).

Common to all these keys is that they only behave electrically when
used in normal code (as contrasted with getting typed in a string
literal or comment).  Those which cause re-indentation do so only when
@code{c-syntactic-indentation} has a non-@code{nil} value (which it
does by default).

These keys and keywords are:
@c ACM, 2004/8/24:  c-electric-pound doesn't check c-s-i: this is more
@c like a bug in the code than a bug in this document.  It'll get
@c fixed in the code sometime.

@table @kbd
@item #
@kindex #
@findex c-electric-pound
@findex electric-pound (c-)
@vindex c-electric-pound-behavior
@vindex electric-pound-behavior (c-)
Pound (bound to @code{c-electric-pound}) is electric when typed as the
first non-whitespace character on a line and not within a macro
definition.  In this case, the variable @code{c-electric-pound-behavior}
is consulted for the electric behavior.  This variable takes a list
value, although the only element currently defined is @code{alignleft},
which tells this command to force the @samp{#} character into column
zero.  This is useful for entering preprocessor macro definitions.

Pound is not electric in AWK buffers, where @samp{#} starts a comment,
and is bound to @code{self-insert-command} like any typical printable
character.
@c ACM, 2004/8/24:  Change this (and the code) to do AWK comment
@c reindentation.

@item *
@kindex *
@itemx /
@kindex /
@findex c-electric-star
@findex electric-star (c-)
@findex c-electric-slash
@findex electric-slash (c-)
A star (bound to @code{c-electric-star}) or a slash
(@code{c-electric-slash}) causes reindentation when you type it as the
second component of a C style block comment opener (@samp{/*}) or a
C++ line comment opener (@samp{//}) respectively, but only if the
comment opener is the first thing on the line (i.e., there's only
whitespace before it).

Additionally, you can configure @ccmode{} so that typing a slash at
the start of a line within a block comment will terminate the
comment.  You don't need to have electric minor mode enabled to get
this behavior.  @xref{Clean-ups}.

In AWK mode, @samp{*} and @samp{/} do not delimit comments and are not
electric.

@item <
@kindex <
@itemx >
@kindex >
@findex c-electric-lt-gt
@findex electric-lt-gt (c-)
A less-than or greater-than sign (bound to @code{c-electric-lt-gt}) is
electric in two circumstances: when it is an angle bracket in a C++
@samp{template} declaration (and similar constructs in other
languages) and when it is the second of two @kbd{<} or @kbd{>}
characters in a C++ style stream operator.  In either case, the line
is reindented.  Angle brackets in C @samp{#include} directives are not
electric.

@item (
@kindex (
@itemx )
@kindex )
@findex c-electric-paren
@findex electric-paren (c-)
The normal parenthesis characters @samp{(} and @samp{)} (bound to
@code{c-electric-paren}) reindent the current line.  This is useful
for getting the closing parenthesis of an argument list aligned
automatically.

You can also configure @ccmode{} to insert a space automatically
between a function name and the @samp{(} you've just typed, and to
remove it automatically after typing @samp{)}, should the argument
list be empty.  You don't need to have electric minor mode enabled to
get these actions.  @xref{Clean-ups}.

@item @{
@kindex @{
@itemx @}
@kindex @}
@findex c-electric-brace
@findex electric-brace (c-)
Typing a brace (bound to @code{c-electric-brace}) reindents the
current line.  Also, one or more newlines might be inserted if
auto-newline minor mode is enabled.  @xref{Auto-newlines}.
Additionally, you can configure @ccmode{} to compact excess whitespace
inserted by auto-newline mode in certain circumstances.
@xref{Clean-ups}.

@item :
@kindex :
@findex c-electric-colon
@findex electric-colon (c-)
Typing a colon (bound to @code{c-electric-colon}) reindents the
current line.  Additionally, one or more newlines might be inserted if
auto-newline minor mode is enabled.  @xref{Auto-newlines}.  If you
type a second colon immediately after such an auto-newline, by default
the whitespace between the two colons is removed, leaving a C++ scope
operator.  @xref{Clean-ups}.

If you prefer, you can insert @samp{::} in a single operation,
avoiding all these spurious reindentations, newlines, and clean-ups.
@xref{Other Commands}.

@item ;
@kindex ;
@itemx ,
@kindex ,
@findex c-electric-semi&comma
@findex electric-semi&comma (c-)
Typing a semicolon or comma (bound to @code{c-electric-semi&comma})
reindents the current line.  Also, a newline might be inserted if
auto-newline minor mode is enabled.  @xref{Auto-newlines}.
Additionally, you can configure @ccmode{} so that when auto-newline
has inserted whitespace after a @samp{@}}, it will be removed again
when you type a semicolon or comma just after it.  @xref{Clean-ups}.

@end table

@deffn Command c-electric-continued-statement
@findex electric-continued-statement (c-)

Certain keywords are electric, causing reindentation when they are
preceded only by whitespace on the line.  The keywords are those that
continue an earlier statement instead of starting a new one:
@code{else}, @code{while}, @code{catch} (only in C++ and Java) and
@code{finally} (only in Java).

An example:

@example
@group
for (i = 0; i < 17; i++)
  if (a[i])
    res += a[i]->offset;
else
@end group
@end example

Here, the @code{else} should be indented like the preceding @code{if},
since it continues that statement. @ccmode{} will automatically
reindent it after the @code{else} has been typed in full, since only
then is it possible to decide whether it's a new statement or a
continuation of the preceding @code{if}.

@vindex abbrev-mode
@findex abbrev-mode
@cindex Abbrev mode
@ccmode{} uses Abbrev mode (@pxref{Abbrevs,,,@emacsman{}, @emacsmantitle{}})
to accomplish this. It's therefore turned on by default in all language
modes except IDL mode, since CORBA IDL doesn't have any statements.
@end deffn


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Auto-newlines, Hungry WS Deletion, Electric Keys, Commands
@comment node-name, next, previous, up
@section Auto-newline Insertion
@cindex auto-newline
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

When you have @dfn{Auto-newline minor mode} enabled (@pxref{Minor
Modes}), @ccmode{} inserts newlines for you automatically (in certain
syntactic contexts) when you type a left or right brace, a colon, a
semicolon, or a comma.  Sometimes a newline appears before the
character you type, sometimes after it, sometimes both.

Auto-newline only triggers when the following conditions hold:

@itemize @bullet
@item
Auto-newline minor mode is enabled, as evidenced by the indicator
@samp{a} after the mode name on the modeline (e.g., @samp{C/a} or
@samp{C/la}).

@item
The character was typed at the end of a line, or with only whitespace
after it, and possibly a @samp{\} escaping the newline.

@item
The character is not on its own line already.  (This applies only to
insertion of a newline @emph{before} the character.)

@item
@cindex literal
@cindex syntactic whitespace
The character was not typed inside of a literal @footnote{A
@dfn{literal} is defined as any comment, string, or preprocessor macro
definition.  These constructs are also known as @dfn{syntactic
whitespace} since they are usually ignored when scanning C code.}.

@item
No numeric argument was supplied to the command (i.e., it was typed as
normal, with no @kbd{C-u} prefix).
@end itemize

You can configure the precise circumstances in which newlines get
inserted (see @pxref{Custom Auto-newlines}).  Typically, the style
system (@pxref{Styles}) will have set this up for you, so you probably
won't have to bother.

Sometimes @ccmode{} inserts an auto-newline where you don't want one,
such as after a @samp{@}} when you're about to type a @samp{;}.
Hungry deletion can help here (@pxref{Hungry WS Deletion}), or you can
activate an appropriate @dfn{clean-up}, which will remove the excess
whitespace after you've typed the @samp{;}.  See @ref{Clean-ups} for a
full description.  See also @ref{Electric Keys} for a summary of
clean-ups listed by key.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Hungry WS Deletion, Subword Movement, Auto-newlines, Commands
@comment node-name, next, previous, up
@section Hungry Deletion of Whitespace
@cindex hungry-deletion
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If you want to delete an entire block of whitespace at point, you can
use @dfn{hungry deletion}.  This deletes all the contiguous whitespace
either before point or after point in a single operation.
``Whitespace'' here includes tabs and newlines, but not comments or
preprocessor commands.  Hungry deletion can markedly cut down on the
number of times you have to hit deletion keys when, for example,
you've made a mistake on the preceding line and have already pressed
@kbd{C-j}.

Hungry deletion is a simple feature that some people find extremely
useful.  In fact, you might find yourself wanting it in @strong{all}
your editing modes!

Loosely speaking, in what follows, @dfn{@key{DEL}} means ``the
backspace key'' and @dfn{@key{DELETE}} means ``the forward delete
key''.  This is discussed in more detail below.

There are two different ways you can use hungry deletion:

@table @asis
@item Using @dfn{Hungry Delete Mode} with @kbd{@key{DEL}} and @kbd{C-d}
Here you toggle Hungry Delete minor mode with @kbd{M-x
c-toggle-hungry-state}@footnote{Prior to @ccmode{} 5.31, this command
was bound to @kbd{C-c C-d}.  @kbd{C-c C-d} is now the default binding
for @code{c-hungry-delete-forward}.} (@pxref{Minor Modes}.)  This
makes @kbd{@key{DEL}} and @kbd{C-d} do backwards and forward hungry
deletion.

@table @asis
@item @kbd{@key{DEL}} (@code{c-electric-backspace})
@kindex DEL
@findex c-electric-backspace
@findex electric-backspace (c-)
This command is run by default when you hit the @kbd{DEL} key.  When
hungry delete mode is enabled, it deletes any amount of whitespace in
the backwards direction.  Otherwise, or when used with a prefix
argument or in a literal (@pxref{Auto-newlines}), the command just
deletes backwards in the usual way.  (More precisely, it calls the
function contained in the variable @code{c-backspace-function},
passing it the prefix argument, if any.)

@item @code{c-backspace-function}
@vindex c-backspace-function
@vindex backspace-function (c-)
@findex backward-delete-char-untabify
Hook that gets called by @code{c-electric-backspace} when it doesn't
do an ``electric'' deletion of the preceding whitespace.  The default
value is @code{backward-delete-char-untabify}
(@pxref{Deletion,,,@lispref{}, @lispreftitle{}}, the function which
deletes a single character.

@item @kbd{C-d} (@code{c-electric-delete-forward})
@kindex C-d
@findex c-electric-delete-forward
@findex electric-delete-forward (c-)
This function, which is bound to @kbd{C-d} by default, works just like
@code{c-electric-backspace} but in the forward direction.  When it
doesn't do an ``electric'' deletion of the following whitespace, it
just does @code{delete-char}, more or less.  (Strictly speaking, it
calls the function in @code{c-delete-function} with the prefix
argument.)

@item @code{c-delete-function}
@vindex c-delete-function
@vindex delete-function (c-)
@findex delete-char
Hook that gets called by @code{c-electric-delete-forward} when it
doesn't do an ``electric'' deletion of the following whitespace.  The
default value is @code{delete-char}.
@end table

@item Using Distinct Bindings
The other (newer and recommended) way to use hungry deletion is to
perform @code{c-hungry-delete-backwards} and
@code{c-hungry-delete-forward} directly through their key sequences
rather than using the minor mode toggling.

@table @asis
@item @kbd{C-c C-@key{DEL}}, or @kbd{C-c @key{DEL}} (@code{c-hungry-delete-backwards})@footnote{This command was formerly known as @code{c-hungry-backspace}.}
@kindex C-c C-<backspace>
@kindex C-c <backspace>
@kindex C-c C-DEL
@kindex C-c DEL
@findex c-hungry-delete-backwards
@findex hungry-delete-backwards (c-)
Delete any amount of whitespace in the backwards direction (regardless
whether hungry-delete mode is enabled or not).  This command is bound
to both @kbd{C-c C-@key{DEL}} and @kbd{C-c @key{DEL}}, since the more
natural one, @kbd{C-c C-@key{DEL}}, is sometimes difficult to type at
a character terminal.

@item @kbd{C-c C-d}, @kbd{C-c C-@key{DELETE}}, or @kbd{C-c @key{DELETE}} (@code{c-hungry-delete-forward})
@kindex C-c C-d
@kindex C-c C-<DELETE>
@kindex C-c <DELETE>
@findex c-hungry-delete-forward
@findex hungry-delete-forward (c-)
Delete any amount of whitespace in the forward direction (regardless
whether hungry-delete mode is enabled or not).  This command is bound
to both @kbd{C-c C-@key{DELETE}} and @kbd{C-c @key{DELETE}} for the
same reason as for @key{DEL} above.
@end table
@end table

@kindex <delete>
@kindex <backspace>

When we talk about @kbd{@key{DEL}}, and @kbd{@key{DELETE}} above, we
actually do so without connecting them to the physical keys commonly
known as @key{Backspace} and @key{Delete}.  The default bindings to
those two keys depends on the flavor of (X)Emacs you are using.

@findex c-electric-delete
@findex electric-delete (c-)
@findex c-hungry-delete
@findex hungry-delete (c-)
@vindex delete-key-deletes-forward
In XEmacs 20.3 and beyond, the @key{Backspace} key is bound to
@code{c-electric-backspace} and the @key{Delete} key is bound to
@code{c-electric-delete}.  You control the direction it deletes in by
setting the variable @code{delete-key-deletes-forward}, a standard
XEmacs variable.
@c This variable is encapsulated by XEmacs's (defsubst delete-forward-p ...).
When this variable is non-@code{nil}, @code{c-electric-delete} will do
forward deletion with @code{c-electric-delete-forward}, otherwise it
does backward deletion with @code{c-electric-backspace}.  Similarly,
@kbd{C-c @key{Delete}} and @kbd{C-c C-@key{Delete}} are bound to
@code{c-hungry-delete} which is controlled in the same way by
@code{delete-key-deletes-forward}.

@findex normal-erase-is-backspace-mode

Emacs 21 and later automatically binds @key{Backspace} and
@key{Delete} to @kbd{DEL} and @kbd{C-d} according to your environment,
and @ccmode{} extends those bindings to @kbd{C-c C-@key{Backspace}}
etc.  If you need to change the bindings through
@code{normal-erase-is-backspace-mode} then @ccmode{} will also adapt
its extended bindings accordingly.

In earlier (X)Emacs versions, @ccmode{} doesn't bind either
@key{Backspace} or @key{Delete} directly.  Only the key codes
@kbd{DEL} and @kbd{C-d} are bound, and it's up to the default bindings
to map the physical keys to them.  You might need to modify this
yourself if the defaults are unsuitable.

Getting your @key{Backspace} and @key{Delete} keys properly set up can
sometimes be tricky.  The information in @ref{DEL Does Not
Delete,,,emacs, GNU Emacs Manual}, might be helpful if you're having
trouble with this in GNU Emacs.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Subword Movement, Other Commands, Hungry WS Deletion, Commands
@comment node-name, next, previous, up
@section Subword Movement and Editing
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex nomenclature
@cindex subword
In spite of the GNU Coding Standards, it is popular to name a symbol
by mixing uppercase and lowercase letters, e.g., @samp{GtkWidget},
@samp{EmacsFrameClass}, or @samp{NSGraphicsContext}.  Here we call
these mixed case symbols @dfn{nomenclatures}.  Also, each capitalized
(or completely uppercase) part of a nomenclature is called a
@dfn{subword}.  Here are some examples:

@multitable {@samp{NSGraphicsContext}} {@samp{NS}, @samp{Graphics}, and @samp{Context}}
@c This could be converted to @headitem when we require Texinfo 4.7
@iftex
@item @b{Nomenclature}
  @tab @b{Subwords}
@end iftex
@ifnottex
@item Nomenclature
  @tab Subwords
@item ---------------------------------------------------------
@end ifnottex
@item @samp{GtkWindow}
  @tab @samp{Gtk} and @samp{Window}
@item @samp{EmacsFrameClass}
  @tab @samp{Emacs}, @samp{Frame}, and @samp{Class}
@item @samp{NSGraphicsContext}
  @tab @samp{NS}, @samp{Graphics}, and @samp{Context}
@end multitable

The subword minor mode replaces the basic word oriented movement and
editing commands with variants that recognize subwords in a
nomenclature and treat them as separate words:

@findex c-forward-subword
@findex forward-subword (c-)
@findex c-backward-subword
@findex backward-subword (c-)
@findex c-mark-subword
@findex mark-subword (c-)
@findex c-kill-subword
@findex kill-subword (c-)
@findex c-backward-kill-subword
@findex backward-kill-subword (c-)
@findex c-transpose-subwords
@findex transpose-subwords (c-)
@findex c-capitalize-subword
@findex capitalize-subword (c-)
@findex c-upcase-subword
@findex upcase-subword (c-)
@findex c-downcase-subword
@findex downcase-subword (c-)
@multitable @columnfractions .20 .40 .40
@c This could be converted to @headitem when we require Texinfo 4.7
@iftex
@item     @b{Key}     @tab @b{Word oriented command} @tab @b{Subword oriented command}
@end iftex
@ifnottex
@item     Key         @tab Word oriented command     @tab Subword oriented command
@item ----------------------------------------------------------------------------
@end ifnottex
@item     @kbd{M-f}   @tab @code{forward-word}       @tab @code{c-forward-subword}
@item     @kbd{M-b}   @tab @code{backward-word}      @tab @code{c-backward-subword}
@item     @kbd{M-@@}  @tab @code{mark-word}          @tab @code{c-mark-subword}
@item     @kbd{M-d}   @tab @code{kill-word}          @tab @code{c-kill-subword}
@item     @kbd{M-DEL} @tab @code{backward-kill-word} @tab @code{c-backward-kill-subword}
@item     @kbd{M-t}   @tab @code{transpose-words}    @tab @code{c-transpose-subwords}
@item     @kbd{M-c}   @tab @code{capitalize-word}    @tab @code{c-capitalize-subword}
@item     @kbd{M-u}   @tab @code{upcase-word}        @tab @code{c-upcase-subword}
@item     @kbd{M-l}   @tab @code{downcase-word}      @tab @code{c-downcase-subword}
@end multitable

Note that if you have changed the key bindings for the word oriented
commands in your @file{.emacs} or a similar place, the keys you have
configured are also used for the corresponding subword oriented
commands.

Type @kbd{C-c C-w} to toggle subword mode on and off.  To make the
mode turn on automatically, put the following code in your
@file{.emacs}:

@example
(add-hook 'c-mode-common-hook
          (lambda () (subword-mode 1)))
@end example

As a bonus, you can also use @code{subword-mode} in non-@ccmode{}
buffers by typing @kbd{M-x subword-mode}.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Other Commands,  , Subword Movement, Commands
@comment node-name, next, previous, up
@section Other Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Here are the various other commands that didn't fit anywhere else:

@table @asis
@item @kbd{C-c .} (@code{c-set-style})
@kindex C-c .
@findex c-set-style
@findex set-style (c-)
Switch to the specified style in the current buffer.  Use like this:

@example
@kbd{C-c . @var{style-name} @key{RET}}
@end example

You can use the @key{TAB} in the normal way to do completion on the
style name.  Note that all style names are case insensitive, even the
ones you define yourself.

Setting a style in this way does @emph{not} automatically reindent your
file.  For commands that you can use to view the effect of your changes,
see @ref{Indentation Commands} and @ref{Filling and Breaking}.

For details of the @ccmode{} style system, see @ref{Styles}.
@item @kbd{C-c :} (@code{c-scope-operator})
@kindex C-c :
@findex c-scope-operator
@findex scope-operator (c-)
In C++, it is also sometimes desirable to insert the double-colon scope
operator without performing the electric behavior of colon insertion.
@kbd{C-c :} does just this.

@item @kbd{C-c C-\} (@code{c-backslash-region})
@kindex C-c C-\
@findex c-backslash-region
@findex backslash-region (c-)
This function inserts and aligns or deletes end-of-line backslashes in
the current region.  These are typically used in multi-line macros.

With no prefix argument, it inserts any missing backslashes and aligns
them according to the @code{c-backslash-column} and
@code{c-backslash-max-column} variables.  With a prefix argument, it
deletes any backslashes.

The function does not modify blank lines at the start of the region.  If
the region ends at the start of a line, it always deletes the backslash
(if any) at the end of the previous line.

To customize the precise workings of this command, @ref{Custom Macros}.
@end table

@noindent
The recommended line breaking function, @code{c-context-line-break}
(@pxref{Filling and Breaking}), is especially nice if you edit
multiline macros frequently.  When used inside a macro, it
automatically inserts and adjusts the mandatory backslash at the end
of the line to keep the macro together, and it leaves the point at the
right indentation column for the code.  Thus you can write code inside
macros almost exactly as you can elsewhere, without having to bother
with the trailing backslashes.

@table @asis
@item @kbd{C-c C-e} (@code{c-macro-expand})
@kindex C-c C-e
@findex c-macro-expand
@findex macro-expand (c-)
This command expands C, C++, Objective C or Pike macros in the region,
using an appropriate external preprocessor program.  Normally it
displays its output in a temporary buffer, but if you give it a prefix
arg (with @kbd{C-u C-c C-e}) it will overwrite the original region
with the expansion.

The command does not work in any of the other modes, and the key
sequence is not bound in these other modes.

@code{c-macro-expand} isn't actually part of @ccmode{}, even though it
is bound to a @ccmode{} key sequence.  If you need help setting it up
or have other problems with it, you can either read its source code or
ask for help in the standard (X)Emacs forums.
@end table

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Font Locking, Config Basics, Commands, Top
@comment node-name, next, previous, up
@chapter Font Locking
@cindex font locking
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex Font Lock mode

@ccmode{} provides font locking for its supported languages by
supplying patterns for use with Font Lock mode.  This means that you
get distinct faces on the various syntactic parts such as comments,
strings, keywords and types, which is very helpful in telling them
apart at a glance and discovering syntactic errors.  @xref{Font
Lock,,, emacs, GNU Emacs Manual}, for ways to enable font locking in
@ccmode{} buffers.

@strong{Please note:} The font locking in AWK mode is currently not
integrated with the rest of @ccmode{}.  Only the last section of this
chapter, @ref{AWK Mode Font Locking}, applies to AWK@.  The other
sections apply to the other languages.

@menu
* Font Locking Preliminaries::
* Faces::
* Doc Comments::
* AWK Mode Font Locking::
@end menu


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Font Locking Preliminaries, Faces, Font Locking, Font Locking
@comment node-name, next, previous, up
@section Font Locking Preliminaries
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The font locking for most of the @ccmode{} languages were provided
directly by the Font Lock package prior to version 5.30 of @ccmode{}.
In the transition to @ccmode{} the patterns have been reworked
completely and are applied uniformly across all the languages except AWK
mode, just like the indentation rules (although each language still has
some peculiarities of its own, of course).  Since the languages
previously had completely separate font locking patterns, this means
that it's a bit different in most languages now.

The main goal for the font locking in @ccmode{} is accuracy, to provide
a dependable aid in recognizing the various constructs.  Some, like
strings and comments, are easy to recognize while others, like
declarations and types, can be very tricky.  @ccmode{} can go to great
lengths to recognize declarations and casts correctly, especially when
the types aren't recognized by standard patterns.  This is a fairly
demanding analysis which can be slow on older hardware, and it can
therefore be disabled by choosing a lower decoration level with the
variable @code{font-lock-maximum-decoration} (@pxref{Font Lock,,,
emacs, GNU Emacs Manual}).

@vindex font-lock-maximum-decoration

The decoration levels are used as follows:

@enumerate
@comment 1
@item
Minimal font locking: Fontify only comments, strings and preprocessor
directives (in the languages that use cpp).

@comment 2
@item
Fast font locking: In addition to level 1, fontify keywords, simple
types and declarations that are easy to recognize.  The variables
@code{*-font-lock-extra-types} (where @samp{*} is the name of the
language) are used to recognize types (see below).  Documentation
comments like Javadoc are fontified according to
@code{c-doc-comment-style} (@pxref{Doc Comments}).

Use this if you think the font locking is too slow.  It's the closest
corresponding level to level 3 in the old font lock patterns.

@comment 3
@item
Accurate font locking: Like level 2 but uses a different approach that
can recognize types and declarations much more accurately.  The
@code{*-font-lock-extra-types} variables are still used, but user
defined types are recognized correctly anyway in most cases.  Therefore
those variables should be fairly restrictive and not contain patterns
that are uncertain.

