3 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4 @comment %**start of header (This is for running Texinfo on a region)
5 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
7 @comment No overfull hbox marks in the dvi file.
10 @setfilename ../info/ccmode
11 @settitle CC Mode Version 5 Documentation
14 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
15 @comment @setchapternewpage odd !! we don't want blank pages !!
16 @comment %**end of header (This is for running Texinfo on a region)
17 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
20 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
22 @comment Texinfo manual for CC Mode
23 @comment Generated from the original README file by Krishna Padmasola
24 @comment <krishna@earth-gw.njit.edu>
26 @comment Maintained by Martin Stjernholm <bug-cc-mode@gnu.org>
28 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
30 @comment Info directory entry for use by install-info
33 * CC Mode: (ccmode). Emacs mode for editing C, C++, Objective-C,
34 Java, Pike, and IDL code.
37 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
38 @comment The following line inserts the copyright notice
39 @comment into the Info file.
40 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
43 Copyright @copyright{} 1995, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
45 Permission is granted to copy, distribute and/or modify this document
46 under the terms of the GNU Free Documentation License, Version 1.1 or
47 any later version published by the Free Software Foundation; with the
48 Invariant Sections being ``The GNU Manifesto'', ``Distribution'' and
49 ``GNU GENERAL PUBLIC LICENSE'', with the Front-Cover texts being ``A GNU
50 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
51 license is included in the section entitled ``GNU Free Documentation
52 License'' in the Emacs manual.
54 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
55 this GNU Manual, like GNU software. Copies published by the Free
56 Software Foundation raise funds for GNU development.''
58 This document is part of a collection distributed under the GNU Free
59 Documentation License. If you want to distribute this document
60 separately from the collection, you can do so by adding a copy of the
61 license to the document, as described in section 6 of the license.
64 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
65 @comment !!!The titlepage section does not appear in the Info file.!!!
66 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
72 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
73 @comment The title is printed in a large font.
74 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
76 @center @titlefont{CC Mode 5.27}
78 @center @subtitlefont{A GNU Emacs mode for editing C and C-like languages}
80 @center Current maintainer:
81 @center Martin Stjernholm
84 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
85 @comment The following two commands start the copyright page
86 @comment for the printed manual. This will not appear in the Info file.
87 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
90 @vskip 0pt plus 1filll
91 Copyright @copyright{} 1995, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
93 Permission is granted to copy, distribute and/or modify this document
94 under the terms of the GNU Free Documentation License, Version 1.1 or
95 any later version published by the Free Software Foundation; with the
96 Invariant Sections being ``The GNU Manifesto'', ``Distribution'' and
97 ``GNU GENERAL PUBLIC LICENSE'', with the Front-Cover texts being ``A GNU
98 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
99 license is included in the section entitled ``GNU Free Documentation
100 License'' in the Emacs manual.
102 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
103 this GNU Manual, like GNU software. Copies published by the Free
104 Software Foundation raise funds for GNU development.''
106 This document is part of a collection distributed under the GNU Free
107 Documentation License. If you want to distribute this document
108 separately from the collection, you can do so by adding a copy of the
109 license to the document, as described in section 6 of the license.
113 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
114 @comment The Top node contains the master menu for the Info file.
115 @comment This appears only in the Info file, not the printed manual.
116 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
118 @node Top, Introduction, (dir), (dir)
119 @comment node-name, next, previous, up
128 @ccmode{} is a GNU Emacs mode for editing files containing C, C++,
129 Objective-C, Java, CORBA IDL, and Pike code. It provides syntax-based
130 indentation and has several handy commands and some minor modes to make
131 the editing easier. Note that @ccmode{} does @emph{not} provide
132 font-locking; there are other Emacs packages for that.
135 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
136 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
140 * Getting Connected::
141 * New Indentation Engine::
143 * Text Filling and Line Breaking::
145 * Customizing Indentation::
146 * Syntactic Symbols::
147 * Indentation Functions::
148 * Performance Issues::
149 * Frequently Asked Questions::
150 * Getting the Latest CC Mode Release::
151 * Sample .emacs File::
152 * Limitations and Known Bugs::
153 * Mailing Lists and Submitting Bug Reports::
162 --- The Detailed Node Listing ---
164 New Indentation Engine
166 * Syntactic Analysis::
167 * Indentation Calculation::
171 * Auto-newline Insertion::
172 * Hungry-deletion of Whitespace::
174 Auto-newline Insertion
178 * Hanging Semi-colons and Commas::
179 * Other Electric Commands::
184 * Indentation Commands::
185 * Movement Commands::
188 Customizing Indentation
190 * Interactive Customization::
191 * Permanent Customization::
194 * Advanced Customizations::
202 Advanced Customizations
204 * Custom Indentation Functions::
205 * Custom Brace and Colon Hanging::
206 * Customizing Semi-colons and Commas::
207 * Other Special Indentations::
211 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
212 @node Introduction, Getting Connected, Top, Top
213 @comment node-name, next, previous, up
214 @chapter Introduction
215 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
219 Welcome to @ccmode{}, a GNU Emacs mode for editing files containing C,
220 C++, Objective-C, Java, CORBA IDL, and Pike code. This incarnation of
221 the mode is descendant from @file{c-mode.el} (also called "Boring Old C
222 Mode" or BOCM @t{:-)}, and @file{c++-mode.el} version 2, which Barry has
223 been maintaining since 1992. @ccmode{} represents a significant
224 milestone in the mode's life. It has been fully merged back with Emacs
225 19's @file{c-mode.el}. Also a new, more intuitive and flexible mechanism
226 for controlling indentation has been developed. Late in 1997, Martin
227 joined the @ccmode{} Maintainers Team, and implemented the Pike support.
228 As of 2000 Martin has taken over as the sole maintainer.
230 This manual describes @ccmode{}
231 @comment The following line must appear on its own, so that the automated
233 @comment Release.py script can update the version number automatically
235 @ccmode{} supports the editing of K&R and ANSI C, @dfn{ARM}
236 @footnote{@cite{The Annotated C++ Reference Manual}, by Ellis and
237 Stroustrup.} C++, Objective-C, Java, CORBA's Interface Definition
238 Language, and Pike@footnote{A C-like scripting language with its roots
239 in the LPC language used in some MUD engines. See
240 @uref{http://pike.idonex.se/}.} files. In this way, you can easily set
241 up consistent coding styles for use in editing all of these languages.
242 @ccmode{} does @emph{not} handle font-locking (a.k.a. syntax coloring,
243 keyword highlighting) or anything of that nature, for any of these
244 modes. Font-locking is handled by other Emacs packages.
246 This manual will describe the following:
250 How to get started using @ccmode{}.
253 How the new indentation engine works.
256 How to customize the new indentation engine.
266 Note that the name of this package is ``@ccmode{}'', but there is no top
267 level @code{cc-mode} entry point. All of the variables, commands, and
268 functions in @ccmode{} are prefixed with @code{c-@var{<thing>}}, and
269 @code{c-mode}, @code{c++-mode}, @code{objc-mode}, @code{java-mode},
270 @code{idl-mode}, and @code{pike-mode} entry points are provided. This
271 package is intended to be a replacement for @file{c-mode.el} and
274 @cindex @file{cc-compat.el} file
275 This distribution also contains a file
276 called @file{cc-compat.el} which should ease your transition from BOCM
277 to @ccmode{}. If you have a BOCM configuration you are really happy
278 with, and want to postpone learning how to configure @ccmode{}, take a
279 look at that file. It maps BOCM configuration variables to @ccmode{}'s
280 new indentation model. It is not actively supported so for the long
281 run, you should learn how to customize @ccmode{} to support your coding
284 A special word of thanks goes to Krishna Padmasola for his work in
285 converting the original @file{README} file to Texinfo format. I'd also
286 like to thank all the @ccmode{} victims who help enormously during the
287 early beta stages of @ccmode{}'s development.
290 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
291 @node Getting Connected, New Indentation Engine, Introduction, Top
292 @comment node-name, next, previous, up
293 @chapter Getting Connected
294 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
296 If you got this version of @ccmode{} with Emacs or XEmacs, it should
297 work just fine right out of the box. Note however that you may not have
298 the latest @ccmode{} release and may want to upgrade your copy.
300 If you are upgrading an existing @ccmode{} installation, please see the
301 @file{README} file for installation details. @ccmode{} may not work
302 with older versions of Emacs or XEmacs. See the @ccmode{} release notes
303 Web pages for the latest information on Emacs version and package
304 compatibility (@pxref{Getting the Latest CC Mode Release}).
306 @cindex @file{cc-mode-18.el} file
307 @emph{Note that @ccmode{} no longer
308 works with Emacs 18!}, so if you haven't upgraded from Emacs 18 by now,
313 You can find out what version of @ccmode{} you are using by visiting a C
314 file and entering @kbd{M-x c-version RET}. You should see this message in
318 Using CC Mode version 5.XX
323 where @samp{XX} is the minor release number.
326 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
327 @node New Indentation Engine, Minor Modes, Getting Connected, Top
328 @comment node-name, next, previous, up
329 @chapter New Indentation Engine
330 @cindex indentation engine
331 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
333 @ccmode{} has a new indentation engine, providing a simplified, yet
334 flexible and general mechanism for customizing indentation. It separates
335 indentation calculation into two steps: first, @ccmode{} analyzes the
336 line of code being indented to determine the kind of language construct
337 it's looking at, then it applies user defined offsets to the current
338 line based on this analysis.
340 This section will briefly cover how indentation is calculated in
341 @ccmode{}. It is important to understand the indentation model
342 being used so that you will know how to customize @ccmode{} for
343 your personal coding style.
346 * Syntactic Analysis::
347 * Indentation Calculation::
351 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
352 @node Syntactic Analysis, Indentation Calculation, , New Indentation Engine
353 @comment node-name, next, previous, up
354 @section Syntactic Analysis
355 @cindex syntactic analysis
356 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
358 @cindex relative buffer position
359 @cindex syntactic symbol
360 @cindex syntactic component
361 @cindex syntactic component list
362 The first thing @ccmode{} does when indenting a line of code, is to
363 analyze the line, determining the @dfn{syntactic component list} of the
364 construct on that line. A syntactic component consists of a pair of
365 information (in lisp parlance, a @emph{cons cell}), where the first part
366 is a @dfn{syntactic symbol}, and the second part is a @dfn{relative
367 buffer position}. Syntactic symbols describe elements of C code
368 @footnote{Unless otherwise noted, the term ``C code'' to refers to all
369 the C-like languages.}, e.g. @code{statement}, @code{substatement},
370 @code{class-open}, @code{class-close}, etc. @xref{Syntactic Symbols},
371 for a complete list of currently recognized syntactic symbols and their
372 semantics. The style variable @code{c-offsets-alist} also contains the
373 list of currently supported syntactic symbols.
375 Conceptually, a line of C code is always indented relative to the
376 indentation of some line higher up in the buffer. This is represented
377 by the relative buffer position in the syntactic component.
379 Here is an example. Suppose we had the following code as the only thing
380 in a C++ buffer @footnote{The line numbers in this and future examples
381 don't actually appear in the buffer, of course!}:
385 1: void swap( int& a, int& b )
396 @findex c-show-syntactic-information
397 @findex show-syntactic-information (c-)
398 We can use the command @kbd{C-c C-s}
399 (@code{c-show-syntactic-information}) to simply report what the
400 syntactic analysis is for the current line. Running this command on
401 line 4 of this example, we'd see in the echo area@footnote{With a universal
402 argument (i.e. @kbd{C-u C-c C-s}) the analysis is inserted into the
404 on the current line.}:
411 This tells us that the line is a statement and it is indented relative
412 to buffer position 35, which happens to be the @samp{i} in @code{int} on
413 line 3. If you were to move point to line 3 and hit @kbd{C-c C-s}, you
417 ((defun-block-intro . 29))
421 This indicates that the @samp{int} line is the first statement in a top
422 level function block, and is indented relative to buffer position 29,
423 which is the brace just after the function header.
425 Here's another example:
429 1: int add( int val, int incr, int doit )
433 5: return( val + incr );
442 Hitting @kbd{C-c C-s} on line 4 gives us:
445 ((substatement-open . 46))
450 @cindex substatement block
452 which tells us that this is a brace that @emph{opens} a substatement
453 block. @footnote{A @dfn{substatement} is the line after a
454 conditional statement, such as @code{if}, @code{else}, @code{while},
455 @code{do}, @code{switch}, etc. A @dfn{substatement
456 block} is a brace block following one of these conditional statements.}
458 @cindex comment-only line
459 Syntactic component lists can contain more than one component, and
460 individual syntactic components need not have relative buffer positions.
461 The most common example of this is a line that contains a @dfn{comment
466 1: void draw_list( List<Drawables>& drawables )
468 3: // call the virtual draw() method on each element in list
469 4: for( int i=0; i < drawables.count(), ++i )
471 6: drawables[i].draw();
479 Hitting @kbd{C-c C-s} on line 3 of this example gives:
482 ((comment-intro) (defun-block-intro . 46))
487 and you can see that the syntactic component list contains two syntactic
488 components. Also notice that the first component,
489 @samp{(comment-intro)} has no relative buffer position.
492 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
493 @node Indentation Calculation, , Syntactic Analysis, New Indentation Engine
494 @comment node-name, next, previous, up
495 @section Indentation Calculation
496 @cindex indentation calculation
497 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
499 Indentation for a line is calculated using the syntactic
500 component list derived in step 1 above (@pxref{Syntactic Analysis}).
501 Each component contributes to the final total indentation of the line in
504 First, the syntactic symbols are looked up in the @code{c-offsets-alist}
505 style variable, which is an association list of syntactic symbols and
506 the offsets to apply for those symbols. These offsets are added to a
509 Second, if the component has a relative buffer position, @ccmode{}
510 adds the column number of that position to the running total. By adding
511 up the offsets and columns for every syntactic component on the list,
512 the final total indentation for the current line is computed.
514 Let's use our two code examples above to see how this works. Here is
515 our first example again:
519 1: void swap( int& a, int& b )
529 Let's say point is on line 3 and we hit the @kbd{TAB} key to re-indent
530 the line. Remember that the syntactic component list for that
534 ((defun-block-intro . 29))
539 @ccmode{} looks up @code{defun-block-intro} in the
540 @code{c-offsets-alist} style variable. Let's say it finds the value
541 @samp{4}; it adds this to the running total (initialized to zero),
542 yielding a running total indentation of 4 spaces.
544 Next @ccmode{} goes to buffer position 29 and asks for the current
545 column. This brace is in column zero, so @ccmode{}
546 adds @samp{0} to the running total. Since there is only one syntactic
547 component on the list for this line, indentation calculation is
548 complete, and the total indentation for the line
551 Here's another example:
555 1: int add( int val, int incr, int doit )
559 5: return( val + incr );
567 If we were to hit @kbd{TAB} on line 4 in the above example, the same
568 basic process is performed, despite the differences in the syntactic
569 component list. Remember that the list for this line is:
572 ((substatement-open . 46))
576 Here, @ccmode{} first looks up the @code{substatement-open} symbol
577 in @code{c-offsets-alist}. Let's say it finds the value @samp{4}. This
578 yields a running total of 4. @ccmode{} then goes to
579 buffer position 46, which is the @samp{i} in @code{if} on line 3. This
580 character is in the fourth column on that line so adding this to the
581 running total yields an indentation for the line of 8 spaces.
585 Actually, the mode usually just does The Right Thing without you having
586 to think about it in this much detail. But when customizing
587 indentation, it's helpful to understand the general indentation model
590 @vindex c-echo-syntactic-information-p
591 @vindex echo-syntactic-information-p (c-)
592 As you configure @ccmode{}, you might want to set the variable
593 @code{c-echo-syntactic-information-p} to non-@code{nil} so that the
594 syntactic component list and calculated offset will always be echoed in
595 the minibuffer when you hit @kbd{TAB}.
598 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
599 @node Minor Modes, Text Filling and Line Breaking, New Indentation Engine, Top
600 @comment node-name, next, previous, up
602 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
604 @ccmode{} contains two minor-mode-like features that you should
605 find useful while you enter new C code. The first is called
606 @dfn{auto-newline} mode, and the second is called @dfn{hungry-delete}
607 mode. These minor modes can be toggled on and off independently, and
608 @ccmode{} can be configured so that it starts up with any
609 combination of these minor modes. By default, both of these minor modes
612 The state of the minor modes is always reflected in the minor mode list
613 on the modeline of the @ccmode{} buffer. When auto-newline mode is
614 enabled, you will see @samp{C/a} on the mode line @footnote{The @samp{C}
615 would be replaced with @samp{C++}, @samp{ObjC}, @samp{Java}, @samp{IDL},
616 or @samp{Pike} for the respective languages.}. When hungry delete mode
617 is enabled you would see @samp{C/h} and when both modes are enabled,
618 you'd see @samp{C/ah}.
623 @findex c-toggle-hungry-state
624 @findex c-toggle-auto-state
625 @findex c-toggle-auto-hungry-state
626 @findex toggle-hungry-state (c-)
627 @findex toggle-auto-state (c-)
628 @findex toggle-auto-hungry-state (c-)
629 @ccmode{} provides keybindings which allow you to toggle the minor
630 modes on the fly while editing code. To toggle just the auto-newline
631 state, hit @kbd{C-c C-a} (@code{c-toggle-auto-state}). When you do
632 this, you should see the @samp{a} indicator either appear or disappear
633 on the modeline. Similarly, to toggle just the hungry-delete state, use
634 @kbd{C-c C-d} (@code{c-toggle-hungry-state}), and to toggle both states,
635 use @kbd{C-c C-t} (@code{c-toggle-auto-hungry-state}).
637 To set up the auto-newline and hungry-delete states to your preferred
638 values, you would need to add some lisp to your @file{.emacs} file that
639 called one of the @code{c-toggle-*-state} functions directly. When
640 called programmatically, each function takes a numeric value, where
641 a positive number enables the minor mode, a negative number disables the
642 mode, and zero toggles the current state of the mode.
