(match): Use yellow background on light-bg terminals.

[emacs.git] / lisp / man.el

;;; man.el --- browse UNIX manual pages -*- coding: iso-8859-1 -*-

;; Copyright (C) 1993, 1994, 1996, 1997, 2001, 2002, 2003,
;;   2004, 2005, 2006, 2007 Free Software Foundation, Inc.

;; Author: Barry A. Warsaw <bwarsaw@cen.com>
;; Maintainer: FSF
;; Keywords: help
;; Adapted-By: ESR, pot

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; This code provides a function, `man', with which you can browse
;; UNIX manual pages.  Formatting is done in background so that you
;; can continue to use your Emacs while processing is going on.
;;
;; The mode also supports hypertext-like following of manual page SEE
;; ALSO references, and other features.  See below or do `?' in a
;; manual page buffer for details.

;; ========== Credits and History ==========
;; In mid 1991, several people posted some interesting improvements to
;; man.el from the standard emacs 18.57 distribution.  I liked many of
;; these, but wanted everything in one single package, so I decided
;; to incorporate them into a single manual browsing mode.  While
;; much of the code here has been rewritten, and some features added,
;; these folks deserve lots of credit for providing the initial
;; excellent packages on which this one is based.

;; Nick Duffek <duffek@chaos.cs.brandeis.edu>, posted a very nice
;; improvement which retrieved and cleaned the manpages in a
;; background process, and which correctly deciphered such options as
;; man -k.

;; Eric Rose <erose@jessica.stanford.edu>, submitted manual.el which
;; provided a very nice manual browsing mode.

;; This package was available as `superman.el' from the LCD package
;; for some time before it was accepted into Emacs 19.  The entry
;; point and some other names have been changed to make it a drop-in
;; replacement for the old man.el package.

;; Francesco Potorti` <pot@cnuce.cnr.it> cleaned it up thoroughly,
;; making it faster, more robust and more tolerant of different
;; systems' man idiosyncrasies.

;; ========== Features ==========
;; + Runs "man" in the background and pipes the results through a
;;   series of sed and awk scripts so that all retrieving and cleaning
;;   is done in the background. The cleaning commands are configurable.
;; + Syntax is the same as Un*x man
;; + Functionality is the same as Un*x man, including "man -k" and
;;   "man <section>", etc.
;; + Provides a manual browsing mode with keybindings for traversing
;;   the sections of a manpage, following references in the SEE ALSO
;;   section, and more.
;; + Multiple manpages created with the same man command are put into
;;   a narrowed buffer circular list.

;; ============= TODO ===========
;; - Add a command for printing.
;; - The awk script deletes multiple blank lines.  This behaviour does
;;   not allow to understand if there was indeed a blank line at the
;;   end or beginning of a page (after the header, or before the
;;   footer).  A different algorithm should be used.  It is easy to
;;   compute how many blank lines there are before and after the page
;;   headers, and after the page footer.  But it is possible to compute
;;   the number of blank lines before the page footer by heuristics
;;   only.  Is it worth doing?
;; - Allow a user option to mean that all the manpages should go in
;;   the same buffer, where they can be browsed with M-n and M-p.
;; - Allow completion on the manpage name when calling man.  This
;;   requires a reliable list of places where manpages can be found.  The
;;   drawback would be that if the list is not complete, the user might
;;   be led to believe that the manpages in the missing directories do
;;   not exist.

\f
;;; Code:

(eval-when-compile (require 'cl))
(require 'assoc)
(require 'button)

;; vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
;; empty defvars (keep the compiler quiet)

(defgroup man nil
  "Browse UNIX manual pages."
  :prefix "Man-"
  :group 'help)


(defvar Man-notify)
(defvar Man-current-page)
(defvar Man-page-list)
(defcustom Man-filter-list nil
  "*Manpage cleaning filter command phrases.
This variable contains a list of the following form:

'((command-string phrase-string*)*)

Each phrase-string is concatenated onto the command-string to form a
command filter.  The (standard) output (and standard error) of the Un*x
man command is piped through each command filter in the order the
commands appear in the association list.  The final output is placed in
the manpage buffer."
  :type '(repeat (list (string :tag "Command String")
                       (repeat :inline t
                               (string :tag "Phrase String"))))
  :group 'man)

(defvar Man-original-frame)
(defvar Man-arguments)
(defvar Man-sections-alist)
(defvar Man-refpages-alist)
(defvar Man-uses-untabify-flag t
  "Non-nil means use `untabify' instead of `Man-untabify-command'.")
(defvar Man-page-mode-string)
(defvar Man-sed-script nil
  "Script for sed to nuke backspaces and ANSI codes from manpages.")

;; vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
;; user variables

(defcustom Man-fontify-manpage-flag t
  "*Non-nil means make up the manpage with fonts."
  :type 'boolean
  :group 'man)

(defcustom Man-overstrike-face 'bold
  "*Face to use when fontifying overstrike."
  :type 'face
  :group 'man)

(defcustom Man-underline-face 'underline
  "*Face to use when fontifying underlining."
  :type 'face
  :group 'man)

(defcustom Man-reverse-face 'highlight
  "*Face to use when fontifying reverse video."
  :type 'face
  :group 'man)

;; Use the value of the obsolete user option Man-notify, if set.
(defcustom Man-notify-method (if (boundp 'Man-notify) Man-notify 'friendly)
  "*Selects the behavior when manpage is ready.
This variable may have one of the following values, where (sf) means
that the frames are switched, so the manpage is displayed in the frame
where the man command was called from:

newframe   -- put the manpage in its own frame (see `Man-frame-parameters')
pushy      -- make the manpage the current buffer in the current window
bully      -- make the manpage the current buffer and only window (sf)
aggressive -- make the manpage the current buffer in the other window (sf)
friendly   -- display manpage in the other window but don't make current (sf)
polite     -- don't display manpage, but prints message and beep when ready
quiet      -- like `polite', but don't beep
meek       -- make no indication that the manpage is ready

Any other value of `Man-notify-method' is equivalent to `meek'."
  :type '(radio (const newframe) (const pushy) (const bully)
                (const aggressive) (const friendly)
                (const polite) (const quiet) (const meek))
  :group 'man)

(defcustom Man-width nil
  "*Number of columns for which manual pages should be formatted.
If nil, the width of the window selected at the moment of man
invocation is used.  If non-nil, the width of the frame selected
at the moment of man invocation is used.  The value also can be a
positive integer."
  :type '(choice (const :tag "Window width" nil)
                 (const :tag "Frame width" t)
                 (integer :tag "Specific width" :value 65))
  :group 'man)

(defcustom Man-frame-parameters nil
  "*Frame parameter list for creating a new frame for a manual page."
  :type 'sexp
  :group 'man)

(defcustom Man-downcase-section-letters-flag t
  "*Non-nil means letters in sections are converted to lower case.
Some Un*x man commands can't handle uppercase letters in sections, for
example \"man 2V chmod\", but they are often displayed in the manpage
with the upper case letter.  When this variable is t, the section
letter (e.g., \"2V\") is converted to lowercase (e.g., \"2v\") before
being sent to the man background process."
  :type 'boolean
  :group 'man)

(defcustom Man-circular-pages-flag t
  "*Non-nil means the manpage list is treated as circular for traversal."
  :type 'boolean
  :group 'man)

(defcustom Man-section-translations-alist
  (list
   '("3C++" . "3")
   ;; Some systems have a real 3x man section, so let's comment this.
   ;; '("3X" . "3")                        ; Xlib man pages
   '("3X11" . "3")
   '("1-UCB" . ""))
  "*Association list of bogus sections to real section numbers.
Some manpages (e.g. the Sun C++ 2.1 manpages) have section numbers in
their references which Un*x `man' does not recognize.  This
association list is used to translate those sections, when found, to
the associated section number."
  :type '(repeat (cons (string :tag "Bogus Section")
                       (string :tag "Real Section")))
  :group 'man)

(defcustom Man-header-file-path
  '("/usr/include" "/usr/local/include")
  "C Header file search path used in Man."
  :type '(repeat string)
  :group 'man)

(defvar manual-program "man"
  "The name of the program that produces man pages.")

(defvar Man-untabify-command "pr"
  "Command used for untabifying.")

(defvar Man-untabify-command-args (list "-t" "-e")
  "List of arguments to be passed to `Man-untabify-command' (which see).")

(defvar Man-sed-command "sed"
  "Command used for processing sed scripts.")

(defvar Man-awk-command "awk"
  "Command used for processing awk scripts.")

(defvar Man-mode-map nil
  "Keymap for Man mode.")