@cindex Lazy Lock mode
@cindex Just-in-time Lock mode

This level is designed for fairly modern hardware and a font lock
support mode like Lazy Lock or Just-in-time Lock mode that only
fontifies the parts that are actually shown.  Fontifying the whole
buffer at once can easily get bothersomely slow even on contemporary
hardware. @xref{Font Lock,,,@emacsman{}, @emacsmantitle{}}.
@end enumerate

@cindex user defined types
@cindex types, user defined

Since user defined types are hard to recognize you can provide
additional regexps to match those you use:

@defopt c-font-lock-extra-types
@defoptx c++-font-lock-extra-types
@defoptx objc-font-lock-extra-types
@defoptx java-font-lock-extra-types
@defoptx idl-font-lock-extra-types
@defoptx pike-font-lock-extra-types
For each language there's a variable @code{*-font-lock-extra-types},
where @samp{*} stands for the language in question.  It contains a list
of regexps that matches identifiers that should be recognized as types,
e.g., @samp{\\sw+_t} to recognize all identifiers ending with @samp{_t}
as is customary in C code.  Each regexp should not match more than a
single identifier.

The default values contain regexps for many types in standard runtime
libraries that are otherwise difficult to recognize, and patterns for
standard type naming conventions like the @samp{_t} suffix in C and C++.
Java, Objective-C and Pike have as a convention to start class names
with capitals, so there are patterns for that in those languages.

Despite the names of these variables, they are not only used for
fontification but in other places as well where @ccmode{} needs to
recognize types.
@end defopt


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Faces, Doc Comments, Font Locking Preliminaries, Font Locking
@comment node-name, next, previous, up
@section Faces
@cindex faces
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ccmode{} attempts to use the standard faces for programming languages
in accordance with their intended purposes as far as possible.  No extra
faces are currently provided, with the exception of a replacement face
@code{c-invalid-face} for emacsen that don't provide
@code{font-lock-warning-face}.

@itemize @bullet
@item
@vindex font-lock-comment-face
Normal comments are fontified in @code{font-lock-comment-face}.

@item
@vindex font-lock-doc-face
@vindex font-lock-doc-string-face
@vindex font-lock-comment-face
Comments that are recognized as documentation (@pxref{Doc Comments})
get @code{font-lock-doc-face} (Emacs) or
@code{font-lock-doc-string-face} (XEmacs) if those faces exist.  If
they don't then @code{font-lock-comment-face} is used.

@item
@vindex font-lock-string-face
String and character literals are fontified in
@code{font-lock-string-face}.

@item
@vindex font-lock-keyword-face
Keywords are fontified with @code{font-lock-keyword-face}.

@item
@vindex font-lock-function-name-face
@code{font-lock-function-name-face} is used for function names in
declarations and definitions, and classes in those contexts.  It's also
used for preprocessor defines with arguments.

@item
@vindex font-lock-variable-name-face
Variables in declarations and definitions, and other identifiers in such
variable contexts, get @code{font-lock-variable-name-face}.  It's also
used for preprocessor defines without arguments.

@item
@vindex font-lock-constant-face
@vindex font-lock-reference-face
Builtin constants are fontified in @code{font-lock-constant-face} if it
exists, @code{font-lock-reference-face} otherwise.  As opposed to the
preceding two faces, this is used on the names in expressions, and it's
not used in declarations, even if there happen to be a @samp{const} in
them somewhere.

@item
@vindex font-lock-type-face
@code{font-lock-type-face} is put on types (both predefined and user
defined) and classes in type contexts.

@item
@vindex font-lock-constant-face
@vindex font-lock-reference-face
Label identifiers get @code{font-lock-constant-face} if it exists,
@code{font-lock-reference-face} otherwise.

@item
Name qualifiers and identifiers for scope constructs are fontified like
labels.

@item
Special markup inside documentation comments are also fontified like
labels.

@item
@vindex font-lock-preprocessor-face
@vindex font-lock-builtin-face
@vindex font-lock-reference-face
Preprocessor directives get @code{font-lock-preprocessor-face} if it
exists (i.e., XEmacs).  In Emacs they get @code{font-lock-builtin-face}
or @code{font-lock-reference-face}, for lack of a closer equivalent.

@item
@vindex font-lock-warning-face
@vindex c-invalid-face
@vindex invalid-face (c-)
Some kinds of syntactic errors are fontified with
@code{font-lock-warning-face} in Emacs.  In older XEmacs versions
there's no corresponding standard face, so there a special
@code{c-invalid-face} is used, which is defined to stand out sharply by
default.

Note that it's not used for @samp{#error} or @samp{#warning} directives,
since those aren't syntactic errors in themselves.
@end itemize


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Doc Comments, AWK Mode Font Locking, Faces, Font Locking
@comment node-name, next, previous, up
@section Documentation Comments
@cindex documentation comments
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

There are various tools to supply documentation in the source as
specially structured comments, e.g., the standard Javadoc tool in Java.
@ccmode{} provides an extensible mechanism to fontify such comments and
the special markup inside them.

@defopt c-doc-comment-style
@vindex doc-comment-style (c-)
This is a style variable that specifies which documentation comment
style to recognize, e.g., @code{javadoc} for Javadoc comments.

The value may also be a list of styles, in which case all of them are
recognized simultaneously (presumably with markup cues that don't
conflict).

The value may also be an association list to specify different comment
styles for different languages.  The symbol for the major mode is then
looked up in the alist, and the value of that element is interpreted as
above if found.  If it isn't found then the symbol `other' is looked up
and its value is used instead.

The default value for @code{c-doc-comment-style} is
@w{@code{((java-mode . javadoc) (pike-mode . autodoc) (c-mode . gtkdoc))}}.

Note that @ccmode{} uses this variable to set other variables that
handle fontification etc.  That's done at mode initialization or when
you switch to a style which sets this variable.  Thus, if you change it
in some other way, e.g., interactively in a CC Mode buffer, you will need
to do @kbd{M-x java-mode} (or whatever mode you're currently using) to
reinitialize.

@findex c-setup-doc-comment-style
@findex setup-doc-comment-style (c-)
Note also that when @ccmode{} starts up, the other variables are
modified before the mode hooks are run.  If you change this variable in
a mode hook, you'll have to call @code{c-setup-doc-comment-style}
afterwards to redo that work.
@end defopt

@ccmode{} currently provides handing of the following doc comment
styles:

@table @code
@item javadoc
@cindex Javadoc markup
Javadoc comments, the standard tool in Java.

@item autodoc
@cindex Pike autodoc markup
For Pike autodoc markup, the standard in Pike.

@item gtkdoc
@cindex GtkDoc markup
For GtkDoc markup, widely used in the Gnome community.
@end table

The above is by no means complete.  If you'd like to see support for
other doc comment styles, please let us know (@pxref{Mailing Lists and
Bug Reports}).

You can also write your own doc comment fontification support to use
with @code{c-doc-comment-style}: Supply a variable or function
@code{*-font-lock-keywords} where @samp{*} is the name you want to use
in @code{c-doc-comment-style}.  If it's a variable, it's prepended to
@code{font-lock-keywords}.  If it's a function, it's called at mode
initialization and the result is prepended.  For an example, see
@code{javadoc-font-lock-keywords} in @file{cc-fonts.el}.

If you add support for another doc comment style, please consider
contributing it: send a note to @email{bug-cc-mode@@gnu.org}.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    AWK Mode Font Locking,  , Doc Comments, Font Locking
@comment  node-name,  next,  previous,  up
@section AWK Mode Font Locking
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The general appearance of font-locking in AWK mode is much like in any
other programming mode.  @xref{Faces For Font Lock,,,elisp, GNU Emacs
Lisp Reference Manual}.

The following faces are, however, used in a non-standard fashion in
AWK mode:

@table @asis
@item @code{font-lock-variable-name-face}
This face was intended for variable declarations.  Since variables are
not declared in AWK, this face is used instead for AWK system
variables (such as @code{NF}) and ``Special File Names'' (such as
@code{"/dev/stderr"}).

@item @code{font-lock-builtin-face} (Emacs)/@code{font-lock-preprocessor-face} (XEmacs)
This face is normally used for preprocessor directives in @ccmode{}.
There are no such things in AWK, so this face is used instead for
standard functions (such as @code{match}).

@item @code{font-lock-string-face}
As well as being used for strings, including localizable strings,
(delimited by @samp{"} and @samp{_"}), this face is also used for AWK
regular expressions (delimited by @samp{/}).

@item @code{font-lock-warning-face} (Emacs)/@code{c-invalid-face} (XEmacs)
This face highlights the following syntactically invalid AWK
constructs:

@itemize @bullet
@item
An unterminated string or regular expression.  Here the opening
delimiter (@samp{"} or @samp{/} or @samp{_"}) is displayed in
@code{font-lock-warning-face}.  This is most noticeable when typing in a
new string/regular expression into a buffer, when the warning-face
serves as a continual reminder to terminate the construct.

AWK mode fontifies unterminated strings/regular expressions
differently from other modes: Only the text up to the end of the line
is fontified as a string (escaped newlines being handled correctly),
rather than the text up to the next string quote.

@item
A space between the function name and opening parenthesis when calling
a user function.  The last character of the function name and the
opening parenthesis are highlighted.  This font-locking rule will
spuriously highlight a valid concatenation expression where an
identifier precedes a parenthesized expression.  Unfortunately.

@item
Whitespace following the @samp{\} in what otherwise looks like an
escaped newline.  The @samp{\} is highlighted.
@end itemize
@end table


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Config Basics, Custom Filling and Breaking, Font Locking, Top
@comment  node-name,  next,  previous,  up
@chapter Configuration Basics
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex Emacs Initialization File
@cindex Configuration
You configure @ccmode{} by setting Lisp variables and calling (and
perhaps writing) Lisp functions@footnote{DON'T PANIC!!!  This isn't
difficult.}, which is usually done by adding code to an Emacs
initialization file.  This file might be @file{site-start.el} or
@file{.emacs} or @file{init.el} or @file{default.el} or perhaps some
other file.  @xref{Init File,,,@emacsman{}, @emacsmantitle{}}.  For
the sake of conciseness, we just call this file ``your @file{.emacs}''
throughout the rest of the manual.

Several of these variables (currently 16), are known collectively as
@dfn{style variables}.  @ccmode{} provides a special mechanism, known
as @dfn{styles} to make it easier to set these variables as a group,
to ``inherit'' settings from one style into another, and so on.  Style
variables remain ordinary Lisp variables, whose values can be read and
changed independently of the style system.  @xref{Style Variables}.

There are several ways you can write the code, depending on the
precise effect you want---they are described further down on this page.
If you are new to @ccmode{}, we suggest you begin with the simplest
method, ``Top-level commands or the customization interface''.

If you make conflicting settings in several of these ways, the way
that takes precedence is the one that appears latest in this list:
@itemize @w{}
@item
@table @asis
@item Style
@itemx File Style@footnote{In earlier versions of @ccmode{}, a File Style setting took precedence over any other setting apart from a File Local Variable setting.}
@itemx Top-level command or ``customization interface''
@itemx Hook
@itemx File Local Variable setting
@end table
@end itemize

Here is a summary of the different ways of writing your configuration
settings:

@table @asis
@item Top-level commands or the ``customization interface''
Most simply, you can write @code{setq} and similar commands at the top
level of your @file{.emacs} file.  When you load a @ccmode{} buffer,
it initializes its configuration from these global values (at least,
for those settings you have given values to), so it makes sense to
have these @code{setq} commands run @emph{before} @ccmode{} is first
initialized---in particular, before any call to @code{desktop-read}
(@pxref{Saving Emacs Sessions,,, emacs, GNU Emacs Manual}).  For
example, you might set c-basic-offset thus:

@example
(setq c-basic-offset 4)
@end example

You can use the more user friendly Customization interface instead,
but this manual does not cover in detail how that works.  To do this,
start by typing @kbd{M-x customize-group @key{RET} c @key{RET}}.
@xref{Easy Customization,,,@emacsman{}, @emacsmantitle{}}.
@c The following note really belongs in the Emacs manual.
Emacs normally writes the customizations at the end of your
@file{.emacs} file.  If you use @code{desktop-read}, you should edit
your @file{.emacs} to place the call to @code{desktop-read} @emph{after}
the customizations.

The first initialization of @ccmode{} puts a snapshot of the
configuration settings into the special style @code{user}.
@xref{Built-in Styles}.

For basic use of Emacs, either of these ways of configuring is
adequate.  However, the settings are then the same in all @ccmode{}
buffers and it can be clumsy to communicate them between programmers.
For more flexibility, you'll want to use one (or both) of @ccmode{}'s
more sophisticated facilities, hooks and styles.

@item Hooks
An Emacs @dfn{hook} is a place to put Lisp functions that you want
Emacs to execute later in specific circumstances.
@xref{Hooks,,,@lispref{}, @lispreftitle{}}.  @ccmode{} supplies a main
hook and a language-specific hook for each language it supports; any
functions you put onto these hooks get executed as the last part of a
buffer's initialization.  Typically you put most of your customization
within the main hook, and use the language-specific hooks to vary the
customization settings between language modes.  For example, if you
wanted different (non-standard) values of @code{c-basic-offset} in C
Mode and Java Mode buffers, you could do it like this:

@example
@group
(defun my-c-mode-hook ()
  (setq c-basic-offset 3))
(add-hook 'c-mode-hook 'my-c-mode-hook)

(defun my-java-mode-hook ()
  (setq c-basic-offset 6))
(add-hook 'java-mode-hook 'my-java-mode-hook)
@end group
@end example

See @ref{CC Hooks} for more details on the use of @ccmode{} hooks.

@item Styles
A @ccmode{} @dfn{style} is a coherent collection of customizations
with a name.  At any time, exactly one style is active in each
@ccmode{} buffer, either the one you have selected or a default.
@ccmode{} is delivered with several existing styles.  Additionally,
you can create your own styles, possibly based on these existing
styles.  If you worked in a programming team called the ``Free
Group'', which had its own coding standards, you might well have this
in your @file{.emacs} file:

@example
(setq c-default-style '((java-mode . "java")
                        (awk-mode . "awk")
                        (other . "free-group-style")))
@end example

See @ref{Styles} for fuller details on using @ccmode{} styles and how
to create them.

@item File Local Variable setting
A @dfn{file local variable setting} is a setting which applies to an
individual source file.  You put this in a @dfn{local variables list},
a special block at the end of the source file (@pxref{Specifying File
Variables,,,@emacsman{}}).

@item File Styles
A @dfn{file style} is a rarely used variant of the ``style'' mechanism
described above, which applies to an individual source file.
@xref{File Styles}.  You use this by setting certain special variables
in a local variables list (@pxref{Specifying File
Variables,,,@emacsman{}}).

@item Hooks with Styles
For ultimate flexibility, you can use hooks and styles together.  For
example, if your team were developing a product which required a
Linux driver, you'd probably want to use the ``linux'' style for the
driver, and your own team's style for the rest of the code.  You
could achieve this with code like this in your @file{.emacs}:

@example
@group
(defun my-c-mode-hook ()
  (c-set-style
   (if (and (buffer-file-name)
            (string-match "/usr/src/linux" (buffer-file-name)))
       "linux"
     "free-group-style")))
(add-hook 'c-mode-hook 'my-c-mode-hook)
@end group
@end example

In a programming team, a hook is a also a good place for each member
to put his own personal preferences.  For example, you might be the
only person in your team who likes Auto-newline minor mode.  You could
have it enabled by default by placing the following in your
@file{.emacs}:

@example
@group
(defun my-turn-on-auto-newline ()
  (c-toggle-auto-newline 1))
(add-hook 'c-mode-common-hook 'my-turn-on-auto-newline)
@end group
@end example
@end table

@menu
* CC Hooks::
* Style Variables::
* Styles::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    CC Hooks, Style Variables, Config Basics, Config Basics
@comment node-name, next, previous, up
@section Hooks
@cindex mode hooks
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@c The node name is "CC Hooks" rather than "Hooks" because of a bug in
@c some older versions of Info, e.g., the info.el in GNU Emacs 21.3.
@c If you go to "Config Basics" and hit <CR> on the xref to "CC
@c Hooks" the function Info-follow-reference searches for "*Note: CC
@c Hooks" from the beginning of the page.  If this node were instead
@c named "Hooks", that search would spuriously find "*Note:
@c Hooks(elisp)" and go to the wrong node.

@ccmode{} provides several hooks that you can use to customize the
mode for your coding style.  The main hook is
@code{c-mode-common-hook}; typically, you'll put the bulk of your
customizations here.  In addition, each language mode has its own
hook, allowing you to fine tune your settings individually for the
different @ccmode{} languages, and there is a package initialization
hook.  Finally, there is @code{c-special-indent-hook}, which enables
you to solve anomalous indentation problems.  It is described in
@ref{Other Indentation}, not here.  All these hooks adhere to the
standard Emacs conventions.

When you open a buffer, @ccmode{} first initializes it with the
currently active style (@pxref{Styles}).  Then it calls
@code{c-mode-common-hook}, and finally it calls the language-specific
hook.  Thus, any style settings done in these hooks will override
those set by @code{c-default-style}.

@defvar c-initialization-hook
@vindex initialization-hook (c-)
Hook run only once per Emacs session, when @ccmode{} is initialized.
This is a good place to change key bindings (or add new ones) in any
of the @ccmode{} key maps.  @xref{Sample .emacs File}.
@end defvar

@defvar c-mode-common-hook
@vindex mode-common-hook (c-)
Common hook across all languages.  It's run immediately before the
language specific hook.
@end defvar

@defvar c-mode-hook
@defvarx c++-mode-hook
@defvarx objc-mode-hook
@defvarx java-mode-hook
@defvarx idl-mode-hook
@defvarx pike-mode-hook
@defvarx awk-mode-hook
The language specific mode hooks.  The appropriate one is run as the
last thing when you enter that language mode.
@end defvar

Although these hooks are variables defined in @ccmode{}, you can give
them values before @ccmode{}'s code is loaded---indeed, this is the
only way to use @code{c-initialization-hook}.  Their values aren't
overwritten when @ccmode{} gets loaded.

Here's a simplified example of what you can add to your @file{.emacs}
file to do things whenever any @ccmode{} language is edited.  See the
Emacs manuals for more information on customizing Emacs via hooks.
@xref{Sample .emacs File}, for a more complete sample @file{.emacs}
file.

@example
(defun my-c-mode-common-hook ()
  ;; my customizations for all of c-mode and related modes
  (no-case-fold-search)
  )
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
@end example

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Style Variables, Styles, CC Hooks, Config Basics
@comment node-name, next, previous, up
@section Style Variables
@cindex styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex style variables
The variables that @ccmode{}'s style system control are called
@dfn{style variables}.  Note that style variables are ordinary Lisp
variables, which the style system initializes; you can change their
values at any time (e.g., in a hook function).  The style system can
also set other variables, to some extent.  @xref{Styles}.

@dfn{Style variables} are handled specially in several ways:

@itemize @bullet
@item
Style variables are by default buffer-local variables.  However, they
can instead be made global by setting
@code{c-style-variables-are-local-p} to @code{nil} before @ccmode{} is
initialized.

@item
@vindex c-old-style-variable-behavior
@vindex old-style-variable-behavior (c-)
The default global binding of any style variable (with two exceptions
- see below) is the special symbol @code{set-from-style}.  When the
style system initializes a buffer-local copy of a style variable for a
@ccmode{} buffer, if its global binding is still that symbol then it
will be set from the current style.  Otherwise it will retain its
global default@footnote{This is a big change from versions of
@ccmode{} earlier than 5.26, where such settings would get overridden
by the style system unless special precautions were taken.  That was
changed since it was counterintuitive and confusing, especially to
novice users.  If your configuration depends on the old overriding
behavior, you can set the variable
@code{c-old-style-variable-behavior} to non-@code{nil}.}.  This
``otherwise'' happens, for example, when you've set the variable with
@code{setq} at the top level of your @file{.emacs} (@pxref{Config
Basics}).

@item
The style variable @code{c-offsets-alist} (@pxref{c-offsets-alist}) is
an association list with an element for each syntactic symbol.  It's
handled a little differently from the other style variables.  It's
default global binding is the empty list @code{nil}, rather than
@code{set-from-style}.  Before the style system is initialized, you
can add individual elements to @code{c-offsets-alist} by calling
@code{c-set-offset}(@pxref{c-offsets-alist}) just like you would set
other style variables with @code{setq}.  Those elements will then
prevail when the style system later initializes a buffer-local copy of
@code{c-offsets-alist}.

@item
The style variable @code{c-special-indent-hook} is also handled in a
special way.  Styles can only add functions to this hook, not remove
them, so any global settings you put on it are always
preserved@footnote{This did not change in version 5.26.}.  The value
you give this variable in a style definition can be either a function
or a list of functions.

@item
The global bindings of the style variables get captured in the special
@code{user} style when the style system is first initialized.
@xref{Built-in Styles}, for details.
@end itemize

The style variables are:@*
@code{c-indent-comment-alist},
@code{c-indent-comments-syntactically-p} (@pxref{Indentation
Commands});@*
@code{c-doc-comment-style} (@pxref{Doc Comments});@*
@code{c-block-comment-prefix}, @code{c-comment-prefix-regexp}
(@pxref{Custom Filling and Breaking});@*
@code{c-hanging-braces-alist} (@pxref{Hanging Braces});@*
@code{c-hanging-colons-alist} (@pxref{Hanging Colons});@*
@code{c-hanging-semi&comma-criteria} (@pxref{Hanging Semicolons and
Commas});@*
@code{c-cleanup-list} (@pxref{Clean-ups});@*
@code{c-basic-offset} (@pxref{Customizing Indentation});@*
@code{c-offsets-alist} (@pxref{c-offsets-alist});@*
@code{c-comment-only-line-offset} (@pxref{Comment Line-Up});@*
@code{c-special-indent-hook}, @code{c-label-minimum-indentation}
(@pxref{Other Indentation});@*
@code{c-backslash-column}, @code{c-backslash-max-column}
(@pxref{Custom Macros}).

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Styles,  , Style Variables, Config Basics
@comment node-name, next, previous, up
@section Styles
@cindex styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

By @dfn{style} we mean the layout of the code---things like how many
columns to indent a block of code, whether an opening brace gets
indented to the level of the code it encloses, or of the construct
that introduces it, or ``hangs'' at the end of a line.

Most people only need to edit code formatted in just a few well-defined
and consistent styles.  For example, their organization might impose a
``blessed'' style that all its programmers must conform to.  Similarly,
people who work on GNU software will have to use the GNU coding style.
Some shops are more lenient, allowing a variety of coding styles, and as
programmers come and go, there could be a number of styles in use.  For
this reason, @ccmode{} makes it convenient for you to set up logical
groupings of customizations called @dfn{styles}, associate a single name
for any particular style, and pretty easily start editing new or
existing code using these styles.

As an alternative to writing a style definition yourself, you can have
@ccmode{} @dfn{guess} (at least part of) your style by looking at an
already formatted piece of your code, @ref{Guessing the Style}.

@menu
* Built-in Styles::
* Choosing a Style::
* Adding Styles::
* Guessing the Style::
* File Styles::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Built-in Styles, Choosing a Style, Styles, Styles
@comment node-name, next, previous, up
@subsection Built-in Styles
@cindex styles, built-in
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If you're lucky, one of @ccmode{}'s built-in styles might be just
what you're looking for.  These are:

@table @code
@item gnu
@cindex GNU style
Coding style blessed by the Free Software Foundation
for C code in GNU programs.

@item k&r
@cindex K&R style
The classic Kernighan and Ritchie style for C code.

@item bsd
@cindex BSD style
Also known as ``Allman style'' after Eric Allman.

@item whitesmith
@cindex Whitesmith style
Popularized by the examples that came with Whitesmiths C, an early
commercial C compiler.

@item stroustrup
@cindex Stroustrup style
The classic Stroustrup style for C++ code.

@item ellemtel
@cindex Ellemtel style
Popular C++ coding standards as defined by ``Programming in C++, Rules
and Recommendations,'' Erik Nyquist and Mats Henricson,
Ellemtel@footnote{This document is available at
@uref{http://www.doc.ic.ac.uk/lab/cplus/c++.rules/} among other
places.}.
@c N.B.  This URL was still valid at 2005/8/28  (ACM).

@item linux
@cindex Linux style
C coding standard for Linux (the kernel).

@item python
@cindex Python style
C coding standard for Python extension modules@footnote{Python is a
high level scripting language with a C/C++ foreign function interface.
For more information, see @uref{http://www.python.org/}.}.