644 So for example, if you wanted to enable both auto-newline and
645 hungry-delete for all your C file editing, you could add the following
646 to your @file{.emacs} file:
649 (add-hook 'c-mode-common-hook
650 (lambda () (c-toggle-auto-hungry-state 1)))
655 @cindex electric characters
658 * Auto-newline Insertion::
659 * Hungry-deletion of Whitespace::
663 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
664 @node Auto-newline Insertion, Hungry-deletion of Whitespace, , Minor Modes
665 @comment node-name, next, previous, up
666 @section Auto-newline Insertion
667 @cindex auto-newline insertion
668 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
670 @cindex electric commands
671 Auto-newline minor mode works by enabling certain @dfn{electric
672 commands}. Electric commands are typically bound to special characters
673 such as the left and right braces, colons, semi-colons, etc., which when
674 typed, perform some magic formatting in addition to inserting the typed
675 character. As a general rule, electric commands are only electric when
676 the following conditions apply:
680 Auto-newline minor mode is enabled, as evidenced by a @samp{C/a} or
681 @samp{C/ah} indicator on the modeline.
684 @cindex syntactic whitespace
686 The character was not typed inside of a literal @footnote{A
687 @dfn{literal} is defined as any comment, string, or C preprocessor macro
688 definition. These constructs are also known as @dfn{syntactic
689 whitespace} since they are usually ignored when scanning C code.}.
693 No numeric argument was supplied to the command (i.e. it was typed as
694 normal, with no @kbd{C-u} prefix).
701 * Hanging Semi-colons and Commas::
702 * Other Electric Commands::
707 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
708 @node Hanging Braces, Hanging Colons, , Auto-newline Insertion
709 @comment node-name, next, previous, up
710 @subsection Hanging Braces
711 @cindex hanging braces
712 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
714 @findex c-electric-brace
715 @findex electric-brace (c-)
716 @vindex c-hanging-braces-alist
717 @vindex hanging-braces-alist (c-)
718 When you type either an open or close brace (i.e. @kbd{@{} or @kbd{@}}),
719 the electric command @code{c-electric-brace} gets run. This command has
720 two electric formatting behaviors. First, it will perform some
721 re-indentation of the line the brace was typed on, and second, it will
722 add various newlines before and/or after the typed brace.
723 Re-indentation occurs automatically whenever the electric behavior is
724 enabled. If the brace ends up on a line other than the one it was typed
725 on, then that line is also re-indented.
727 @cindex class-open syntactic symbol
728 @cindex class-close syntactic symbol
729 @cindex defun-open syntactic symbol
730 @cindex defun-close syntactic symbol
731 @cindex inline-open syntactic symbol
732 @cindex inline-close syntactic symbol
733 @cindex brace-list-open syntactic symbol
734 @cindex brace-list-close syntactic symbol
735 @cindex brace-list-intro syntactic symbol
736 @cindex brace-entry-open syntactic symbol
737 @cindex block-open syntactic symbol
738 @cindex block-close syntactic symbol
739 @cindex substatement-open syntactic symbol
740 @cindex statement-case-open syntactic symbol
741 @cindex extern-lang-open syntactic symbol
742 @cindex extern-lang-close syntactic symbol
743 @cindex namespace-open syntactic symbol
744 @cindex namespace-close syntactic symbol
745 @cindex inexpr-class-open symbol
746 @cindex inexpr-class-close symbol
748 The default in auto-newline mode is to insert newlines both before and
749 after a brace, but that can be controlled by the
750 @code{c-hanging-braces-alist} style variable. This variable contains a
751 mapping between syntactic symbols related to braces, and a list of
752 places to insert a newline. The syntactic symbols that are useful for
753 this list are: @code{class-open}, @code{class-close}, @code{defun-open},
754 @code{defun-close}, @code{inline-open}, @code{inline-close},
755 @code{brace-list-open}, @code{brace-list-close},
756 @code{brace-list-intro}, @code{brace-entry-open}, @code{block-open},
757 @code{block-close}, @code{substatement-open},
758 @code{statement-case-open}, @code{extern-lang-open},
759 @code{extern-lang-close}, @code{namespace-open}, @code{namespace-close},
760 @code{inexpr-class-open}, and @code{inexpr-class-close}@footnote{Note
761 that the aggregate constructs in Pike mode, @samp{(@{}, @samp{@})},
762 @samp{([}, @samp{])}, and @samp{(<}, @samp{>)}, do not count as brace
763 lists in this regard, even though they do for normal indentation
764 purposes. It's currently not possible to set automatic newlines on
765 these constructs.}. @xref{Syntactic Symbols}, for a more detailed
766 description of these syntactic symbols, except for
767 @code{inexpr-class-open} and @code{inexpr-class-close}, which aren't
768 actual syntactic symbols.
770 The braces of anonymous inner classes in Java are given the special
771 symbols @code{inexpr-class-open} and @code{inexpr-class-close}, so that
772 they can be distinguished from the braces of normal classes@footnote{The
773 braces of anonymous classes produces a combination of
774 @code{inexpr-class}, and @code{class-open} or @code{class-close} in
775 normal indentation analysis.}.
777 The value associated with each syntactic symbol in this association list
778 is called an @var{ACTION} which can be either a function or a list.
779 @xref{Custom Brace and Colon Hanging}, for a more detailed discussion of
780 using a function as a brace hanging @var{ACTION}.
782 When the @var{ACTION} is a list, it can contain any combination of the
783 symbols @code{before} and @code{after}, directing @ccmode{} where to
784 put newlines in relationship to the brace being inserted. Thus, if the
785 list contains only the symbol @code{after}, then the brace is said to
786 @dfn{hang} on the right side of the line, as in:
790 // here, open braces always `hang'
791 void spam( int i ) @{
801 When the list contains both @code{after} and @code{before}, the braces
802 will appear on a line by themselves, as shown by the close braces in the
803 above example. The list can also be empty, in which case no newlines
804 are added either before or after the brace.
806 If a syntactic symbol is missing entirely from
807 @code{c-hanging-braces-alist}, it's treated in the same way as an
808 @var{ACTION} with a list containing @code{before} and @code{after}, so
809 that braces by default end up on their own line.
811 For example, the default value of @code{c-hanging-braces-alist} is:
817 (substatement-open after)
818 (block-close . c-snug-do-while)
819 (extern-lang-open after)
820 (inexpr-class-open after)
821 (inexpr-class-close before))
826 @noindent which says that @code{brace-list-open} and
827 @code{brace-entry-open} braces should both hang on the right side, and
828 allow subsequent text to follow on the same line as the brace. Also,
829 @code{substatement-open}, @code{extern-lang-open}, and
830 @code{inexpr-class-open} braces should hang on the right side, but
831 subsequent text should follow on the next line. The opposite holds for
832 @code{inexpr-class-close} braces; they won't hang, but the following
833 text continues on the same line. Here, in the @code{block-close} entry,
834 you also see an example of using a function as an @var{ACTION}. In all
835 other cases, braces are put on a line by themselves.
837 A word of caution: it is not a good idea to hang top-level construct
838 introducing braces, such as @code{class-open} or @code{defun-open}.
839 Emacs makes an assumption that such braces will always appear in column
840 zero, hanging them can introduce performance problems.
841 @xref{Performance Issues}, for more information.
844 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
845 @node Hanging Colons, Hanging Semi-colons and Commas, Hanging Braces, Auto-newline Insertion
846 @comment node-name, next, previous, up
847 @subsection Hanging Colons
848 @cindex hanging colons
849 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
851 @vindex hanging-colons-alist (c-)
852 @vindex c-hanging-colons-alist
853 Using a mechanism similar to brace hanging (@pxref{Hanging Braces}),
854 colons can also be made to hang using the style variable
855 @code{c-hanging-colons-alist}. The syntactic symbols appropriate for
856 this assocation list are: @code{case-label}, @code{label},
857 @code{access-label}, @code{member-init-intro}, and @code{inher-intro}.
858 Note however that for @code{c-hanging-colons-alist}, @var{ACTION}s as
859 functions are not supported. See also @ref{Custom Brace and Colon
860 Hanging} for details.
862 In C++, double-colons are used as a scope operator but because these
863 colons always appear right next to each other, newlines before and after
864 them are controlled by a different mechanism, called @dfn{clean-ups} in
865 @ccmode{}. @xref{Clean-ups}, for details.
868 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
869 @node Hanging Semi-colons and Commas, Other Electric Commands, Hanging Colons, Auto-newline Insertion
870 @comment node-name, next, previous, up
871 @subsection Hanging Semi-colons and Commas
872 @cindex hanging semi-colons
873 @cindex hanging commas
874 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
876 Semicolons and commas are also electric in @ccmode{}, but since
877 these characters do not correspond directly to syntactic symbols, a
878 different mechanism is used to determine whether newlines should be
879 automatically inserted after these characters. @xref{Customizing
880 Semi-colons and Commas}, for details.
883 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
884 @node Other Electric Commands, Clean-ups, Hanging Semi-colons and Commas, Auto-newline Insertion
885 @comment node-name, next, previous, up
886 @subsection Other Electric Commands
887 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
890 @findex c-electric-pound
891 @vindex c-electric-pound-behavior
892 @findex electric-pound (c-)
893 @vindex electric-pound-behavior (c-)
894 A few other keys also provide electric behavior. For example
895 @kbd{#} (@code{c-electric-pound}) is electric when typed as
896 the first non-whitespace character on a line. In this case, the
897 variable @code{c-electric-pound-behavior} is consulted for the electric
898 behavior. This variable takes a list value, although the only element
899 currently defined is @code{alignleft}, which tells this command to force
900 the @samp{#} character into column zero. This is useful for entering
901 C preprocessor macro definitions.
903 @findex c-electric-star
904 @findex c-electric-slash
905 @findex electric-star (c-)
906 @findex electric-slash (c-)
907 Stars and slashes (i.e. @kbd{*} and @kbd{/}, @code{c-electric-star} and
908 @code{c-electric-slash} respectively) are also electric under
909 certain circumstances. If a star is inserted as the second character of
910 a C style block comment on a comment-only line, then the comment
911 delimiter is indented as defined by @code{c-offsets-alist}. A
912 comment-only line is defined as a line which contains only a comment, as
919 // this is a comment-only line...
920 if( i == 7 ) // but this is not
929 Likewise, if a slash is inserted as the second slash in a C++ style line
930 comment (also only on a comment-only line), then the line is indented as
931 defined by @code{c-offsets-alist}.
933 @findex c-electric-lt-gt
934 @findex electric-lt-gt (c-)
937 Less-than and greater-than signs (@code{c-electric-lt-gt}) are also
938 electric, but only in C++ mode. Hitting the second of two @kbd{<} or
939 @kbd{>} keys re-indents the line if it is a C++ style stream operator.
941 @findex c-electric-paren
942 @findex electric-paren (c-)
945 The normal parenthesis characters @samp{(} and @samp{)} also reindent
946 the current line if they are used in normal code. This is useful for
947 getting the closing parenthesis of an argument list aligned
951 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
952 @node Clean-ups, , Other Electric Commands, Auto-newline Insertion
953 @comment node-name, next, previous, up
954 @subsection Clean-ups
956 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
958 @dfn{Clean-ups} are a mechanism complementary to colon and brace
959 hanging. On the surface, it would seem that clean-ups overlap the
960 functionality provided by the @code{c-hanging-*-alist} variables, and
961 similarly, clean-ups are only enabled when auto-newline minor mode is
962 enabled. Clean-ups are used however to adjust code ``after-the-fact'',
963 i.e. to eliminate some whitespace that is inserted by electric
964 commands, or whitespace that contains intervening constructs.
966 @vindex c-cleanup-list
967 @vindex cleanup-list (c-)
969 You can configure @ccmode{}'s clean-ups by setting the style variable
970 @code{c-cleanup-list}, which is a list of clean-up symbols. By default,
971 @ccmode{} cleans up only the @code{scope-operator} construct, which is
972 necessary for proper C++ support. Note that clean-ups are only
973 performed when the construct does not occur within a literal
974 (@pxref{Auto-newline Insertion}), and when there is nothing but
975 whitespace appearing between the individual components of the construct.
977 There are currently only five specific constructs that @ccmode{}
978 can clean up, as indicated by these symbols:
982 @code{brace-else-brace} --- cleans up @samp{@} else @{} constructs by
983 placing the entire construct on a single line. Clean-up occurs when the
984 open brace after the @samp{else} is typed. So for example, this:
1000 appears like this after the open brace is typed:
1014 @code{brace-elseif-brace} --- similar to the @code{brace-else-brace}
1015 clean-up, but this cleans up @samp{@} else if (...) @{} constructs. For
1032 appears like this after the open parenthesis is typed:
1046 and like this after the open brace is typed:
1054 @} else if( i==3 ) @{
1060 @code{brace-catch-brace} --- analogous to @code{brace-elseif-brace}, but
1061 cleans up @samp{@} catch (...) @{} in C++ and Java mode.
1064 @code{empty-defun-braces} --- cleans up braces following a top-level
1065 function or class definition that contains no body. Clean up occurs
1066 when the closing brace is typed. Thus the following:
1077 is transformed into this when the close brace is typed:
1088 @code{defun-close-semi} --- cleans up the terminating semi-colon on
1089 top-level function or class definitions when they follow a close
1090 brace. Clean up occurs when the semi-colon is typed.
1091 So for example, the following:
1103 is transformed into this when the semi-colon is typed:
1116 @code{list-close-comma} --- cleans up commas following braces in array
1117 and aggregate initializers. Clean up occurs when the comma is typed.
1120 @code{scope-operator} --- cleans up double colons which may designate a
1121 C++ scope operator split across multiple lines@footnote{Certain C++
1122 constructs introduce ambiguous situations, so @code{scope-operator}
1123 clean-ups may not always be correct. This usually only occurs when
1124 scoped identifiers appear in switch label tags.}. Clean up occurs when
1125 the second colon is typed. You will always want @code{scope-operator}
1126 in the @code{c-cleanup-list} when you are editing C++ code.
1131 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1132 @node Hungry-deletion of Whitespace, , Auto-newline Insertion, Minor Modes
1133 @comment node-name, next, previous, up
1134 @section Hungry-deletion of Whitespace
1135 @cindex hungry-deletion of whitespace
1136 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1138 Hungry deletion of whitespace, or as it more commonly called,
1139 @dfn{hungry-delete mode}, is a simple feature that some people find
1140 extremely useful. In fact, you might find yourself wanting
1141 hungry-delete in @strong{all} your editing modes!
1145 In a nutshell, when hungry-delete mode is enabled, hitting the
1146 @key{Backspace} key@footnote{I say ``hit the @key{Backspace} key'' but
1147 what I really mean is ``when Emacs receives the @code{BackSpace} key
1148 event''. The difference usually isn't significant to most users, but
1149 advanced users will realize that under window systems such as X, any
1150 physical key (keycap) on the keyboard can be configured to generate any
1151 keysym, and thus any Emacs key event. Also, the use of Emacs on TTYs
1152 will affect which keycap generates which key event. From a pedantic
1153 point of view, here we are only concerned with the key event that
1154 Emacs receives.} will consume all preceding whitespace, including
1155 newlines and tabs. This can really cut down on the number of
1156 @key{Backspace}'s you have to type if, for example you made a mistake on
1159 @findex c-electric-backspace
1160 @findex electric-backspace (c-)
1161 @vindex c-backspace-function
1162 @vindex backspace-function (c-)
1164 @findex c-electric-delete
1165 @findex electric-delete (c-)
1166 @vindex c-delete-function
1167 @vindex delete-function (c-)
1170 @findex backward-delete-char-untabify
1172 By default, when you hit the @key{Backspace} key @ccmode{} runs the
1173 command @code{c-electric-backspace}, which deletes text in the backwards
1174 direction. When deleting a single character, or when @key{Backspace} is
1175 hit in a literal (@pxref{Auto-newline Insertion}), or when hungry-delete
1176 mode is disabled, the function contained in the
1177 @code{c-backspace-function} variable is called with one argument (the
1178 number of characters to delete). This variable is set to
1179 @code{backward-delete-char-untabify} by default.
1181 @vindex delete-key-deletes-forward
1184 The default behavior of the @key{Delete} key depends on the flavor of
1185 Emacs you are using. By default in XEmacs 20.3 and beyond, the
1186 @key{Delete} key is bound to @code{c-electric-delete}. You control the
1187 direction that the @key{Delete} key deletes by setting the variable
1188 @code{delete-key-deletes-forward}, a standard XEmacs variable. When
1189 this variable is non-@code{nil} and hungry-delete mode is enabled,
1190 @code{c-electric-delete} will consume all whitespace @emph{following}
1191 point. When @code{delete-key-deletes-forward} is @code{nil}, it deletes
1192 all whitespace @emph{preceding} point@footnote{i.e. it literally calls
1193 @code{c-electric-backspace}.} When deleting a single character, or if
1194 @key{Delete} is hit in a literal, or hungry-delete mode is disabled, the
1195 function contained in @code{c-delete-function} is called with one
1196 argument: the number of characters to delete. This variable is set to
1197 @code{delete-char} by default.
1199 In Emacs 19 or Emacs 20, both the @key{Delete} and @key{Backspace} keys
1200 are bound to @code{c-electric-backspace}, however you can change this by
1201 explicitly binding @code{[delete]}@footnote{E.g. to
1202 @code{c-electric-delete} in your @file{.emacs} file. Note however, that
1203 Emacs 20 does not have a standard variable such as
1204 @code{delete-key-deletes-forward}.}.