(defvar Man-mode-hook nil
  "Hook run when Man mode is enabled.")

(defvar Man-cooked-hook nil
  "Hook run after removing backspaces but before `Man-mode' processing.")

(defvar Man-name-regexp "[-a-zA-Z0-9_­+][-a-zA-Z0-9_.:­+]*"
  "Regular expression describing the name of a manpage (without section).")

(defvar Man-section-regexp "[0-9][a-zA-Z0-9+]*\\|[LNln]"
  "Regular expression describing a manpage section within parentheses.")

(defvar Man-page-header-regexp
  (if (and (string-match "-solaris2\\." system-configuration)
           (not (string-match "-solaris2\\.[123435]$" system-configuration)))
      (concat "^[-A-Za-z0-9_].*[ \t]\\(" Man-name-regexp
              "(\\(" Man-section-regexp "\\))\\)$")
    (concat "^[ \t]*\\(" Man-name-regexp
            "(\\(" Man-section-regexp "\\))\\).*\\1"))
  "Regular expression describing the heading of a page.")

(defvar Man-heading-regexp "^\\([A-Z][A-Z /-]+\\)$"
  "Regular expression describing a manpage heading entry.")

(defvar Man-see-also-regexp "SEE ALSO"
  "Regular expression for SEE ALSO heading (or your equivalent).
This regexp should not start with a `^' character.")

(defvar Man-first-heading-regexp "^[ \t]*NAME$\\|^[ \t]*No manual entry fo.*$"
  "Regular expression describing first heading on a manpage.
This regular expression should start with a `^' character.")

(defvar Man-reference-regexp
  (concat "\\(" Man-name-regexp "\\)[ \t]*(\\(" Man-section-regexp "\\))")
  "Regular expression describing a reference to another manpage.")

(defvar Man-apropos-regexp
  (concat "\\\[\\(" Man-name-regexp "\\)\\\][ \t]*(\\(" Man-section-regexp "\\))")
  "Regular expression describing a reference to manpages in \"man -k output\".")

(defvar Man-synopsis-regexp "SYNOPSIS"
  "Regular expression for SYNOPSIS heading (or your equivalent).
This regexp should not start with a `^' character.")

(defvar Man-files-regexp "FILES"
  "Regular expression for FILES heading (or your equivalent).
This regexp should not start with a `^' character.")

(defvar Man-include-regexp "#[ \t]*include[ \t]*"
  "Regular expression describing the #include (directive of cpp).")

(defvar Man-file-name-regexp "[^<>\", \t\n]+"
  "Regular expression describing <> in #include line (directive of cpp).")

(defvar Man-normal-file-prefix-regexp "[/~$]"
  "Regular expression describing a file path appeared in FILES section.")

(defvar Man-header-regexp
  (concat "\\(" Man-include-regexp "\\)"
          "[<\"]"
          "\\(" Man-file-name-regexp "\\)"
          "[>\"]")
  "Regular expression describing references to header files.")

(defvar Man-normal-file-regexp
  (concat Man-normal-file-prefix-regexp Man-file-name-regexp)
  "Regular expression describing references to normal files.")

;; This includes the section as an optional part to catch hyphenated
;; refernces to manpages.
(defvar Man-hyphenated-reference-regexp
  (concat "\\(" Man-name-regexp "\\)\\((\\(" Man-section-regexp "\\))\\)?")
  "Regular expression describing a reference in the SEE ALSO section.")

(defvar Man-switches ""
  "Switches passed to the man command, as a single string.

If you want to be able to see all the manpages for a subject you type,
make -a one of the switches, if your `man' program supports it.")

(defvar Man-specified-section-option
  (if (string-match "-solaris[0-9.]*$" system-configuration)
      "-s"
    "")
  "Option that indicates a specified a manual section name.")

(defvar Man-support-local-filenames 'auto-detect
  "Internal cache for the value of the function `Man-support-local-filenames'.
`auto-detect' means the value is not yet determined.
Otherwise, the value is whatever the function
`Man-support-local-filenames' should return.")

;; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
;; end user variables
\f
;; other variables and keymap initializations
(make-variable-buffer-local 'Man-sections-alist)
(make-variable-buffer-local 'Man-refpages-alist)
(make-variable-buffer-local 'Man-page-list)
(make-variable-buffer-local 'Man-current-page)
(make-variable-buffer-local 'Man-page-mode-string)
(make-variable-buffer-local 'Man-original-frame)
(make-variable-buffer-local 'Man-arguments)
(put 'Man-arguments 'permanent-local t)

(setq-default Man-sections-alist nil)
(setq-default Man-refpages-alist nil)
(setq-default Man-page-list nil)
(setq-default Man-current-page 0)
(setq-default Man-page-mode-string "1 of 1")

(defconst Man-sysv-sed-script "\
/\b/ {  s/_\b//g
        s/\b_//g
        s/o\b+/o/g
        s/+\bo/o/g
        :ovstrk
        s/\\(.\\)\b\\1/\\1/g
        t ovstrk
        }
/\e\\[[0-9][0-9]*m/ s///g"
  "Script for sysV-like sed to nuke backspaces and ANSI codes from manpages.")

(defconst Man-berkeley-sed-script "\
/\b/ {  s/_\b//g\\
        s/\b_//g\\
        s/o\b+/o/g\\
        s/+\bo/o/g\\
        :ovstrk\\
        s/\\(.\\)\b\\1/\\1/g\\
        t ovstrk\\
        }\\
/\e\\[[0-9][0-9]*m/ s///g"
  "Script for berkeley-like sed to nuke backspaces and ANSI codes from manpages.")

(defvar Man-topic-history nil "Topic read history.")

(defvar man-mode-syntax-table
  (let ((table (copy-syntax-table (standard-syntax-table))))
    (modify-syntax-entry ?. "w" table)
    (modify-syntax-entry ?_ "w" table)
    (modify-syntax-entry ?: "w" table)  ; for PDL::Primitive in Perl man pages
    table)
  "Syntax table used in Man mode buffers.")

(unless Man-mode-map
  (setq Man-mode-map (make-sparse-keymap))
  (suppress-keymap Man-mode-map)
  (set-keymap-parent Man-mode-map button-buffer-map)

  (define-key Man-mode-map " "    'scroll-up)
  (define-key Man-mode-map "\177" 'scroll-down)
  (define-key Man-mode-map "n"    'Man-next-section)
  (define-key Man-mode-map "p"    'Man-previous-section)
  (define-key Man-mode-map "\en"  'Man-next-manpage)
  (define-key Man-mode-map "\ep"  'Man-previous-manpage)
  (define-key Man-mode-map ">"    'end-of-buffer)
  (define-key Man-mode-map "<"    'beginning-of-buffer)
  (define-key Man-mode-map "."    'beginning-of-buffer)
  (define-key Man-mode-map "r"    'Man-follow-manual-reference)
  (define-key Man-mode-map "g"    'Man-goto-section)
  (define-key Man-mode-map "s"    'Man-goto-see-also-section)
  (define-key Man-mode-map "k"    'Man-kill)
  (define-key Man-mode-map "q"    'Man-quit)
  (define-key Man-mode-map "m"    'man)
  ;; Not all the man references get buttons currently. The text in the
  ;; manual page can contain references to other man pages
  (define-key Man-mode-map "\r"   'man-follow)
  (define-key Man-mode-map "?"    'describe-mode))

;; buttons
(define-button-type 'Man-abstract-xref-man-page
  'follow-link t
  'help-echo "mouse-2, RET: display this man page"
  'func nil
  'action #'Man-xref-button-action)

(defun Man-xref-button-action (button) 
  (let ((target (button-get button 'Man-target-string)))
    (funcall 
     (button-get button 'func)
     (cond ((null target)
            (button-label button))
           ((functionp target)
            (funcall target (button-start button)))
           (t target)))))

(define-button-type 'Man-xref-man-page 
  :supertype 'Man-abstract-xref-man-page
  'func 'man-follow)


(define-button-type 'Man-xref-header-file
    'action (lambda (button)
              (let ((w (button-get button 'Man-target-string)))
                (unless (Man-view-header-file w)
                  (error "Cannot find header file: %s" w))))
    'follow-link t
    'help-echo "mouse-2: display this header file")

(define-button-type 'Man-xref-normal-file
  'action (lambda (button)
            (let ((f (substitute-in-file-name
                      (button-get button 'Man-target-string))))
              (if (file-exists-p f)
                  (if (file-readable-p f)
                      (view-file f)
                    (error "Cannot read a file: %s" f))
                (error "Cannot find a file: %s" f))))
  'follow-link t
  'help-echo "mouse-2: display this file")

\f
;; ======================================================================
;; utilities

(defun Man-init-defvars ()
  "Used for initializing variables based on display's color support.
This is necessary if one wants to dump man.el with Emacs."