@item java
@cindex Java style
The style for editing Java code.  Note that the default
value for @code{c-default-style} installs this style when you enter
@code{java-mode}.

@item awk
@cindex AWK style
The style for editing AWK code.  Note that the default value for
@code{c-default-style} installs this style when you enter
@code{awk-mode}.

@item user
@cindex User style
This is a special style created by you.  It consists of the factory
defaults for all the style variables as modified by the customizations
you do either with the Customization interface or by writing
@code{setq}s and @code{c-set-offset}s at the top level of your
@file{.emacs} file (@pxref{Config Basics}).  The style system creates
this style as part of its initialization and doesn't modify it
afterwards.
@end table


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Choosing a Style, Adding Styles, Built-in Styles, Styles
@comment node-name, next, previous, up
@subsection Choosing a Style
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

When you create a new buffer, its style will be set from
@code{c-default-style}.  The factory default is the style @code{gnu},
except in Java and AWK modes where it's @code{java} and @code{awk}.

Remember that if you set a style variable with the Customization
interface or at the top level of your @file{.emacs} file before the
style system is initialized (@pxref{Config Basics}), this setting will
override the one that the style system would have given the variable.

To set a buffer's style interactively, use the command @kbd{C-c .}
(@pxref{Other Commands}).  To set it from a file's local variable
list, @ref{File Styles}.

@defopt c-default-style
@vindex default-style (c-)
This variable specifies which style to install by default in new
buffers.  It takes either a style name string, or an association list
of major mode symbols to style names:

@enumerate
@item
When @code{c-default-style} is a string, it must be an existing style
name.  This style is then used for all modes.

@item
When @code{c-default-style} is an association list, the mode language
is looked up to find a style name string.

@item
If @code{c-default-style} is an association list where the mode
language mode isn't found then the special symbol @samp{other} is
looked up.  If it's found then the associated style is used.

@item
If @samp{other} is not found then the @samp{gnu} style is used.
@end enumerate

In all cases, the style described in @code{c-default-style} is installed
@emph{before} the language hooks are run, so you can always override
this setting by including an explicit call to @code{c-set-style} in your
language mode hook, or in @code{c-mode-common-hook}.

The standard value of @code{c-default-style} is @w{@code{((java-mode
. "java") (awk-mode . "awk") (other . "gnu"))}}.
@end defopt

@defvar c-indentation-style
@vindex indentation-style (c-)
This variable always contains the buffer's current style name, as a
string.
@end defvar

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Adding Styles, Guessing the Style, Choosing a Style, Styles
@comment node-name, next, previous, up
@subsection Adding and Amending Styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If none of the built-in styles is appropriate, you'll probably want to
create a new @dfn{style definition}, possibly based on an existing
style.  To do this, put the new style's settings into a list with the
following format; the list can then be passed as an argument to the
function @code{c-add-style}.  You can see an example of a style
definition in @ref{Sample .emacs File}.

@cindex style definition
@c @defvr {List} style definition
@table @asis
@item Structure of a Style Definition List
([@var{base-style}] [(@var{variable} . @var{value}) @dots{}])

Optional @var{base-style}, if present, must be a string which is the
name of the @dfn{base style} from which this style inherits.  At most
one @var{base-style} is allowed in a style definition.  If
@var{base-style} is not specified, the style inherits from the table
of factory default values@footnote{This table is stored internally in
the variable c-fallback-style.} instead.  All styles eventually
inherit from this internal table.  Style loops generate errors.  The
list of pre-existing styles can be seen in @ref{Built-in Styles}.

The dotted pairs (@var{variable} . @var{value}) each consist of a
variable and the value it is to be set to when the style is later
activated.@footnote{Note that if the variable has been given a value
by the Customization interface or a @code{setq} at the top level of
your @file{.emacs}, this value will override the one the style system
tries to give it. @xref{Config Basics}.} The variable can be either a
@ccmode{} style variable or an arbitrary Emacs variable.  In the
latter case, it is @emph{not} made buffer-local by the @ccmode{} style
system.
@c @end defvr

Two variables are treated specially in the dotted pair list:

@table @code
@item c-offsets-alist
The value is in turn a list of dotted pairs of the form

@example
(@r{@var{syntactic-symbol}} . @r{@var{offset}})
@end example

as described in @ref{c-offsets-alist}.  These are passed to
@code{c-set-offset} so there is no need to set every syntactic symbol
in your style, only those that are different from the inherited style.

@item c-special-indent-hook
The value is added to @code{c-special-indent-hook} using
@code{add-hook}, so any functions already on it are kept.  If the value
is a list, each element of the list is added with @code{add-hook}.
@end table
@end table

Styles are kept in the @code{c-style-alist} variable, but you
should never modify this variable directly.  Instead, @ccmode{}
provides the function @code{c-add-style} for this purpose.

@defun c-add-style stylename description &optional set-p
@findex add-style (c-)
Add or update a style called @var{stylename}, a string.
@var{description} is the new style definition in the form described
above.  If @var{stylename} already exists in @code{c-style-alist} then
it is replaced by @var{description}.  (Note, this replacement is
total.  The old style is @emph{not} merged into the new one.)
Otherwise, a new style is added.

If the optional @var{set-p} is non-@code{nil} then the new style is
applied to the current buffer as well.  The use of this facility is
deprecated and it might be removed from @ccmode{} in a future release.
You should use @code{c-set-style} instead.

The sample @file{.emacs} file provides a concrete example of how a new
style can be added and automatically set.  @xref{Sample .emacs File}.
@end defun

@defvar c-style-alist
@vindex style-alist (c-)
This is the variable that holds the definitions for the styles.  It
should not be changed directly; use @code{c-add-style} instead.
@end defvar

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Guessing the Style, File Styles, Adding Styles, Styles
@comment node-name, next, previous, up
@subsection Guessing the Style
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Instead of specifying a style, you can get @ccmode{} to @dfn{guess}
your style by examining an already formatted code buffer.  @ccmode{}
then determines the ''most frequent'' offset (@pxref{c-offsets-alist})
for each of the syntactic symbols (@pxref{Indentation Engine Basics})
encountered in the buffer, and the ''most frequent'' value of
c-basic-offset (@pxref{Customizing Indentation}), then merges the
current style with these ''guesses'' to form a new style.  This
combined style is known as the @dfn{guessed style}.

To do this, call @code{c-guess} (or one of the other 5 guessing
commands) on your sample buffer.  The analysis of your code may take
some time.

You can then set the guessed style in any @ccmode{} buffer with
@code{c-guess-install}.  You can display the style with
@code{c-guess-view}, and preserve it by copying it into your
@file{.emacs} for future use, preferably after editing it.

@table @asis
@item @kbd{M-x c-guess-no-install}
@itemx @kbd{M-x c-guess-buffer-no-install}
@itemx @kbd{M-x c-guess-region-no-install}
@findex c-guess-no-install
@findex c-guess-buffer-no-install
@findex c-guess-region-no-install
@findex guess-no-install (c-)
@findex guess-buffer-no-install (c-)
@findex guess-region-no-install (c-)
These commands analyze a part of the current buffer and guess the
style from it.

The part of the buffer examined is either the region
(@code{c-guess-region-no-install}), the entire buffer
(@code{c-guess-buffer-no-install}), or the first
@code{c-guess-region-max} bytes (@code{c-guess-no-install}).

Each of these commands can be given an optional prefix argument.  This
instructs @ccmode{} to combine the new guesses with the current
guesses before forming the guessed style.
@end table

@table @asis
@item @kbd{M-x c-guess}
@itemx @kbd{M-x c-guess-buffer}
@itemx @kbd{M-x c-guess-region}
@findex c-guess
@findex c-guess-buffer
@findex c-guess-region
@findex guess (c-)
@findex guess-buffer (c-)
@findex guess-region (c-)
These commands analyze a part of the current buffer, guess the style
from it, then install the guessed style on the buffer.  The guessed
style is given a name based on the buffer's absolute file name, and
you can then set this style on any @ccmode{} buffer with @kbd{C-c .}.

The part of the buffer examined is either the region
(@code{c-guess-region}), the entire buffer (@code{c-guess-buffer}), or
the first @code{c-guess-region-max} bytes (@code{c-guess}).

Each of these commands can be given an optional prefix argument.  This
instructs @ccmode{} to combine the new guesses with the current
guesses before forming the guessed style.
@end table

@defopt c-guess-region-max
@vindex guess-region-max (c-)
This variable, default 50000, is the size in bytes of the buffer
portion examined by c-guess and c-guess-no-install.  If set to
@code{nil}, the entire buffer is examined.
@end defopt

@defopt c-guess-offset-threshold
@vindex guess-offset-threshold (c-)
This variable, default 10, is the maximum offset, either outwards or
inwards, which will be taken into account by the analysis process.
Any offset bigger than this will be ignored.  For no limit, set this
variable to a large number.
@end defopt

@table @asis
@item  @kbd{M-x c-guess-install}
@findex c-guess-install
@findex guess-install (c-)

Set the current buffer's style to the guessed style.  This prompts you
to enter an optional new style name to give to the guessed style.  By
default, this name is based on the buffer's absolute file name.  You
can then use this style like any other.

@item  @kbd{M-x c-guess-view}
@findex c-guess-view
@findex guess-view (c-)
Display the most recently guessed style in a temporary buffer.  This
display is in the form of a @code{c-add-style} form (@pxref{Adding
Styles}) which can be easily copied to your @file{.emacs}.  You will
probably want to edit it first.

The display of the guessed style contains these elements:

@table @asis
@item Placeholder Name
You should replace this with a style name of your own.
@item Parent Style
The style current when the guessing began, from which the guessed
style inherits (@pxref{Config Basics}) the settings which weren't
guessed.
@item Guessed Offsets
These are the core result of the guessing process.  Each of them is
marked by a comment.
@item Inherited Offsets
These are syntactic offsets which have been taken over from the parent
style.  To avoid possible future conflicts, you should remove either
these offsets or the parent style name.
@end table
@end table

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    File Styles,  , Guessing the Style, Styles
@comment node-name, next, previous, up
@subsection File Styles
@cindex styles, file local
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex file local variables

The Emacs manual describes how you can customize certain variables on a
per-file basis by including a @dfn{file local variable} block at the end
of the file (@pxref{File Variables,, Local Variables in Files,@emacsman{},
@emacsmantitle{}}).

So far, you've only seen a functional interface for setting styles in
@ccmode{}, and this can't be used here.  @ccmode{} fills the gap by
providing two variables for use in a file's local variable list.
Don't use them anywhere else!  These allow you to customize the style
on a per-file basis:

@defvar c-file-style
@vindex file-style (c-)
Set this variable to a style name string in the Local Variables list.
From now on, when you visit the file, @ccmode{} will automatically set
the file's style to this one using @code{c-set-style}.
@end defvar

@defvar c-file-offsets
@vindex file-offsets (c-)
Set this variable (in the Local Variables list) to an association list
of the same format as @code{c-offsets-alist}.  From now on, when you
visit the file, @ccmode{} will automatically institute these offsets
using @code{c-set-offset}.
@end defvar

Note that file style settings (i.e., @code{c-file-style}) are applied
before file offset settings
(i.e., @code{c-file-offsets})@footnote{Also, if either of these are set
in a file's local variable section, all the style variable values are
made local to that buffer, even if
@code{c-style-variables-are-local-p} is @code{nil}.  Since this
variable is virtually always non-@code{nil} anyhow, you're unlikely to
notice this effect.}.

If you set any variable by the file local variables mechanism, that
setting takes priority over all other settings, even those in your
mode hooks (@pxref{CC Hooks}).  Any individual setting of a variable
will override one made through @code{c-file-style} or
@code{c-file-offsets}.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Custom Filling and Breaking, Custom Auto-newlines, Config Basics, Top
@comment node-name, next, previous, up
@chapter Customizing Filling and Line Breaking
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Since there's a lot of normal text in comments and string literals,
@ccmode{} provides features to edit these like in text mode.  It does
this by hooking in on the different line breaking functions and tuning
relevant variables as necessary.

@vindex c-comment-prefix-regexp
@vindex comment-prefix-regexp (c-)
@cindex comment line prefix
@vindex comment-start
@vindex comment-end
@vindex comment-start-skip
@vindex paragraph-start
@vindex paragraph-separate
@vindex paragraph-ignore-fill-prefix
@vindex adaptive-fill-mode
@vindex adaptive-fill-regexp
@vindex adaptive-fill-first-line-regexp
To make Emacs recognize comments and treat text in them as normal
paragraphs, @ccmode{} makes several standard
variables@footnote{@code{comment-start}, @code{comment-end},
@code{comment-start-skip}, @code{paragraph-start},
@code{paragraph-separate}, @code{paragraph-ignore-fill-prefix},
@code{adaptive-fill-mode}, @code{adaptive-fill-regexp}, and
@code{adaptive-fill-first-line-regexp}.} buffer-local and modifies them
according to the language syntax and the comment line prefix.

@defopt c-comment-prefix-regexp
@vindex comment-prefix-regexp (c-)
This style variable contains the regexp used to recognize the
@dfn{comment line prefix}, which is the line decoration that starts
every line in a comment.  The variable is either the comment line
prefix itself, or (more usually) an association list with different
values for different languages.  The symbol for the major mode is
looked up in the alist to get the regexp for the language, and if it
isn't found then the special symbol @samp{other} is looked up instead.

When a comment line gets divided by @kbd{M-j} or the like, @ccmode{}
inserts the comment line prefix from a neighboring line at the start
of the new line.  The default value of c-comment-prefix-regexp is
@samp{//+\\|\\**}, which matches C++ style line comments like

@example
// blah blah
@end example

@noindent
with two or more slashes in front of them, and the second and
subsequent lines of C style block comments like

@example
@group
/*
 * blah blah
 */
@end group
@end example

@noindent
with zero or more stars at the beginning of every line.  If you change
this variable, please make sure it still matches the comment starter
(i.e., @code{//}) of line comments @emph{and} the line prefix inside
block comments.

@findex c-setup-paragraph-variables
@findex setup-paragraph-variables (c-)
Also note that since @ccmode{} uses the value of
@code{c-comment-prefix-regexp} to set up several other variables at
mode initialization, there won't be any effect if you just change it
inside a @ccmode{} buffer.  You need to call the command
@code{c-setup-paragraph-variables} too, to update those other
variables.  That's also the case if you modify
@code{c-comment-prefix-regexp} in a mode hook, since @ccmode{} will
already have set up these variables before calling the hook.
@end defopt

In comments, @ccmode{} uses @code{c-comment-prefix-regexp} to adapt
the line prefix from the other lines in the comment.

@vindex adaptive-fill-mode
@cindex Adaptive Fill mode
@ccmode{} uses adaptive fill mode (@pxref{Adaptive Fill,,, emacs, GNU
Emacs Manual}) to make Emacs correctly keep the line prefix when
filling paragraphs.  That also makes Emacs preserve the text
indentation @emph{inside} the comment line prefix.  E.g., in the
following comment, both paragraphs will be filled with the left
margins of the texts kept intact:

@example
@group
/* Make a balanced b-tree of the nodes in the incoming
 * stream.  But, to quote the famous words of Donald E.
 * Knuth,
 *
 *     Beware of bugs in the above code; I have only
 *     proved it correct, not tried it.
 */
@end group
@end example

@findex c-setup-filladapt
@findex setup-filladapt (c-)
@findex filladapt-mode
@vindex filladapt-mode
@cindex Filladapt mode
It's also possible to use other adaptive filling packages, notably Kyle
E. Jones' Filladapt package@footnote{It's available from
@uref{http://www.wonderworks.com/}.  As of version 2.12, it does however
lack a feature that makes it work suboptimally when
@code{c-comment-prefix-regexp} matches the empty string (which it does
by default).  A patch for that is available from
@uref{http://cc-mode.sourceforge.net/,, the CC Mode web site}.},
@c 2005/11/22:  The above is still believed to be the case.
which handles things like bulleted lists nicely.  There's a convenience
function @code{c-setup-filladapt} that tunes the relevant variables in
Filladapt for use in @ccmode{}.  Call it from a mode hook, e.g., with
something like this in your @file{.emacs}:

@example
(defun my-c-mode-common-hook ()
  (c-setup-filladapt)
  (filladapt-mode 1))
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
@end example

@defopt c-block-comment-prefix
@vindex block-comment-prefix (c-)
@vindex c-comment-continuation-stars
@vindex comment-continuation-stars (c-)
Normally the comment line prefix inserted for a new line inside a
comment is deduced from other lines in it.  However there's one
situation when there's no hint about what the prefix should look like,
namely when a block comment is broken for the first time.  This style
variable@footnote{In versions before 5.26, this variable was called
@code{c-comment-continuation-stars}.  As a compatibility measure,
@ccmode{} still uses the value on that variable if it's set.} is used
then as the comment prefix.  It defaults to @samp{*
}@footnote{Actually, this default setting of
@code{c-block-comment-prefix} typically gets overridden by the default
style @code{gnu}, which sets it to blank.  You can see the line
splitting effect described here by setting a different style,
e.g., @code{k&r} @xref{Choosing a Style}.}, which makes a comment

@example
/* Got O(n^2) here, which is a Bad Thing. */
@end example

@noindent
break into

@example
@group
/* Got O(n^2) here, which
 * is a Bad Thing. */
@end group
@end example

Note that it won't work to adjust the indentation by putting leading
spaces in @code{c-block-comment-prefix}, since @ccmode{} still uses the
normal indentation engine to indent the line.  Thus, the right way to
fix the indentation is by customizing the @code{c} syntactic symbol.  It
defaults to @code{c-lineup-C-comments}, which handles the indentation of
most common comment styles, see @ref{Line-Up Functions}.
@end defopt

@defopt c-ignore-auto-fill
@vindex ignore-auto-fill (c-)
When auto fill mode is enabled, @ccmode{} can selectively ignore it
depending on the context the line break would occur in, e.g., to never
break a line automatically inside a string literal.  This variable
takes a list of symbols for the different contexts where auto-filling
never should occur:

@table @code
@item string
Inside a string or character literal.
@item c
Inside a C style block comment.
@item c++
Inside a C++ style line comment.
@item cpp
Inside a preprocessor directive.
@item code
Anywhere else, i.e., in normal code.
@end table

By default, @code{c-ignore-auto-fill} is set to @code{(string cpp
code)}, which means that when auto-fill mode is activated,
auto-filling only occurs in comments.  In literals, it's often
desirable to have explicit control over newlines.  In preprocessor
directives, the necessary @samp{\} escape character before the newline
is not automatically inserted, so an automatic line break would
produce invalid code.  In normal code, line breaks are normally
dictated by some logical structure in the code rather than the last
whitespace character, so automatic line breaks there will produce poor
results in the current implementation.
@end defopt

@vindex comment-multi-line
If inside a comment and @code{comment-multi-line} (@pxref{Auto
Fill,,,@emacsman{}, @emacsmantitle{}} is non-@code{nil}, the
indentation and
line prefix are preserved.  If inside a comment and
@code{comment-multi-line} is @code{nil}, a new comment of the same
type is started on the next line and indented as appropriate for
comments.

Note that @ccmode{} sets @code{comment-multi-line} to @code{t} at
startup.  The reason is that @kbd{M-j} could otherwise produce sequences
of single line block comments for texts that should logically be treated
as one comment, and the rest of the paragraph handling code
(e.g., @kbd{M-q} and @kbd{M-a}) can't cope with that, which would lead to
inconsistent behavior.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Custom Auto-newlines, Clean-ups, Custom Filling and Breaking, Top
@comment node-name, next, previous, up
@chapter Customizing Auto-newlines
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ccmode{} determines whether to insert auto-newlines in two basically
different ways, depending on the character just typed:

@table @asis
@item Braces and Colons
@ccmode{} first determines the syntactic context of the brace or colon
(@pxref{Syntactic Symbols}), then looks for a corresponding element in
an alist.  This element specifies where to put newlines: this is any
combination of before and after the brace or colon.  If no alist
element is found, newlines are inserted both before and after a brace,
but none are inserted around a colon.  See @ref{Hanging Braces} and
@ref{Hanging Colons}.

@item Semicolons and Commas
The variable @code{c-hanging-semi&comma-criteria} contains a list of
functions which determine whether to insert a newline after a newly
typed semicolon or comma.  @xref{Hanging Semicolons and Commas}.
@end table

The names of these configuration variables contain @samp{hanging}
because they let you @dfn{hang} the pertinent characters.  A character
which introduces a C construct is said to @dfn{hang on the right} when
it appears at the end of a line after other code, being separated by a
line break from the construct it introduces, like the opening brace in:

@example
@group
while (i < MAX) @{
    total += entry[i];
    entry [i++] = 0;
@}
@end group
@end example

@noindent
A character @dfn{hangs on the left} when it appears at the start of
the line after the construct it closes off, like the above closing
brace.

The next chapter, ``Clean-ups'', describes how to configure @ccmode{}
to remove these automatically added newlines in certain specific
circumstances.  @xref{Clean-ups}.

@menu
* Hanging Braces::
* Hanging Colons::
* Hanging Semicolons and Commas::
@end menu


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Hanging Braces, Hanging Colons, Custom Auto-newlines, Custom Auto-newlines
@comment node-name, next, previous, up
@section Hanging Braces
@cindex hanging braces
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

To specify which kinds of braces you want auto-newlines put around,
you set the style variable @code{c-hanging-braces-alist}.  Its
structure and semantics are described in this section.  Details of how
to set it up, and its relationship to CC Mode's style system are given
in @ref{Style Variables}.

Say you wanted an auto-newline after (but not before) the following
@samp{@{}:

@example
if (foo < 17) @{
@end example

@noindent
First you need to find the @dfn{syntactic context} of the brace---type
a @key{RET} before the brace to get it on a line of its
own@footnote{Also insert a @samp{\} at the end of the previous line if
you're in AWK Mode.}, then type @kbd{C-c C-s}.  That will tell you
something like:

@example
((substatement-open 1061))
@end example

@noindent
So here you need to put the entry @code{(substatement-open . (after))}
into @code{c-hanging-braces-alist}.

If you don't want any auto-newlines for a particular syntactic symbol,
put this into @code{c-hanging-braces-alist}:

@example
(brace-entry-open)
@end example

If some brace syntactic symbol is not in @code{c-hanging-brace-alist},
its entry is taken by default as @code{(before after)}---insert a
newline both before and after the brace.  In place of a
``before/after'' list you can specify a function in this alist---this
is useful when the auto newlines depend on the code around the brace.

@defopt c-hanging-braces-alist
@vindex hanging-braces-alist (c-)

This variable is an association list which maps syntactic symbols to
lists of places to insert a newline.  @xref{Association
Lists,,,@lispref{}, @lispreftitle{}}.  The key of each element is the
syntactic symbol, the associated value is either @code{nil}, a list,
or a function.

@table @asis
@item The Key: the syntactic symbol
The syntactic symbols that are useful as keys in this list are
@code{brace-list-intro}, @code{statement-cont},
@code{inexpr-class-open}, @code{inexpr-class-close}, and all the
@code{*-open} and @code{*-close} symbols.  @xref{Syntactic Symbols},
for a more detailed description of these syntactic symbols, except for
@code{inexpr-class-open} and @code{inexpr-class-close}, which aren't
actual syntactic symbols.  Elements with any other value as a key get
ignored.

The braces of anonymous inner classes in Java are given the special
symbols @code{inexpr-class-open} and @code{inexpr-class-close}, so that
they can be distinguished from the braces of normal classes@footnote{The
braces of anonymous classes produce a combination of
@code{inexpr-class}, and @code{class-open} or @code{class-close} in
normal indentation analysis.}.

Note that the aggregate constructs in Pike mode, @samp{(@{}, @samp{@})},
@samp{([}, @samp{])}, and @samp{(<}, @samp{>)}, do not count as brace
lists in this regard, even though they do for normal indentation
purposes.  It's currently not possible to set automatic newlines on
these constructs.

@item The associated value: the ``ACTION'' list or function
The value associated with each syntactic symbol in this association
list is called an @var{action}, which can be either a list or a
function which returns a list.  @xref{Custom Braces}, for how to use
a function as a brace hanging @var{action}.