1206 XEmacsen older than 20.3 behave similar to Emacs 19 and Emacs 20.
1209 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1210 @node Text Filling and Line Breaking, Commands, Minor Modes, Top
1211 @comment node-name, next, previous, up
1212 @chapter Text Filling and Line Breaking
1213 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1215 Since there's a lot of normal text in comments and string literals,
1216 @ccmode{} provides features to edit these like in text mode. The goal
1217 is to do it as seamlessly as possible, i.e. you can use auto fill mode,
1218 sentence and paragraph movement, paragraph filling, adaptive filling etc
1219 wherever there's a piece of normal text without having to think much
1220 about it. @ccmode{} should keep the indentation, fix the comment line
1221 decorations, and so on, for you. It does that by hooking in on the
1222 different line breaking functions and tuning relevant variables as
1225 @vindex c-comment-prefix-regexp
1226 @vindex comment-prefix-regexp (c-)
1227 @cindex comment line prefix
1228 @vindex comment-start
1230 @vindex comment-start-skip
1231 @vindex paragraph-start
1232 @vindex paragraph-separate
1233 @vindex paragraph-ignore-fill-prefix
1234 @vindex adaptive-fill-mode
1235 @vindex adaptive-fill-regexp
1236 @vindex adaptive-fill-first-line-regexp
1237 To make Emacs recognize comments and treat text in them as normal
1238 paragraphs, @ccmode{} makes several standard
1239 variables@footnote{@code{comment-start}, @code{comment-end},
1240 @code{comment-start-skip}, @code{paragraph-start},
1241 @code{paragraph-separate}, @code{paragraph-ignore-fill-prefix},
1242 @code{adaptive-fill-mode}, @code{adaptive-fill-regexp}, and
1243 @code{adaptive-fill-first-line-regexp}.} buffer local and modifies them
1244 according to the language syntax and the style of line decoration that
1245 starts every line in a comment. The style variable
1246 @code{c-comment-prefix-regexp} contains the regexp used to recognize
1247 this @dfn{comment line prefix}. The default is @samp{//+\\|\\**}, which
1248 matches C++ style line comments like
1256 with two or more slashes in front of them, and C style block comments
1269 with zero or more stars at the beginning of every line. If you change
1270 that variable, please make sure it still matches the comment starter
1271 (i.e. @code{//}) of line comments @emph{and} the line prefix inside
1272 block comments. Also note that since @ccmode{} uses the value of
1273 @code{c-comment-prefix-regexp} to set up several other variables at mode
1274 initialization, you need to reinitialize the program mode if you change
1275 it inside a @ccmode{} buffer.
1277 @findex auto-fill-mode
1278 @cindex auto fill mode
1279 @cindex paragraph fill
1280 Line breaks are by default handled (almost) the same regardless whether
1281 they are made by auto fill mode (@pxref{Auto Fill,,, emacs, The Emacs
1282 Editor}), paragraph filling (e.g. with @kbd{M-q}), or explicitly with
1283 @kbd{M-j} or similar methods. In string literals, the new line gets the
1284 same indentation as the previous nonempty line (may be changed with the
1285 @code{string} syntactic symbol). In comments, @ccmode{} uses
1286 @code{c-comment-prefix-regexp} to adapt the line prefix from the other
1287 lines in the comment.
1289 @vindex adaptive-fill-mode
1290 @cindex adaptive fill mode
1291 @ccmode{} uses adaptive fill mode (@pxref{Adaptive Fill,,, emacs, The
1292 Emacs Editor}) to make Emacs correctly keep the line prefix when filling
1293 paragraphs. That also makes Emacs preserve the text indentation
1294 @emph{inside} the comment line prefix. E.g. in the following comment,
1295 both paragraphs will be filled with the left margins kept intact:
1299 /* Make a balanced b-tree of the nodes in the incoming
1300 * stream. But, to quote the famous words of Donald E.
1303 * Beware of bugs in the above code; I have only
1304 * proved it correct, not tried it.
1310 @findex c-setup-filladapt
1311 @findex setup-filladapt (c-)
1312 @findex filladapt-mode
1313 @vindex filladapt-mode
1314 @cindex Filladapt mode
1315 It's also possible to use other adaptive filling packages, notably Kyle
1316 E. Jones' Filladapt package@footnote{It's available from
1317 @uref{http://www.wonderworks.com/}. As of version 2.12, it does however
1318 lack a feature that makes it work suboptimally when
1319 @code{c-comment-prefix-regexp} matches the empty string (which it does
1320 by default). A patch for that is available from
1321 @uref{http://cc-mode.sourceforge.net/,, the CC Mode site}.},
1322 which handles things like bulleted lists nicely. There's a convenience
1323 function @code{c-setup-filladapt} that tunes the relevant variables in
1324 Filladapt for use in @ccmode{}. Call it from a mode hook, e.g. with
1325 something like this in your @file{.emacs}:
1329 (defun my-c-mode-common-hook ()
1332 (add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
1337 @vindex c-block-comment-prefix
1338 @vindex block-comment-prefix (c-)
1339 @vindex c-comment-continuation-stars
1340 @vindex comment-continuation-stars (c-)
1341 Normally the comment line prefix inserted for a new line inside a
1342 comment is deduced from other lines in it. However there's one
1343 situation when there's no clue about how the prefix should look, namely
1344 when a block comment is broken for the first time. The string in the
1345 style variable @code{c-block-comment-prefix}@footnote{In versions before
1346 5.26, this variable was called @code{c-comment-continuation-stars}. As
1347 a compatibility measure, @ccmode{} still uses the value on that variable
1348 if it's set.} is used in that case. It defaults to @samp{* }, which
1352 /* Got O(n^2) here, which is a Bad Thing. */
1362 * which is a Bad Thing. */
1367 Note that it won't work to justify the indentation by putting leading
1368 spaces in the @code{c-block-comment-prefix} string, since @ccmode{}
1369 still uses the normal indentation engine to indent the line. Thus, the
1370 right way to fix the indentation is by setting the @code{c} syntactic
1371 symbol. It defaults to @code{c-lineup-C-comments}, which handles the
1372 indentation of most common comment styles, see @ref{Indentation
1375 @vindex c-ignore-auto-fill
1376 @vindex ignore-auto-fill (c-)
1377 When auto fill mode is enabled, @ccmode{} can selectively ignore it
1378 depending on the context the line break would occur in, e.g. to never
1379 break a line automatically inside a string literal. This behavior can
1380 be controlled with the @code{c-ignore-auto-fill} variable. It takes a
1381 list of symbols for the different contexts where auto-filling never
1385 @item @code{string} --- Inside a string or character literal.
1386 @item @code{c} --- Inside a C style block comment.
1387 @item @code{c++} --- Inside a C++ style line comment.
1388 @item @code{cpp} --- Inside a preprocessor directive.
1389 @item @code{code} --- Anywhere else, i.e. in normal code.
1392 By default, @code{c-ignore-auto-fill} is set to @code{'(string cpp
1393 code)}, which means that auto-filling only occurs in comments when
1394 auto-fill mode is activated. In literals, it's often desirable to have
1395 explicit control over newlines. In preprocessor directives, the
1396 necessary @samp{\} escape character before the newline is not
1397 automatically inserted, so an automatic line break would produce invalid
1398 code. In normal code, line breaks are normally dictated by some logical
1399 structure in the code rather than the last whitespace character, so
1400 automatic line breaks there will produce poor results in the current
1403 The commands that does the actual work follows.
1408 @findex c-fill-paragraph
1409 @findex fill-paragraph (c-)
1410 @cindex Javadoc markup
1411 @item @kbd{M-q} (@code{c-fill-paragraph})
1412 This is the replacement for @code{fill-paragraph} in @ccmode{}
1413 buffers. It's used to fill multiline string literals and both block and
1414 line style comments. In Java buffers, the Javadoc markup words are
1415 recognized as paragraph starters.
1417 The function keeps the comment starters and enders of block comments as
1418 they were before the filling. This means that a comment ender on the
1419 same line as the paragraph being filled will be filled with the
1420 paragraph, and one on a line by itself will stay as it is. The comment
1421 starter is handled similarly@footnote{This means that the variables
1422 @code{c-hanging-comment-starter-p} and @code{c-hanging-comment-ender-p},
1423 which controlled this behavior in earlier versions of @ccmode{}, are now
1427 @findex c-indent-new-comment-line
1428 @findex indent-new-comment-line (c-)
1429 @item @kbd{M-j} (@code{c-indent-new-comment-line})
1430 This is the replacement for @code{indent-new-comment-line}. It breaks
1431 the line at point and indents the new line like the current one.
1433 @vindex comment-multi-line
1434 If inside a comment and @code{comment-multi-line} is non-@code{nil}, the
1435 indentation and line prefix are preserved. If inside a comment and
1436 @code{comment-multi-line} is @code{nil}, a new comment of the same type
1437 is started on the next line and indented as appropriate for comments.
1439 @findex c-context-line-break
1440 @findex context-line-break (c-)
1441 @item @kbd{M-x c-context-line-break}
1442 This is a function that works like @code{indent-new-comment-line} in
1443 comments and @code{newline-and-indent} elsewhere, thus combining those
1444 two in a way that uses each one in the context it's best suited for.
1445 I.e. in comments the comment line prefix and indentation is kept for the
1446 new line, and in normal code it's indented according to context by the
1449 It's not bound to a key by default, but it's intended to be used on the
1450 @kbd{RET} key. If you like the behavior of @code{newline-and-indent} on
1451 @kbd{RET}, you might consider switching to this function.
1456 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1457 @node Commands, Customizing Indentation, Text Filling and Line Breaking, Top
1458 @comment node-name, next, previous, up
1460 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1463 * Indentation Commands::
1464 * Movement Commands::
1468 See also @ref{Text Filling and Line Breaking}, for commands concerning
1472 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1473 @node Indentation Commands, Movement Commands, , Commands
1474 @comment node-name, next, previous,up
1475 @section Indentation Commands
1476 @cindex indentation commands
1477 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1479 The following list of commands re-indent C constructs. Note that when
1480 you change your coding style, either interactively or through some other
1481 means, your file does @emph{not} automatically get re-indented. You
1482 will need to execute one of the following commands to see the effects of
1485 @cindex GNU indent program
1486 Also, variables like @code{c-hanging-*} and @code{c-cleanup-list}
1487 only affect how on-the-fly code is formatted. Changing the
1488 ``hanginess'' of a brace and then re-indenting, will not move the brace
1489 to a different line. For this, you're better off getting an external
1490 program like GNU @code{indent}, which will re-arrange brace location,
1493 Re-indenting large sections of code can take a long time. When
1494 @ccmode{} reindents a region of code, it is essentially equivalent to
1495 hitting @kbd{TAB} on every line of the region. Especially vulnerable is
1496 code generator output@footnote{In particular, I have had people
1497 complain about the speed with which @code{lex(1)} output is re-indented.
1498 Lex, yacc, and other code generators usually output some pretty
1499 perversely formatted code. Re-indenting such code will be slow.}.
1501 These commands are useful when indenting code:
1506 @findex c-indent-command
1507 @findex indent-command (c-)
1508 @item @kbd{TAB} (@code{c-indent-command})
1509 Indents the current line. The actual behavior is controlled by several
1510 variables, described below. See @code{c-tab-always-indent},
1511 @code{c-insert-tab-function}, and @code{indent-tabs-mode}. With a
1512 numeric argument, this command rigidly indents the region, preserving
1513 the relative indentation among the lines.
1516 @findex c-indent-exp
1517 @findex indent-exp (c-)
1518 @item @kbd{M-C-q} (@code{c-indent-exp})
1519 Indent an entire balanced brace or parenthesis expression. Note that
1520 point must be on the opening brace or parenthesis of the expression you
1524 @findex c-indent-defun
1525 @findex indent-defun (c-)
1526 @item @kbd{C-c C-q} (@code{c-indent-defun})
1527 Indents the entire top-level function or class definition encompassing
1528 point. It leaves point unchanged. This function can't be used to
1529 re-indent a nested brace construct, such as a nested class or function,
1530 or a Java method. The top-level construct being re-indented must be
1531 complete, i.e. it must have both a beginning brace and an ending brace.
1534 @findex indent-region
1535 @item @kbd{M-C-\} (@code{indent-region})
1536 Indents an arbitrary region of code. This is a standard Emacs command,
1537 tailored for C code in a @ccmode{} buffer. Note that of course, point
1538 and mark must delineate the region you want to indent.
1541 @findex c-mark-function
1542 @findex mark-function (c-)
1543 @item @kbd{M-C-h} (@code{c-mark-function})
1544 While not strictly an indentation command, this is useful for marking
1545 the current top-level function or class definition as the current
1546 region. As with @code{c-indent-defun}, this command operates on
1547 top-level constructs, and can't be used to mark say, a Java method.
1551 These variables are also useful when indenting code:
1555 @vindex c-tab-always-indent
1556 @vindex tab-always-indent (c-)
1559 @item c-tab-always-indent
1560 This variable controls how @kbd{TAB} @code{c-indent-command} operates.
1561 When this variable is @code{t}, @kbd{TAB} always just indents the
1562 current line. When it is @code{nil}, the line is indented only if point
1563 is at the left margin, or on or before the first non-whitespace
1564 character on the line, otherwise some whitespace is inserted. If this
1565 variable is the symbol @code{other}, then some whitespace is inserted
1566 only within strings and comments (literals), an inside preprocessor
1567 directives, but the line is always reindented.
1569 @vindex c-insert-tab-function
1570 @vindex insert-tab-function (c-)
1571 @findex tab-to-tab-stop
1572 @item c-insert-tab-function
1573 When ``some whitespace'' is inserted as described above, what actually
1574 happens is that the function stored in @code{c-insert-tab-function} is
1575 called. Normally, this just inserts a real tab character, or the
1576 equivalent number of spaces, depending on @code{indent-tabs-mode}.
1577 Some people, however, set @code{c-insert-tab-function} to
1578 @code{tab-to-tab-stop} so as to get hard tab stops when indenting.
1580 @vindex indent-tabs-mode
1581 @item indent-tabs-mode
1582 This is a standard Emacs variable that controls how line indentation is
1583 composed. When this variable is non-@code{nil}, then tabs can be used
1584 in a line's indentation, otherwise only spaces can be used.
1586 @vindex c-progress-interval
1587 @vindex progress-interval (c-)
1588 @item c-progress-interval
1589 When indenting large regions of code, this variable controls how often a
1590 progress message is displayed. Set this variable to @code{nil} to
1591 inhibit the progress messages, or set it to an integer which is the
1592 interval in seconds that progress messages are displayed.
1597 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1598 @node Movement Commands, Other Commands, Indentation Commands, Commands
1599 @comment node-name, next, previous, up
1600 @section Movement Commands
1601 @cindex movement commands
1602 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1604 @ccmode{} contains some useful command for moving around in C
1609 @findex c-beginning-of-defun
1610 @findex beginning-of-defun (c-)
1611 @findex beginning-of-defun
1612 @item @kbd{M-x c-beginning-of-defun}
1613 Moves point back to the least-enclosing brace. This function is
1614 analogous to the Emacs built-in command @code{beginning-of-defun},
1615 except it eliminates the constraint that the top-level opening brace
1616 must be in column zero. See @code{beginning-of-defun} for more
1619 Depending on the coding style being used, you might prefer
1620 @code{c-beginning-of-defun} to @code{beginning-of-defun}. If so,
1621 consider binding @kbd{C-M-a} to the former instead. For backwards
1622 compatibility reasons, the default binding remains in effect.
1624 @findex c-end-of-defun
1625 @findex end-of-defun (c-)
1626 @findex end-of-defun
1627 @item @kbd{M-x c-end-of-defun}
1628 Moves point to the end of the current top-level definition. This
1629 function is analogous to the Emacs built-in command @code{end-of-defun},
1630 except it eliminates the constraint that the top-level opening brace of
1631 the defun must be in column zero. See @code{beginning-of-defun} for more
1634 Depending on the coding style being used, you might prefer
1635 @code{c-end-of-defun} to @code{end-of-defun}. If so,
1636 consider binding @kbd{C-M-e} to the former instead. For backwards
1637 compatibility reasons, the default binding remains in effect.
1640 @findex c-up-conditional
1641 @findex up-conditional (c-)
1642 @item @kbd{C-c C-u} (@code{c-up-conditional})
1643 Move point back to the containing preprocessor conditional, leaving the
1644 mark behind. A prefix argument acts as a repeat count. With a negative
1645 argument, move point forward to the end of the containing
1646 preprocessor conditional.
1648 @samp{#elif} is treated like @samp{#else} followed by @samp{#if}, so the
1649 function stops at them when going backward, but not when going forward.
1651 @findex c-up-conditional-with-else
1652 @findex up-conditional-with-else (c-)
1653 @item @kbd{M-x c-up-conditional-with-else}
1654 A variety of @code{c-up-conditional} that also stops at @samp{#else}
1655 lines. Normally those lines are ignored.
1657 @findex c-down-conditional
1658 @findex down-conditional (c-)
1659 @item @kbd{M-x c-down-conditional}
1660 Move point forward into the next nested preprocessor conditional,
1661 leaving the mark behind. A prefix argument acts as a repeat count.
1662 With a negative argument, move point backward into the previous
1663 nested preprocessor conditional.
1665 @samp{#elif} is treated like @samp{#else} followed by @samp{#if}, so the
1666 function stops at them when going forward, but not when going backward.
1668 @findex c-down-conditional-with-else
1669 @findex down-conditional-with-else (c-)
1670 @item @kbd{M-x c-down-conditional-with-else}
1671 A variety of @code{c-down-conditional} that also stops at @samp{#else}
1672 lines. Normally those lines are ignored.
1675 @findex c-backward-conditional
1676 @findex backward-conditional (c-)
1677 @item @kbd{C-c C-p} (@code{c-backward-conditional})
1678 Move point back over a preprocessor conditional, leaving the mark
1679 behind. A prefix argument acts as a repeat count. With a negative
1680 argument, move forward.
1683 @findex c-forward-conditional
1684 @findex forward-conditional (c-)
1685 @item @kbd{C-c C-n} (@code{c-forward-conditional})
1686 Move point forward across a preprocessor conditional, leaving the mark
1687 behind. A prefix argument acts as a repeat count. With a negative
1688 argument, move backward.
1691 @findex c-beginning-of-statement
1692 @findex beginning-of-statement (c-)
1693 @item @kbd{M-a} (@code{c-beginning-of-statement})
1694 Move point to the beginning of the innermost C statement. If point is
1695 already at the beginning of a statement, it moves to the beginning of
1696 the closest preceding statement, even if that means moving into a block
1697 (you can use @kbd{M-C-b} to move over a balanced block). With prefix
1698 argument @var{n}, move back @var{n} @minus{} 1 statements.
1700 If point is within a comment, or next to a comment, this command moves
1701 by sentences instead of statements.
1703 When called from a program, this function takes three optional
1704 arguments: the numeric prefix argument, a buffer position limit which is
1705 the farthest back to search, and a flag to enable moving by sentence
1709 @findex c-end-of-statement
1710 @findex end-of-statement (c-)
1711 @item @kbd{M-e} (@code{c-end-of-statement})
1712 Move point to the end of the innermost C statement. If point is at the
1713 end of a statement, move to the end of the next statement, even if it's
1714 inside a nested block (use @kbd{M-C-f} to move to the other side of the
1715 block). With prefix argument @var{n}, move forward @var{n} @minus{} 1
1718 If point is within a comment, or next to a comment, this command moves
1719 by sentences instead of statements.