  ;; Avoid possible error in call-process by using a directory that must exist.
  (let ((default-directory "/"))
    (setq Man-sed-script
          (cond
           (Man-fontify-manpage-flag
            nil)
           ((eq 0 (call-process Man-sed-command nil nil nil Man-sysv-sed-script))
            Man-sysv-sed-script)
           ((eq 0 (call-process Man-sed-command nil nil nil Man-berkeley-sed-script))
            Man-berkeley-sed-script)
           (t
            nil))))

  (setq Man-filter-list
        ;; Avoid trailing nil which confuses customize.
        (apply 'list
         (cons
          Man-sed-command
          (list
           (if Man-sed-script
               (concat "-e '" Man-sed-script "'")
             "")
           "-e '/^[\001-\032][\001-\032]*$/d'"
           "-e '/\e[789]/s///g'"
           "-e '/Reformatting page.  Wait/d'"
           "-e '/Reformatting entry.  Wait/d'"
           "-e '/^[ \t]*Hewlett-Packard[ \t]Company[ \t]*-[ \t][0-9]*[ \t]-/d'"
           "-e '/^[ \t]*Hewlett-Packard[ \t]*-[ \t][0-9]*[ \t]-.*$/d'"
           "-e '/^[ \t][ \t]*-[ \t][0-9]*[ \t]-[ \t]*Formatted:.*[0-9]$/d'"
           "-e '/^[ \t]*Page[ \t][0-9]*.*(printed[ \t][0-9\\/]*)$/d'"
           "-e '/^Printed[ \t][0-9].*[0-9]$/d'"
           "-e '/^[ \t]*X[ \t]Version[ \t]1[01].*Release[ \t][0-9]/d'"
           "-e '/^[A-Za-z].*Last[ \t]change:/d'"
           "-e '/^Sun[ \t]Release[ \t][0-9].*[0-9]$/d'"
           "-e '/[ \t]*Copyright [0-9]* UNIX System Laboratories, Inc.$/d'"
           "-e '/^[ \t]*Rev\\..*Page [0-9][0-9]*$/d'"
           ))
         (cons
          Man-awk-command
          (list
           "'\n"
           "BEGIN { blankline=0; anonblank=0; }\n"
           "/^$/ { if (anonblank==0) next; }\n"
           "{ anonblank=1; }\n"
           "/^$/ { blankline++; next; }\n"
           "{ if (blankline>0) { print \"\"; blankline=0; } print $0; }\n"
           "'"
           ))
         (if (not Man-uses-untabify-flag)
             ;; The outer list will be stripped off by apply.
             (list (cons
                    Man-untabify-command
                    Man-untabify-command-args))
           )))
)

(defsubst Man-make-page-mode-string ()
  "Formats part of the mode line for Man mode."
  (format "%s page %d of %d"
          (or (nth 2 (nth (1- Man-current-page) Man-page-list))
              "")
          Man-current-page
          (length Man-page-list)))

(defsubst Man-build-man-command ()
  "Builds the entire background manpage and cleaning command."
  (let ((command (concat manual-program " " Man-switches
                         (cond
                          ;; Already has %s
                          ((string-match "%s" manual-program) "")
                          ;; Stock MS-DOS shells cannot redirect stderr;
                          ;; `call-process' below sends it to /dev/null,
                          ;; so we don't need `2>' even with DOS shells
                          ;; which do support stderr redirection.
                          ((not (fboundp 'start-process)) " %s")
                          ((concat " %s 2>" null-device)))))
        (flist Man-filter-list))
    (while (and flist (car flist))
      (let ((pcom (car (car flist)))
            (pargs (cdr (car flist))))
        (setq command
              (concat command " | " pcom " "
                      (mapconcat (lambda (phrase)
                                   (if (not (stringp phrase))
                                       (error "Malformed Man-filter-list"))
                                   phrase)
                                 pargs " ")))
        (setq flist (cdr flist))))
    command))