The list @var{action} (or the list returned by @var{action} when it's
a function) contains some combination of the symbols @code{before} and
@code{after}, directing @ccmode{} where to put newlines in
relationship to the brace being inserted.  Thus, if the list contains
only the symbol @code{after}, then the brace hangs on the right side
of the line, as in:

@example
// here, open braces always `hang'
void spam( int i ) @{
    if( i == 7 ) @{
        dosomething(i);
    @}
@}
@end example

When the list contains both @code{after} and @code{before}, the braces
will appear on a line by themselves, as shown by the close braces in
the above example.  The list can also be empty, in which case newlines
are added neither before nor after the brace.
@end table

If a syntactic symbol is missing entirely from
@code{c-hanging-braces-alist}, it's treated in the same way as an
@var{action} with a list containing @code{before} and @code{after}, so
that braces by default end up on their own line.

For example, the default value of @code{c-hanging-braces-alist} is:

@example
((brace-list-open)
 (brace-entry-open)
 (statement-cont)
 (substatement-open after)
 (block-close . c-snug-do-while)
 (extern-lang-open after)
 (namespace-open after)
 (module-open after)
 (composition-open after)
 (inexpr-class-open after)
 (inexpr-class-close before))
@end example

@noindent which says that @code{brace-list-open},
@code{brace-entry-open} and @code{statement-cont}@footnote{Brace lists
inside statements, such as initializers for static array variables
inside functions in C, are recognized as @code{statement-cont}.  All
normal substatement blocks are recognized with other symbols.} braces
should both hang on the right side and allow subsequent text to follow
on the same line as the brace.  Also, @code{substatement-open},
@code{extern-lang-open}, and @code{inexpr-class-open} braces should hang
on the right side, but subsequent text should follow on the next line.
The opposite holds for @code{inexpr-class-close} braces; they won't
hang, but the following text continues on the same line.  Here, in the
@code{block-close} entry, you also see an example of using a function as
an @var{action}.  In all other cases, braces are put on a line by
themselves.
@end defopt

@menu
* Custom Braces::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Custom Braces,  , Hanging Braces, Hanging Braces
@comment node-name, next, previous, up
@subsection Custom Brace Hanging
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-hanging-braces-alist
@vindex hanging-braces-alist (c-)
@cindex action functions
Syntactic symbols aren't the only place where you can customize
@ccmode{} with the lisp equivalent of callback functions.  Remember
that @var{action}s are usually a list containing some combination of
the symbols @code{before} and @code{after} (@pxref{Hanging Braces}).
For more flexibility, you can instead specify brace ``hanginess'' by
giving a syntactic symbol an @dfn{action function} in
@code{c-hanging-braces-alist}; this function determines the
``hanginess'' of a brace, usually by looking at the code near it.

@cindex customization, brace hanging
An action function is called with two arguments: the syntactic symbol
for the brace (e.g., @code{substatement-open}), and the buffer position
where the brace has been inserted.  Point is undefined on entry to an
action function, but the function must preserve it (e.g., by using
@code{save-excursion}).  The return value should be a list containing
some combination of @code{before} and @code{after}, including neither
of them (i.e., @code{nil}).

@defvar c-syntactic-context
@vindex syntactic-context (c-)
During the call to the indentation or brace hanging @var{action}
function, this variable is bound to the full syntactic analysis list.
This might be, for example, @samp{((block-close 73))}.  Don't ever
give @code{c-syntactic-context} a value yourself---this would disrupt
the proper functioning of @ccmode{}.

This variable is also bound in three other circumstances:
(i)@w{ }when calling a c-hanging-semi&comma-criteria function
(@pxref{Hanging Semicolons and Commas}); (ii)@w{ }when calling a
line-up function (@pxref{Custom Line-Up}); (iii)@w{ }when calling a
c-special-indent-hook function (@pxref{Other Indentation}).
@end defvar

As an example, @ccmode{} itself uses this feature to dynamically
determine the hanginess of braces which close ``do-while''
constructs:

@example
void do_list( int count, char** atleast_one_string )
@{
    int i=0;
    do @{
        handle_string( atleast_one_string[i] );
        i++;
    @} while( i < count );
@}
@end example

@ccmode{} assigns the @code{block-close} syntactic symbol to the
brace that closes the @code{do} construct, and normally we'd like the
line that follows a @code{block-close} brace to begin on a separate
line.  However, with ``do-while'' constructs, we want the
@code{while} clause to follow the closing brace.  To do this, we
associate the @code{block-close} symbol with the @var{action} function
@code{c-snug-do-while}:

@example
(defun c-snug-do-while (syntax pos)
  "Dynamically calculate brace hanginess for do-while statements."
  (save-excursion
    (let (langelem)
      (if (and (eq syntax 'block-close)
               (setq langelem (assq 'block-close c-syntactic-context))
               (progn (goto-char (cdr langelem))
                      (if (= (following-char) ?@{)
                          (forward-sexp -1))
                      (looking-at "\\<do\\>[^_]")))
          '(before)
        '(before after)))))
@end example

@findex c-snug-do-while
@findex snug-do-while (c-)
This function simply looks to see if the brace closes a ``do-while''
clause and if so, returns the list @samp{(before)} indicating
that a newline should be inserted before the brace, but not after it.
In all other cases, it returns the list @samp{(before after)} so
that the brace appears on a line by itself.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Hanging Colons, Hanging Semicolons and Commas, Hanging Braces, Custom Auto-newlines
@comment node-name, next, previous, up
@section Hanging Colons
@cindex hanging colons
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex customization, colon hanging
@vindex c-hanging-colons-alist
@vindex hanging-colons-alist (c-)

Using a mechanism similar to brace hanging (@pxref{Hanging Braces}),
colons can also be made to hang using the style variable
@code{c-hanging-colons-alist}: when a colon is typed, @ccmode
determines its syntactic context, looks this up in the alist
@code{c-changing-colons-alist} and inserts up to two newlines
accordingly.  Here, however, If @ccmode fails to find an entry for a
syntactic symbol in the alist, no newlines are inserted around the
newly typed colon.

@defopt c-hanging-colons-alist
@vindex hanging-colons-alist (c-)

@table @asis
@item The Key: the syntactic symbol
The syntactic symbols appropriate as keys in this association list
are: @code{case-label}, @code{label}, @code{access-label},
@code{member-init-intro}, and @code{inher-intro}.  @xref{Syntactic
Symbols}.  Elements with any other value as a key get ignored.

@item The associated value: the ``ACTION'' list
The @var{action} here is simply a list containing a combination of the
symbols @code{before} and @code{after}.  Unlike in
@code{c-hanging-braces-alist}, functions as @var{actions} are not
supported; there doesn't seem to be any need for them.
@end table
@end defopt

In C++, double-colons are used as a scope operator but because these
colons always appear right next to each other, newlines before and after
them are controlled by a different mechanism, called @dfn{clean-ups} in
@ccmode{}.  @xref{Clean-ups}, for details.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Hanging Semicolons and Commas,  , Hanging Colons, Custom Auto-newlines
@comment node-name, next, previous, up
@section Hanging Semicolons and Commas
@cindex hanging semicolons
@cindex hanging commas
@cindex customization, semicolon newlines
@cindex customization, comma newlines
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@defopt c-hanging-semi&comma-criteria
@vindex hanging-semi&comma-criteria (c-)
This style variable takes a list of functions; these get called when
you type a semicolon or comma.  The functions are called in order
without arguments.  When these functions are entered, point is just
after the newly inserted @samp{;} or @samp{,} and they must preserve
point (e.g., by using @code{save-excursion}).  During the call, the
variable @code{c-syntactic-context} is bound to the syntactic context
of the current line@footnote{This was first introduced in @ccmode{}
5.31.} @pxref{Custom Braces}.  These functions don't insert newlines
themselves, rather they direct @ccmode{} whether or not to do so.
They should return one of the following values:

@table @code
@item t
A newline is to be inserted after the @samp{;} or @samp{,}, and no
more functions from the list are to be called.
@item stop
No more functions from the list are to be called, and no newline is to
be inserted.
@item nil
No determination has been made, and the next function in the list is
to be called.
@end table

Note that auto-newlines are never inserted @emph{before} a semicolon
or comma.  If every function in the list is called without a
determination being made, then no newline is added.

In AWK mode, this variable is set by default to @code{nil}.  In the
other modes, the default value is a list containing a single function,
@code{c-semi&comma-inside-parenlist}.  This inserts newlines after all
semicolons, apart from those separating @code{for}-clause statements.
@end defopt

@defun c-semi&comma-no-newlines-before-nonblanks
@findex semi&comma-no-newlines-before-nonblanks (c-)
This is an example of a criteria function, provided by @ccmode{}.  It
prevents newlines from being inserted after semicolons when there is a
non-blank following line.  Otherwise, it makes no determination.  To
use, add this function to the front of the
@code{c-hanging-semi&comma-criteria} list.

@example
(defun c-semi&comma-no-newlines-before-nonblanks ()
  (save-excursion
    (if (and (eq last-command-char ?\;)
             (zerop (forward-line 1))
             (not (looking-at "^[ \t]*$")))
        'stop
      nil)))
@end example
@end defun

@defun c-semi&comma-inside-parenlist
@findex semi&comma-inside-parenlist (c-)
@defunx c-semi&comma-no-newlines-for-oneline-inliners
@findex semi&comma-no-newlines-for-oneline-inliners (c-)
The function @code{c-semi&comma-inside-parenlist} is what prevents
newlines from being inserted inside the parenthesis list of @code{for}
statements.  In addition to
@code{c-semi&comma-no-newlines-before-nonblanks} described above,
@ccmode{} also comes with the criteria function
@code{c-semi&comma-no-newlines-for-oneline-inliners}, which suppresses
newlines after semicolons inside one-line inline method definitions
(e.g., in C++ or Java).
@end defun


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Clean-ups, Indentation Engine Basics, Custom Auto-newlines, Top
@comment node-name, next, previous, up
@chapter Clean-ups
@cindex clean-ups
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@dfn{Clean-ups} are mechanisms which remove (or exceptionally, add)
whitespace in specific circumstances and are complementary to colon
and brace hanging.  You enable a clean-up by adding its symbol into
@code{c-cleanup-list}, e.g., like this:

@example
(add-to-list 'c-cleanup-list 'space-before-funcall)
@end example

On the surface, it would seem that clean-ups overlap the functionality
provided by the @code{c-hanging-*-alist} variables.  Clean-ups,
however, are used to adjust code ``after-the-fact'', i.e., to adjust
the whitespace in constructs later than when they were typed.

Most of the clean-ups remove automatically inserted newlines, and are
only active when auto-newline minor mode is turned on.  Others will
work all the time.  Note that clean-ups are only performed when there
is nothing but whitespace appearing between the individual components
of the construct, and (apart from @code{comment-close-slash}) when the
construct does not occur within a literal (@pxref{Auto-newlines}).

@defopt c-cleanup-list
@vindex cleanup-list (c-)
@cindex literal

You configure @ccmode{}'s clean-ups by setting the style variable
@code{c-cleanup-list}, which is a list of clean-up symbols.  By
default, @ccmode{} cleans up only the @code{scope-operator} construct,
which is necessary for proper C++ support.
@end defopt

These are the clean-ups that are only active when electric and
auto-newline minor modes are enabled:

@c TBD: Would like to use some sort of @deffoo here; @table indents a
@c bit too much in dvi output.
@table @code
@item brace-else-brace
Clean up @samp{@} else @{} constructs by placing the entire construct on
a single line.  Clean up occurs when the open brace after the
@samp{else} is typed.  So for example, this:

@example
@group
void spam(int i)
@{
    if( i==7 ) @{
        dosomething();
    @}
    else
    @{
@end group
@end example

@noindent
appears like this after the last open brace is typed:

@example
@group
void spam(int i)
@{
    if( i==7 ) @{
        dosomething();
    @} else @{
@end group
@end example

@item brace-elseif-brace
Similar to the @code{brace-else-brace} clean-up, but this cleans up
@samp{@} else if (...) @{} constructs.  For example:

@example
@group
void spam(int i)
@{
    if( i==7 ) @{
        dosomething();
    @}
    else if( i==3 )
    @{
@end group
@end example

@noindent
appears like this after the last open parenthesis is typed:

@example
@group
void spam(int i)
@{
    if( i==7 ) @{
        dosomething();
    @} else if(
@end group
@end example

@noindent
and like this after the last open brace is typed:

@example
@group
void spam(int i)
@{
    if( i==7 ) @{
        dosomething();
    @} else if( i==3 ) @{
@end group
@end example

@item brace-catch-brace
Analogous to @code{brace-elseif-brace}, but cleans up @samp{@} catch
(...) @{} in C++ and Java mode.

@item empty-defun-braces
Clean up braces following a top-level function or class definition that
contains no body.  Clean up occurs when the closing brace is typed.
Thus the following:

@example
@group
class Spam
@{
@}
@end group
@end example

@noindent
is transformed into this when the close brace is typed:

@example
@group
class Spam
@{@}
@end group
@end example

@item defun-close-semi
Clean up the terminating semicolon on top-level function or class
definitions when they follow a close brace.  Clean up occurs when the
semicolon is typed.  So for example, the following:

@example
@group
class Spam
@{
...
@}
;
@end group
@end example

@noindent
is transformed into this when the semicolon is typed:

@example
@group
class Spam
@{
...
@};
@end group
@end example

@item list-close-comma
Clean up commas following braces in array and aggregate initializers.
Clean up occurs when the comma is typed.  The space before the comma
is zapped just like the space before the semicolon in
@code{defun-close-semi}.

@item scope-operator
Clean up double colons which might designate a C++ scope operator split
across multiple lines@footnote{Certain C++ constructs introduce
ambiguous situations, so @code{scope-operator} clean-ups might not
always be correct.  This usually only occurs when scoped identifiers
appear in switch label tags.}.  Clean up occurs when the second colon is
typed.  You will always want @code{scope-operator} in the
@code{c-cleanup-list} when you are editing C++ code.

@item one-liner-defun
Clean up a single line of code enclosed by defun braces by removing
the whitespace before and after the code.  The clean-up happens when
the closing brace is typed.  If the variable
@code{c-max-one-liner-length} is set, the cleanup is only done if the
resulting line would be no longer than the value of that variable.

For example, consider this AWK code:

@example
@group
BEGIN @{
    FS = "\t" # use <TAB> as a field separator
@}
@end group
@end example

@noindent
It gets compacted to the following when the closing brace is typed:

@example
@group
BEGIN @{FS = "\t"@} # use <TAB> as a field separator
@end group
@end example

@defopt c-max-one-liner-length
@vindex max-one-liner-length (c-)
The maximum length of the resulting line for which the clean-up
@code{one-liner-defun} will be triggered.  This length is that of the entire
line, including any leading whitespace and any trailing comment.  Its
default value is 80.  If the value is zero or @code{nil}, no limit
applies.
@end defopt
@end table

The following clean-ups are always active when they occur on
@code{c-cleanup-list}, regardless of whether Electric minor mode or
Auto-newline minor mode are enabled:

@table @code
@item space-before-funcall
Insert a space between the function name and the opening parenthesis
of a function call.  This produces function calls in the style
mandated by the GNU coding standards, e.g., @samp{signal@w{ }(SIGINT,
SIG_IGN)} and @samp{abort@w{ }()}.  Clean up occurs when the opening
parenthesis is typed.  This clean-up should never be active in AWK
Mode, since such a space is syntactically invalid for user defined
functions.

@item compact-empty-funcall
Clean up any space between the function name and the opening parenthesis
of a function call that has no arguments.  This is typically used
together with @code{space-before-funcall} if you prefer the GNU function
call style for functions with arguments but think it looks ugly when
it's only an empty parenthesis pair.  I.e., you will get @samp{signal
(SIGINT, SIG_IGN)}, but @samp{abort()}.  Clean up occurs when the
closing parenthesis is typed.

@item comment-close-slash
When inside a block comment, terminate the comment when you type a slash
at the beginning of a line (i.e., immediately after the comment prefix).
This clean-up removes whitespace preceding the slash and if needed,
inserts a star to complete the token @samp{*/}.  Type @kbd{C-q /} in this
situation if you just want a literal @samp{/} inserted.
@end table


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Indentation Engine Basics, Customizing Indentation, Clean-ups, Top
@comment node-name, next, previous, up
@chapter Indentation Engine Basics
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

This chapter will briefly cover how @ccmode{} indents lines of code.
It is helpful to understand the indentation model being used so that
you will know how to customize @ccmode{} for your personal coding
style.  All the details are in @ref{Customizing Indentation}.

@ccmode{} has an indentation engine that provides a flexible and
general mechanism for customizing indentation.  When @ccmode{} indents
a line of code, it separates its calculations into two steps:

@enumerate
@item
@cindex syntactic symbol
@cindex anchor position
It analyzes the line to determine its @dfn{syntactic symbol(s)} (the
kind of language construct it's looking at) and its @dfn{anchor
position} (the position earlier in the file that @ccmode{} will indent
the line relative to).  The anchor position might be the location of
an opening brace in the previous line, for example.  @xref{Syntactic
Analysis}.
@item
@cindex offsets
@cindex indentation offset specifications
It looks up the syntactic symbol(s) in the configuration to get the
corresponding @dfn{offset(s)}.  The symbol @code{+}, which means
``indent this line one more level'' is a typical offset.  @ccmode{}
then applies these offset(s) to the anchor position, giving the
indentation for the line.  The different sorts of offsets are
described in @ref{c-offsets-alist}.
@end enumerate

In exceptional circumstances, the syntax directed indentation
described here may be a nuisance rather than a help.  You can disable
it by setting @code{c-syntactic-indentation} to @code{nil}.  (To set
the variable interactively, @ref{Minor Modes}).

@defopt c-syntactic-indentation
@vindex syntactic-indentation (c-)
When this is non-@code{nil} (which it is by default), the indentation
of code is done according to its syntactic structure.  When it's
@code{nil}, every line is just indented to the same level as the
previous one, and @kbd{TAB} (@code{c-indent-command}) adjusts the
indentation in steps of @code{c-basic-offset}.  The current style
(@pxref{Config Basics}) then has no effect on indentation, nor do any
of the variables associated with indentation, not even
@code{c-special-indent-hook}.
@end defopt

@menu
* Syntactic Analysis::
* Syntactic Symbols::
* Indentation Calculation::
@end menu


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Syntactic Analysis, Syntactic Symbols, Indentation Engine Basics, Indentation Engine Basics
@comment node-name, next, previous, up
@section Syntactic Analysis
@cindex syntactic analysis
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex syntactic element
@cindex syntactic context
The first thing @ccmode{} does when indenting a line of code, is to
analyze the line, determining the @dfn{syntactic context} of the
(first) construct on that line.  It's a list of @dfn{syntactic
elements}, where each syntactic element in turn is a list@footnote{In
@ccmode 5.28 and earlier, a syntactic element was a dotted pair; the
cons was the syntactic symbol and the cdr was the anchor position.
For compatibility's sake, the parameter passed to a line-up function
still has this dotted pair form (@pxref{Custom Line-Up}).}  Here is a
brief and typical example:

@example
((defun-block-intro 1959))
@end example

@cindex syntactic symbol
@noindent
The first thing inside each syntactic element is always a
@dfn{syntactic symbol}.  It describes the kind of construct that was
recognized, e.g., @code{statement}, @code{substatement},
@code{class-open}, @code{class-close}, etc.  @xref{Syntactic Symbols},
for a complete list of currently recognized syntactic symbols and
their semantics.  The remaining entries are various data associated
with the recognized construct; there might be zero or more.

@cindex anchor position
Conceptually, a line of code is always indented relative to some
position higher up in the buffer (typically the indentation of the
previous line).  That position is the @dfn{anchor position} in the
syntactic element.  If there is an entry after the syntactic symbol in
the syntactic element list then it's either nil or that anchor position.

Here is an example.  Suppose we had the following code as the only thing
in a C++ buffer @footnote{The line numbers in this and future examples
don't actually appear in the buffer, of course!}:

@example
 1: void swap( int& a, int& b )
 2: @{
 3:     int tmp = a;
 4:     a = b;
 5:     b = tmp;
 6: @}
@end example

@noindent
We can use @kbd{C-c C-s} (@code{c-show-syntactic-information}) to
report what the syntactic analysis is for the current line:

@table @asis
@item @kbd{C-c C-s} (@code{c-show-syntactic-information})
@kindex C-c C-s
@findex c-show-syntactic-information
@findex show-syntactic-information (c-)
This command calculates the syntactic analysis of the current line and
displays it in the minibuffer.  The command also highlights the anchor
position(s).
@end table

  Running this command on line 4 of this example, we'd see in the echo
area@footnote{With a universal argument (i.e., @kbd{C-u C-c C-s}) the
analysis is inserted into the buffer as a comment on the current
line.}:

@example
((statement 35))
@end example

@noindent
and the @samp{i} of @code{int} on line 3 would be highlighted.  This
tells us that the line is a statement and it is indented relative to
buffer position 35, the highlighted position.  If you were to move
point to line 3 and hit @kbd{C-c C-s}, you would see:

@example
((defun-block-intro 29))
@end example

@noindent
This indicates that the @samp{int} line is the first statement in a top
level function block, and is indented relative to buffer position 29,
which is the brace just after the function header.

Here's another example:

@example
 1: int add( int val, int incr, int doit )
 2: @{
 3:     if( doit )
 4:         @{
 5:             return( val + incr );
 6:         @}
 7:     return( val );
 8: @}
@end example

@noindent
Hitting @kbd{C-c C-s} on line 4 gives us:

@example
((substatement-open 46))
@end example

@cindex substatement
@cindex substatement block
@noindent
which tells us that this is a brace that @emph{opens} a substatement
block. @footnote{A @dfn{substatement} is the line after a
conditional statement, such as @code{if}, @code{else}, @code{while},
@code{do}, @code{switch}, etc.  A @dfn{substatement
block} is a brace block following one of these conditional statements.}

@cindex comment-only line
Syntactic contexts can contain more than one element, and syntactic
elements need not have anchor positions.  The most common example of
this is a @dfn{comment-only line}:

@example
 1: void draw_list( List<Drawables>& drawables )
 2: @{
 3:         // call the virtual draw() method on each element in list
 4:     for( int i=0; i < drawables.count(), ++i )
 5:     @{
 6:         drawables[i].draw();
 7:     @}
 8: @}
@end example

@noindent
Hitting @kbd{C-c C-s} on line 3 of this example gives:

@example
((comment-intro) (defun-block-intro 46))
@end example

@noindent
and you can see that the syntactic context contains two syntactic
elements.  Notice that the first element, @samp{(comment-intro)}, has no
anchor position.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Syntactic Symbols, Indentation Calculation, Syntactic Analysis, Indentation Engine Basics
@comment node-name, next, previous, up
@section Syntactic Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex syntactic symbols, brief list
@vindex c-offsets-alist
@vindex offsets-alist (c-)
This section is a complete list of the syntactic symbols which appear
in the @code{c-offsets-alist} style variable, along with brief
descriptions.  The previous section (@pxref{Syntactic Analysis})
states what syntactic symbols are and how the indentation engine uses
them.

More detailed descriptions of these symbols, together with snippets of
source code to which they apply, appear in the examples in the
subsections below.  Note that, in the interests of brevity, the anchor
position associated with most syntactic symbols is @emph{not}
specified.  In cases of doubt, type @kbd{C-c C-s} on a pertinent
line---this highlights the anchor position.

@ssindex -open symbols
@ssindex -close symbols
@ssindex -block-intro symbols
The syntactic symbols which indicate brace constructs follow a general
naming convention.  When a line begins with an open or close brace,
its syntactic symbol will contain the suffix @code{-open} or
@code{-close} respectively.  The first line within the brace block
construct will contain the suffix @code{-block-intro}.

@ssindex -intro symbols
@ssindex -cont symbols
In constructs which can span several lines, a distinction is usually
made between the first line that introduces the construct and the
lines that continue it.  The syntactic symbols that indicate these
lines will contain the suffixes @code{-intro} or @code{-cont}
respectively.

The best way to understand how all this works is by looking at some
examples.  Remember that you can see the syntax of any source code
line by using @kbd{C-c C-s}.