1721 When called from a program, this function takes three optional
1722 arguments: the numeric prefix argument, a buffer position limit which is
1723 the farthest back to search, and a flag to enable moving by sentence
1726 @findex c-forward-into-nomenclature
1727 @findex forward-into-nomenclature (c-)
1728 @item @kbd{M-x c-forward-into-nomenclature}
1729 A popular programming style, especially for object-oriented languages
1730 such as C++ is to write symbols in a mixed case format, where the first
1731 letter of each word is capitalized, and not separated by underscores.
1732 E.g. @samp{SymbolsWithMixedCaseAndNoUnderlines}.
1734 This command moves point forward to next capitalized word. With prefix
1735 argument @var{n}, move @var{n} times.
1737 @findex c-backward-into-nomenclature
1738 @findex backward-into-nomenclature (c-)
1739 @item @kbd{M-x c-backward-into-nomenclature}
1740 Move point backward to beginning of the next capitalized
1741 word. With prefix argument @var{n}, move @var{n} times. If
1742 @var{n} is negative, move forward.
1747 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1748 @node Other Commands, , Movement Commands, Commands
1749 @comment node-name, next, previous, up
1750 @section Other Commands
1751 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1753 @ccmode{} contains a few other useful commands:
1758 @findex c-scope-operator
1759 @findex scope-operator (c-)
1760 @item @kbd{C-c :} (@code{c-scope-operator})
1761 In C++, it is also sometimes desirable to insert the double-colon scope
1762 operator without performing the electric behavior of colon insertion.
1763 @kbd{C-c :} does just this.
1766 @findex c-backslash-region
1767 @findex backslash-region (c-)
1768 @item @kbd{C-c C-\} (@code{c-backslash-region})
1769 This function is handy when editing macros split over several lines by
1770 ending each line with a backslash. It inserts and aligns, or deletes
1771 these end-of-line backslashes in the current region.
1773 @vindex c-backslash-column
1774 @vindex backslash-column (c-)
1775 With no prefix argument, it inserts any missing backslashes and aligns
1776 them to the column specified by the @code{c-backslash-column} style
1777 variable. With a prefix argument, it deletes any backslashes.
1779 The function does not modify blank lines at the start of the region. If
1780 the region ends at the start of a line, it always deletes the backslash
1781 (if any) at the end of the previous line.
1786 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1787 @node Customizing Indentation, Syntactic Symbols, Commands, Top
1788 @comment node-name, next, previous, up
1789 @chapter Customizing Indentation
1790 @cindex customizing indentation
1791 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1793 @vindex c-offsets-alist
1794 @vindex offsets-alist (c-)
1795 The style variable @code{c-offsets-alist} contains the mappings between
1796 syntactic symbols and the offsets to apply for those symbols. It's set
1797 at mode initialization from a @emph{style} you may specify. Styles are
1798 groupings of syntactic symbol offsets and other style variable values.
1799 Most likely, you'll find that one of the pre-defined styles will suit
1800 your needs. @xref{Styles}, for an explanation of how to set up named
1803 Only syntactic symbols not already bound on @code{c-offsets-alist} will
1804 be set from styles. This means that any association you set on it, be
1805 it before or after mode initialization, will not be changed. The
1806 @code{c-offsets-alist} variable may therefore be used from e.g. the
1807 Customization interface@footnote{Available in Emacs 20 and later, and
1808 XEmacs 19.15 and later.} to easily change indentation offsets without
1809 having to bother about styles. Initially @code{c-offsets-alist} is
1810 empty, so that all syntactic symbols are set by the style system.
1813 @findex c-set-offset
1814 @findex set-offset (c-)
1815 You can use the command @kbd{C-c C-o} (@code{c-set-offset}) as the way
1816 to set offsets, both interactively and from your mode
1817 hook@footnote{Obviously, you use the keybinding interactively, and the
1818 function call programmatically!}.
1820 @vindex c-basic-offset
1821 @vindex basic-offset (c-)
1822 The offset associated with any particular syntactic symbol can be any of
1823 an integer, a function or lambda expression, a variable name, or one of
1824 the following symbols: @code{+}, @code{-}, @code{++}, @code{--},
1825 @code{*}, or @code{/}. These latter describe offset in multiples of the
1826 value of the style variable @code{c-basic-offset}. By defining a
1827 style's indentation in terms of this fundamental variable, you can
1828 change the amount of whitespace given to an indentation level while
1829 maintaining the same basic shape of your code. Here are the values that
1830 the special symbols correspond to:
1835 @code{c-basic-offset} times 1
1837 @code{c-basic-offset} times -1
1839 @code{c-basic-offset} times 2
1841 @code{c-basic-offset} times -2
1843 @code{c-basic-offset} times 0.5
1845 @code{c-basic-offset} times -0.5
1849 @cindex indentation functions
1851 When a function is used as offset, it's called an @dfn{indentation
1852 function}. Such functions are useful when more context than just the
1853 syntactic symbol is needed to get the desired indentation.
1854 @xref{Indentation Functions}, and @ref{Custom Indentation Functions},
1855 for details about them.
1857 @vindex c-strict-syntax-p
1858 @vindex strict-syntax-p (c-)
1859 The offset can also be a list, in which case it is evaluated recursively
1860 using the semantics described above. The first element of the list that
1861 returns a non-@code{nil} value succeeds and the evaluation stops. If
1862 none of the list elements return a non-@code{nil} value, then an offset
1863 of 0 (zero) is used@footnote{There is however a variable
1864 @code{c-strict-syntax-p} that, when set to non-@code{nil}, will cause an
1865 error to be signalled in that case. It's now considered obsolete since
1866 it doesn't work well with some of the alignment functions that now
1867 returns @code{nil} instead of zero to be more usable in lists. You
1868 should therefore leave @code{c-strict-syntax-p} set to @code{nil}.}.
1870 So, for example, because most of the default offsets are defined in
1871 terms of @code{+}, @code{-}, and @code{0}, if you like the general
1872 indentation style, but you use 4 spaces instead of 2 spaces per level,
1873 you can probably achieve your style just by changing
1874 @code{c-basic-offset} like so@footnote{You can try this interactively in
1875 a C buffer by typing the text that appears in italics.}:
1878 @emph{M-x set-variable RET}
1879 Set variable: @emph{c-basic-offset RET}
1880 Set c-basic-offset to value: @emph{4 RET}
1889 int add( int val, int incr, int doit )
1893 return( val + incr );
1905 int add( int val, int incr, int doit )
1909 return( val + incr );
1917 To change indentation styles more radically, you will want to change the
1918 offsets associated with other syntactic symbols. First, I'll show you
1919 how to do that interactively, then I'll describe how to make changes to
1920 your @file{.emacs} file so that your changes are more permanent.
1923 * Interactive Customization::
1924 * Permanent Customization::
1927 * Advanced Customizations::
1931 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1932 @node Interactive Customization, Permanent Customization, , Customizing Indentation
1933 @comment node-name, next, previous, up
1934 @section Interactive Customization
1935 @cindex interactive customization
1936 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1938 As an example of how to customize indentation, let's change the
1939 style of this example@footnote{In this an subsequent examples, the
1940 original code is formatted using the @samp{gnu} style unless otherwise
1941 indicated. @xref{Styles}.}:
1945 1: int add( int val, int incr, int doit )
1949 5: return( val + incr );
1961 1: int add( int val, int incr, int doit )
1965 5: return( val + incr );
1973 In other words, we want to change the indentation of braces that open a
1974 block following a condition so that the braces line up under the
1975 conditional, instead of being indented. Notice that the construct we
1976 want to change starts on line 4. To change the indentation of a line,
1977 we need to see which syntactic components affect the offset calculations
1978 for that line. Hitting @kbd{C-c C-s} on line 4 yields:
1981 ((substatement-open . 44))
1986 so we know that to change the offset of the open brace, we need to
1987 change the indentation for the @code{substatement-open} syntactic
1988 symbol. To do this interactively, just hit @kbd{C-c C-o}. This prompts
1989 you for the syntactic symbol to change, providing a reasonable default.
1990 In this case, the default is @code{substatement-open}, which is just the
1991 syntactic symbol we want to change!
1993 After you hit return, @ccmode{} will then prompt you for the new
1994 offset value, with the old value as the default. The default in this
1995 case is @samp{+}, but we want no extra indentation so enter
1996 @samp{0} and @kbd{RET}. This will associate the offset 0 with the
1997 syntactic symbol @code{substatement-open}.
1999 To check your changes quickly, just hit @kbd{C-c C-q}
2000 (@code{c-indent-defun}) to reindent the entire function. The example
2001 should now look like:
2005 1: int add( int val, int incr, int doit )
2009 5: return( val + incr );
2017 Notice how just changing the open brace offset on line 4 is all we
2018 needed to do. Since the other affected lines are indented relative to
2019 line 4, they are automatically indented the way you'd expect. For more
2020 complicated examples, this may not always work. The general approach to
2021 take is to always start adjusting offsets for lines higher up in the
2022 file, then re-indent and see if any following lines need further
2026 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2027 @node Permanent Customization, Hooks, Interactive Customization, Customizing Indentation
2028 @comment node-name, next, previous, up
2029 @section Permanent Customization
2030 @cindex permanent customization
2031 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2033 To make your changes permanent, you need to add some lisp code to your
2034 @file{.emacs} file. @ccmode{} supports many different ways to be
2035 configured, from the straightforward way by setting variables globally
2036 in @file{.emacs} or in the Customization interface, to the complex and
2037 precisely controlled way by using styles and hook functions.
2039 The simplest way of customizing @ccmode{} permanently is to set the
2040 variables in your @file{.emacs} with @code{setq} and similar commands.
2041 So to make the setting of @code{substatement-open} permanent, add this
2042 to the @file{.emacs} file:
2047 (c-set-offset 'substatement-open 0)
2052 The @code{require} line is only needed once in the beginning to make
2053 sure @ccmode{} is loaded so that the @code{c-set-offset} function is
2056 You can also use the more user friendly Customization interface, but
2057 this manual does not cover how that works.
2059 Variables set like this at the top level in @file{.emacs} take effect in
2060 all @ccmode{} buffers, regardless of language. The indentation style
2061 related variables, e.g. @code{c-basic-offset}, that you don't set this
2062 way get their value from the style system (@pxref{Styles}), and they
2063 therefore depend on the setting of @code{c-default-style}. Note that if
2064 you use Customize, this means that the greyed-out default values
2065 presented there might not be the ones you actually get, since the actual
2066 values depend on the style, which may very well be different for
2067 different languages.
2069 If you want to make more advanced configurations, e.g. language-specific
2070 customization, global variable settings isn't enough. For that you can
2071 use the language hooks, see @ref{Hooks}, and/or the style system, see
2074 @vindex c-style-variables-are-local-p
2075 @vindex style-variables-are-local-p (c-)
2076 By default, all style variables are global, so that every buffer will
2077 share the same style settings. This is fine if you primarily edit one
2078 style of code, but if you edit several languages and want to use
2079 different styles for them, you need finer control by making the style
2080 variables buffer local. The recommended way to do this is to set the
2081 variable @code{c-style-variables-are-local-p} to @code{t}. The
2082 variables will be made buffer local when @ccmode{} is activated in a
2083 buffer for the first time in the Emacs session. Note that once the
2084 style variables are made buffer local, they cannot be made global again,
2085 without restarting Emacs.
2088 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2089 @node Hooks, Styles, Permanent Customization, Customizing Indentation
2090 @comment node-name, next, previous, up
2093 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2095 @vindex c-mode-common-hook
2096 @vindex mode-common-hook (c-)
2098 @vindex c++-mode-hook
2099 @vindex objc-mode-hook
2100 @vindex java-mode-hook
2101 @vindex idl-mode-hook
2102 @vindex pike-mode-hook
2103 @vindex c-initialization-hook
2104 @vindex initialization-hook (c-)
2105 @ccmode{} provides several hooks that you can use to customize the mode
2106 according to your coding style. Each language mode has its own hook,
2107 adhering to standard Emacs major mode conventions. There is also one
2108 general hook and one package initialization hook:
2113 @code{c-mode-hook} --- For C buffers only.
2115 @code{c++-mode-hook} --- For C++ buffers only.
2117 @code{objc-mode-hook} --- For Objective-C buffers only.
2119 @code{java-mode-hook} --- For Java buffers only.
2121 @code{idl-mode-hook} --- For CORBA IDL buffers only.
2123 @code{pike-mode-hook} --- For Pike buffers only.
2125 @code{c-mode-common-hook} --- Common across all languages.
2127 @code{c-initialization-hook} --- Hook run only once per Emacs session,
2128 when @ccmode{} is initialized.
2132 The language hooks get run as the last thing when you enter that
2133 language mode. The @code{c-mode-common-hook} is run by all supported
2134 modes @emph{before} the language specific hook, and thus can contain
2135 customizations that are common across all languages. Most of the
2136 examples in this section will assume you are using the common
2137 hook.@footnote{@code{java-mode} and the hook variables interact in a
2138 slightly different way than the other modes. @code{java-mode} normally
2139 sets the style of the buffer to @samp{java} @emph{before} running the
2140 @code{c-mode-common-hook} or @code{java-mode-hook}. You need to be
2141 aware of this so that style settings in @code{c-mode-common-hook} don't
2142 clobber your Java style. This is arguably bogus, but it's kept for
2143 historical reasons. @xref{Built-in Styles}, the documentation of
2144 @code{c-default-style}, for details.}
2146 Here's a simplified example of what you can add to your @file{.emacs}
2147 file to do things whenever any @ccmode{} language is edited. See the
2148 Emacs manuals for more information on customizing Emacs via hooks.
2149 @xref{Sample .emacs File}, for a more complete sample @file{.emacs}
2154 (defun my-c-mode-common-hook ()
2155 ;; my customizations for all of c-mode and related modes
2156 (no-case-fold-search)
2158 (add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
2164 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2165 @node Styles, Advanced Customizations, Hooks, Customizing Indentation
2166 @comment node-name, next, previous, up
2169 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2171 Most people only need to edit code formatted in just a few well-defined
2172 and consistent styles. For example, their organization might impose a
2173 ``blessed'' style that all its programmers must conform to. Similarly,
2174 people who work on GNU software will have to use the GNU coding style.
2175 Some shops are more lenient, allowing a variety of coding styles, and as
2176 programmers come and go, there could be a number of styles in use. For
2177 this reason, @ccmode{} makes it convenient for you to set up logical
2178 groupings of customizations called @dfn{styles}, associate a single name
2179 for any particular style, and pretty easily start editing new or
2180 existing code using these styles.
2182 @cindex style variables
2183 The variables that the style system affect are called @dfn{style
2184 variables}. They are handled specially in several ways:
2188 Style variables are by default global variables, i.e. they have the same
2189 value in all Emacs buffers. However, they can instead be made always
2190 buffer local by setting @code{c-style-variables-are-local-p} to
2191 non-@code{nil} before @ccmode{} is initialized.
2193 @vindex c-old-style-variable-behavior
2194 @vindex old-style-variable-behavior (c-)
2196 The default value of any style variable (with two exceptions --- see
2197 below) is the special symbol @code{set-from-style}. Variables that are
2198 still set to that symbol when a @ccmode{} buffer is initialized will be
2199 set according to the current style, otherwise they will keep their
2200 current value@footnote{This is a big change from versions of @ccmode{}
2201 earlier than 5.26, where such settings would get overridden by the style
2202 system unless special precautions were taken. That was changed since it
2203 was counterintuitive and confusing, especially to novice users. If your
2204 configuration depends on the old overriding behavior, you can set the
2205 variable @code{c-old-style-variable-behavior} to non-@code{nil}.}.
2207 Note that when we talk about the ``default value'' for a style variable,
2208 we don't mean the @code{set-from-style} symbol that all style variables
2209 are set to initially, but instead the value it will get at mode
2210 initialization when neither a style nor a global setting has set its
2213 The style variable @code{c-offsets-alist} is handled a little
2214 differently from the other style variables. It's an association list,
2215 and is thus by default set to the empty list, @code{nil}. When the
2216 style system is initialized, any syntactic symbols already on it are
2217 kept --- only the missing ones are filled in from the chosen style.
2219 The style variable @code{c-special-indent-hook} is also handled in a
2220 special way. Styles may only add more functions on this hook, so the
2221 global settings on it are always preserved@footnote{This did not change
2225 The global settings of style variables get captured in the special
2226 @code{user} style, which is used as the base for all the other styles.
2227 @xref{Built-in Styles}, for details.
2231 The style variables are:
2232 @code{c-basic-offset},
2233 @code{c-comment-only-line-offset},
2234 @code{c-block-comment-prefix},
2235 @code{c-comment-prefix-regexp},
2236 @code{c-cleanup-list},
2237 @code{c-hanging-braces-alist},
2238 @code{c-hanging-colons-alist},
2239 @code{c-hanging-semi&comma-criteria},
2240 @code{c-backslash-column},
2241 @code{c-special-indent-hook},
2242 @code{c-label-minimum-indentation}, and
2243 @code{c-offsets-alist}.
2252 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2253 @node Built-in Styles, Adding Styles, , Styles
2254 @comment node-name, next, previous, up
2255 @subsection Built-in Styles
2256 @cindex built-in styles
2257 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2259 If you're lucky, one of @ccmode{}'s built-in styles might be just
2260 what you're looking for. These include:
2265 @code{gnu} --- Coding style blessed by the Free Software Foundation
2266 for C code in GNU programs.
2270 @code{k&r} --- The classic Kernighan and Ritchie style for C code.
2274 @code{bsd} --- Also known as ``Allman style'' after Eric Allman.
2276 @cindex Whitesmith style
2278 @code{whitesmith} --- Popularized by the examples that came with
2279 Whitesmiths C, an early commercial C compiler.
2281 @cindex Stroustrup style
2283 @code{stroustrup} --- The classic Stroustrup style for C++ code.
2285 @cindex Ellemtel style
2287 @code{ellemtel} --- Popular C++ coding standards as defined by
2288 ``Programming in C++, Rules and Recommendations'', Erik Nyquist and Mats
2289 Henricson, Ellemtel@footnote{This document is available at
2290 @uref{http://www.doc.ic.ac.uk/lab/cplus/c++.rules/} among other
2295 @code{linux} --- C coding standard for Linux development.