(defun Man-translate-cleanup (string)
  "Strip leading, trailing and middle spaces."
  (when (stringp string)
    ;;  Strip leading and trailing
    (if (string-match "^[ \t\f\r\n]*\\(.+[^ \t\f\r\n]\\)" string)
        (setq string (match-string 1 string)))
    ;; middle spaces
    (setq string (replace-regexp-in-string "[\t\r\n]" " " string))
    (setq string (replace-regexp-in-string "  +" " " string))
    string))

(defun Man-translate-references (ref)
  "Translates REF from \"chmod(2V)\" to \"2v chmod\" style.
Leave it as is if already in that style.  Possibly downcase and
translate the section (see the `Man-downcase-section-letters-flag'
and the `Man-section-translations-alist' variables)."
  (let ((name "")
        (section "")
        (slist Man-section-translations-alist))
    (setq ref (Man-translate-cleanup ref))
    (cond
     ;; "chmod(2V)" case ?
     ((string-match (concat "^" Man-reference-regexp "$") ref)
      (setq name (match-string 1 ref)
            section (match-string 2 ref)))
     ;; "2v chmod" case ?
     ((string-match (concat "^\\(" Man-section-regexp
                            "\\) +\\(" Man-name-regexp "\\)$") ref)
      (setq name (match-string 2 ref)
            section (match-string 1 ref))))
    (if (string= name "")
        ref                             ; Return the reference as is
      (if Man-downcase-section-letters-flag
          (setq section (downcase section)))
      (while slist
        (let ((s1 (car (car slist)))
              (s2 (cdr (car slist))))
          (setq slist (cdr slist))
          (if Man-downcase-section-letters-flag
              (setq s1 (downcase s1)))
          (if (not (string= s1 section)) nil
            (setq section (if Man-downcase-section-letters-flag
                              (downcase s2)
                            s2)
                  slist nil))))
      (concat Man-specified-section-option section " " name))))

(defun Man-support-local-filenames ()
  "Check the availability of `-l' option of the man command.
This option allows `man' to interpret command line arguments
as local filenames.
Return the value of the variable `Man-support-local-filenames'
if it was set to nil or t before the call of this function.
If t, the man command supports `-l' option.  If nil, it doesn't.
Otherwise, if the value of `Man-support-local-filenames'
is neither t nor nil, then determine a new value, set it
to the variable `Man-support-local-filenames' and return
a new value."
  (if (or (not Man-support-local-filenames)
          (eq Man-support-local-filenames t))
      Man-support-local-filenames
    (setq Man-support-local-filenames
          (with-temp-buffer
            (and (equal (condition-case nil
                            (call-process manual-program nil t nil "--help")
                          (error nil))
                        0)
                 (progn
                   (goto-char (point-min))
                   (search-forward "--local-file" nil t))
                 t)))))

\f
;; ======================================================================
;; default man entry: get word under point

(defsubst Man-default-man-entry (&optional pos)
  "Make a guess at a default manual entry based on the text at POS.
If POS is nil, the current point is used."
  (let (word)
    (save-excursion
      (if pos (goto-char pos))
      ;; Default man entry title is any word the cursor is on, or if
      ;; cursor not on a word, then nearest preceding word.
      (skip-chars-backward "-a-zA-Z0-9._+:")
      (let ((start (point)))
        (skip-chars-forward "-a-zA-Z0-9._+:")
        (setq word (buffer-substring-no-properties start (point))))
      (if (string-match "[._]+$" word)
          (setq word (substring word 0 (match-beginning 0))))
      ;; If looking at something like *strcat(... , remove the '*'
      (if (string-match "^*" word)
          (setq word (substring word 1)))
      ;; If looking at something like ioctl(2) or brc(1M), include the
      ;; section number in the returned value.  Remove text properties.
      (concat word
              (if (looking-at
                   (concat "[ \t]*([ \t]*\\(" Man-section-regexp "\\)[ \t]*)"))
                  (format "(%s)" (match-string-no-properties 1)))))))

\f
;; ======================================================================
;; Top level command and background process sentinel

;; For compatibility with older versions.
;;;###autoload
(defalias 'manual-entry 'man)


;;;###autoload
(defun man (man-args)
  "Get a Un*x manual page and put it in a buffer.
This command is the top-level command in the man package.  It runs a Un*x
command to retrieve and clean a manpage in the background and places the
results in a Man mode (manpage browsing) buffer.  See variable
`Man-notify-method' for what happens when the buffer is ready.
If a buffer already exists for this man page, it will display immediately.