@table @code
@item string
Inside a multiline string.  @ref{Literal Symbols}.
@item c
Inside a multiline C style block comment.  @ref{Literal Symbols}.
@item defun-open
Brace that opens a top-level function definition.  @ref{Function
Symbols}.
@item defun-close
Brace that closes a top-level function definition.  @ref{Function
Symbols}.
@item defun-block-intro
The first line in a top-level defun.  @ref{Function Symbols}.
@item class-open
Brace that opens a class definition.  @ref{Class Symbols}.
@item class-close
Brace that closes a class definition.  @ref{Class Symbols}.
@item inline-open
Brace that opens an in-class inline method.  @ref{Class Symbols}.
@item inline-close
Brace that closes an in-class inline method.  @ref{Class Symbols}.
@item func-decl-cont
The region between a function definition's argument list and the
function opening brace (excluding K&R argument declarations).  In C,
you cannot put anything but whitespace and comments in this region,
however in C++ and Java, @code{throws} declarations and other things
can appear here.  @ref{Literal Symbols}. @c @emph{FIXME!!!  Can it not
@c go somewhere better?}
@item knr-argdecl-intro
First line of a K&R C argument declaration.  @ref{K&R Symbols}.
@item knr-argdecl
Subsequent lines in a K&R C argument declaration.  @ref{K&R Symbols}.
@item topmost-intro
The first line in a ``topmost'' definition.  @ref{Function Symbols}.
@item topmost-intro-cont
Topmost definition continuation lines.  This is only used in the parts
that aren't covered by other symbols such as @code{func-decl-cont} and
@code{knr-argdecl}.  @ref{Function Symbols}.
@item annotation-top-cont
Topmost definition continuation lines where all previous items are
annotations.  @ref{Java Symbols}.
@item member-init-intro
First line in a member initialization list.  @ref{Class Symbols}.
@item member-init-cont
Subsequent member initialization list lines.  @ref{Class Symbols}.
@item inher-intro
First line of a multiple inheritance list.  @ref{Class Symbols}.
@item inher-cont
Subsequent multiple inheritance lines.  @ref{Class Symbols}.
@item block-open
Statement block open brace.  @ref{Literal Symbols}.
@item block-close
Statement block close brace.  @ref{Conditional Construct Symbols}.
@item brace-list-open
Open brace of an enum or static array list.  @ref{Brace List Symbols}.
@item brace-list-close
Close brace of an enum or static array list.  @ref{Brace List Symbols}.
@item brace-list-intro
First line in an enum or static array list.  @ref{Brace List Symbols}.
@item brace-list-entry
Subsequent lines in an enum or static array list.  @ref{Brace List
Symbols}.
@item brace-entry-open
Subsequent lines in an enum or static array list where the line begins
with an open brace.  @ref{Brace List Symbols}.
@item statement
A statement.  @ref{Function Symbols}.
@item statement-cont
A continuation of a statement.  @ref{Function Symbols}.
@item annotation-var-cont
A continuation of a statement where all previous items are
annotations.  @ref{Java Symbols}.
@item statement-block-intro
The first line in a new statement block.  @ref{Conditional Construct
Symbols}.
@item statement-case-intro
The first line in a case block.  @ref{Switch Statement Symbols}.
@item statement-case-open
The first line in a case block that starts with a brace.  @ref{Switch
Statement Symbols}.
@item substatement
The first line after a conditional or loop construct.
@ref{Conditional Construct Symbols}.
@item substatement-open
The brace that opens a substatement block.  @ref{Conditional Construct
Symbols}.
@item substatement-label
The first line after a conditional or loop construct if it's a label.
@ref{Conditional Construct Symbols}.
@item case-label
A label in a @code{switch} block.  @ref{Switch Statement Symbols}.
@item access-label
C++ access control label.  @ref{Class Symbols}.
@item label
Any other label.  @ref{Literal Symbols}.
@item do-while-closure
The @code{while} line that ends a @code{do}-@code{while} construct.
@ref{Conditional Construct Symbols}.
@item else-clause
The @code{else} line of an @code{if}-@code{else} construct.
@ref{Conditional Construct Symbols}.
@item catch-clause
The @code{catch} or @code{finally} (in Java) line of a
@code{try}-@code{catch} construct.  @ref{Conditional Construct
Symbols}.
@item comment-intro
A line containing only a comment introduction.  @ref{Literal Symbols}.
@item arglist-intro
The first line in an argument list.  @ref{Paren List Symbols}.
@item arglist-cont
Subsequent argument list lines when no arguments follow on the same
line as the arglist opening paren.  @ref{Paren List Symbols}.
@item arglist-cont-nonempty
Subsequent argument list lines when at least one argument follows on
the same line as the arglist opening paren.  @ref{Paren List Symbols}.
@item arglist-close
The solo close paren of an argument list.  @ref{Paren List Symbols}.
@item stream-op
Lines continuing a stream operator (C++ only).  @ref{Literal
Symbols}. @c @emph{FIXME!!!  Can this not be moved somewhere better?}
@item inclass
The line is nested inside a class definition.  @ref{Class Symbols}.
@item cpp-macro
The start of a preprocessor macro definition.  @ref{Literal Symbols}.
@item cpp-define-intro
The first line inside a multiline preprocessor macro if
@code{c-syntactic-indentation-in-macros} is set.  @ref{Multiline Macro
Symbols}.
@item cpp-macro-cont
All lines inside multiline preprocessor macros if
@code{c-syntactic-indentation-in-macros} is @code{nil}.
@ref{Multiline Macro Symbols}.
@item friend
A C++ friend declaration.  @ref{Class Symbols}.
@item objc-method-intro
The first line of an Objective-C method definition.  @ref{Objective-C
Method Symbols}.
@item objc-method-args-cont
Lines continuing an Objective-C method definition.  @ref{Objective-C
Method Symbols}.
@item objc-method-call-cont
Lines continuing an Objective-C method call.  @ref{Objective-C Method
Symbols}.
@item extern-lang-open
Brace that opens an @code{extern} block (e.g., @code{extern "C"
@{...@}}).  @ref{External Scope Symbols}.
@item extern-lang-close
Brace that closes an @code{extern} block.  @ref{External Scope
Symbols}.
@item inextern-lang
Analogous to @code{inclass} syntactic symbol, but used inside
@code{extern} blocks.  @ref{External Scope Symbols}.
@item namespace-open
@itemx namespace-close
@itemx innamespace
These are analogous to the three @code{extern-lang} symbols above, but
are returned for C++ namespace blocks.  @ref{External Scope Symbols}.
@item module-open
@itemx module-close
@itemx inmodule
Analogous to the above, but for CORBA IDL @code{module} blocks.
@ref{External Scope Symbols}.
@item composition-open
@itemx composition-close
@itemx incomposition
Analogous to the above, but for CORBA CIDL @code{composition} blocks.
@ref{External Scope Symbols}.
@item template-args-cont
C++ template argument list continuations.  @ref{Class Symbols}.
@item inlambda
Analogous to @code{inclass} syntactic symbol, but used inside lambda
(i.e., anonymous) functions.  Only used in Pike mode.  @ref{Statement
Block Symbols}.
@item lambda-intro-cont
Lines continuing the header of a lambda function, i.e., between the
@code{lambda} keyword and the function body.  Only used in Pike mode.
@ref{Statement Block Symbols}.
@item inexpr-statement
A statement block inside an expression.  The gcc C and C++ extension
for this is recognized.  It's also used for the special functions that
take a statement block as an argument in Pike.  @ref{Statement Block
Symbols}.
@item inexpr-class
A class definition inside an expression.  This is used for anonymous
classes in Java.  It's also used for anonymous array initializers in
Java.  @ref{Java Symbols}.
@end table

@menu
* Function Symbols::
* Class Symbols::
* Conditional Construct Symbols::
* Switch Statement Symbols::
* Brace List Symbols::
* External Scope Symbols::
* Paren List Symbols::
* Literal Symbols::
* Multiline Macro Symbols::
* Objective-C Method Symbols::
* Java Symbols::
* Statement Block Symbols::
* K&R Symbols::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Function Symbols, Class Symbols, Syntactic Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Function Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

This example shows a typical function declaration.

@example
 1: void
 2: swap( int& a, int& b )
 3: @{
 4:     int tmp = a;
 5:     a = b;
 6:     b = tmp;
 7:     int ignored =
 8:         a + b;
 9: @}
@end example

@ssindex topmost-intro
@ssindex topmost-intro-cont
@ssindex defun-open
@ssindex defun-close
@ssindex defun-block-intro
Line 1 shows a @code{topmost-intro} since it is the first line that
introduces a top-level construct.  Line 2 is a continuation of the
top-level construct introduction so it has the syntax
@code{topmost-intro-cont}.  Line 3 shows a @code{defun-open} since it is
the brace that opens a top-level function definition.  Line 9 is the
corresponding
@code{defun-close} since it contains the brace that closes the top-level
function definition.  Line 4 is a @code{defun-block-intro}, i.e., it is
the first line of a brace-block, enclosed in a
top-level function definition.

@ssindex statement
@ssindex statement-cont
Lines 5, 6, and 7 are all given @code{statement} syntax since there
isn't much special about them.  Note however that line 8 is given
@code{statement-cont} syntax since it continues the statement begun
on the previous line.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Class Symbols, Conditional Construct Symbols, Function Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Class related Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Here's an example which illustrates some C++ class syntactic symbols:

@example
 1: class Bass
 2:     : public Guitar,
 3:       public Amplifiable
 4: @{
 5: public:
 6:     Bass()
 7:         : eString( new BassString( 0.105 )),
 8:           aString( new BassString( 0.085 )),
 9:           dString( new BassString( 0.065 )),
10:           gString( new BassString( 0.045 ))
11:     @{
12:         eString.tune( 'E' );
13:         aString.tune( 'A' );
14:         dString.tune( 'D' );
15:         gString.tune( 'G' );
16:     @}
17:     friend class Luthier;
18: @};
@end example

@ssindex class-open
@ssindex class-close
As in the previous example, line 1 has the @code{topmost-intro} syntax.
Here however, the brace that opens a C++ class definition on line 4 is
assigned the @code{class-open} syntax.  Note that in C++, classes,
structs, and unions are essentially equivalent syntactically (and are
very similar semantically), so replacing the @code{class} keyword in the
example above with @code{struct} or @code{union} would still result in a
syntax of @code{class-open} for line 4 @footnote{This is the case even
for C and Objective-C@.  For consistency, structs in all supported
languages are syntactically equivalent to classes.  Note however that
the keyword @code{class} is meaningless in C and Objective-C.}.
Similarly, line 18 is assigned @code{class-close} syntax.

@ssindex inher-intro
@ssindex inher-cont
Line 2 introduces the inheritance list for the class so it is assigned
the @code{inher-intro} syntax, and line 3, which continues the
inheritance list is given @code{inher-cont} syntax.

@ssindex access-label
@ssindex inclass
Hitting @kbd{C-c C-s} on line 5 shows the following analysis:

@example
((inclass 58) (access-label 58))
@end example

@noindent
The primary syntactic symbol for this line is @code{access-label} as
this is a label keyword that specifies access protection in C++.  However,
because this line is also a top-level construct inside a class
definition, the analysis actually shows two syntactic symbols.  The
other syntactic symbol assigned to this line is @code{inclass}.
Similarly, line 6 is given both @code{inclass} and @code{topmost-intro}
syntax:

@example
((inclass 58) (topmost-intro 60))
@end example

@ssindex member-init-intro
@ssindex member-init-cont
Line 7 introduces a C++ member initialization list and as such is given
@code{member-init-intro} syntax.  Note that in this case it is
@emph{not} assigned @code{inclass} since this is not considered a
top-level construct.  Lines 8 through 10 are all assigned
@code{member-init-cont} since they continue the member initialization
list started on line 7.

@cindex in-class inline methods
@ssindex inline-open
@ssindex inline-close
Line 11's analysis is a bit more complicated:

@example
((inclass 58) (inline-open))
@end example

This line is assigned a syntax of both @code{inline-open} and
@code{inclass} because it opens an @dfn{in-class} C++ inline method
definition.  This is distinct from, but related to, the C++ notion of an
inline function in that its definition occurs inside an enclosing class
definition, which in C++ implies that the function should be inlined.
However, if the definition of the @code{Bass} constructor appeared
outside the class definition, the construct would be given the
@code{defun-open} syntax, even if the keyword @code{inline} appeared
before the method name, as in:

@example
 1: class Bass
 2:     : public Guitar,
 3:       public Amplifiable
 4: @{
 5: public:
 6:     Bass();
 7: @};
 8:
 9: inline
10: Bass::Bass()
11:     : eString( new BassString( 0.105 )),
12:       aString( new BassString( 0.085 )),
13:       dString( new BassString( 0.065 )),
14:       gString( new BassString( 0.045 ))
15: @{
16:     eString.tune( 'E' );
17:     aString.tune( 'A' );
18:     dString.tune( 'D' );
19:     gString.tune( 'G' );
20: @}
@end example

@ssindex friend
Returning to the previous example, line 16 is given @code{inline-close}
syntax, while line 12 is given @code{defun-block-open} syntax, and lines
13 through 15 are all given @code{statement} syntax.  Line 17 is
interesting in that its syntactic analysis list contains three
elements:

@example
((inclass 58) (topmost-intro 380) (friend))
@end example

The @code{friend} and @code{inline-open} syntactic symbols are
modifiers that do not have anchor positions.

@ssindex template-args-cont
Template definitions introduce yet another syntactic symbol:

@example
 1: ThingManager <int,
 2:    Framework::Callback *,
 3:    Mutex> framework_callbacks;
@end example

Here, line 1 is analyzed as a @code{topmost-intro}, but lines 2 and 3
are both analyzed as @code{template-args-cont} lines.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Conditional Construct Symbols, Switch Statement Symbols, Class Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Conditional Construct Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Here is a (totally contrived) example which illustrates how syntax is
assigned to various conditional constructs:

@example
 1: void spam( int index )
 2: @{
 3:     for( int i=0; i<index; i++ )
 4:     @{
 5:         if( i == 10 )
 6:             do_something_special();
 7:         else
 8:           silly_label:
 9:             do_something( i );
10:     @}
11:     do @{
12:         another_thing( i-- );
13:     @}
14:     while( i > 0 );
15: @}
@end example

Only the lines that illustrate new syntactic symbols will be discussed.

@ssindex substatement-open
@ssindex statement-block-intro
@ssindex block-close
Line 4 has a brace which opens a conditional's substatement block.  It
is thus assigned @code{substatement-open} syntax, and since line 5 is
the first line in the substatement block, it is assigned
@code{statement-block-intro} syntax.  Line 10 contains the brace
that closes the inner substatement block, and is therefore given the
syntax @code{block-close}@footnote{@code{block-open} is used only for
``free-standing'' blocks, and is somewhat rare (@pxref{Literal
Symbols} for an example.)}.  Line 13 is treated the same way.

@ssindex substatement
Lines 6 and 9 are also substatements of conditionals, but since they
don't start blocks they are given @code{substatement} syntax
instead of @code{substatement-open}.

@ssindex substatement-label
Line 8 contains a label, which is normally given @code{label} syntax.
This one is however a bit special since it's between a conditional and
its substatement.  It's analyzed as @code{substatement-label} to let you
handle this rather odd case differently from normal labels.

@ssindex else-clause
@ssindex catch-clause
Line 7 start with an @code{else} that matches the @code{if} statement on
line 5.  It is therefore given the @code{else-clause} syntax and is
anchored on the matching @code{if}.  The @code{try}-@code{catch}
constructs in C++ and Java are treated this way too, except that
@code{catch} and (in Java) @code{finally}, are marked with
@code{catch-clause}.

@ssindex do-while-closure
The @code{while} construct on line 14 that closes a @code{do}
conditional is given the special syntax @code{do-while-closure} if it
appears on a line by itself.  Note that if the @code{while} appeared on
the same line as the preceding close brace, that line would still have
@code{block-close} syntax.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Switch Statement Symbols, Brace List Symbols, Conditional Construct Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Switch Statement Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Switch statements have their own set of syntactic symbols.  Here's an
example:

@example
 1: void spam( enum Ingredient i )
 2: @{
 3:     switch( i ) @{
 4:     case Ham:
 5:         be_a_pig();
 6:         break;
 7:     case Salt:
 8:         drink_some_water();
 9:         break;
10:     default:
11:         @{
12:             what_is_it();
13:             break;
14:         @}
15:     @}
14: @}
@end example

@ssindex case-label
@ssindex statement-case-intro
@ssindex statement-case-open
Here, lines 4, 7, and 10 are all assigned @code{case-label} syntax,
while lines 5 and 8 are assigned @code{statement-case-intro}.  Line 11
is treated slightly differently since it contains a brace that opens a
block; it is given @code{statement-case-open} syntax.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Brace List Symbols, External Scope Symbols, Switch Statement Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Brace List Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex brace lists
There are a set of syntactic symbols that are used to recognize
constructs inside of brace lists.  A brace list is defined as an
@code{enum} or aggregate initializer list, such as might statically
initialize an array of structs.  The three special aggregate constructs
in Pike, @code{(@{ @})}, @code{([ ])} and @code{(< >)}, are treated as
brace lists too.  An example:

@example
 1: static char* ingredients[] =
 2: @{
 3:     "Ham",
 4:     "Salt",
 5:     NULL
 6: @};
@end example

@ssindex brace-list-open
@ssindex brace-list-intro
@ssindex brace-list-close
@ssindex brace-list-entry
Following convention, line 2 in this example is assigned
@code{brace-list-open} syntax, and line 3 is assigned
@code{brace-list-intro} syntax.  Likewise, line 6 is assigned
@code{brace-list-close} syntax.  Lines 4 and 5 however, are assigned
@code{brace-list-entry} syntax, as would all subsequent lines in this
initializer list.

@ssindex brace-entry-open
Your static initializer might be initializing nested structures, for
example:

@example
 1: struct intpairs[] =
 2: @{
 3:     @{ 1, 2 @},
 4:     @{
 5:         3,
 6:         4
 7:     @}
 8:     @{ 1,
 9:       2 @},
10:     @{ 3, 4 @}
11: @};
@end example

Here, you've already seen the analysis of lines 1, 2, 3, and 11.  On
line 4, things get interesting; this line is assigned
@code{brace-entry-open} syntactic symbol because it's a bracelist entry
line that starts with an open brace.  Lines 5 and 6 (and line 9) are
pretty standard, and line 7 is a @code{brace-list-close} as you'd
expect.  Once again, line 8 is assigned as @code{brace-entry-open} as is
line 10.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    External Scope Symbols, Paren List Symbols, Brace List Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection External Scope Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

External language definition blocks also have their own syntactic
symbols.  In this example:

@example
 1: extern "C"
 2: @{
 3:     int thing_one( int );
 4:     int thing_two( double );
 5: @}
@end example

@ssindex extern-lang-open
@ssindex extern-lang-close
@ssindex inextern-lang
@ssindex inclass
@noindent
line 2 is given the @code{extern-lang-open} syntax, while line 5 is given
the @code{extern-lang-close} syntax.  The analysis for line 3 yields:

@example
((inextern-lang) (topmost-intro 14))
@end example

@noindent
where @code{inextern-lang} is a modifier similar in purpose to
@code{inclass}.

There are various other top level blocks like @code{extern}, and they
are all treated in the same way except that the symbols are named after
the keyword that introduces the block.  E.g., C++ namespace blocks get
the three symbols @code{namespace-open}, @code{namespace-close} and
@code{innamespace}.  The currently recognized top level blocks are:

@table @asis
@item @code{extern-lang-open}, @code{extern-lang-close}, @code{inextern-lang}
@code{extern} blocks in C and C++.@footnote{These should logically be
named @code{extern-open}, @code{extern-close} and @code{inextern}, but
that isn't the case for historical reasons.}

@item @code{namespace-open}, @code{namespace-close}, @code{innamespace}
@ssindex namespace-open
@ssindex namespace-close
@ssindex innamespace
@code{namespace} blocks in C++.

@item @code{module-open}, @code{module-close}, @code{inmodule}
@ssindex module-open
@ssindex module-close
@ssindex inmodule
@code{module} blocks in CORBA IDL.

@item @code{composition-open}, @code{composition-close}, @code{incomposition}
@ssindex composition-open
@ssindex composition-close
@ssindex incomposition
@code{composition} blocks in CORBA CIDL.
@end table

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Paren List Symbols, Literal Symbols, External Scope Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Parenthesis (Argument) List Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

A number of syntactic symbols are associated with parenthesis lists,
a.k.a argument lists, as found in function declarations and function
calls.  This example illustrates these:

@example
 1: void a_function( int line1,
 2:                  int line2 );
 3:
 4: void a_longer_function(
 5:     int line1,
 6:     int line2
 7:     );
 8:
 9: void call_them( int line1, int line2 )
10: @{
11:     a_function(
12:         line1,
13:         line2
14:         );
15:
16:     a_longer_function( line1,
17:                        line2 );
18: @}
@end example

@ssindex arglist-intro
@ssindex arglist-close
Lines 5 and 12 are assigned @code{arglist-intro} syntax since they are
the first line following the open parenthesis, and lines 7 and 14 are
assigned @code{arglist-close} syntax since they contain the parenthesis
that closes the argument list.

@ssindex arglist-cont-nonempty
@ssindex arglist-cont
Lines that continue argument lists can be assigned one of two syntactic
symbols.  For example, Lines 2 and 17
are assigned @code{arglist-cont-nonempty} syntax.  What this means
is that they continue an argument list, but that the line containing the
parenthesis that opens the list is @emph{not empty} following the open
parenthesis.  Contrast this against lines 6 and 13 which are assigned
@code{arglist-cont} syntax.  This is because the parenthesis that opens
their argument lists is the last character on that line.

Syntactic elements with @code{arglist-intro},
@code{arglist-cont-nonempty}, and @code{arglist-close} contain two
buffer positions: the anchor position (the beginning of the
declaration or statement) and the position of the open parenthesis.
The latter position can be used in a line-up function (@pxref{Line-Up
Functions}).

Note that there is no @code{arglist-open} syntax.  This is because any
parenthesis that opens an argument list, appearing on a separate line,
is assigned the @code{statement-cont} syntax instead.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Literal Symbols, Multiline Macro Symbols, Paren List Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Comment String Label and Macro Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

A few miscellaneous syntactic symbols that haven't been previously
covered are illustrated by this C++ example:

@example
 1: void Bass::play( int volume )
 2: const
 3: @{
 4:     /* this line starts a multiline
 5:      * comment.  This line should get `c' syntax */
 6:
 7:     char* a_multiline_string = "This line starts a multiline \
 8: string.  This line should get `string' syntax.";
 9:
10:   note:
11:     @{
12: #ifdef LOCK
13:         Lock acquire();
14: #endif // LOCK
15:         slap_pop();
16:         cout << "I played "
17:              << "a note\n";
18:     @}
19: @}
@end example

The lines to note in this example include:

@itemize @bullet
@item
@ssindex func-decl-cont
Line 2 is assigned the @code{func-decl-cont} syntax.

@item
@ssindex comment-intro
Line 4 is assigned both @code{defun-block-intro} @emph{and}
@code{comment-intro} syntax.  A syntactic element with
@code{comment-intro} has no anchor point.  It is always accompanied
by another syntactic element which does have one.

@item
@ssindex c
Line 5 is assigned @code{c} syntax.

@item
@cindex syntactic whitespace
Line 6 which, even though it contains nothing but whitespace, is
assigned @code{defun-block-intro}.  Note that the appearance of the
comment on lines 4 and 5 do not cause line 6 to be assigned
@code{statement} syntax because comments are considered to be
@dfn{syntactic whitespace}, which are ignored when analyzing
code.

@item
@ssindex string
Line 8 is assigned @code{string} syntax.

@item
@ssindex label
Line 10 is assigned @code{label} syntax.

@item
@ssindex block-open
Line 11 is assigned @code{block-open} as well as @code{statement}
syntax.  A @code{block-open} syntactic element doesn't have an anchor
position, since it always appears with another syntactic element which
does have one.

@item
@ssindex cpp-macro
Lines 12 and 14 are assigned @code{cpp-macro} syntax in addition to the
normal syntactic symbols (@code{statement-block-intro} and
@code{statement}, respectively).  Normally @code{cpp-macro} is
configured to cancel out the normal syntactic context to make all
preprocessor directives stick to the first column, but that's easily
changed if you want preprocessor directives to be indented like the rest
of the code.  Like @code{comment-intro}, a syntactic element with
@code{cpp-macro} doesn't contain an anchor position.