2297 @cindex Python style
2299 @code{python} --- C coding standard for Python extension
2300 modules@footnote{Python is a high level scripting language with a C/C++
2301 foreign function interface. For more information, see
2302 @uref{http://www.python.org/}.}.
2307 @code{java} --- The style for editing Java code. Note that this style is
2308 automatically installed when you enter @code{java-mode}.
2312 @code{user} --- This is a special style for several reasons. First, the
2313 @ccmode{} customizations you do by using either the Customization
2314 interface, or by writing @code{setq}'s at the top level of your
2315 @file{.emacs} file, will be captured in the @code{user} style. Also,
2316 all other styles implicitly inherit their settings from @code{user}
2317 style. This means that for any styles you add via @code{c-add-style}
2318 (@pxref{Adding Styles}) you need only define the differences between
2319 your new style and @code{user} style.
2323 @vindex c-default-style
2324 @vindex default-style (c-)
2325 The default style in all newly created buffers is @code{gnu}, but you
2326 can change this by setting variable @code{c-default-style}. Although
2327 the @code{user} style is not the default style, any style variable
2328 settings you do with the Customization interface or on the top level in
2329 your @file{.emacs} file will by default override the style system, so
2330 you don't need to set @code{c-default-style} to @code{user} to see the
2331 effect of these settings.
2333 @code{c-default-style} takes either a style name string, or an
2334 association list of major mode symbols to style names. Thus you can
2335 control exactly which default style is used for which @ccmode{} language
2336 mode. Here are the rules:
2338 @vindex c-style-alist
2339 @vindex style-alist (c-)
2340 @vindex c-mode-common-hook
2341 @vindex mode-common-hook (c-)
2344 When @code{c-default-style} is a string, it must be an existing style
2345 name as found in @code{c-style-alist}. This style is then used for all
2346 modes @emph{except} @code{java-mode}, where the style @samp{java} is
2347 used by default@footnote{This is for backwards compatibility reasons.
2348 The hard-coding of @code{java-mode} style is admittedly bogus!}.
2351 When @code{c-default-style} is an association list, the current major
2352 mode is looked up to find a style name string. In this case, this style
2353 is always used exactly as specified and an error will occur if the named
2354 style does not exist.
2357 If @code{c-default-style} is an association list, but the current major
2358 mode isn't found, then the special symbol @samp{other} is looked up. If
2359 this value is found, the associated style is used.
2362 If @samp{other} is not found, then the @samp{gnu} style is used.
2365 In all cases, the style described in @code{c-default-style} is installed
2366 @emph{before} the language hooks are run, so you can always override
2367 this setting by including an explicit call to @code{c-set-style} in your
2368 language mode hook, or in @code{c-mode-common-hook}.
2373 @findex set-style (c-)
2375 If you'd like to experiment with these built-in styles you can simply
2376 type the following in a @ccmode{} buffer:
2380 @kbd{C-c . @var{STYLE-NAME} RET}
2385 @kbd{C-c .} runs the command @code{c-set-style}. Note that all style
2386 names are case insensitive, even the ones you define.
2388 Setting a style in this way does @emph{not} automatically re-indent your
2389 file. For commands that you can use to view the effect of your changes,
2392 @vindex c-indentation-style
2393 @vindex indentation-style (c-)
2394 Note that for BOCM compatibility, @samp{gnu} is the default style, and
2395 any non-style based customizations you make (i.e. in
2396 @code{c-mode-common-hook} in your @file{.emacs} file) will be based on
2397 @samp{gnu} style unless you set @code{c-default-style} or do a
2398 @code{c-set-style} as the first thing in your hook. The variable
2399 @code{c-indentation-style} always contains the buffer's current style
2403 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2404 @node Adding Styles, File Styles, Built-in Styles, Styles
2405 @comment node-name, next, previous, up
2406 @subsection Adding Styles
2407 @cindex adding styles
2408 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2410 @vindex c-style-alist
2411 @vindex style-alist (c-)
2413 @findex add-style (c-)
2414 If none of the built-in styles is appropriate, you'll probably want to
2415 add a new @dfn{style definition}. Styles are kept in the
2416 @code{c-style-alist} variable, but you should never modify this variable
2417 directly. Instead, @ccmode{} provides the function
2418 @code{c-add-style} that you can use to easily add new styles or change
2419 existing styles. This function takes two arguments, a @var{stylename}
2420 string, and an association list @var{description} of style
2421 customizations. If @var{stylename} is not already in
2422 @code{c-style-alist}, the new style is added, otherwise the style is
2423 changed to the new @var{description}.
2424 This function also takes an optional third argument, which if
2425 non-@code{nil}, automatically applies the new style to the current
2428 @comment TBD: The next paragraph is bogus. I really need to better
2429 @comment document adding styles, including setting up inherited styles.
2431 The sample @file{.emacs} file provides a concrete example of how a new
2432 style can be added and automatically set. @xref{Sample .emacs File}.
2435 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2436 @node File Styles, , Adding Styles, Styles
2437 @comment node-name, next, previous, up
2438 @subsection File Styles
2440 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2442 @cindex local variables
2444 The Emacs manual describes how you can customize certain variables on a
2445 per-file basis by including a @dfn{Local Variable} block at the end of
2446 the file. So far, you've only seen a functional interface to @ccmode{}
2447 customization, which is highly inconvenient for use in a Local Variable
2448 block. @ccmode{} provides two variables that make it easier for you to
2449 customize your style on a per-file basis.
2451 @vindex c-file-style
2452 @vindex file-style (c-)
2453 @vindex c-file-offsets
2454 @vindex file-offsets (c-)
2456 The variable @code{c-file-style} can be set to a style name string.
2457 When the file is visited, @ccmode{} will automatically set the
2458 file's style to this style using @code{c-set-style}.
2460 Another variable, @code{c-file-offsets}, takes an association list
2461 similar to what is allowed in @code{c-offsets-alist}. When the file is
2462 visited, @ccmode{} will automatically institute these offsets using
2463 @code{c-set-offset}.
2465 Note that file style settings (i.e. @code{c-file-style}) are applied
2466 before file offset settings (i.e. @code{c-file-offsets}). Also, if
2467 either of these are set in a file's local variable section, all the
2468 style variable values are made local to that buffer.
2471 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2472 @node Advanced Customizations, , Styles, Customizing Indentation
2473 @comment node-name, next, previous, up
2474 @section Advanced Customizations
2475 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2477 @vindex c-style-alist
2478 @vindex style-alist (c-)
2479 For most users, @ccmode{} will support their coding styles with
2480 very little need for more advanced customizations. Usually, one of the
2481 standard styles defined in @code{c-style-alist} will do the trick. At
2482 most, perhaps one of the syntactic symbol offsets will need to be
2483 tweaked slightly, or maybe @code{c-basic-offset} will need to be
2484 changed. However, some styles require a more flexible framework for
2485 customization, and one of the real strengths of @ccmode{} is that
2486 the syntactic analysis model provides just such a framework. This allows
2487 you to implement custom indentation calculations for situations not
2488 handled by the mode directly.
2491 * Custom Indentation Functions::
2492 * Custom Brace and Colon Hanging::
2493 * Customizing Semi-colons and Commas::
2494 * Other Special Indentations::
2497 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2498 @node Custom Indentation Functions, Custom Brace and Colon Hanging, , Advanced Customizations
2499 @comment node-name, next, previous, up
2500 @subsection Custom Indentation Functions
2501 @cindex custom indentation functions
2502 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2504 The most flexible way to customize @ccmode{} is by writing custom
2505 indentation functions, and associating them with specific syntactic
2506 symbols (@pxref{Syntactic Symbols}). @ccmode{} itself uses indentation
2507 functions to provide more sophisticated indentation, for example when
2508 lining up C++ stream operator blocks:
2512 1: void main(int argc, char**)
2514 3: cout << "There were "
2516 5: << "arguments passed to the program"
2523 In this example, lines 4 through 6 are assigned the @code{stream-op}
2524 syntactic symbol. Here, @code{stream-op} has an offset of @code{+}, and
2525 with a @code{c-basic-offset} of 2, you can see that lines 4 through 6
2526 are simply indented two spaces to the right of line 3. But perhaps we'd
2527 like @ccmode{} to be a little more intelligent so that it aligns
2528 all the @samp{<<} symbols in lines 3 through 6. To do this, we have
2529 to write a custom indentation function which finds the column of first
2530 stream operator on the first line of the statement. Here is sample
2531 lisp code implementing this:
2535 (defun c-lineup-streamop (langelem)
2536 ;; lineup stream operators
2538 (let* ((relpos (cdr langelem))
2539 (curcol (progn (goto-char relpos)
2541 (re-search-forward "<<\\|>>" (c-point 'eol) 'move)
2542 (goto-char (match-beginning 0))
2543 (- (current-column) curcol))))
2548 Indentation functions take a single argument, which is a syntactic
2549 component cons cell (@pxref{Syntactic Analysis}). The function returns
2550 an integer offset value that will be added to the running total
2551 indentation for the line. Note that what actually gets returned is the
2552 difference between the column that the first stream operator is on, and
2553 the column of the buffer relative position passed in the function's
2554 argument. Remember that @ccmode{} automatically adds in the column of
2555 the component's relative buffer position and we don't the column offset
2558 The function should return @code{nil} if it's used in a situation where
2559 it doesn't want to do any decision. If the function is used in a list
2560 expression (@pxref{Customizing Indentation}), that will cause @ccmode{}
2561 to go on and check the next entry in the list.
2563 @cindex stream-op syntactic symbol
2564 @findex c-lineup-streamop
2565 @findex lineup-streamop (c-)
2566 Now, to associate the function @code{c-lineup-streamop} with the
2567 @code{stream-op} syntactic symbol, we can add something like the
2568 following to our @code{c++-mode-hook}@footnote{It probably makes more
2569 sense to add this to @code{c++-mode-hook} than @code{c-mode-common-hook}
2570 since stream operators are only relevant for C++.}:
2573 (c-set-offset 'stream-op 'c-lineup-streamop)
2577 Now the function looks like this after re-indenting (using @kbd{C-c
2582 1: void main(int argc, char**)
2584 3: cout << "There were "
2586 5: << " arguments passed to the program"
2593 Custom indentation functions can be as simple or as complex as you like,
2594 and any syntactic symbol that appears in @code{c-offsets-alist} can have
2595 a custom indentation function associated with it.
2597 @ccmode{} comes with an extensive set of predefined indentation
2598 functions, not all of which are used by the default styles. So there's
2599 a good chance the function you want already exists. @xref{Indentation
2600 Functions}, for a list of them. If you have written an indentation
2601 function that you think is generally useful, you're very welcome to
2602 contribute it; please contact @email{bug-cc-mode@@gnu.org}.
2605 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2606 @node Custom Brace and Colon Hanging, Customizing Semi-colons and Commas, Custom Indentation Functions, Advanced Customizations
2607 @comment node-name, next, previous, up
2608 @subsection Custom Brace and Colon Hanging
2609 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2611 @vindex c-hanging-braces-alist
2612 @vindex hanging-braces-alist (c-)
2613 Syntactic symbols aren't the only place where you can customize
2614 @ccmode{} with the lisp equivalent of callback functions. Brace
2615 ``hanginess'' can also be determined by custom functions associated with
2616 syntactic symbols on the @code{c-hanging-braces-alist} style variable.
2617 Remember that @var{ACTION}'s are typically a list containing some
2618 combination of the symbols @code{before} and @code{after}
2619 (@pxref{Hanging Braces}). However, an @var{ACTION} can also be a
2620 function which gets called when a brace matching that syntactic symbol
2623 @cindex customizing brace hanging
2624 These @var{ACTION} functions are called with two arguments: the
2625 syntactic symbol for the brace, and the buffer position at which the
2626 brace was inserted. The @var{ACTION} function is expected to return a
2627 list containing some combination of @code{before} and @code{after},
2628 including neither of them (i.e. @code{nil}). This return value has the
2629 normal brace hanging semantics.
2631 As an example, @ccmode{} itself uses this feature to dynamically
2632 determine the hanginess of braces which close ``do-while''
2637 void do_list( int count, char** atleast_one_string )
2641 handle_string( atleast_one_string[i] );
2643 @} while( i < count );
2649 @findex c-snug-do-while
2650 @findex snug-do-while (c-)
2651 @ccmode{} assigns the @code{block-close} syntactic symbol to the
2652 brace that closes the @code{do} construct, and normally we'd like the
2653 line that follows a @code{block-close} brace to begin on a separate
2654 line. However, with ``do-while'' constructs, we want the
2655 @code{while} clause to follow the closing brace. To do this, we
2656 associate the @code{block-close} symbol with the @var{ACTION} function
2657 @code{c-snug-do-while}:
2660 (defun c-snug-do-while (syntax pos)
2661 "Dynamically calculate brace hanginess for do-while statements.
2662 Using this function, `while' clauses that end a `do-while' block will
2663 remain on the same line as the brace that closes that block.
2665 See `c-hanging-braces-alist' for how to utilize this function as an
2666 ACTION associated with `block-close' syntax."
2669 (if (and (eq syntax 'block-close)
2670 (setq langelem (assq 'block-close c-syntactic-context))
2671 (progn (goto-char (cdr langelem))
2672 (if (= (following-char) ?@{)
2674 (looking-at "\\<do\\>[^_]")))
2680 This function simply looks to see if the brace closes a ``do-while''
2681 clause and if so, returns the list @samp{(before)} indicating
2682 that a newline should be inserted before the brace, but not after it.
2683 In all other cases, it returns the list @samp{(before after)} so
2684 that the brace appears on a line by itself.
2686 @vindex c-syntactic-context
2687 @vindex syntactic-context (c-)
2688 During the call to the brace hanging @var{ACTION} function, the variable
2689 @code{c-syntactic-context} is bound to the full syntactic analysis list.
2691 @cindex customizing colon hanging
2692 @vindex c-hanging-colon-alist
2693 @vindex hanging-colon-alist (c-)
2694 Note that for symmetry, colon hanginess should be customizable by
2695 allowing function symbols as @var{ACTION}s on the
2696 @code{c-hanging-colon-alist} style variable. Since no use has actually
2697 been found for this feature, it isn't currently implemented!
2700 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2701 @node Customizing Semi-colons and Commas, Other Special Indentations, Custom Brace and Colon Hanging, Advanced Customizations
2702 @comment node-name, next, previous, up
2703 @subsection Customizing Semi-colons and Commas
2704 @cindex customizing semi-colons and commas
2705 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2707 @vindex c-hanging-semi&comma-criteria
2708 @vindex hanging-semi&comma-criteria (c-)
2709 You can also customize the insertion of newlines after semi-colons and
2710 commas, when the auto-newline minor mode is enabled (@pxref{Minor
2711 Modes}). This is controlled by the style variable
2712 @code{c-hanging-semi&comma-criteria}, which contains a list of functions
2713 that are called in the order they appear. Each function is called with
2714 zero arguments, and is expected to return one of the following values:
2718 non-@code{nil} --- A newline is inserted, and no more functions from the
2722 @code{stop} --- No more functions from the list are called, but no
2723 newline is inserted.
2726 @code{nil} --- No determination is made, and the next function in the
2731 If every function in the list is called without a determination being
2732 made, then no newline is added. The default value for this variable is a
2733 list containing a single function which inserts newlines only after
2734 semi-colons which do not appear inside parenthesis lists (i.e. those
2735 that separate @code{for}-clause statements).
2737 @findex c-semi&comma-no-newlines-before-nonblanks
2738 @findex semi&comma-no-newlines-before-nonblanks (c-)
2739 Here's an example of a criteria function, provided by @ccmode{}, that
2740 will prevent newlines from being inserted after semicolons when there is
2741 a non-blank following line. Otherwise, it makes no determination. To
2742 use, add this to the front of the @code{c-hanging-semi&comma-criteria}
2748 (defun c-semi&comma-no-newlines-before-nonblanks ()
2750 (if (and (eq last-command-char ?\;)
2751 (zerop (forward-line 1))
2752 (not (looking-at "^[ \t]*$")))
2759 @findex c-semi&comma-inside-parenlist
2760 @findex c-semi&comma-no-newlines-for-oneline-inliners
2761 @findex semi&comma-inside-parenlist (c-)
2762 @findex semi&comma-no-newlines-for-oneline-inliners (c-)
2763 The function @code{c-semi&comma-inside-parenlist} is what prevents
2764 newlines from being inserted inside the parenthesis list of @code{for}
2765 statements. In addition to
2766 @code{c-semi&comma-no-newlines-before-nonblanks} described above,
2767 @ccmode{} also comes with the criteria function
2768 @code{c-semi&comma-no-newlines-for-oneline-inliners}, which suppresses
2769 newlines after semicolons inside one-line inline method definitions
2770 (i.e. in C++ or Java).
2773 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2774 @node Other Special Indentations, , Customizing Semi-colons and Commas, Advanced Customizations
2775 @comment node-name, next, previous, up
2776 @subsection Other Special Indentations
2777 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2779 @vindex c-label-minimum-indentation
2780 @vindex label-minimum-indentation (c-)
2781 In @samp{gnu} style (@pxref{Built-in Styles}), a minimum indentation
2782 is imposed on lines inside top-level constructs. This minimum
2783 indentation is controlled by the style variable
2784 @code{c-label-minimum-indentation}. The default value for this variable
2787 @vindex c-special-indent-hook
2788 @vindex special-indent-hook (c-)
2789 One other customization variable is available in @ccmode{}: The style
2790 variable @code{c-special-indent-hook}. This is a standard hook variable
2791 that is called after every line is indented by @ccmode{}. You can use
2792 it to do any special indentation or line adjustments your style
2793 dictates, such as adding extra indentation to constructors or destructor
2794 declarations in a class definition, etc. Note however, that you should
2795 not change point or mark inside your @code{c-special-indent-hook}
2796 functions (i.e. you'll probably want to wrap your function in a
2797 @code{save-excursion}).
2799 Setting @code{c-special-indent-hook} in your style definition is handled
2800 slightly differently than other variables. In your style definition,
2801 you should set the value for
2802 @code{c-special-indent-hook} to a function or list of functions, which
2803 will be appended to @code{c-special-indent-hook} using @code{add-hook}.
2804 That way, the current setting for the buffer local value of
2805 @code{c-special-indent-hook} won't be overridden.
2808 @findex indent-for-comment
2809 @vindex c-indent-comments-syntactically-p
2810 @vindex indent-comments-syntactically-p (c-)
2811 @vindex comment-column
2812 Normally, the standard Emacs command @kbd{M-;}
2813 (@code{indent-for-comment}) will indent comment only lines to
2814 @code{comment-column}. Some users however, prefer that @kbd{M-;} act
2815 just like @kbd{TAB} for purposes of indenting comment-only lines;
2816 i.e. they want the comments to always indent as they would for normal
2817 code, regardless of whether @kbd{TAB} or @kbd{M-;} were used. This
2818 behavior is controlled by the variable
2819 @code{c-indent-comments-syntactically-p}. When @code{nil} (the
2820 default), @kbd{M-;} indents comment-only lines to @code{comment-column},
2821 otherwise, they are indented just as they would be if @kbd{TAB} were
2824 Note that this has no effect for comment lines that are inserted with
2825 @kbd{M-;} at the end of regular code lines. These comments will always
2826 start at @code{comment-column}.
2829 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2830 @node Syntactic Symbols, Indentation Functions, Customizing Indentation, Top
2831 @comment node-name, next, previous, up
2832 @chapter Syntactic Symbols
2833 @cindex syntactic symbols
2834 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2836 @vindex c-offsets-alist
2837 @vindex offsets-alist (c-)
2838 Here is a complete list of the recognized syntactic symbols as described
2839 in the @code{c-offsets-alist} style variable, along with a brief
2840 description. More detailed descriptions follow.
2844 Inside a multi-line string.
2846 Inside a multi-line C style block comment.
2848 Brace that opens a top-level function definition.
2850 Brace that closes a top-level function definition.
2851 @item defun-block-intro
2852 The first line in a top-level defun.
2854 Brace that opens a class definition.
2856 Brace that closes a class definition.
2858 Brace that opens an in-class inline method.
2860 Brace that closes an in-class inline method.
2861 @item func-decl-cont
2862 The region between a function definition's argument list and the
2863 function opening brace (excluding K&R argument declarations). In C, you
2864 cannot put anything but whitespace and comments in this region, however
2865 in C++ and Java, @code{throws} declarations and other things can appear
2867 @item knr-argdecl-intro
2868 First line of a K&R C argument declaration.
2870 Subsequent lines in a K&R C argument declaration.
2872 The first line in a ``topmost'' definition.
2873 @item topmost-intro-cont
2874 Topmost definition continuation lines.
2875 @item member-init-intro
2876 First line in a member initialization list.
2877 @item member-init-cont
2878 Subsequent member initialization list lines.
2880 First line of a multiple inheritance list.
2882 Subsequent multiple inheritance lines.
2884 Statement block open brace.
2886 Statement block close brace.
2887 @item brace-list-open
2888 Open brace of an enum or static array list.
2889 @item brace-list-close
2890 Close brace of an enum or static array list.
2891 @item brace-list-intro
2892 First line in an enum or static array list.
2893 @item brace-list-entry
2894 Subsequent lines in an enum or static array list.
2895 @item brace-entry-open
2896 Subsequent lines in an enum or static array list where the line begins
2900 @item statement-cont
2901 A continuation of a statement.
2902 @item statement-block-intro
2903 The first line in a new statement block.
2904 @item statement-case-intro
2905 The first line in a case block.
2906 @item statement-case-open
2907 The first line in a case block that starts with a brace.
2909 The first line after a conditional or loop construct.
2910 @item substatement-open
2911 The brace that opens a substatement block.
2913 A @code{case} or @code{default} label.
2915 C++ access control label.
2917 Any non-special C label.
2918 @item do-while-closure
2919 The @code{while} line that ends a @code{do}-@code{while} construct.
2921 The @code{else} line of an @code{if}-@code{else} construct.
2923 The @code{catch} or @code{finally} (in Java) line of a
2924 @code{try}-@code{catch} construct.
2926 A line containing only a comment introduction.
2928 The first line in an argument list.
2930 Subsequent argument list lines when no arguments follow on the same line
2931 as the the arglist opening paren.
2932 @item arglist-cont-nonempty
2933 Subsequent argument list lines when at least one argument follows on the
2934 same line as the arglist opening paren.
2936 The solo close paren of an argument list.
2938 Lines continuing a stream operator (C++ only).
2940 The line is nested inside a class definition.
2942 The start of a C preprocessor macro definition.
2943 @item cpp-macro-cont
2944 Subsequent lines of a multi-line C preprocessor macro definition.
2946 A C++ friend declaration.
2947 @item objc-method-intro
2948 The first line of an Objective-C method. definition.
2949 @item objc-method-args-cont
2950 Lines continuing an Objective-C method. definition
2951 @item objc-method-call-cont
2952 Lines continuing an Objective-C method call.
2953 @item extern-lang-open
2954 Brace that opens an external language block.
2955 @item extern-lang-close
2956 Brace that closes an external language block.
2958 Analogous to @code{inclass} syntactic symbol, but used inside external
2959 language blocks (e.g. @code{extern "C" @{}).
2960 @item namespace-open
2961 Brace that opens a C++ namespace block.
2962 @item namespace-close
2963 Brace that closes a C++ namespace block.
2965 Analogous to @code{inextern-lang} syntactic symbol, but used inside C++
2967 @item template-args-cont
2968 C++ template argument list continuations.
2970 Analogous to @code{inclass} syntactic symbol, but used inside lambda
2971 (i.e. anonymous) functions. Only used in Pike mode.
2972 @item lambda-intro-cont
2973 Lines continuing the header of a lambda function, i.e. between the
2974 @code{lambda} keyword and the function body. Only used in Pike mode.
2975 @item inexpr-statement
2976 A statement block inside an expression. The gcc C extension of this is
2977 recognized. It's also used for the special functions that takes a
2978 statement block as an argument in Pike.
2980 A class definition inside an expression. This is used for anonymous
2981 classes in Java. It's also used for anonymous array initializers in
2985 @cindex -open syntactic symbols
2986 @cindex -close syntactic symbols
2987 Most syntactic symbol names follow a general naming convention. When a
2988 line begins with an open or close brace, the syntactic symbol will
2989 contain the suffix @code{-open} or @code{-close} respectively.
2991 @cindex -intro syntactic symbols
2992 @cindex -cont syntactic symbols
2993 @cindex -block-intro syntactic symbols
2994 Usually, a distinction is made between the first line that introduces a
2995 construct and lines that continue a construct, and the syntactic symbols
2996 that represent these lines will contain the suffix @code{-intro} or
2997 @code{-cont} respectively. As a sub-classification of this scheme, a
2998 line which is the first of a particular brace block construct will
2999 contain the suffix @code{-block-intro}.
3001 Let's look at some examples to understand how this works. Remember that
3002 you can check the syntax of any line by using @kbd{C-c C-s}.
3007 2: swap( int& a, int& b )
3019 @cindex topmost-intro syntactic symbol
3020 @cindex topmost-intro-cont syntactic symbol
3021 @cindex defun-open syntactic symbol
3022 @cindex defun-close syntactic symbol
3023 @cindex defun-block-intro syntactic symbol
3024 Line 1 shows a @code{topmost-intro} since it is the first line that
3025 introduces a top-level construct. Line 2 is a continuation of the
3026 top-level construct introduction so it has the syntax
3027 @code{topmost-intro-cont}. Line 3 shows a @code{defun-open} since it is
3028 the brace that opens a top-level function definition. Line 9 is the
3030 @code{defun-close} since it contains the brace that closes the top-level
3031 function definition. Line 4 is a @code{defun-block-intro}, i.e. it is
3032 the first line of a brace-block, enclosed in a
3033 top-level function definition.
3035 @cindex statement syntactic symbol
3036 @cindex statement-cont syntactic symbol
3037 Lines 5, 6, and 7 are all given @code{statement} syntax since there
3038 isn't much special about them. Note however that line 8 is given
3039 @code{statement-cont} syntax since it continues the statement begun
3040 on the previous line.
3042 Here's another example, which illustrates some C++ class syntactic
3049 3: public Amplifiable
3053 7: : eString( new BassString( 0.105 )),
3054 8: aString( new BassString( 0.085 )),
3055 9: dString( new BassString( 0.065 )),
3056 10: gString( new BassString( 0.045 ))
3058 12: eString.tune( 'E' );
3059 13: aString.tune( 'A' );
3060 14: dString.tune( 'D' );
3061 15: gString.tune( 'G' );
3063 17: friend class Luthier;
3069 @cindex class-open syntactic symbol
3070 @cindex class-close syntactic symbol
3071 As in the previous example, line 1 has the @code{topmost-intro} syntax.
3072 Here however, the brace that opens a C++ class definition on line 4 is
3073 assigned the @code{class-open} syntax. Note that in C++, classes,
3074 structs, and unions are essentially equivalent syntactically (and are
3075 very similar semantically), so replacing the @code{class} keyword in the
3076 example above with @code{struct} or @code{union} would still result in a
3077 syntax of @code{class-open} for line 4 @footnote{This is the case even
3078 for C and Objective-C. For consistency, structs in all supported
3079 languages are syntactically equivalent to classes. Note however that
3080 the keyword @code{class} is meaningless in C and Objective-C.}.
3081 Similarly, line 18 is assigned @code{class-close} syntax.
3083 @cindex inher-intro syntactic symbol
3084 @cindex inher-cont syntactic symbol
3085 Line 2 introduces the inheritance list for the class so it is assigned
3086 the @code{inher-intro} syntax, and line 3, which continues the
3087 inheritance list is given @code{inher-cont} syntax.
3089 @cindex access-label syntactic symbol
3090 @cindex inclass syntactic symbol
3091 Hitting @kbd{C-c C-s} on line 5 shows the following analysis:
3096 @code{((inclass . 58) (access-label . 67))}
3102 The primary syntactic symbol for this line is @code{access-label} as
3103 this a label keyword that specifies access protection in C++. However,
3104 because this line is also a top-level construct inside a class
3105 definition, the analysis actually shows two syntactic symbols. The
3106 other syntactic symbol assigned to this line is @code{inclass}.
3107 Similarly, line 6 is given both @code{inclass} and @code{topmost-intro}
3113 @code{((inclass . 58) (topmost-intro . 60))}
3118 @cindex member-init-intro syntactic symbol
3119 @cindex member-init-cont syntactic symbol
3120 Line 7 introduces a C++ member initialization list and as such is given
3121 @code{member-init-intro} syntax. Note that in this case it is
3122 @emph{not} assigned @code{inclass} since this is not considered a
3123 top-level construct. Lines 8 through 10 are all assigned
3124 @code{member-init-cont} since they continue the member initialization
3125 list started on line 7.
3127 @cindex in-class inline methods
3128 @cindex inline-open syntactic symbol
3129 @cindex inline-close syntactic symbol
3130 Line 11's analysis is a bit more complicated:
3135 @code{((inclass . 58) (inline-open))}
3140 This line is assigned a syntax of both @code{inline-open} and
3141 @code{inclass} because it opens an @dfn{in-class} C++ inline method
3142 definition. This is distinct from, but related to, the C++ notion of an
3143 inline function in that its definition occurs inside an enclosing class
3144 definition, which in C++ implies that the function should be inlined.
3145 If though, the definition of the @code{Bass} constructor appeared
3146 outside the class definition, the construct would be given the
3147 @code{defun-open} syntax, even if the keyword @code{inline} appeared
3148 before the method name, as in:
3162 : eString( new BassString( 0.105 )),
3163 aString( new BassString( 0.085 )),
3164 dString( new BassString( 0.065 )),
3165 gString( new BassString( 0.045 ))
3167 eString.tune( 'E' );
3168 aString.tune( 'A' );
3169 dString.tune( 'D' );
3170 gString.tune( 'G' );
3176 @cindex friend syntactic symbol
3177 Returning to the previous example, line 16 is given @code{inline-close}
3178 syntax, while line 12 is given @code{defun-block-open} syntax, and lines
3179 13 through 15 are all given @code{statement} syntax. Line 17 is
3180 interesting in that its syntactic analysis list contains three
3185 @code{((friend) (inclass . 58) (topmost-intro . 380))}
3189 The @code{friend} syntactic symbol is a modifier that typically does not
3190 have a relative buffer position.
3192 Template definitions introduce yet another syntactic symbol:
3197 1: ThingManager <int,
3198 2: Framework::Callback *,
3199 3: Mutex> framework_callbacks;
3204 Here, line 1 is analyzed as a @code{topmost-intro}, but lines 2 and 3
3205 are both analyzed as @code{template-args-cont} lines.
3207 Here is another (totally contrived) example which illustrates how syntax
3208 is assigned to various conditional constructs:
3212 1: void spam( int index )
3214 3: for( int i=0; i<index; i++ )
3218 7: do_something_special();
3221 10: do_something( i );
3224 13: another_thing( i-- );
3234 Only the lines that illustrate new syntactic symbols will be discussed.
3236 @cindex substatement-open syntactic symbol
3237 @cindex substatement-block-intro syntactic symbol
3238 @cindex block-close syntactic symbol
3239 Line 4 has a brace which opens a conditional's substatement block. It
3240 is thus assigned @code{substatement-open} syntax, and since line 5 is
3241 the first line in the substatement block, it is assigned
3242 @code{substatement-block-intro} syntax. Lines 6 and 7 are assigned
3243 similar syntax. Line 8 contains the brace that closes the inner
3244 substatement block. It is given the syntax @code{block-close},
3245 as are lines 11 and 14.
3247 @cindex else-clause syntactic symbol
3248 @cindex catch-clause syntactic symbol
3249 Line 9 is a little different --- since it contains the keyword
3250 @code{else} matching the @code{if} statement introduced on line 5, it is
3251 given the @code{else-clause} syntax. The @code{try}-@code{catch}
3252 constructs in C++ and Java are treated this way too, with the only
3253 difference that the @code{catch}, and in Java also @code{finally}, is
3254 marked with @code{catch-clause}.
3256 @cindex substatement syntactic symbol
3257 Line 10 is also slightly different. Because @code{else} is considered a
3258 conditional introducing keyword @footnote{The list of conditional
3259 keywords are (in C, C++, Objective-C, Java, and Pike): @code{for},
3260 @code{if}, @code{do}, @code{else}, @code{while}, and @code{switch}. C++
3261 and Java have two additional conditional keywords: @code{try} and
3262 @code{catch}. Java also has the @code{finally} and @code{synchronized}
3263 keywords.}, and because the following substatement is not a brace block,
3264 line 10 is assigned the @code{substatement} syntax.
3266 @cindex do-while-closure syntactic symbol
3267 One other difference is seen on line 15. The @code{while} construct
3268 that closes a @code{do} conditional is given the special syntax
3269 @code{do-while-closure} if it appears on a line by itself. Note that if
3270 the @code{while} appeared on the same line as the preceding close brace,
3271 that line would have been assigned @code{block-close} syntax instead.
3273 Switch statements have their own set of syntactic symbols. Here's an
3278 1: void spam( enum Ingredient i )
3285 8: drink_some_water();
3298 @cindex case-label syntactic symbol
3299 @cindex statement-case-intro syntactic symbol
3300 @cindex statement-case-open syntactic symbol
3301 Here, lines 4, 7, and 10 are all assigned @code{case-label} syntax,
3302 while lines 5 and 8 are assigned @code{statement-case-intro}. Line 11
3303 is treated slightly differently since it contains a brace that opens a
3304 block --- it is given @code{statement-case-open} syntax.
3307 There are a set of syntactic symbols that are used to recognize
3308 constructs inside of brace lists. A brace list is defined as an
3309 @code{enum} or aggregate initializer list, such as might statically
3310 initialize an array of structs. The three special aggregate constructs
3311 in Pike, @code{(@{ @})}, @code{([ ])} and @code{(< >)}, are treated as
3312 brace lists too. An example:
3316 1: static char* ingredients[] =
3326 @cindex brace-list-open syntactic symbol
3327 @cindex brace-list-intro syntactic symbol
3328 @cindex brace-list-close syntactic symbol
3329 @cindex brace-list-entry syntactic symbol
3330 Following convention, line 2 in this example is assigned
3331 @code{brace-list-open} syntax, and line 3 is assigned
3332 @code{brace-list-intro} syntax. Likewise, line 6 is assigned
3333 @code{brace-list-close} syntax. Lines 4 and 5 however, are assigned
3334 @code{brace-list-entry} syntax, as would all subsequent lines in this
3337 @cindex brace-entry-open syntactic symbol
3338 Your static initializer might be initializing nested structures, for
3343 1: struct intpairs[] =
3358 Here, you've already seen the analysis of lines 1, 2, 3, and 11. On
3359 line 4, things get interesting; this line is assigned
3360 @code{brace-entry-open} syntactic symbol because it's a bracelist entry
3361 line that starts with an open brace. Lines 5 and 6 (and line 9) are
3362 pretty standard, and line 7 is a @code{brace-list-close} as you'd
3363 expect. Once again, line 8 is assigned as @code{brace-entry-open} as is
3366 External language definition blocks also have their own syntactic
3367 symbols. In this example:
3373 3: int thing_one( int );
3374 4: int thing_two( double );
3380 @cindex extern-lang-open syntactic symbol
3381 @cindex extern-lang-close syntactic symbol
3382 @cindex inextern-lang syntactic symbol
3383 @cindex inclass syntactic symbol
3385 line 2 is given the @code{extern-lang-open} syntax, while line 5 is given
3386 the @code{extern-lang-close} syntax. The analysis for line 3 yields:
3387 @code{((inextern-lang) (topmost-intro . 14))}, where
3388 @code{inextern-lang} is a modifier similar in purpose to @code{inclass}.
3390 Similarly, C++ namespace constructs have their own associated syntactic
3391 symbols. In this example:
3403 @cindex namespace-open syntactic symbol
3404 @cindex namespace-close syntactic symbol
3405 @cindex innamespace syntactic symbol
3407 line 2 is given the @code{namespace-open} syntax, while line 4 is given
3408 the @code{namespace-close} syntax. The analysis for line 3 yields:
3409 @code{((innamespace) (topmost-intro . 17))}, where @code{innamespace} is
3410 a modifier similar in purpose to @code{inextern-lang} and @code{inclass}.