@item
@ssindex stream-op
Line 17 is assigned @code{stream-op} syntax.
@end itemize

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Multiline Macro Symbols, Objective-C Method Symbols, Literal Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Multiline Macro Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex multiline macros
@cindex syntactic whitespace
@ssindex cpp-define-intro
@ssindex cpp-macro-cont
Multiline preprocessor macro definitions are normally handled just like
other code, i.e., the lines inside them are indented according to the
syntactic analysis of the preceding lines inside the macro.  The first
line inside a macro definition (i.e., the line after the starting line of
the cpp directive itself) gets @code{cpp-define-intro}.  In this example:

@example
 1: #define LIST_LOOP(cons, listp)                         \
 2:   for (cons = listp; !NILP (cons); cons = XCDR (cons)) \
 3:     if (!CONSP (cons))                                 \
 4:       signal_error ("Invalid list format", listp);     \
 5:     else
@end example

@noindent
line 1 is given the syntactic symbol @code{cpp-macro}.  The first line
of a cpp directive is always given that symbol.  Line 2 is given
@code{cpp-define-intro}, so that you can give the macro body as a whole
some extra indentation.  Lines 3 through 5 are then analyzed as normal
code, i.e., @code{substatement} on lines 3 and 4, and @code{else-clause}
on line 5.

The syntactic analysis inside macros can be turned off with
@code{c-syntactic-indentation-in-macros} (@pxref{Custom Macros}).  In
that case, lines 2 through 5 would all be given @code{cpp-macro-cont}
with an anchor position pointing to the @code{#} which starts the cpp
directive@footnote{This is how @ccmode{} 5.28 and earlier analyzed
macros.}.

@xref{Custom Macros}, for more info about the treatment of macros.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Objective-C Method Symbols, Java Symbols, Multiline Macro Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Objective-C Method Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

In Objective-C buffers, there are three additional syntactic symbols
assigned to various message calling constructs.  Here's an example
illustrating these:

@example
 1: - (void)setDelegate:anObject
 2:           withStuff:stuff
 3: @{
 4:     [delegate masterWillRebind:self
 5:               toDelegate:anObject
 6:               withExtraStuff:stuff];
 7: @}
@end example

@ssindex objc-method-intro
@ssindex objc-method-args-cont
@ssindex objc-method-call-cont
Here, line 1 is assigned @code{objc-method-intro} syntax, and line 2 is
assigned @code{objc-method-args-cont} syntax.  Lines 5 and 6 are both
assigned @code{objc-method-call-cont} syntax.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Java Symbols, Statement Block Symbols, Objective-C Method Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Java Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Java has a concept of anonymous classes which can look something like
this:

@example
 1:  @@Test
 2:  public void watch(Observable o) @{
 3:      @@NonNull
 4:      Observer obs = new Observer() @{
 5:          public void update(Observable o, Object arg) @{
 6:              history.addElement(arg);
 7:          @}
 8:      @};
 9:      o.addObserver(obs);
 10: @}
@end example

@ssindex inexpr-class
The brace following the @code{new} operator opens the anonymous class.
Lines 5 and 8 are assigned the @code{inexpr-class} syntax, besides the
@code{inclass} symbol used in normal classes.  Thus, the class will be
indented just like a normal class, with the added indentation given to
@code{inexpr-class}.  An @code{inexpr-class} syntactic element doesn't
have an anchor position.

@ssindex annotation-top-cont
@ssindex annotation-var-cont
Line 2 is assigned the @code{annotation-top-cont} syntax, due to it being a
continuation of a topmost introduction with an annotation symbol preceding
the current line.  Similarly, line 4 is assigned the @code{annotation-var-cont}
syntax due to it being a continuation of a variable declaration where preceding
the declaration is an annotation.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Statement Block Symbols, K&R Symbols, Java Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection Statement Block Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

There are a few occasions where a statement block might be used inside
an expression.  One is in C or C++ code using the gcc extension for
this, e.g:

@example
 1: int res = (@{
 2:         int y = foo (); int z;
 3:         if (y > 0) z = y; else z = - y;
 4:         z;
 5:     @});
@end example

@ssindex inexpr-statement
Lines 2 and 5 get the @code{inexpr-statement} syntax, besides the
symbols they'd get in a normal block.  Therefore, the indentation put on
@code{inexpr-statement} is added to the normal statement block
indentation.  An @code{inexpr-statement} syntactic element doesn't
contain an anchor position.

In Pike code, there are a few other situations where blocks occur inside
statements, as illustrated here:

@example
 1: array itgob()
 2: @{
 3:     string s = map (backtrace()[-2][3..],
 4:                     lambda
 5:                         (mixed arg)
 6:                     @{
 7:                         return sprintf ("%t", arg);
 8:                     @}) * ", " + "\n";
 9:     return catch @{
10:             write (s + "\n");
11:         @};
12: @}
@end example

@ssindex inlambda
@ssindex lambda-intro-cont
Lines 4 through 8 contain a lambda function, which @ccmode{} recognizes
by the @code{lambda} keyword.  If the function argument list is put
on a line of its own, as in line 5, it gets the @code{lambda-intro-cont}
syntax.  The function body is handled as an inline method body, with the
addition of the @code{inlambda} syntactic symbol.  This means that line
6 gets @code{inlambda} and @code{inline-open}, and line 8 gets
@code{inline-close}@footnote{You might wonder why it doesn't get
@code{inlambda} too.  It's because the closing brace is relative to the
opening brace, which stands on its own line in this example.  If the
opening brace was hanging on the previous line, then the closing brace
would get the @code{inlambda} syntax too to be indented correctly.}.

@ssindex inexpr-statement
On line 9, @code{catch} is a special function taking a statement block
as its argument.  The block is handled as an in-expression statement
with the @code{inexpr-statement} syntax, just like the gcc extended C
example above.  The other similar special function, @code{gauge}, is
handled like this too.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    K&R Symbols,  , Statement Block Symbols, Syntactic Symbols
@comment node-name, next, previous, up
@subsection K&R Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ssindex knr-argdecl-intro
@ssindex knr-argdecl
Two other syntactic symbols can appear in old style, non-prototyped C
code @footnote{a.k.a.@: K&R C, or Kernighan & Ritchie C}:

@example
 1: int add_three_integers(a, b, c)
 2:      int a;
 3:      int b;
 4:      int c;
 5: @{
 6:     return a + b + c;
 7: @}
@end example

Here, line 2 is the first line in an argument declaration list and so is
given the @code{knr-argdecl-intro} syntactic symbol.  Subsequent lines
(i.e., lines 3 and 4 in this example), are given @code{knr-argdecl}
syntax.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Indentation Calculation,  , Syntactic Symbols, Indentation Engine Basics
@comment node-name, next, previous, up
@section Indentation Calculation
@cindex indentation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Indentation for a line is calculated from the syntactic context
(@pxref{Syntactic Analysis}).

First, a buffer position is found whose column will be the base for the
indentation calculation.  It's the anchor position in the first
syntactic element that provides one that is used.  If no syntactic
element has an anchor position then column zero is used.

Second, the syntactic symbols in each syntactic element are looked up
in the @code{c-offsets-alist} style variable
(@pxref{c-offsets-alist}), which is an association list of syntactic
symbols and the offsets to apply for those symbols.  These offsets are
added together with the base column to produce the new indentation
column.

Let's use our two code examples above to see how this works.  Here is
our first example again:

@example
 1: void swap( int& a, int& b )
 2: @{
 3:     int tmp = a;
 4:     a = b;
 5:     b = tmp;
 6: @}
@end example

Let's say point is on line 3 and we hit the @key{TAB} key to reindent
the line.  The syntactic context for that line is:

@example
((defun-block-intro 29))
@end example

@noindent
Since buffer position 29 is the first and only anchor position in the
list, @ccmode{} goes there and asks for the current column.  This brace
is in column zero, so @ccmode{} uses @samp{0} as the base column.

Next, @ccmode{} looks up @code{defun-block-intro} in the
@code{c-offsets-alist} style variable.  Let's say it finds the value
@samp{4}; it adds this to the base column @samp{0}, yielding a running
total indentation of 4 spaces.

Since there is only one syntactic element on the list for this line,
indentation calculation is complete, and the total indentation for the
line is 4 spaces.

Here's another example:

@example
 1: int add( int val, int incr, int doit )
 2: @{
 3:     if( doit )
 4:         @{
 5:             return( val + incr );
 6:         @}
 7:     return( val );
 8: @}
@end example

If we were to hit @kbd{TAB} on line 4 in the above example, the same
basic process is performed, despite the differences in the syntactic
context.  The context for this line is:

@example
((substatement-open 46))
@end example

Here, @ccmode{} goes to buffer position 46, which is the @samp{i} in
@code{if} on line 3.  This character is in the fourth column on that
line so the base column is @samp{4}.  Then @ccmode{} looks up the
@code{substatement-open} symbol in @code{c-offsets-alist}.  Let's say it
finds the value @samp{4}.  It's added with the base column and yields an
indentation for the line of 8 spaces.

Simple, huh?

Actually, it's a bit more complicated than that since the entries on
@code{c-offsets-alist} can be much more than plain offsets.
@xref{c-offsets-alist}, for the full story.

Anyway, the mode usually just does The Right Thing without you having to
think about it in this much detail.  But when customizing indentation,
it's helpful to understand the general indentation model being used.

As you configure @ccmode{}, you might want to set the variable
@code{c-echo-syntactic-information-p} to non-@code{nil} so that the
syntactic context and calculated offset always is echoed in the
minibuffer when you hit @kbd{TAB}.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Customizing Indentation, Custom Macros, Indentation Engine Basics, Top
@comment node-name, next, previous, up
@chapter Customizing Indentation
@cindex customization, indentation
@cindex indentation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The principal variable for customizing indentation is the style
variable @code{c-offsets-alist}, which gives an @dfn{offset} (an
indentation rule) for each syntactic symbol.  Its structure and
semantics are completely described in @ref{c-offsets-alist}.  The
various ways you can set the variable, including the use of the
@ccmode{} style system, are described in @ref{Config Basics} and its
sections, in particular @ref{Style Variables}.

The simplest and most used kind of ``offset'' setting in
@code{c-offsets-alist} is in terms of multiples of
@code{c-basic-offset}:

@defopt c-basic-offset
@vindex basic-offset (c-)
This style variable holds the basic offset between indentation levels.
It's factory default is 4, but all the built-in styles set it
themselves, to some value between 2 (for @code{gnu} style) and 8 (for
@code{bsd}, @code{linux}, and @code{python} styles).
@end defopt

The most flexible ``offset'' setting you can make in
@code{c-offsets-alist} is a line-up function (or even a list of them),
either one supplied by @ccmode{} (@pxref{Line-Up Functions}) or one
you write yourself (@pxref{Custom Line-Up}).

Finally, in @ref{Other Indentation} you'll find the tool of last
resort: a hook which is called after a line has been indented.  You
can install functions here to make ad-hoc adjustments to any line's
indentation.

@menu
* c-offsets-alist::
* Interactive Customization::
* Line-Up Functions::
* Custom Line-Up::
* Other Indentation::
@end menu


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    c-offsets-alist, Interactive Customization, Customizing Indentation, Customizing Indentation
@comment node-name, next, previous, up
@section c-offsets-alist
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

This section explains the structure and semantics of the style
variable @code{c-offsets-alist}, the principal variable for configuring
indentation.  Details of how to set it up, and its relationship to
@ccmode{}'s style system are given in @ref{Style Variables}.

@defopt c-offsets-alist
@vindex offsets-alist (c-)
This is an alist which associates an offset with each syntactic
symbol.  This @dfn{offset} is a rule specifying how to indent a line
whose syntactic context matches the symbol.  @xref{Syntactic
Analysis}.

Note that the buffer-local binding of this alist in a @ccmode{} buffer
contains an entry for @emph{every} syntactic symbol.  Its global
binding and its settings within style specifications usually contain
only a few entries.  @xref{Style Variables}.

The offset specification associated with any particular syntactic
symbol can be an integer, a variable name, a vector, a function or
lambda expression, a list, or one of the following special symbols:
@code{+}, @code{-}, @code{++}, @code{--}, @code{*}, or @code{/}.  The
meanings of these values are described in detail below.

Here is an example fragment of a @code{c-offsets-alist}, showing some
of these kinds of offsets:

@example
((statement . 0)
 (substatement . +)
 (cpp-macro . [0])
 (topmost-intro-cont . c-lineup-topmost-intro-cont)
 (statement-block-intro . (add c-lineup-whitesmith-in-block
                               c-indent-multi-line-block))
 @dots{}
@*)
@end example
@end defopt

@deffn Command c-set-offset (@kbd{C-c C-o})
@findex set-offset (c-)
@kindex C-c C-o
This command changes the entry for a syntactic symbol in the current
binding of @code{c-offsets-alist}, or it inserts a new entry if there
isn't already one for that syntactic symbol.

You can use @code{c-set-offsets} interactively within a @ccmode{}
buffer to make experimental changes to your indentation settings.
@kbd{C-c C-o} prompts you for the syntactic symbol to change
(defaulting to that of the current line) and the new offset
(defaulting to the current offset).

@code{c-set-offsets} takes two arguments when used programmatically:
@var{symbol}, the syntactic element symbol to change and @var{offset},
the new offset for that syntactic element.  You can call the command
in your @file{.emacs} to change the global binding of
@code{c-offsets-alist} (@pxref{Style Variables}); you can use it in a
hook function to make changes from the current style.  @ccmode{}
itself uses this function when initializing styles.
@end deffn

@cindex offset specification
The ``offset specifications'' in @code{c-offsets-alist} can be any of
the following:

@table @asis
@item An integer
The integer specifies a relative offset.  All relative
offsets@footnote{The syntactic context @code{@w{((defun-block-intro
2724) (comment-intro))}} would likely have two relative offsets.} will
be added together and used to calculate the indentation relative to an
anchor position earlier in the buffer.  @xref{Indentation
Calculation}, for details.  Most of the time, it's probably better to
use one of the special symbols like @code{+} than an integer (apart
from zero).

@item One of the symbols @code{+}, @code{-}, @code{++}, @code{--}, @code{*}, or @code{/}
These special symbols describe a relative offset in multiples of
@code{c-basic-offset}:

By defining a style's indentation in terms of @code{c-basic-offset},
you can change the amount of whitespace given to an indentation level
while maintaining the same basic shape of your code.  Here are the
values that the special symbols correspond to:

@table @code
@item +
@code{c-basic-offset} times 1
@item -
@code{c-basic-offset} times @minus{}1
@item ++
@code{c-basic-offset} times 2
@item --
@code{c-basic-offset} times @minus{}2
@item *
@code{c-basic-offset} times 0.5
@item /
@code{c-basic-offset} times @minus{}0.5
@end table

@item A vector
The first element of the vector, an integer, sets the absolute
indentation column.  This will override any previously calculated
indentation, but won't override relative indentation calculated from
syntactic elements later on in the syntactic context of the line being
indented.  @xref{Indentation Calculation}.  Any elements in the vector
beyond the first will be ignored.

@item A function or lambda expression
The function will be called and its return value will in turn be
evaluated as an offset specification.  Functions are useful when more
context than just the syntactic symbol is needed to get the desired
indentation.  @xref{Line-Up Functions}, and @ref{Custom Line-Up}, for
details about them.

@item A symbol with a variable binding
If the symbol also has a function binding, the function takes
precedence over the variable.  Otherwise the value of the variable is
used.  It must be an integer (which is used as relative offset) or a
vector (an absolute offset).

@item A list
The offset can also be a list containing several offset
specifications; these are evaluated recursively and combined.  A list
is typically only useful when some of the offsets are line-up
functions.  A common strategy is calling a sequence of functions in
turn until one of them recognizes that it is appropriate for the
source line and returns a non-@code{nil} value.

@code{nil} values are always ignored when the offsets are combined.
The first element of the list specifies the method of combining the
non-@code{nil} offsets from the remaining elements:

@table @code
@item first
Use the first offset that doesn't evaluate to @code{nil}.  Subsequent
elements of the list don't get evaluated.
@item min
Use the minimum of all the offsets.  All must be either relative or
absolute; they can't be mixed.
@item max
Use the maximum of all the offsets.  All must be either relative or
absolute; they can't be mixed.
@item add
Add all the evaluated offsets together.  Exactly one of them may be
absolute, in which case the result is absolute.  Any relative offsets
that preceded the absolute one in the list will be ignored in that case.
@end table

As a compatibility measure, if the first element is none of the above
then it too will be taken as an offset specification and the whole list
will be combined according to the method @code{first}.
@end table

@vindex c-strict-syntax-p
@vindex strict-syntax-p (c-)
If an offset specification evaluates to @code{nil}, then a relative
offset of 0 (zero) is used@footnote{There is however a variable
@code{c-strict-syntax-p} that when set to non-@code{nil} will cause an
error to be signaled in that case.  It's now considered obsolete since
it doesn't work well with some of the alignment functions that return
@code{nil} instead of zero.  You should therefore leave
@code{c-strict-syntax-p} set to @code{nil}.}.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Interactive Customization, Line-Up Functions, c-offsets-alist, Customizing Indentation
@comment node-name, next, previous, up
@section Interactive Customization
@cindex customization, interactive
@cindex interactive customization
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

As an example of how to customize indentation, let's change the
style of this example@footnote{In this and subsequent examples, the
original code is formatted using the @samp{gnu} style unless otherwise
indicated.  @xref{Styles}.}:

@example
@group
 1: int add( int val, int incr, int doit )
 2: @{
 3:   if( doit )
 4:     @{
 5:       return( val + incr );
 6:     @}
 7:   return( val );
 8: @}
@end group
@end example

@noindent
to:

@example
@group
 1: int add( int val, int incr, int doit )
 2: @{
 3:   if( doit )
 4:   @{
 5:     return( val + incr );
 6:   @}
 7:   return( val );
 8: @}
@end group
@end example

In other words, we want to change the indentation of braces that open a
block following a condition so that the braces line up under the
conditional, instead of being indented.  Notice that the construct we
want to change starts on line 4.  To change the indentation of a line,
we need to see which syntactic symbols affect the offset calculations
for that line.  Hitting @kbd{C-c C-s} on line 4 yields:

@example
((substatement-open 44))
@end example

@noindent
so we know that to change the offset of the open brace, we need to
change the indentation for the @code{substatement-open} syntactic
symbol.

To do this interactively, just hit @kbd{C-c C-o}.  This prompts
you for the syntactic symbol to change, providing a reasonable default.
In this case, the default is @code{substatement-open}, which is just the
syntactic symbol we want to change!

After you hit return, @ccmode{} will then prompt you for the new
offset value, with the old value as the default.  The default in this
case is @samp{+}, but we want no extra indentation so enter
@samp{0} and @kbd{RET}.  This will associate the offset 0 with the
syntactic symbol @code{substatement-open}.

To check your changes quickly, just hit @kbd{C-c C-q}
(@code{c-indent-defun}) to reindent the entire function.  The example
should now look like:

@example
@group
 1: int add( int val, int incr, int doit )
 2: @{
 3:   if( doit )
 4:   @{
 5:     return( val + incr );
 6:   @}
 7:   return( val );
 8: @}
@end group
@end example

Notice how just changing the open brace offset on line 4 is all we
needed to do.  Since the other affected lines are indented relative to
line 4, they are automatically indented the way you'd expect.  For more
complicated examples, this might not always work.  The general approach
to take is to always start adjusting offsets for lines higher up in the
file, then reindent and see if any following lines need further
adjustments.

@c Move this bit to "Styles" (2005/10/7)
@deffn Command c-set-offset symbol offset
@findex set-offset (c-)
@kindex C-c C-o
This is the command bound to @kbd{C-c C-o}.  It provides a convenient
way to set offsets on @code{c-offsets-alist} both interactively (see
the example above) and from your mode hook.

It takes two arguments when used programmatically: @var{symbol} is the
syntactic element symbol to change and @var{offset} is the new offset
for that syntactic element.
@end deffn
@c End of MOVE THIS BIT.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Line-Up Functions, Custom Line-Up, Interactive Customization, Customizing Indentation
@comment node-name, next, previous, up
@section Line-Up Functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex line-up function
@cindex indentation function
Often there are cases when a simple offset setting on a syntactic
symbol isn't enough to get the desired indentation---for example, you
might want to line up a closing parenthesis with the matching opening
one rather than indenting relative to its ``anchor point''.  @ccmode{}
provides this flexibility with @dfn{line-up functions}.

The way you associate a line-up function with a syntactic symbol is
described in @ref{c-offsets-alist}.  @ccmode{} comes with many
predefined line-up functions for common situations.  If none of these
does what you want, you can write your own.  @xref{Custom Line-Up}.
Sometimes, it is easier to tweak the standard indentation by adding a
function to @code{c-special-indent-hook} (@pxref{Other Indentation}).

The line-up functions haven't been adapted for AWK buffers or tested
with them.  Some of them might work serendipitously.  There shouldn't be
any problems writing custom line-up functions for AWK mode.

The calling convention for line-up functions is described fully in
@ref{Custom Line-Up}.  Roughly speaking, the return value is either an
offset itself (such as @code{+} or @code{[0]}) or it's @code{nil},
meaning ``this function is inappropriate in this case; try a
different one''.  @xref{c-offsets-alist}.

The subsections below describe all the standard line-up functions,
categorized by the sort of token the lining-up centers around.  For
each of these functions there is a ``works with'' list that indicates
which syntactic symbols the function is intended to be used with.

@macro workswith
@emph{Works with:@ }
@end macro
@ifinfo
@unmacro workswith
@macro workswith
Works with:
@end macro
@end ifinfo

@macro sssTBasicOffset
<--> @i{c-basic-offset}@c
@end macro

@macro sssTsssTBasicOffset
<--><--> @i{c-basic-offset}@c
@end macro

@macro hereFn{func}
<- @i{\func\}@c
@end macro

@c The TeX backend seems to insert extra spaces around the argument. :P
@iftex
@unmacro hereFn
@macro hereFn{func}
<-@i{\func\}@c
@end macro
@end iftex

@menu
* Brace/Paren Line-Up::
* List Line-Up::
* Operator Line-Up::
* Comment Line-Up::
* Misc Line-Up::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Brace/Paren Line-Up, List Line-Up, Line-Up Functions, Line-Up Functions
@comment node-name, next, previous, up
@subsection Brace and Parenthesis Line-Up Functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The line-up functions here calculate the indentation for braces,
parentheses and statements within brace blocks.

@defun c-lineup-close-paren
@findex lineup-close-paren (c-)
Line up the closing paren under its corresponding open paren if the
open paren is followed by code.  If the open paren ends its line, no
indentation is added.  E.g:

@example
@group
main (int,
      char **
     )                @hereFn{c-lineup-close-paren}
@end group
@end example

@noindent
and

@example
@group
main (
    int, char **
)                     @hereFn{c-lineup-close-paren}
@end group
@end example

As a special case, if a brace block is opened at the same line as the
open parenthesis of the argument list, the indentation is
@code{c-basic-offset} instead of the open paren column.  See
@code{c-lineup-arglist} for further discussion of this ``DWIM'' measure.

@workswith All @code{*-close} symbols.
@end defun

@comment ------------------------------------------------------------

@anchor{c-lineup-arglist-close-under-paren}
@defun c-lineup-arglist-close-under-paren
@findex lineup-arglist-close-under-paren (c-)
Set your @code{arglist-close} syntactic symbol to this line-up function
so that parentheses that close argument lists will line up under the
parenthesis that opened the argument list.  It can also be used with
@code{arglist-cont} and @code{arglist-cont-nonempty} to line up all
lines inside a parenthesis under the open paren.

As a special case, if a brace block is opened at the same line as the
open parenthesis of the argument list, the indentation is
@code{c-basic-offset} only.  See @code{c-lineup-arglist} for further
discussion of this ``DWIM'' measure.

@workswith Almost all symbols, but are typically most useful on
@code{arglist-close}, @code{brace-list-close}, @code{arglist-cont} and
@code{arglist-cont-nonempty}.
@end defun

@comment ------------------------------------------------------------

@defun c-indent-one-line-block
@findex indent-one-line-block (c-)
Indent a one line block @code{c-basic-offset} extra.  E.g:

@example
@group
if (n > 0)
    @{m+=n; n=0;@}      @hereFn{c-indent-one-line-block}
@sssTBasicOffset{}
@end group
@end example

@noindent
and

@example
@group
if (n > 0)
@{                     @hereFn{c-indent-one-line-block}
    m+=n; n=0;
@}
@end group
@end example

The block may be surrounded by any kind of parenthesis characters.
@code{nil} is returned if the line doesn't start with a one line block,
which makes the function usable in list expressions.