3412 A number of syntactic symbols are associated with parenthesis lists,
3413 a.k.a argument lists, as found in function declarations and function
3414 calls. This example illustrates these:
3418 1: void a_function( int line1,
3421 4: void a_longer_function(
3426 9: void call_them( int line1, int line2 )
3433 16: a_longer_function( line1,
3440 @cindex arglist-intro syntactic symbol
3441 @cindex arglist-close syntactic symbol
3442 Lines 5 and 12 are assigned @code{arglist-intro} syntax since they are
3443 the first line following the open parenthesis, and lines 7 and 14 are
3444 assigned @code{arglist-close} syntax since they contain the parenthesis
3445 that closes the argument list.
3447 @cindex arglist-cont-nonempty syntactic symbol
3448 @cindex arglist-cont syntactic symbol
3449 Lines that continue argument lists can be assigned one of two syntactic
3450 symbols. For example, Lines 2 and 17
3451 are assigned @code{arglist-cont-nonempty} syntax. What this means
3452 is that they continue an argument list, but that the line containing the
3453 parenthesis that opens the list is @emph{not empty} following the open
3454 parenthesis. Contrast this against lines 6 and 13 which are assigned
3455 @code{arglist-cont} syntax. This is because the parenthesis that opens
3456 their argument lists is the last character on that line.
3458 Note that there is no @code{arglist-open} syntax. This is because any
3459 parenthesis that opens an argument list, appearing on a separate line,
3460 is assigned the @code{statement-cont} syntax instead.
3462 A few miscellaneous syntactic symbols that haven't been previously
3463 covered are illustrated by this C++ example:
3467 1: void Bass::play( int volume )
3470 4: /* this line starts a multi-line
3471 5: * comment. This line should get `c' syntax */
3473 7: char* a_multiline_string = "This line starts a multi-line \
3474 8: string. This line should get `string' syntax.";
3482 16: cout << "I played "
3490 The lines to note in this example include:
3494 @cindex func-decl-cont syntactic symbol
3496 Line 2 is assigned the @code{func-decl-cont} syntax.
3498 @cindex comment-intro syntactic symbol
3500 Line 4 is assigned both @code{defun-block-intro} @emph{and}
3501 @code{comment-intro} syntax.
3503 @cindex c syntactic symbol
3505 Line 5 is assigned @code{c} syntax.
3508 @cindex syntactic whitespace
3509 Line 6 which, even though it contains nothing but whitespace, is
3510 assigned @code{defun-block-intro}. Note that the appearance of the
3511 comment on lines 4 and 5 do not cause line 6 to be assigned
3512 @code{statement} syntax because comments are considered to be
3513 @dfn{syntactic whitespace}, which are ignored when analyzing
3516 @cindex string syntactic symbol
3518 Line 8 is assigned @code{string} syntax.
3520 @cindex label syntactic symbol
3522 Line 10 is assigned @code{label} syntax.
3524 @cindex block-open syntactic symbol
3526 Line 11 is assigned @code{block-open} syntax.
3528 @cindex cpp-macro syntactic symbol
3529 @cindex cpp-macro-cont syntactic symbol
3531 Lines 12 and 14 are assigned @code{cpp-macro} syntax in addition to the
3532 normal syntactic symbols (@code{statement-block-intro} and
3533 @code{statement}, respectively). Normally @code{cpp-macro} is
3534 configured to cancel out the normal syntactic context to make all
3535 preprocessor directives stick to the first column, but that's easily
3536 changed if you want preprocessor directives to be indented like the rest
3539 @cindex stream-op syntactic symbol
3541 Line 17 is assigned @code{stream-op} syntax.
3545 @cindex multi-line macros
3546 @cindex syntactic whitespace
3547 Multi-line C preprocessor macros are now (somewhat) supported. At least
3548 @ccmode{} now recognizes the fact that it is inside a multi-line macro,
3549 and it properly skips such macros as syntactic whitespace. In this
3554 1: #define LIST_LOOP(cons, listp) \
3555 2: for (cons = listp; !NILP (cons); cons = XCDR (cons)) \
3556 3: if (!CONSP (cons)) \
3557 4: signal_error ("Invalid list format", listp); \
3563 line 1 is given the syntactic symbol @code{cpp-macro}. This first line
3564 of a macro is always given this symbol. The second and subsequent lines
3565 (e.g. lines 2 through 5) are given the @code{cpp-macro-cont} syntactic
3566 symbol, with a relative buffer position pointing to the @code{#} which
3567 starts the macro definition.
3569 In Objective-C buffers, there are three additional syntactic symbols
3570 assigned to various message calling constructs. Here's an example
3575 1: - (void)setDelegate:anObject
3578 4: [delegate masterWillRebind:self
3579 5: toDelegate:anObject
3580 6: withExtraStuff:stuff];
3586 @cindex objc-method-intro syntactic symbol
3587 @cindex objc-method-args-cont syntactic symbol
3588 @cindex objc-method-call-cont syntactic symbol
3589 Here, line 1 is assigned @code{objc-method-intro} syntax, and line 2 is
3590 assigned @code{objc-method-args-cont} syntax. Lines 5 and 6 are both
3591 assigned @code{objc-method-call-cont} syntax.
3593 Java has a concept of anonymous classes, which may look something like
3598 1: public void watch(Observable o) @{
3599 2: o.addObserver(new Observer() @{
3600 3: public void update(Observable o, Object arg) @{
3601 4: history.addElement(arg);
3609 @cindex inexpr-class syntactic symbol
3610 The brace following the @code{new} operator opens the anonymous class.
3611 Lines 3 and 6 are assigned the @code{inexpr-class} syntax, besides the
3612 @code{inclass} symbol used in normal classes. Thus, the class will be
3613 indented just like a normal class, with the added indentation given to
3614 @code{inexpr-class}.
3616 There are a few occasions where a statement block may be used inside an
3617 expression. One is in C code using the gcc extension for this, e.g:
3622 2: int y = foo (); int z;
3623 3: if (y > 0) z = y; else z = - y;
3630 @cindex inexpr-statement syntactic symbol
3631 Lines 2 and 5 get the @code{inexpr-statement} syntax, besides the
3632 symbols they'd get in a normal block. Therefore, the indentation put on
3633 @code{inexpr-statement} is added to the normal statement block
3636 In Pike code, there are a few other situations where blocks occur inside
3637 statements, as illustrated here:
3643 3: string s = map (backtrace()[-2][3..],
3647 7: return sprintf ("%t", arg);
3648 8: @}) * ", " + "\n";
3650 10: write (s + "\n");
3657 @cindex inlambda syntactic symbol
3658 @cindex lambda-intro-cont syntactic symbol
3659 Lines 4 through 8 contain a lambda function, which @ccmode{} recognizes
3660 by the @code{lambda} keyword. If the function argument list is put
3661 on a line of its own, as in line 5, it gets the @code{lambda-intro-cont}
3662 syntax. The function body is handled as an inline method body, with the
3663 addition of the @code{inlambda} syntactic symbol. This means that line
3664 6 gets @code{inlambda} and @code{inline-open}, and line 8 gets
3665 @code{inline-close}@footnote{You might wonder why it doesn't get
3666 @code{inlambda} too. It's because the closing brace is relative to the
3667 opening brace, which stands on its own line in this example. If the
3668 opening brace was hanging on the previous line, then the closing brace
3669 would get the @code{inlambda} syntax too to be indented correctly.}.
3671 @cindex inexpr-statement syntactic symbol
3672 On line 9, @code{catch} is a special function taking a statement block
3673 as its argument. The block is handled as an in-expression statement
3674 with the @code{inexpr-statement} syntax, just like the gcc extended C
3675 example above. The other similar special function, @code{gauge}, is
3676 handled like this too.
3678 @cindex knr-argdecl-intro syntactic symbol
3679 @cindex knr-argdecl syntactic symbol
3680 Two other syntactic symbols can appear in old style, non-prototyped C
3681 code @footnote{a.k.a. K&R C, or Kernighan & Ritchie C}:
3685 1: int add_three_integers(a, b, c)
3690 6: return a + b + c;
3696 Here, line 2 is the first line in an argument declaration list and so is
3697 given the @code{knr-argdecl-intro} syntactic symbol. Subsequent lines
3698 (i.e. lines 3 and 4 in this example), are given @code{knr-argdecl}
3702 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
3703 @node Indentation Functions, Performance Issues, Syntactic Symbols, Top
3704 @comment node-name, next, previous, up
3705 @chapter Indentation Functions
3706 @cindex indentation functions
3707 @cindex line-up functions
3708 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
3710 Often there are cases when a simple offset setting on a syntactic symbol
3711 isn't enough to get the desired indentation. Therefore, it's also
3712 possible to use a @dfn{indentation function} (a.k.a. line-up function)
3713 for a syntactic symbol.
3715 @ccmode{} comes with many predefined indentation functions for common
3716 situations. If none of these does what you want, you can write your
3717 own, see @ref{Custom Indentation Functions}. If you do, it's probably a
3718 good idea to start working from one of these predefined functions, they
3719 can be found in the file @file{cc-align.el}.
3721 For every function below there is a ``works with'' list that indicates
3722 which syntactic symbols the function is intended to be used with.
3736 @findex c-lineup-arglist
3737 @findex lineup-arglist (c-)
3738 @item c-lineup-arglist
3739 Line up the current argument line under the first argument.
3741 @workswith @code{arglist-cont-nonempty}.
3743 @findex c-lineup-arglist-intro-after-paren
3744 @findex lineup-arglist-intro-after-paren (c-)
3745 @item c-lineup-arglist-intro-after-paren
3746 Line up a line just after the open paren of the surrounding paren or
3749 @workswith @code{defun-block-intro}, @code{brace-list-intro},
3750 @code{statement-block-intro}, @code{statement-case-intro},
3751 @code{arglist-intro}.
3753 @findex c-lineup-arglist-close-under-paren
3754 @findex lineup-arglist-close-under-paren (c-)
3755 @item c-lineup-arglist-close-under-paren
3756 Set e.g. your @code{arglist-close} syntactic symbol to this line-up
3757 function so that parentheses that close argument lists will line up
3758 under the parenthesis that opened the argument list.
3760 @workswith @code{defun-close}, @code{class-close}, @code{inline-close},
3761 @code{block-close}, @code{brace-list-close}, @code{arglist-close},
3762 @code{extern-lang-close}, @code{namespace-close} (for most of these, a
3763 zero offset will normally produce the same result, though).
3765 @findex c-lineup-close-paren
3766 @findex lineup-close-paren (c-)
3767 @item c-lineup-close-paren
3768 Line up the closing paren under its corresponding open paren if the
3769 open paren is followed by code. If the open paren ends its line, no
3770 indentation is added. E.g:
3776 ) // c-lineup-close-paren
3787 ) // c-lineup-close-paren
3792 @workswith @code{defun-close}, @code{class-close}, @code{inline-close},
3793 @code{block-close}, @code{brace-list-close}, @code{arglist-close},
3794 @code{extern-lang-close}, @code{namespace-close}.
3796 @findex c-lineup-streamop
3797 @findex lineup-streamop (c-)
3798 @item c-lineup-streamop
3799 Line up C++ stream operators (i.e. @samp{<<} and @samp{>>}).
3801 @workswith @code{stream-op}.
3803 @findex c-lineup-multi-inher
3804 @findex lineup-multi-inher (c-)
3805 @item c-lineup-multi-inher
3806 Line up the classes in C++ multiple inheritance clauses and member
3807 initializers under each other. E.g:
3811 Foo::Foo (int a, int b):
3813 Bar (b) // c-lineup-multi-inher
3824 public Bar // c-lineup-multi-inher
3833 Foo::Foo (int a, int b)
3835 , Bar (b) // c-lineup-multi-inher
3840 @workswith @code{inher-cont}, @code{member-init-cont}.
3842 @findex c-lineup-java-inher
3843 @findex lineup-java-inher (c-)
3844 @item c-lineup-java-inher
3845 Line up Java implements and extends declarations. If class names
3846 follows on the same line as the @samp{implements}/@samp{extends}
3847 keyword, they are lined up under each other. Otherwise, they are
3848 indented by adding @code{c-basic-offset} to the column of the keyword.
3855 Bar // c-lineup-java-inher
3868 Bar // c-lineup-java-inher
3873 @workswith @code{inher-cont}.
3875 @findex c-lineup-java-throws
3876 @findex lineup-java-throws (c-)
3877 @item c-lineup-java-throws
3878 Line up Java throws declarations. If exception names follows on the
3879 same line as the throws keyword, they are lined up under each other.
3880 Otherwise, they are indented by adding @code{c-basic-offset} to the
3881 column of the @samp{throws} keyword. The @samp{throws} keyword itself
3882 is also indented by @code{c-basic-offset} from the function declaration
3883 start if it doesn't hang. E.g:
3888 throws // c-lineup-java-throws
3889 Bar // c-lineup-java-throws
3891 <--><--> c-basic-offset
3900 int foo() throws Cyphr,
3901 Bar, // c-lineup-java-throws
3902 Vlod // c-lineup-java-throws
3907 @workswith @code{func-decl-cont}.
3909 @findex c-indent-one-line-block
3910 @findex indent-one-line-block (c-)
3911 @item c-indent-one-line-block
3912 Indent a one line block @code{c-basic-offset} extra. E.g:
3917 @{m+=n; n=0;@} // c-indent-one-line-block
3929 @{ // c-indent-one-line-block
3936 The block may be surrounded by any kind of parenthesis characters.
3937 @code{nil} is returned if the line doesn't start with a one line block,
3938 which makes the function usable in list expressions.
3940 @workswith Almost all syntactic symbols, but most useful on the
3941 @code{-open} symbols.
3943 @findex c-indent-multi-line-block
3944 @findex indent-multi-line-block (c-)
3945 @item c-indent-multi-line-block
3946 Indent a multi line block @code{c-basic-offset} extra. E.g:
3952 @{17@}, // c-indent-multi-line-block
3963 @{ // c-indent-multi-line-block
3972 The block may be surrounded by any kind of parenthesis characters.
3973 @code{nil} is returned if the line doesn't start with a multi line
3974 block, which makes the function usable in list expressions.
3976 @workswith Almost all syntactic symbols, but most useful on the
3977 @code{-open} symbols.
3979 @findex c-lineup-C-comments
3980 @findex lineup-C-comments (c-)
3981 @item c-lineup-C-comments
3982 Line up C block comment continuation lines. Various heuristics are used
3983 to handle most of the common comment styles. Some examples:
3994 text ** text ** text
3999 /**************************************************
4001 *************************************************/
4004 @vindex comment-start-skip
4006 /**************************************************
4007 Free form text comments:
4008 In comments with a long delimiter line at the
4009 start, the indentation is kept unchanged for lines
4010 that start with an empty comment line prefix. The
4011 delimiter line is whatever matches the
4012 @code{comment-start-skip} regexp.
4013 **************************************************/
4018 The style variable @code{c-comment-prefix-regexp} is used to recognize
4019 the comment line prefix, e.g. the @samp{*} that usually starts every
4020 line inside a comment.
4022 @workswith The @code{c} syntactic symbol.
4024 @findex c-lineup-comment
4025 @findex lineup-comment (c-)
4026 @item c-lineup-comment
4027 Line up a comment-only line according to the style variable
4028 @code{c-comment-only-line-offset}. If the comment is lined up with a
4029 comment starter on the previous line, that alignment is preserved.
4031 @vindex c-comment-only-line-offset
4032 @vindex comment-only-line-offset (c-)
4033 @code{c-comment-only-line-offset} specifies the extra offset for the
4034 line. It can contain an integer or a cons cell of the form
4037 (@r{<non-anchored-offset>} . @r{<anchored-offset>})
4042 where @var{non-anchored-offset} is the amount of offset given to
4043 non-column-zero anchored lines, and @var{anchored-offset} is the amount
4044 of offset to give column-zero anchored lines. Just an integer as value
4045 is equivalent to @code{(@r{<value>} . -1000)}.
4047 @workswith @code{comment-intro}.
4049 @findex c-lineup-runin-statements
4050 @findex lineup-runin-statements (c-)
4051 @item c-lineup-runin-statements
4052 Line up statements for coding standards which place the first statement
4053 in a block on the same line as the block opening brace@footnote{Run-in
4054 style doesn't really work too well. You might need to write your own
4055 custom indentation functions to better support this style.}. E.g:
4060 @{ puts (\"Hello world!\");
4061 return 0; // c-lineup-runin-statements
4067 If there is no statement after the opening brace to align with,
4068 @code{nil} is returned. This makes the function usable in list
4071 @workswith The @code{statement} syntactic symbol.
4073 @findex c-lineup-math
4074 @findex lineup-math (c-)
4076 Line up the current line after the equal sign on the first line in the
4077 statement. If there isn't any, indent with @code{c-basic-offset}. If
4078 the current line contains an equal sign too, try to align it with the
4081 @workswith @code{statement-cont}.
4083 @findex c-lineup-template-args
4084 @findex lineup-template-args (c-)
4085 @item c-lineup-template-args
4086 Line up the arguments of a template argument list under each other, but
4087 only in the case where the first argument is on the same line as the
4090 To allow this function to be used in a list expression, @code{nil} is
4091 returned if there's no template argument on the first line.
4093 @workswith @code{template-args-cont}.
4095 @findex c-lineup-ObjC-method-call
4096 @findex lineup-ObjC-method-call (c-)
4097 @item c-lineup-ObjC-method-call
4098 For Objective-C code, line up selector args as @code{elisp-mode} does
4099 with function args: go to the position right after the message receiver,
4100 and if you are at the end of the line, indent the current line
4101 c-basic-offset columns from the opening bracket; otherwise you are
4102 looking at the first character of the first method call argument, so
4103 lineup the current line with it.
4105 @workswith @code{objc-method-call-cont}.
4107 @findex c-lineup-ObjC-method-args
4108 @findex lineup-ObjC-method-args (c-)
4109 @item c-lineup-ObjC-method-args
4110 For Objective-C code, line up the colons that separate args. The colon
4111 on the current line is aligned with the one on the first line.
4113 @workswith @code{objc-method-args-cont}.
4115 @findex c-lineup-ObjC-method-args-2
4116 @findex lineup-ObjC-method-args-2 (c-)
4117 @item c-lineup-ObjC-method-args-2
4118 Similar to @code{c-lineup-ObjC-method-args} but lines up the colon on
4119 the current line with the colon on the previous line.
4121 @workswith @code{objc-method-args-cont}.