@workswith Almost all syntactic symbols, but most useful on the
@code{-open} symbols.
@end defun

@comment ------------------------------------------------------------

@defun c-indent-multi-line-block
@findex indent-multi-line-block (c-)
Indent a multiline block @code{c-basic-offset} extra.  E.g:

@example
@group
int *foo[] = @{
    NULL,
    @{17@},             @hereFn{c-indent-multi-line-block}
@end group
@end example

@noindent
and

@example
@group
int *foo[] = @{
    NULL,
        @{             @hereFn{c-indent-multi-line-block}
        17
        @},
    @sssTBasicOffset{}
@end group
@end example

The block may be surrounded by any kind of parenthesis characters.
@code{nil} is returned if the line doesn't start with a multiline
block, which makes the function usable in list expressions.

@workswith Almost all syntactic symbols, but most useful on the
@code{-open} symbols.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-runin-statements
@findex lineup-runin-statements (c-)
Line up statements for coding standards which place the first statement
in a block on the same line as the block opening brace@footnote{Run-in
style doesn't really work too well.  You might need to write your own
custom line-up functions to better support this style.}.  E.g:

@example
@group
int main()
@{ puts ("Hello!");
  return 0;           @hereFn{c-lineup-runin-statements}
@}
@end group
@end example

If there is no statement after the opening brace to align with,
@code{nil} is returned.  This makes the function usable in list
expressions.

@workswith The @code{statement} syntactic symbol.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-inexpr-block
@findex lineup-inexpr-block (c-)
This can be used with the in-expression block symbols to indent the
whole block to the column where the construct is started.  E.g., for Java
anonymous classes, this lines up the class under the @samp{new} keyword,
and in Pike it lines up the lambda function body under the @samp{lambda}
keyword.  Returns @code{nil} if the block isn't part of such a
construct.

@workswith @code{inlambda}, @code{inexpr-statement},
@code{inexpr-class}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-after-whitesmith-blocks
@findex lineup-after-whitesmith-blocks (c-)
Compensate for Whitesmith style indentation of blocks.  Due to the way
@ccmode{} calculates anchor positions for normal lines inside blocks,
this function is necessary for those lines to get correct Whitesmith
style indentation.  Consider the following examples:

@example
@group
int foo()
    @{
    a;
    x;                 @hereFn{c-lineup-after-whitesmith-blocks}
@end group
@end example

@example
@group
int foo()
    @{
        @{
        a;
        @}
    x;                 @hereFn{c-lineup-after-whitesmith-blocks}
@end group
@end example

The fact that the line with @code{x} is preceded by a Whitesmith style
indented block in the latter case and not the first should not affect
its indentation.  But since CC Mode in cases like this uses the
indentation of the preceding statement as anchor position, the @code{x}
would in the second case be indented too much if the offset for
@code{statement} was set simply to zero.

This lineup function corrects for this situation by detecting if the
anchor position is at an open paren character.  In that case, it instead
indents relative to the surrounding block just like
@code{c-lineup-whitesmith-in-block}.

@workswith @code{brace-list-entry}, @code{brace-entry-open},
@code{statement}, @code{arglist-cont}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-whitesmith-in-block
@findex lineup-whitesmith-in-block (c-)
Line up lines inside a block in Whitesmith style.  It's done in a way
that works both when the opening brace hangs and when it doesn't.  E.g:

@example
@group
something
    @{
    foo;              @hereFn{c-lineup-whitesmith-in-block}
    @}
@end group
@end example

@noindent
and

@example
@group
something @{
    foo;              @hereFn{c-lineup-whitesmith-in-block}
    @}
@sssTBasicOffset{}
@end group
@end example

In the first case the indentation is kept unchanged, in the second
@code{c-basic-offset} is added.

@workswith @code{defun-close}, @code{defun-block-intro},
@code{inline-close}, @code{block-close}, @code{brace-list-close},
@code{brace-list-intro}, @code{statement-block-intro},
@code{arglist-intro}, @code{arglist-cont-nonempty},
@code{arglist-close}, and all @code{in*} symbols, e.g., @code{inclass}
and @code{inextern-lang}.
@end defun

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    List Line-Up, Operator Line-Up, Brace/Paren Line-Up, Line-Up Functions
@comment node-name, next, previous, up
@subsection List Line-Up Functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The line-up functions here calculate the indentation for lines which
form lists of items, usually separated by commas.

The function @ref{c-lineup-arglist-close-under-paren}, which is mainly
for indenting a close parenthesis, is also useful for the lines
contained within parentheses.

@defun c-lineup-arglist
@findex lineup-arglist (c-)
Line up the current argument line under the first argument.

As a special case, if an argument on the same line as the open
parenthesis starts with a brace block opener, the indentation is
@code{c-basic-offset} only.  This is intended as a ``DWIM'' measure in
cases like macros that contain statement blocks, e.g:

@example
@group
A_VERY_LONG_MACRO_NAME (@{
        some (code, with + long, lines * in[it]);
    @});
@sssTBasicOffset{}
@end group
@end example

This is motivated partly because it's more in line with how code
blocks are handled, and partly since it approximates the behavior of
earlier CC Mode versions, which due to inaccurate analysis tended to
indent such cases this way.

@workswith @code{arglist-cont-nonempty}, @code{arglist-close}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-arglist-intro-after-paren
@findex lineup-arglist-intro-after-paren (c-)
Line up a line to just after the open paren of the surrounding paren or
brace block.

@workswith @code{defun-block-intro}, @code{brace-list-intro},
@code{statement-block-intro}, @code{statement-case-intro},
@code{arglist-intro}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-multi-inher
@findex lineup-multi-inher (c-)
Line up the classes in C++ multiple inheritance clauses and member
initializers under each other.  E.g:

@example
@group
Foo::Foo (int a, int b):
    Cyphr (a),
    Bar (b)           @hereFn{c-lineup-multi-inher}
@end group
@end example

@noindent
and

@example
@group
class Foo
    : public Cyphr,
      public Bar      @hereFn{c-lineup-multi-inher}
@end group
@end example

@noindent
and

@example
@group
Foo::Foo (int a, int b)
    : Cyphr (a)
    , Bar (b)         @hereFn{c-lineup-multi-inher}
@end group
@end example

@workswith @code{inher-cont}, @code{member-init-cont}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-java-inher
@findex lineup-java-inher (c-)
Line up Java implements and extends declarations.  If class names
follow on the same line as the @samp{implements}/@samp{extends}
keyword, they are lined up under each other.  Otherwise, they are
indented by adding @code{c-basic-offset} to the column of the keyword.
E.g:

@example
@group
class Foo
    extends
        Bar           @hereFn{c-lineup-java-inher}
    @sssTBasicOffset{}
@end group
@end example

@noindent
and

@example
@group
class Foo
    extends Cyphr,
            Bar       @hereFn{c-lineup-java-inher}
@end group
@end example

@workswith @code{inher-cont}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-java-throws
@findex lineup-java-throws (c-)
Line up Java throws declarations.  If exception names follow on the
same line as the throws keyword, they are lined up under each other.
Otherwise, they are indented by adding @code{c-basic-offset} to the
column of the @samp{throws} keyword.  The @samp{throws} keyword itself
is also indented by @code{c-basic-offset} from the function declaration
start if it doesn't hang.  E.g:

@example
@group
int foo()
    throws            @hereFn{c-lineup-java-throws}
        Bar           @hereFn{c-lineup-java-throws}
@sssTsssTBasicOffset{}
@end group
@end example

@noindent
and

@example
@group
int foo() throws Cyphr,
                 Bar,    @hereFn{c-lineup-java-throws}
                 Vlod    @hereFn{c-lineup-java-throws}
@end group
@end example

@workswith @code{func-decl-cont}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-template-args
@findex lineup-template-args (c-)
Line up the arguments of a template argument list under each other, but
only in the case where the first argument is on the same line as the
opening @samp{<}.

To allow this function to be used in a list expression, @code{nil} is
returned if there's no template argument on the first line.

@workswith @code{template-args-cont}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-ObjC-method-call
@findex lineup-ObjC-method-call (c-)
For Objective-C code, line up selector args as Emacs Lisp mode does
with function args: go to the position right after the message receiver,
and if you are at the end of the line, indent the current line
c-basic-offset columns from the opening bracket; otherwise you are
looking at the first character of the first method call argument, so
lineup the current line with it.

@workswith @code{objc-method-call-cont}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-ObjC-method-args
@findex lineup-ObjC-method-args (c-)
For Objective-C code, line up the colons that separate args.  The colon
on the current line is aligned with the one on the first line.

@workswith @code{objc-method-args-cont}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-ObjC-method-args-2
@findex lineup-ObjC-method-args-2 (c-)
Similar to @code{c-lineup-ObjC-method-args} but lines up the colon on
the current line with the colon on the previous line.

@workswith @code{objc-method-args-cont}.
@end defun

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Operator Line-Up, Comment Line-Up, List Line-Up, Line-Up Functions
@comment node-name, next, previous, up
@subsection Operator Line-Up Functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The line-up functions here calculate the indentation for lines which
start with an operator, by lining it up with something on the previous
line.

@defun c-lineup-argcont
@findex lineup-argcont (c-)
Line up a continued argument.  E.g:

@example
@group
foo (xyz, aaa + bbb + ccc
          + ddd + eee + fff);  @hereFn{c-lineup-argcont}
@end group
@end example

Only continuation lines like this are touched, @code{nil} is returned on
lines which are the start of an argument.

Within a gcc @code{asm} block, @code{:} is recognized as an argument
separator, but of course only between operand specifications, not in the
expressions for the operands.

@workswith @code{arglist-cont}, @code{arglist-cont-nonempty}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-arglist-operators
@findex lineup-arglist-operators (c-)
Line up lines starting with an infix operator under the open paren.
Return @code{nil} on lines that don't start with an operator, to leave
those cases to other line-up functions.  Example:

@example
@group
if (  x < 10
   || at_limit (x,     @hereFn{c-lineup-arglist-operators}
                list)  @hereFn{c-lineup-arglist-operators@r{ returns nil}}
   )
@end group
@end example

Since this function doesn't do anything for lines without an infix
operator you typically want to use it together with some other lineup
settings, e.g., as follows (the @code{arglist-close} setting is just a
suggestion to get a consistent style):

@example
(c-set-offset 'arglist-cont
              '(c-lineup-arglist-operators 0))
(c-set-offset 'arglist-cont-nonempty
              '(c-lineup-arglist-operators c-lineup-arglist))
(c-set-offset 'arglist-close
              '(c-lineup-arglist-close-under-paren))
@end example

@workswith @code{arglist-cont}, @code{arglist-cont-nonempty}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-assignments
@findex lineup-assignments (c-)
Line up the current line after the assignment operator on the first line
in the statement.  If there isn't any, return nil to allow stacking with
other line-up functions.  If the current line contains an assignment
operator too, try to align it with the first one.

@workswith @code{topmost-intro-cont}, @code{statement-cont},
@code{arglist-cont}, @code{arglist-cont-nonempty}.

@end defun

@comment ------------------------------------------------------------

@defun c-lineup-math
@findex lineup-math (c-)
Like @code{c-lineup-assignments} but indent with @code{c-basic-offset}
if no assignment operator was found on the first line.  I.e., this
function is the same as specifying a list @code{(c-lineup-assignments
+)}.  It's provided for compatibility with old configurations.

@workswith @code{topmost-intro-cont}, @code{statement-cont},
@code{arglist-cont}, @code{arglist-cont-nonempty}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-cascaded-calls
@findex lineup-cascaded-calls (c-)
Line up ``cascaded calls'' under each other.  If the line begins with
@code{->} or @code{.} and the preceding line ends with one or more
function calls preceded by the same token, then the arrow is lined up
with the first of those tokens.  E.g:

@example
@group
r = proc->add(17)->add(18)
        ->add(19) +         @hereFn{c-lineup-cascaded-calls}
  offset;                   @hereFn{c-lineup-cascaded-calls@r{ (inactive)}}
@end group
@end example

In any other situation @code{nil} is returned to allow use in list
expressions.

@workswith @code{topmost-intro-cont}, @code{statement-cont},
@code{arglist-cont}, @code{arglist-cont-nonempty}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-streamop
@findex lineup-streamop (c-)
Line up C++ stream operators (i.e., @samp{<<} and @samp{>>}).

@workswith @code{stream-op}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-string-cont
@findex lineup-string-cont (c-)
Line up a continued string under the one it continues.  A continued
string in this sense is where a string literal follows directly after
another one.  E.g:

@example
@group
result = prefix + "A message "
                  "string.";    @hereFn{c-lineup-string-cont}
@end group
@end example

@code{nil} is returned in other situations, to allow stacking with other
lineup functions.

@workswith @code{topmost-intro-cont}, @code{statement-cont},
@code{arglist-cont}, @code{arglist-cont-nonempty}.
@end defun


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Comment Line-Up, Misc Line-Up, Operator Line-Up, Line-Up Functions
@comment node-name, next, previous, up
@subsection Comment Line-Up Functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The lineup functions here calculate the indentation for several types
of comment structure.

@defun c-lineup-C-comments
@findex lineup-C-comments (c-)
Line up C block comment continuation lines.  Various heuristics are used
to handle most of the common comment styles.  Some examples:

@example
@group
/*                 /**               /*
 * text             * text             text
 */                 */               */
@end group
@end example

@example
@group
/* text            /*                /**
   text            ** text            ** text
*/                 */                 */
@end group
@end example

@example
@group
/**************************************************
 * text
 *************************************************/
@end group
@end example

@vindex comment-start-skip
@example
@group
/**************************************************
    Free form text comments:
 In comments with a long delimiter line at the
 start, the indentation is kept unchanged for lines
 that start with an empty comment line prefix.  The
 delimiter line is whatever matches the
 @code{comment-start-skip} regexp.
**************************************************/
@end group
@end example

The style variable @code{c-comment-prefix-regexp} is used to recognize
the comment line prefix, e.g., the @samp{*} that usually starts every
line inside a comment.

@workswith The @code{c} syntactic symbol.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-comment
@findex lineup-comment (c-)
Line up a comment-only line according to the style variable
@code{c-comment-only-line-offset}.  If the comment is lined up with a
comment starter on the previous line, that alignment is preserved.

@defopt c-comment-only-line-offset
@vindex comment-only-line-offset (c-)
This style variable specifies the extra offset for the line.  It can
contain an integer or a cons cell of the form

@example
(@r{@var{non-anchored-offset}} . @r{@var{anchored-offset}})
@end example

@noindent
where @var{non-anchored-offset} is the amount of offset given to
non-column-zero anchored lines, and @var{anchored-offset} is the amount
of offset to give column-zero anchored lines.  Just an integer as value
is equivalent to @code{(@r{@var{value}} . -1000)}.
@end defopt

@workswith @code{comment-intro}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-knr-region-comment
@findex lineup-knr-region-comment (c-)
Line up a comment in the ``K&R region'' with the declaration.  That is
the region between the function or class header and the beginning of the
block.  E.g:

@example
@group
int main()
/* Called at startup. */  @hereFn{c-lineup-knr-region-comment}
@{
  return 0;
@}
@end group
@end example

Return @code{nil} if called in any other situation, to be useful in list
expressions.

@workswith @code{comment-intro}.
@end defun

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Misc Line-Up,  , Comment Line-Up, Line-Up Functions
@comment node-name, next, previous, up
@subsection Miscellaneous Line-Up Functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The line-up functions here are the odds and ends which didn't fit into
any earlier category.

@defun c-lineup-dont-change
@findex lineup-dont-change (c-)
This lineup function makes the line stay at whatever indentation it
already has; think of it as an identity function for lineups.

@workswith Any syntactic symbol.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-cpp-define
@findex lineup-cpp-define (c-)
Line up macro continuation lines according to the indentation of the
construct preceding the macro.  E.g:

@example
@group
const char msg[] =    @hereFn{@r{The beginning of the preceding construct.}}
  \"Some text.\";

#define X(A, B)  \
do @{             \    @hereFn{c-lineup-cpp-define}
  printf (A, B); \
@} while (0)
@end group
@end example

@noindent
and:

@example
@group
int dribble() @{
  if (!running)       @hereFn{@r{The beginning of the preceding construct.}}
    error(\"Not running!\");

#define X(A, B)    \
  do @{             \  @hereFn{c-lineup-cpp-define}
    printf (A, B); \
  @} while (0)
@end group
@end example

If @code{c-syntactic-indentation-in-macros} is non-@code{nil}, the
function returns the relative indentation to the macro start line to
allow accumulation with other offsets.  E.g., in the following cases,
@code{cpp-define-intro} is combined with the
@code{statement-block-intro} that comes from the @samp{do @{} that hangs
on the @samp{#define} line:

@example
@group
const char msg[] =
  \"Some text.\";

#define X(A, B) do @{ \
  printf (A, B);     \  @hereFn{c-lineup-cpp-define}
  this->refs++;      \
@} while (0)             @hereFn{c-lineup-cpp-define}
@end group
@end example

@noindent
and:

@example
@group
int dribble() @{
  if (!running)
    error(\"Not running!\");

#define X(A, B) do @{ \
    printf (A, B);   \  @hereFn{c-lineup-cpp-define}
    this->refs++;    \
  @} while (0)           @hereFn{c-lineup-cpp-define}
@end group
@end example

The relative indentation returned by @code{c-lineup-cpp-define} is zero
and two, respectively, on the two lines in each of these examples.  They
are then added to the two column indentation that
@code{statement-block-intro} gives in both cases here.

If the relative indentation is zero, then @code{nil} is returned
instead.  That is useful in a list expression to specify the default
indentation on the top level.

If @code{c-syntactic-indentation-in-macros} is @code{nil} then this
function keeps the current indentation, except for empty lines (ignoring
the ending backslash) where it takes the indentation from the closest
preceding nonempty line in the macro.  If there's no such line in the
macro then the indentation is taken from the construct preceding it, as
described above.

@workswith @code{cpp-define-intro}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-gcc-asm-reg
@findex lineup-gcc-asm-reg (c-)
Line up a gcc asm register under one on a previous line.

@example
@group
    asm ("foo %1, %0\n"
         "bar %0, %1"
         : "=r" (w),
           "=r" (x)
         :  "0" (y),
            "1" (z));
@end group
@end example

The @samp{x} line is aligned to the text after the @samp{:} on the
@samp{w} line, and similarly @samp{z} under @samp{y}.

This is done only in an @samp{asm} or @samp{__asm__} block, and only to
those lines mentioned.  Anywhere else @code{nil} is returned.  The usual
arrangement is to have this routine as an extra feature at the start of
arglist lineups, e.g.:

@example
(c-lineup-gcc-asm-reg c-lineup-arglist)
@end example

@workswith @code{arglist-cont}, @code{arglist-cont-nonempty}.
@end defun

@comment ------------------------------------------------------------

@defun c-lineup-topmost-intro-cont
@findex lineup-topmost-intro-cont (c-)
Line up declaration continuation lines zero or one indentation
step@footnote{This function is mainly provided to mimic the behavior of
CC Mode 5.28 and earlier where this case wasn't handled consistently so
that those lines could be analyzed as either topmost-intro-cont or
statement-cont.  It's used for @code{topmost-intro-cont} by default, but
you might consider using @code{+} instead.}.  For lines preceding a
definition, zero is used.  For other lines, @code{c-basic-offset} is
added to the indentation.  E.g:

@example
@group
int
neg (int i)           @hereFn{c-lineup-topmost-intro-cont}
@{
    return -i;
@}
@end group
@end example

@noindent
and

@example
@group
struct
larch                 @hereFn{c-lineup-topmost-intro-cont}
@{
    double height;
@}
    the_larch,        @hereFn{c-lineup-topmost-intro-cont}
    another_larch;    @hereFn{c-lineup-topmost-intro-cont}
@sssTBasicOffset{}
@end group
@end example

@noindent
and

@example
@group
struct larch
the_larch,            @hereFn{c-lineup-topmost-intro-cont}
    another_larch;    @hereFn{c-lineup-topmost-intro-cont}
@end group
@end example

@workswith @code{topmost-intro-cont}.
@end defun

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Custom Line-Up, Other Indentation, Line-Up Functions, Customizing Indentation
@comment node-name, next, previous, up
@section Custom Line-Up Functions
@cindex customization, indentation functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The most flexible way to customize indentation is by writing custom
line-up functions, and associating them with specific syntactic
symbols (@pxref{c-offsets-alist}).  Depending on the effect you want,
it might be better to write a @code{c-special-indent-hook} function
rather than a line-up function (@pxref{Other Indentation}).

@ccmode{} comes with an extensive set of predefined line-up functions,
not all of which are used by the default styles.  So there's a good
chance the function you want already exists.  @xref{Line-Up
Functions}, for a list of them.  If you write your own line-up
function, it's probably a good idea to start working from one of these
predefined functions, which can be found in the file
@file{cc-align.el}.  If you have written a line-up function that you
think is generally useful, you're very welcome to contribute it;
please contact @email{bug-cc-mode@@gnu.org}.

   Line-up functions are passed a single argument, the syntactic
element (see below).  The return value is a @code{c-offsets-alist}
offset specification: for example, an integer, a symbol such as
@code{+}, a vector, @code{nil}@footnote{Returning @code{nil} is useful
when the offset specification for a syntactic element is a list
containing the line-up function (@pxref{c-offsets-alist}).}, or even
another line-up function.  Full details of these are in
@ref{c-offsets-alist}.

Line-up functions must not move point or change the content of the
buffer (except temporarily).  They are however allowed to do
@dfn{hidden buffer changes}, i.e., setting text properties for caching
purposes etc.  Buffer undo recording is disabled while they run.

The syntactic element passed as the parameter to a line-up function is
a cons cell of the form

@example
(@r{@var{syntactic-symbol}} . @r{@var{anchor-position}})
@end example

@noindent
@c FIXME!!! The following sentence might be better omitted, since the
@c information is in the cross reference "Syntactic Analysis".  2005/10/2.
where @var{syntactic-symbol} is the symbol that the function was
called for, and @var{anchor-position} is the anchor position (if any)
for the construct that triggered the syntactic symbol
(@pxref{Syntactic Analysis}).  This cons cell is how the syntactic
element of a line used to be represented in @ccmode{} 5.28 and
earlier.  Line-up functions are still passed this cons cell, so as to
preserve compatibility with older configurations.  In the future, we
may decide to convert to using the full list format---you can prepare
your setup for this by using the access functions
(@code{c-langelem-sym}, etc.)  described below.

@vindex c-syntactic-element
@vindex syntactic-element (c-)
@vindex c-syntactic-context
@vindex syntactic-context (c-)
Some syntactic symbols, e.g., @code{arglist-cont-nonempty}, have more
info in the syntactic element: typically other positions that can be
interesting besides the anchor position.  That info can't be accessed
through the passed argument, which is a cons cell.  Instead, you can
get this information from the variable @code{c-syntactic-element},
which is dynamically bound to the complete syntactic element.  The
variable @code{c-syntactic-context} might also be useful: it gets
dynamically bound to the complete syntactic context.  @xref{Custom
Braces}.

@ccmode{} provides a few functions to access parts of syntactic
elements in a more abstract way.  Besides making the code easier to
read, they also hide the difference between the old cons cell form
used in the line-up function argument and the new list form used in
@code{c-syntactic-element} and everywhere else.  The functions are:

@defun c-langelem-sym langelem
@findex langelem-sym (c-)
Return the syntactic symbol in @var{langelem}.
@end defun

@defun c-langelem-pos langelem
@findex langelem-pos (c-)
Return the anchor position in @var{langelem}, or nil if there is none.
@end defun

@defun c-langelem-col langelem &optional preserve-point
@findex langelem-col (c-)
Return the column of the anchor position in @var{langelem}.  Also move
the point to that position unless @var{preserve-point} is
non-@code{nil}.
@end defun

@defun c-langelem-2nd-pos langelem
@findex langelem-2nd-pos (c-)
Return the secondary position in @var{langelem}, or @code{nil} if there
is none.

Note that the return value of this function is always @code{nil} if
@var{langelem} is in the old cons cell form.  Thus this function is
only meaningful when used on syntactic elements taken from
@code{c-syntactic-element} or @code{c-syntactic-context}.
@end defun

Custom line-up functions can be as simple or as complex as you like, and
any syntactic symbol that appears in @code{c-offsets-alist} can have a
custom line-up function associated with it.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Other Indentation,  , Custom Line-Up, Customizing Indentation
@comment node-name, next, previous, up
@section Other Special Indentations
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

To configure macros which you invoke without a terminating @samp{;},
see @xref{Macros with ;}.

Here are the remaining odds and ends regarding indentation:

@defopt c-label-minimum-indentation
@vindex label-minimum-indentation (c-)
In @samp{gnu} style (@pxref{Built-in Styles}), a minimum indentation is
imposed on lines inside code blocks.  This minimum indentation is
controlled by this style variable.  The default value is 1.

@findex c-gnu-impose-minimum
@findex gnu-impose-minimum (c-)
It's the function @code{c-gnu-impose-minimum} that enforces this minimum
indentation.  It must be present on @code{c-special-indent-hook} to
work.
@end defopt

@defopt c-special-indent-hook
@vindex special-indent-hook (c-)
This style variable is a standard hook variable that is called after
every line is indented by @ccmode{}.  It is called only if
@code{c-syntactic-indentation} is non-@code{nil} (which it is by
default (@pxref{Indentation Engine Basics})).  You can put a function
on this hook to do any special indentation or ad hoc line adjustments
your style dictates, such as adding extra indentation to constructors
or destructor declarations in a class definition, etc.  Sometimes it
is better to write a custom Line-up Function instead (@pxref{Custom
Line-Up}).

When the indentation engine calls this hook, the variable
@code{c-syntactic-context} is bound to the current syntactic context
(i.e., what you would get by typing @kbd{C-c C-s} on the source line.
@xref{Custom Braces}.).  Note that you should not change point or mark
inside a @code{c-special-indent-hook} function, i.e., you'll probably
want to wrap your function in a @code{save-excursion}@footnote{The
numerical value returned by @code{point} will change if you change the
indentation of the line within a @code{save-excursion} form, but point
itself will still be over the same piece of text.}.

Setting @code{c-special-indent-hook} in style definitions is handled
slightly differently from other variables---A style can only add
functions to this hook, not remove them.  @xref{Style Variables}.
@end defopt


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Custom Macros, Odds and Ends, Customizing Indentation, Top
@comment node-name, next, previous, up
@chapter Customizing Macros
@cindex macros
@cindex preprocessor directives
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Preprocessor macros in C, C++, and Objective C (introduced by
@code{#define}) have a syntax different from the main language---for
example, a macro declaration is not terminated by a semicolon, and if
it is more than a line long, line breaks in it must be escaped with
backslashes.  @ccmode{} has some commands to manipulate these, see
@ref{Macro Backslashes}.

Normally, the lines in a multi-line macro are indented relative to
each other as though they were code.  You can suppress this behavior
by setting the following user option:

@defopt c-syntactic-indentation-in-macros
@vindex syntactic-indentation-in-macros (c-)
Enable syntactic analysis inside macros, which is the default.  If this
is @code{nil}, all lines inside macro definitions are analyzed as
@code{cpp-macro-cont}.
@end defopt

Because a macro can expand into anything at all, near where one is
invoked @ccmode{} can only indent and fontify code heuristically.
Sometimes it gets it wrong.  Usually you should try to design your
macros so that they ''look like ordinary code'' when you invoke them.
However, one situation is so common that @ccmode{} handles it
specially: that is when certain macros needn't (or mustn't) be
followed by a @samp{;}.  You need to configure @ccmode{} to handle
these macros properly, see @ref{Macros with ;}.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@menu
* Macro Backslashes::
* Macros with ;::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Macro Backslashes, Macros with ;, Custom Macros, Custom Macros
@comment  node-name,  next,  previous,  up
@section Customizing Macro Backslashes
@cindex @code{#define}
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ccmode{} provides some tools to help keep the line continuation
backslashes in macros neat and tidy.  Their precise action is
customized with these variables:

@defopt c-backslash-column
@vindex backslash-column (c-)
@defoptx c-backslash-max-column
@vindex backslash-max-column (c-)
These variables control the alignment columns for line continuation
backslashes in multiline macros.  They are used by the functions that
automatically insert or align such backslashes,
e.g., @code{c-backslash-region} and @code{c-context-line-break}.

@code{c-backslash-column} specifies the minimum column for the
backslashes.  If any line in the macro goes past this column, then the
next tab stop (i.e., next multiple of @code{tab-width}) in that line is
used as the alignment column for all the backslashes, so that they
remain in a single column.  However, if any lines go past
@code{c-backslash-max-column} then the backslashes in the rest of the
macro will be kept at that column, so that the lines which are too
long ``stick out'' instead.

Don't ever set these variables to @code{nil}.  If you want to disable
the automatic alignment of backslashes, use
@code{c-auto-align-backslashes}.
@end defopt

@defopt c-auto-align-backslashes
@vindex auto-align-backslashes (c-)
Align automatically inserted line continuation backslashes if
non-@code{nil}.  When line continuation backslashes are inserted
automatically for line breaks in multiline macros, e.g., by
@code{c-context-line-break}, they are aligned with the other
backslashes in the same macro if this flag is set.

If @code{c-auto-align-backslashes} is @code{nil}, automatically
inserted backslashes are preceded by a single space, and backslashes
get aligned only when you explicitly invoke the command
@code{c-backslash-region} (@kbd{C-c C-\}).
@end defopt

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Macros with ;,  , Macro Backslashes, Custom Macros
@comment  node-name,  next,  previous,  up
@section Macros with semicolons
@cindex macros with semicolons
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Macros which needn't (or mustn't) be followed by a semicolon when you
invoke them, @dfn{macros with semicolons}, are very common.  These can
cause @ccmode{} to parse the next line wrongly as a
@code{statement-cont} (@pxref{Function Symbols}) and thus mis-indent
it.

You can prevent this by specifying which macros have semicolons.  It
doesn't matter whether or not such a macro has a parameter list:

@defopt c-macro-names-with-semicolon
@vindex macro-names-with-semicolon (c-)
This buffer-local variable specifies which macros have semicolons.
After setting its value, you need to call
@code{c-make-macro-with-semi-re} for it to take effect.  It should be
set to one of these values:

@table @asis
@item nil
There are no macros with semicolons.
@item a list of strings
Each string is the name of a macro with a semicolon.  Only valid
@code{#define} names are allowed here.  For example, to set the
default value, you could write the following into your @file{.emacs}:

@example
(setq c-macro-names-with-semicolon
      '("Q_OBJECT" "Q_PROPERTY" "Q_DECLARE" "Q_ENUMS"))
@end example

@item a regular expression
This matches each symbol which is a macro with a semicolon.  It must
not match any string which isn't a valid @code{#define} name.  For
example:

@example
(setq c-macro-names-with-semicolon
      "\\<\\(CLEAN_UP_AND_RETURN\\|Q_[[:upper:]]+\\)\\>")
@end example
@end table
@end defopt

@defun c-make-macro-with-semi-re
@findex make-macro-with-semi-re (c-)
Call this (non-interactive) function, which sets internal variables,
each time you change the value of
@code{c-macro-names-with-semicolon}.  It takes no arguments, and its
return value has no meaning.  This function is called by @ccmode{}'s
initialization code.
@end defun

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Odds and Ends, Sample .emacs File, Custom Macros, Top
@comment node-name, next, previous, up
@chapter Odds and Ends
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The stuff that didn't fit in anywhere else is documented here.

@defopt c-require-final-newline
@vindex require-final-newline (c-)
Controls whether a final newline is enforced when the file is saved.
The value is an association list that for each language mode specifies
the value to give to @code{require-final-newline} (@pxref{Saving
Buffers,,,@lispref{}, @lispreftitle{}}) at mode initialization.  If a
language isn't present on the association list, CC Mode won't touch
@code{require-final-newline} in buffers for that language.

The default is to set @code{require-final-newline} to @code{t} in the
languages that mandate that source files should end with newlines.
These are C, C++ and Objective-C.
@end defopt

@defopt c-echo-syntactic-information-p
@vindex echo-syntactic-information-p (c-)
If non-@code{nil}, the syntactic analysis for the current line is shown
in the echo area when it's indented (unless
@code{c-syntactic-indentation} is @code{nil}).  That's useful when
finding out which syntactic symbols to modify to get the indentation you
want.
@end defopt

@defopt c-report-syntactic-errors
@vindex report-syntactic-errors (c-)
If non-@code{nil}, certain syntactic errors are reported with a ding and
a message, for example when an @code{else} is indented for which there
is no corresponding @code{if}.

Note however that @ccmode{} doesn't make any special effort to check for
syntactic errors; that's the job of the compiler.  The reason it can
report cases like the one above is that it can't find the correct
anchoring position to indent the line in that case.
@end defopt


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Sample .emacs File, Performance Issues, Odds and Ends, Top
@comment node-name, next, previous, up
@appendix Sample .emacs File
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Here's a sample .emacs file fragment that might help you along the way.
Just copy this region and paste it into your .emacs file.  You might want
to change some of the actual values.

@verbatim
;; Make a non-standard key binding.  We can put this in
;; c-mode-base-map because c-mode-map, c++-mode-map, and so on,
;; inherit from it.
(defun my-c-initialization-hook ()
  (define-key c-mode-base-map "\C-m" 'c-context-line-break))
(add-hook 'c-initialization-hook 'my-c-initialization-hook)

;; offset customizations not in my-c-style
;; This will take precedence over any setting of the syntactic symbol
;; made by a style.
(setq c-offsets-alist '((member-init-intro . ++)))

;; Create my personal style.
(defconst my-c-style
  '((c-tab-always-indent        . t)
    (c-comment-only-line-offset . 4)
    (c-hanging-braces-alist     . ((substatement-open after)
                                   (brace-list-open)))
    (c-hanging-colons-alist     . ((member-init-intro before)
                                   (inher-intro)
                                   (case-label after)
                                   (label after)
                                   (access-label after)))
    (c-cleanup-list             . (scope-operator
                                   empty-defun-braces
                                   defun-close-semi))
    (c-offsets-alist            . ((arglist-close . c-lineup-arglist)
                                   (substatement-open . 0)
                                   (case-label        . 4)
                                   (block-open        . 0)
                                   (knr-argdecl-intro . -)))
    (c-echo-syntactic-information-p . t))
  "My C Programming Style")
(c-add-style "PERSONAL" my-c-style)

;; Customizations for all modes in CC Mode.
(defun my-c-mode-common-hook ()
  ;; set my personal style for the current buffer
  (c-set-style "PERSONAL")
  ;; other customizations
  (setq tab-width 8
        ;; this will make sure spaces are used instead of tabs
        indent-tabs-mode nil)
  ;; we like auto-newline, but not hungry-delete
  (c-toggle-auto-newline 1))
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
@end verbatim

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Performance Issues, Limitations and Known Bugs, Sample .emacs File, Top
@comment node-name, next, previous, up
@chapter Performance Issues
@cindex performance
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@comment FIXME: (ACM, 2003/5/24).  Check whether AWK needs mentioning here.

C and its derivative languages are highly complex creatures.  Often,
ambiguous code situations arise that require @ccmode{} to scan large
portions of the buffer to determine syntactic context.  Such
pathological code can cause @ccmode{} to perform fairly badly.  This
section gives some insight in how @ccmode{} operates, how that interacts
with some coding styles, and what you can use to improve performance.

The overall goal is that @ccmode{} shouldn't be overly slow (i.e., take
more than a fraction of a second) in any interactive operation.
I.e., it's tuned to limit the maximum response time in single operations,
which is sometimes at the expense of batch-like operations like
reindenting whole blocks.  If you find that @ccmode{} gradually gets
slower and slower in certain situations, perhaps as the file grows in
size or as the macro or comment you're editing gets bigger, then chances
are that something isn't working right.  You should consider reporting
it, unless it's something that's mentioned in this section.

Because @ccmode{} has to scan the buffer backwards from the current
insertion point, and because C's syntax is fairly difficult to parse in
the backwards direction, @ccmode{} often tries to find the nearest
position higher up in the buffer from which to begin a forward scan
(it's typically an opening or closing parenthesis of some kind).  The
farther this position is from the current insertion point, the slower it
gets.

@findex beginning-of-defun
In earlier versions of @ccmode{}, we used to recommend putting the
opening brace of a top-level construct@footnote{E.g., a function in C,
or outermost class definition in C++ or Java.} into the leftmost
column.  Earlier still, this used to be a rigid Emacs constraint, as
embodied in the @code{beginning-of-defun} function.  @ccmode now
caches syntactic information much better, so that the delay caused by
searching for such a brace when it's not in column 0 is minimal,
except perhaps when you've just moved a long way inside the file.

@findex defun-prompt-regexp
@vindex c-Java-defun-prompt-regexp
@vindex Java-defun-prompt-regexp (c-)
A special note about @code{defun-prompt-regexp} in Java mode: The common
style is to hang the opening braces of functions and classes on the
right side of the line, and that doesn't work well with the Emacs
approach.  @ccmode{} comes with a constant
@code{c-Java-defun-prompt-regexp} which tries to define a regular
expression usable for this style, but there are problems with it.  In
some cases it can cause @code{beginning-of-defun} to hang@footnote{This
has been observed in Emacs 19.34 and XEmacs 19.15.}.  For this reason,
it is not used by default, but if you feel adventurous, you can set
@code{defun-prompt-regexp} to it in your mode hook.  In any event,
setting and relying on @code{defun-prompt-regexp} will definitely slow
things down because (X)Emacs will be doing regular expression searches a
lot, so you'll probably be taking a hit either way!

@ccmode{} maintains a cache of the opening parentheses of the blocks
surrounding the point, and it adapts that cache as the point is moved
around.  That means that in bad cases it can take noticeable time to
indent a line in a new surrounding, but after that it gets fast as long
as the point isn't moved far off.  The farther the point is moved, the
less useful is the cache.  Since editing typically is done in ``chunks''
rather than on single lines far apart from each other, the cache
typically gives good performance even when the code doesn't fit the
Emacs approach to finding the defun starts.

@vindex c-enable-xemacs-performance-kludge-p
@vindex enable-xemacs-performance-kludge-p (c-)
XEmacs users can set the variable
@code{c-enable-xemacs-performance-kludge-p} to non-@code{nil}.  This
tells @ccmode{} to use XEmacs-specific built-in functions which, in some
circumstances, can locate the top-most opening brace much more quickly than
@code{beginning-of-defun}.  Preliminary testing has shown that for
styles where these braces are hung (e.g., most JDK-derived Java styles),
this hack can improve performance of the core syntax parsing routines
from 3 to 60 times.  However, for styles which @emph{do} conform to
Emacs's recommended style of putting top-level braces in column zero,
this hack can degrade performance by about as much.  Thus this variable
is set to @code{nil} by default, since the Emacs-friendly styles should
be more common (and encouraged!).  Note that this variable has no effect
in Emacs since the necessary built-in functions don't exist (in Emacs
22.1 as of this writing in February 2007).

Text properties are used to speed up skipping over syntactic whitespace,
i.e., comments and preprocessor directives.  Indenting a line after a
huge macro definition can be slow the first time, but after that the
text properties are in place and it should be fast (even after you've
edited other parts of the file and then moved back).

Font locking can be a CPU hog, especially the font locking done on
decoration level 3 which tries to be very accurate.  Note that that
level is designed to be used with a font lock support mode that only
fontifies the text that's actually shown, i.e., Lazy Lock or Just-in-time
Lock mode, so make sure you use one of them.  Fontification of a whole
buffer with some thousand lines can often take over a minute.  That is
a known weakness; the idea is that it never should happen.

The most effective way to speed up font locking is to reduce the
decoration level to 2 by setting @code{font-lock-maximum-decoration}
appropriately.  That level is designed to be as pretty as possible
without sacrificing performance.  @xref{Font Locking Preliminaries}, for
more info.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Limitations and Known Bugs, FAQ, Performance Issues, Top
@comment node-name, next, previous, up
@chapter Limitations and Known Bugs
@cindex limitations
@cindex bugs
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@itemize @bullet
@item
@ccmode{} doesn't support trigraphs.  (These are character sequences
such as @samp{??(}, which represents @samp{[}.  They date from a time
when some character sets didn't have all the characters that C needs,
and are now utterly obsolete.)

@item
There is no way to apply auto newline settings (@pxref{Auto-newlines})
on already typed lines.  That's only a feature to ease interactive
editing.

To generalize this issue a bit: @ccmode{} is not intended to be used as
a reformatter for old code in some more or less batch-like way.  With
the exception of some functions like @code{c-indent-region}, it's only
geared to be used interactively to edit new code.  There's currently no
intention to change this goal.

If you want to reformat old code, you're probably better off using some
other tool instead, e.g., @ref{Top, , GNU indent, indent, The `indent'
Manual}, which has more powerful reformatting capabilities than
@ccmode{}.

@item
The support for C++ templates (in angle brackets) is not yet complete.
When a non-nested template is used in a declaration, @ccmode{} indents
it and font-locks it OK@.  Templates used in expressions, and nested
templates do not fare so well.  Sometimes a workaround is to refontify
the expression after typing the closing @samp{>}.

@item
In a @dfn{k&r region} (the part of an old-fashioned C function
declaration which specifies the types of its parameters, coming
between the parameter list and the opening brace), there should be at
most 20 top-level parenthesis and bracket pairs.  This limit has been
imposed for performance reasons.  If it is violated, the source file
might be incorrectly indented or fontified.

@item
On loading @ccmode{}, sometimes this error message appears:

@example
File mode specification error: (void-variable c-font-lock-keywords-3)
@end example

This is due to a bug in the function @code{eval-after-load} in some
versions of (X)Emacs.  It can manifest itself when there is a symbolic
link in the path of the directory which contains (X)Emacs.  As a
workaround, put the following into your @file{.emacs} file, fairly
early on:

@example
(defun my-load-cc-fonts ()
  (require "cc-fonts"))
(add-hook 'c-initialization-hook 'my-load-cc-fonts)
@end example
@end itemize

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    FAQ, Updating CC Mode, Limitations and Known Bugs, Top
@comment node-name, next, previous, up
@appendix Frequently Asked Questions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@itemize @bullet
@item
@emph{How can I change the indent level from 4 spaces to 2 spaces?}

Set the variable @code{c-basic-offset}.  @xref{Getting Started}.

@item
@kindex RET
@kindex C-j
@emph{Why doesn't the @kbd{RET} key indent the new line?}

Emacs's convention is that @kbd{RET} just adds a newline, and that
@kbd{C-j} adds a newline and indents it.  You can make @kbd{RET} do this
too by adding this to your @code{c-initialization-hook}:

@example
(define-key c-mode-base-map "\C-m" 'c-context-line-break)
@end example

@xref{Getting Started}.  This is a very common question.  If you want
this to be the default behavior, don't lobby us, lobby RMS@!  @t{:-)}

@item
@emph{How do I stop my code jumping all over the place when I type?}

Deactivate ``electric minor mode'' with @kbd{C-c C-l}.  @xref{Getting
Started}.

@item
@kindex C-x h
@kindex C-M-\
@emph{How do I reindent the whole file?}

Visit the file and hit @kbd{C-x h} to mark the whole buffer. Then hit
@kbd{C-M-\}.  @xref{Indentation Commands}.

@item
@kindex C-M-q
@kindex C-M-u
@emph{How do I reindent the current block?}

First move to the brace which opens the block with @kbd{C-M-u}, then
reindent that expression with @kbd{C-M-q}.  @xref{Indentation
Commands}.

@item
@emph{I put @code{(c-set-offset 'substatement-open 0)} in my
@file{.emacs} file but I get an error saying that @code{c-set-offset}'s
function definition is void.  What's wrong?}

This means that @ccmode{} hasn't yet been loaded into your Emacs
session by the time the @code{c-set-offset} call is reached, most
likely because @ccmode{} is being autoloaded.  Instead of putting the
@code{c-set-offset} line in your top-level @file{.emacs} file, put it
in your @code{c-initialization-hook} (@pxref{CC Hooks}), or simply
modify @code{c-offsets-alist} directly:

@example
(setq c-offsets-alist '((substatement-open . 0)))
@end example

@item
@cindex open paren in column zero
@emph{I have an open paren character at column zero inside a comment or
multiline string literal, and it causes the fontification and/or
indentation to go haywire.  What gives?}

It's due to the ad-hoc rule in (X)Emacs that such open parens always
start defuns (which translates to functions, classes, namespaces or any
other top-level block constructs in the @ccmode{} languages).
@ifset XEMACS
@xref{Defuns,,, xemacs, XEmacs User's Manual}, for details.
@end ifset
@ifclear XEMACS
@xref{Left Margin Paren,,, emacs, GNU Emacs Manual}, for details
(@xref{Defuns,,, emacs, GNU Emacs Manual}, in the Emacs 20 manual).
@end ifclear

This heuristic is built into the core syntax analysis routines in
(X)Emacs, so it's not really a @ccmode{} issue.  However, in Emacs
21.1 it became possible to turn it off@footnote{Using the variable
@code{open-paren-in-column-0-is-defun-start}.} and @ccmode{} does so
there since it's got its own system to keep track of blocks.

@end itemize


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Updating CC Mode, Mailing Lists and Bug Reports, FAQ, Top
@comment node-name, next, previous, up
@appendix Getting the Latest CC Mode Release
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ccmode{} has been standard with all versions of Emacs since 19.34 and
of XEmacs since 19.16.

@cindex web site
Due to release schedule skew, it is likely that all of these Emacsen
have old versions of @ccmode{} and so should be upgraded.  Access to the
@ccmode{} source code, as well as more detailed information on Emacsen
compatibility, etc. are all available on the web site:

@quotation
@uref{http://cc-mode.sourceforge.net/}
@end quotation


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Mailing Lists and Bug Reports, GNU Free Documentation License, Updating CC Mode, Top
@comment node-name, next, previous, up
@appendix Mailing Lists and Submitting Bug Reports
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@kindex C-c C-b
@findex c-submit-bug-report
@findex submit-bug-report (c-)
To report bugs, use the @kbd{C-c C-b} (bound to
@code{c-submit-bug-report}) command.  This provides vital information
we need to reproduce your problem.  Make sure you include a concise,
but complete code example.  Please try to boil your example down to
just the essential code needed to reproduce the problem, and include
an exact recipe of steps needed to expose the bug.  Be especially sure
to include any code that appears @emph{before} your bug example, if
you think it might affect our ability to reproduce it.

Please try to produce the problem in an Emacs instance without any
customizations loaded (i.e., start it with the @samp{-q --no-site-file}
arguments).  If it works correctly there, the problem might be caused
by faulty customizations in either your own or your site
configuration.  In that case, we'd appreciate it if you isolate the
Emacs Lisp code that triggers the bug and include it in your report.

@cindex bug report mailing list
Bug reports should be sent to @email{bug-cc-mode@@gnu.org}.  You can
also send other questions and suggestions (kudos? @t{;-)} to that
address.  It's a mailing list which you can join or browse an archive
of; see the web site at @uref{http://cc-mode.sourceforge.net/} for
further details.

@cindex announcement mailing list
If you want to get announcements of new @ccmode{} releases, send the
word @emph{subscribe} in the body of a message to
@email{cc-mode-announce-request@@lists.sourceforge.net}.  It's possible
to subscribe from the web site too.  Announcements will also be posted
to the Usenet newsgroups @code{gnu.emacs.sources}, @code{comp.emacs},
@code{comp.emacs.xemacs}, @code{comp.lang.c}, @code{comp.lang.c++},
@code{comp.lang.objective-c}, @code{comp.lang.java.softwaretools},
@code{comp.lang.idl}, and @code{comp.lang.awk}.
@c There is no newsgroup for Pike.  :-(


@node GNU Free Documentation License, Command and Function Index, Mailing Lists and Bug Reports, Top
@appendix GNU Free Documentation License
@include doclicense.texi


@c Removed the tentative node "Mode Initialization" from here, 2005/8/27.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Command and Function Index, Variable Index, GNU Free Documentation License, Top
@comment node-name, next, previous, up
@unnumbered Command and Function Index
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Since most @ccmode{} commands are prepended with the string
@samp{c-}, each appears under its @code{c-@var{thing}} name and its
@code{@var{thing} (c-)} name.
@iftex
@sp 2
@end iftex
@printindex fn


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Variable Index, Concept and Key Index, Command and Function Index, Top
@comment node-name, next, previous, up
@unnumbered Variable Index
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Since most @ccmode{} variables are prepended with the string
@samp{c-}, each appears under its @code{c-@var{thing}} name and its
@code{@var{thing} (c-)} name.
@iftex
@sp 2
@end iftex
@printindex vr


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Concept and Key Index,  , Variable Index, Top
@comment node-name, next, previous, up
@unnumbered Concept and Key Index
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@printindex cp


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment Epilogue.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@bye