4123 @findex c-lineup-inexpr-block
4124 @findex lineup-inexpr-block (c-)
4125 @item c-lineup-inexpr-block
4126 This can be used with the in-expression block symbols to indent the
4127 whole block to the column where the construct is started. E.g. for Java
4128 anonymous classes, this lines up the class under the @samp{new} keyword,
4129 and in Pike it lines up the lambda function body under the @samp{lambda}
4130 keyword. Returns @code{nil} if the block isn't part of such a
4133 @workswith @code{inlambda}, @code{inexpr-statement},
4134 @code{inexpr-class}.
4136 @findex c-lineup-whitesmith-in-block
4137 @findex lineup-whitesmith-in-block (c-)
4138 @item c-lineup-whitesmith-in-block
4139 Line up lines inside a block in Whitesmith style. It's done in a way
4140 that works both when the opening brace hangs and when it doesn't. E.g:
4146 foo; // c-lineup-whitesmith-in-block
4157 foo; // c-lineup-whitesmith-in-block
4165 In the first case the indentation is kept unchanged, in the second
4166 @code{c-basic-offset} is added.
4168 @workswith @code{defun-close}, @code{defun-block-intro},
4169 @code{block-close}, @code{brace-list-close}, @code{brace-list-intro},
4170 @code{statement-block-intro}, @code{inclass}, @code{inextern-lang},
4173 @findex c-lineup-dont-change
4174 @findex lineup-dont-change (c-)
4175 @item c-lineup-dont-change
4176 This lineup function returns the indentation of the current line. Think
4177 of it as an identity function for lineups; it is used for
4178 @code{cpp-macro-cont} lines.
4180 @workswith Any syntactic symbol.
4185 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4186 @node Performance Issues, Frequently Asked Questions, Indentation Functions, Top
4187 @comment node-name, next, previous, up
4188 @chapter Performance Issues
4189 @cindex performance issues
4190 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4192 C and its derivative languages are highly complex creatures. Often,
4193 ambiguous code situations arise that require @ccmode{} to scan
4194 large portions of the buffer to determine syntactic context. Such
4195 pathological code@footnote{such as the output of @code{lex(1)}!}
4196 can cause @ccmode{} to perform fairly badly.
4197 This section identifies some of the coding styles to watch out for, and
4198 suggests some workarounds that you can use to improve performance.
4200 Because @ccmode{} has to scan the buffer backwards from the current
4201 insertion point, and because C's syntax is fairly difficult to parse in
4202 the backwards direction, @ccmode{} often tries to find the nearest
4203 position higher up in the buffer from which to begin a forward scan.
4204 The farther this position is from the current insertion point, the
4205 slower the mode gets. Some coding styles can even force @ccmode{}
4206 to scan from the beginning of the buffer for every line of code!
4208 @findex beginning-of-defun
4209 @findex defun-prompt-regexp
4210 One of the simplest things you can do to reduce scan time, is make sure
4211 any brace that opens a top-level construct@footnote{E.g. a function in
4212 C, or outermost class definition in C++ or Java.} always appears in the
4213 leftmost column. This is actually an Emacs constraint, as embodied in
4214 the @code{beginning-of-defun} function which @ccmode{} uses heavily. If
4215 you insist on hanging top-level open braces on the right side of the
4216 line, then you might want to set the variable @code{defun-prompt-regexp}
4217 to something reasonable, however that ``something reasonable'' is
4218 difficult to define, so @ccmode{} doesn't do it for you.
4220 @vindex c-Java-defun-prompt-regexp
4221 @vindex Java-defun-prompt-regexp (c-)
4222 A special note about @code{defun-prompt-regexp} in Java mode: while much
4223 of the early sample Java code seems to encourage a style where the brace
4224 that opens a class is hung on the right side of the line, this is not a
4225 good style to pursue in Emacs. @ccmode{} comes with a variable
4226 @code{c-Java-defun-prompt-regexp} which tries to define a regular
4227 expression usable for this style, but there are problems with it. In
4228 some cases it can cause @code{beginning-of-defun} to hang@footnote{This
4229 has been observed in Emacs 19.34 and XEmacs 19.15.}. For this reason,
4230 it is not used by default, but if you feel adventurous, you can set
4231 @code{defun-prompt-regexp} to it in your mode hook. In any event,
4232 setting and rely on @code{defun-prompt-regexp} will definitely slow
4233 things down anyway because you'll be doing regular expression searches
4234 for every line you indent, so you're probably screwed either way!
4236 @vindex c-enable-xemacs-performance-kludge-p
4237 @vindex enable-xemacs-performance-kludge-p (c-)
4238 Another alternative for XEmacs users, is to set the variable
4239 @code{c-enable-xemacs-performance-kludge-p} to non-@code{nil}. This
4240 tells @ccmode{} to use XEmacs-specific built-in functions which, in some
4241 circumstances, can locate the top-most opening brace much quicker than
4242 @code{beginning-of-defun}. Preliminary testing has shown that for
4243 styles where these braces are hung (e.g. most JDK-derived Java styles),
4244 this hack can improve performance of the core syntax parsing routines
4245 from 3 to 60 times. However, for styles which @emph{do} conform to
4246 Emacs' recommended style of putting top-level braces in column zero,
4247 this hack can degrade performance by about as much. Thus this variable
4248 is set to @code{nil} by default, since the Emacs-friendly styles
4249 should be more common (and
4250 encouraged!). Note that this variable has no effect in Emacs since the
4251 necessary built-in functions don't exist (in Emacs 20.2 or 20.3 as of
4252 this writing 27-Apr-1998).
4254 You will probably notice pathological behavior from @ccmode{} when
4255 working in files containing large amounts of C preprocessor macros.
4256 This is because Emacs cannot skip backwards over these lines as quickly
4259 @vindex c-recognize-knr-p
4260 @vindex recognize-knr-p (c-)
4261 Previous versions of @ccmode{} had potential performance problems
4262 when recognizing K&R style function argument declarations. This was
4263 because there are ambiguities in the C syntax when K&R style argument
4264 lists are used@footnote{It is hard to distinguish them from top-level
4265 declarations.}. @ccmode{} has adopted BOCM's convention for
4266 limiting the search: it assumes that argdecls are indented at least one
4267 space, and that the function headers are not indented at all. With
4268 current versions of @ccmode{}, user customization of
4269 @code{c-recognize-knr-p} is deprecated. Just don't put argdecls in
4272 @cindex @file{cc-lobotomy.el} file
4273 @vindex cc-lobotomy-pith-list
4274 You might want to investigate the speed-ups contained in the
4275 file @file{cc-lobotomy.el}, which comes as part of the @ccmode{}
4276 distribution, but is completely unsupported.
4277 As mentioned previous, @ccmode{} always trades speed for accuracy,
4278 however it is recognized that sometimes you need speed and can sacrifice
4279 some accuracy in indentation. The file @file{cc-lobotomy.el} contains
4280 hacks that will ``dumb down'' @ccmode{} in some specific ways, making
4281 that trade-off of accurancy for speed. I won't go into details of its
4282 use here; you should read the comments at the top of the file, and look
4283 at the variable @code{cc-lobotomy-pith-list} for details.
4286 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4287 @node Frequently Asked Questions, Getting the Latest CC Mode Release, Performance Issues, Top
4288 @comment node-name, next, previous, up
4289 @chapter Frequently Asked Questions
4290 @cindex frequently asked questions
4292 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4303 @strong{Q.} @emph{How do I re-indent the whole file?}
4305 @strong{A.} Visit the file and hit @kbd{C-x h} to mark the whole
4306 buffer. Then hit @kbd{C-M-\}.
4309 @strong{Q.} @emph{How do I re-indent the entire function?
4310 @kbd{C-M-x} doesn't work.}
4312 @strong{A.} @kbd{C-M-x} is reserved for future Emacs use.
4313 To re-indent the entire function hit @kbd{C-c C-q}.
4316 @strong{Q.} @emph{How do I re-indent the current block?}
4318 @strong{A.} First move to the brace which opens the block with
4319 @kbd{C-M-u}, then re-indent that expression with
4323 @strong{Q.} @emph{Why doesn't the @kbd{RET} key indent the new line?}
4325 @strong{A.} Emacs' convention is that @kbd{RET} just adds a newline,
4326 and that @kbd{C-j} adds a newline and indents it. You can make
4327 @kbd{RET} do this too by adding this to your
4328 @code{c-mode-common-hook}:
4331 (define-key c-mode-base-map "\C-m" 'c-context-line-break)
4335 This is a very common question. If you want this to be the default
4336 behavior, don't lobby me, lobby RMS! @t{:-)}
4339 @strong{Q.} @emph{I put @code{(c-set-offset 'substatement-open 0)}
4340 in my @file{.emacs} file but I get an error saying that
4341 @code{c-set-offset}'s function definition is void.}
4343 @strong{A.} This means that @ccmode{} wasn't loaded into your
4344 Emacs session by the time the @code{c-set-offset} call was reached,
4345 mostly likely because @ccmode{} is being autoloaded. Instead
4346 of putting the @code{c-set-offset} line in your top-level
4347 @file{.emacs} file, put it in your @code{c-mode-common-hook}, or
4348 simply modify @code{c-offsets-alist} directly:
4351 (setq c-offsets-alist '((substatement-open . 0)))
4356 @strong{Q.} @emph{My style settings works in all the @ccmode{} language
4357 modes except for Java, where I still get e.g. 4 column indentation.}
4359 @strong{A.} Java mode switches to the @samp{java} style by default for
4360 historical reasons. You can override it by putting an association list
4361 on @code{c-default-style}:
4364 (setq c-default-style '((other . "my-style")))
4368 The @samp{other} symbol says that @ccmode{} should use "my-style" in all
4369 modes not explicitly listed. Since there's nothing else on the list
4370 this causes "my-style" to be used in every mode.
4373 @strong{Q.} @emph{How do I make strings, comments, keywords, and other
4374 constructs appear in different colors, or in bold face, etc.?}
4376 @strong{A.} ``Syntax Colorization'' is a standard Emacs feature,
4377 controlled by @code{font-lock-mode}. @ccmode{} does not contain
4378 font-lock definitions for any of its supported languages.
4381 @strong{Q.} @emph{@kbd{M-a} and @kbd{M-e} used to move over entire
4382 balanced brace lists, but now they move into blocks. How do I get the
4385 @strong{A.} Use @kbd{C-M-f} and @kbd{C-M-b} to move over balanced brace
4386 blocks. Use @kbd{M-a} and @kbd{M-e} to move by statements, which will
4387 also move into blocks.
4390 @strong{Q.} @emph{Whenever I try to indent a line or type an
4391 ``electric'' key such as @kbd{;}, @kbd{@{}, or @kbd{@}}, I get an error
4392 that look like this: @code{Invalid function: (macro . #[...}. What
4395 @strong{A.} This is a common error when @ccmode{} hasn't been compiled
4396 correctly, especially under Emacs 19.34@footnote{Technically, it's
4397 because some macros wasn't defined during the compilation, so the byte
4398 compiler put in function calls instead of the macro expansions. Later,
4399 when the interpreter tries to call the macros as functions, it shows
4400 this (somewhat cryptic) error message.}. If you are using the standalone
4401 @ccmode{} distribution, try recompiling it according to the instructions
4402 in the @file{README} file.
4407 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4408 @node Getting the Latest CC Mode Release, Sample .emacs File, Frequently Asked Questions, Top
4409 @comment node-name, next, previous, up
4410 @chapter Getting the Latest CC Mode Release
4411 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4413 @ccmode{} is standard with all versions of Emacs since 19.34 and of
4416 Due to release schedule skew, it is likely that all of these Emacsen
4417 have old versions of @ccmode{} and so should be upgraded. Access to the
4418 @ccmode{} source code, as well as more detailed information on Emacsen
4419 compatibility, etc. are all available via the Web at:
4424 @uref{http://cc-mode.sourceforge.net/}
4429 @emph{Old URLs, including the FTP URLs, should no longer be used.}
4431 There are many files under these directories; you can pick up the entire
4432 distribution (named @code{cc-mode.tar.gz}; a gzip'd tar file), or any of
4433 the individual files, including PostScript documentation.
4436 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4437 @node Sample .emacs File, Limitations and Known Bugs, Getting the Latest CC Mode Release, Top
4438 @comment node-name, next, previous, up
4439 @chapter Sample .emacs file
4440 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4443 ;; Here's a sample .emacs file that might help you along the way. Just
4444 ;; copy this region and paste it into your .emacs file. You may want to
4445 ;; change some of the actual values.
4447 (defconst my-c-style
4448 '((c-tab-always-indent . t)
4449 (c-comment-only-line-offset . 4)
4450 (c-hanging-braces-alist . ((substatement-open after)
4452 (c-hanging-colons-alist . ((member-init-intro before)
4456 (access-label after)))
4457 (c-cleanup-list . (scope-operator
4460 (c-offsets-alist . ((arglist-close . c-lineup-arglist)
4461 (substatement-open . 0)
4464 (knr-argdecl-intro . -)))
4465 (c-echo-syntactic-information-p . t)
4467 "My C Programming Style")
4469 ;; offset customizations not in my-c-style
4470 (setq c-offsets-alist '((member-init-intro . ++)))
4472 ;; Customizations for all modes in CC Mode.
4473 (defun my-c-mode-common-hook ()
4474 ;; add my personal style and set it for the current buffer
4475 (c-add-style "PERSONAL" my-c-style t)
4476 ;; other customizations
4478 ;; this will make sure spaces are used instead of tabs
4479 indent-tabs-mode nil)
4480 ;; we like auto-newline and hungry-delete
4481 (c-toggle-auto-hungry-state 1)
4482 ;; keybindings for all supported languages. We can put these in
4483 ;; c-mode-base-map because c-mode-map, c++-mode-map, objc-mode-map,
4484 ;; java-mode-map, idl-mode-map, and pike-mode-map inherit from it.
4485 (define-key c-mode-base-map "\C-m" 'c-context-line-break)
4488 (add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
4492 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4493 @node Limitations and Known Bugs, Mailing Lists and Submitting Bug Reports, Sample .emacs File, Top
4494 @comment node-name, next, previous, up
4495 @chapter Limitations and Known Bugs
4498 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4502 Re-indenting large regions or expressions can be slow.
4504 @findex c-indent-exp
4505 @findex indent-exp (c-)
4507 @code{c-indent-exp} has not been fully optimized. It essentially
4508 equivalent to hitting @kbd{TAB} (@code{c-indent-command}) on every
4509 line. Some information is cached from line to line, but such caching
4510 invariable causes inaccuracies in analysis in some bizarre situations.
4512 @vindex signal-error-on-buffer-boundary
4514 XEmacs versions from 19.15 until (as of this writing 12-Mar-1998) 20.4
4515 contain a variable called @code{signal-error-on-buffer-boundary}. This
4516 was intended as a solution to user interface problems associated with
4517 buffer movement and the @code{zmacs-region} deactivation on errors.
4518 However, setting this variable to a non-default value had the
4519 deleterious side effect of breaking many built-in primitive functions.
4520 Most users will not be affected since they never change the value of
4521 this variable. @strong{Do not set this variable to @code{nil}}; you
4522 will cause serious problems in @ccmode{} and probably other XEmacs
4523 packages! As of at least XEmacs 20.4, the effects this variable tried
4524 to correct have been fixed in other, better ways.
4529 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4530 @node Mailing Lists and Submitting Bug Reports, Concept Index, Limitations and Known Bugs, Top
4531 @comment node-name, next, previous, up
4532 @chapter Mailing Lists and Submitting Bug Reports
4533 @cindex mailing lists
4534 @cindex reporting bugs
4535 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4538 @findex c-submit-bug-report
4539 @findex submit-bug-report (c-)
4540 To report bugs, use the @kbd{C-c C-b} (@code{c-submit-bug-report})
4541 command. This provides vital information we need to reproduce your
4542 problem. Make sure you include a concise, but complete code example.
4543 Please try to boil your example down to just the essential code needed
4544 to reproduce the problem, and include an exact recipe of steps needed to
4545 expose the bug. Be especially sure to include any code that appears
4546 @emph{before} your bug example, if you think it might affect our ability
4549 Please try to produce the problem in an Emacs instance without any
4550 customizations loaded (i.e. start it with the @code{-q -no-site-file}
4551 arguments). If it works correctly there, the problem might be caused by
4552 faulty customizations in either your own or your site configuration. In
4553 that case, we'd appreciate if you isolate the Emacs Lisp code that trigs
4554 the bug and include it in your report.
4556 Bug reports are now sent to the following email addresses:
4557 @email{bug-cc-mode@@gnu.org} and @email{bug-gnu-emacs@@gnu.org}; the
4558 latter is mirrored on the Usenet newsgroup @code{gnu.emacs.bug}. You
4559 can send other questions and suggestions (kudos? @t{;-)} to
4560 @email{bug-cc-mode@@gnu.org}, or @email{help-gnu-emacs@@gnu.org} which is
4561 mirrored on newsgroup @code{gnu.emacs.help}.
4563 @cindex beta testers mailing list
4564 @cindex announcement mailing list
4565 If you want to get announcements of new @ccmode{} releases, send the
4566 word @emph{subscribe} in the body of a message to
4567 @email{cc-mode-announce-request@@lists.sourceforge.net}. Announcements
4568 will also be posted to the Usenet newsgroups @code{gnu.emacs.sources},
4569 @code{comp.emacs}, @code{comp.emacs.xemacs}, and possibly some of the
4570 language oriented newsgroups.
4573 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4574 @node Concept Index, Command Index, Mailing Lists and Submitting Bug Reports, Top
4575 @comment node-name, next, previous, up
4576 @unnumbered Concept Index
4577 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4582 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4583 @node Command Index, Key Index, Concept Index, Top
4584 @comment node-name, next, previous, up
4585 @unnumbered Command Index
4586 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4588 Since most @ccmode{} commands are prepended with the string
4589 @samp{c-}, each appears under its @code{c-@var{<thing>}} name and its
4590 @code{@var{<thing>} (c-)} name.
4597 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4598 @node Key Index, Variable Index, Command Index, Top
4599 @comment node-name, next, previous, up
4600 @unnumbered Key Index
4601 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4606 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4607 @node Variable Index, , Key Index, Top
4608 @comment node-name, next, previous, up
4609 @unnumbered Variable Index
4610 @comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4612 Since most @ccmode{} variables are prepended with the string
4613 @samp{c-}, each appears under its @code{c-@var{<thing>}} name and its
4614 @code{@var{<thing>} (c-)} name.