To specify a man page from a certain section, type SUBJECT(SECTION) or
SECTION SUBJECT when prompted for a manual entry.  To see manpages from
all sections related to a subject, put something appropriate into the
`Man-switches' variable, which see."
  (interactive
   (list (let* ((default-entry (Man-default-man-entry))
                (input (read-string
                        (format "Manual entry%s"
                                (if (string= default-entry "")
                                    ": "
                                  (format " (default %s): " default-entry)))
                        nil 'Man-topic-history default-entry)))
           (if (string= input "")
               (error "No man args given")
             input))))

  ;; Possibly translate the "subject(section)" syntax into the
  ;; "section subject" syntax and possibly downcase the section.
  (setq man-args (Man-translate-references man-args))

  (Man-getpage-in-background man-args))

;;;###autoload
(defun man-follow (man-args)
  "Get a Un*x manual page of the item under point and put it in a buffer."
  (interactive (list (Man-default-man-entry)))
  (if (or (not man-args)
          (string= man-args ""))
      (error "No item under point")
    (man man-args)))

(defun Man-getpage-in-background (topic)
  "Use TOPIC to build and fire off the manpage and cleaning command."
  (let* ((man-args topic)
         (bufname (concat "*Man " man-args "*"))
         (buffer  (get-buffer bufname)))
    (if buffer
        (Man-notify-when-ready buffer)
      (require 'env)
      (message "Invoking %s %s in the background" manual-program man-args)
      (setq buffer (generate-new-buffer bufname))
      (save-excursion
        (set-buffer buffer)
        (setq buffer-undo-list t)
        (setq Man-original-frame (selected-frame))
        (setq Man-arguments man-args))
      (let ((process-environment (copy-sequence process-environment))
            ;; The following is so Awk script gets \n intact
            ;; But don't prevent decoding of the outside.
            (coding-system-for-write 'raw-text-unix)
            ;; We must decode the output by a coding system that the
            ;; system's locale suggests in multibyte mode.
            (coding-system-for-read
             (if default-enable-multibyte-characters
                 locale-coding-system 'raw-text-unix))
            ;; Avoid possible error by using a directory that always exists.
            (default-directory
              (if (and (file-directory-p default-directory)
                       (not (find-file-name-handler default-directory
                                                    'file-directory-p)))
                  default-directory
                "/")))
        ;; Prevent any attempt to use display terminal fanciness.
        (setenv "TERM" "dumb")
        ;; In Debian Woody, at least, we get overlong lines under X
        ;; unless COLUMNS or MANWIDTH is set.  This isn't a problem on
        ;; a tty.  man(1) says:
        ;;        MANWIDTH
        ;;               If $MANWIDTH is set, its value is used as the  line
        ;;               length  for which manual pages should be formatted.
        ;;               If it is not set, manual pages  will  be  formatted
        ;;               with  a line length appropriate to the current ter-
        ;;               minal (using an ioctl(2) if available, the value of
        ;;               $COLUMNS,  or falling back to 80 characters if nei-
        ;;               ther is available).
        (if window-system
            (unless (or (getenv "MANWIDTH") (getenv "COLUMNS"))
              ;; This isn't strictly correct, since we don't know how
              ;; the page will actually be displayed, but it seems
              ;; reasonable.
              (setenv "COLUMNS" (number-to-string
                                 (cond
                                  ((and (integerp Man-width) (> Man-width 0))
                                   Man-width)
                                  (Man-width (frame-width))
                                  ((window-width)))))))
        (setenv "GROFF_NO_SGR" "1")
        (if (fboundp 'start-process)
            (set-process-sentinel
             (start-process manual-program buffer
                            (if (memq system-type '(cygwin windows-nt))
                                shell-file-name
                              "sh")
                            shell-command-switch
                            (format (Man-build-man-command) man-args))
             'Man-bgproc-sentinel)
          (let ((exit-status
                 (call-process shell-file-name nil (list buffer nil) nil
                               shell-command-switch
                               (format (Man-build-man-command) man-args)))
                (msg ""))
            (or (and (numberp exit-status)
                     (= exit-status 0))
                (and (numberp exit-status)
                     (setq msg
                           (format "exited abnormally with code %d"
                                   exit-status)))
                (setq msg exit-status))
            (Man-bgproc-sentinel bufname msg)))))))

(defun Man-notify-when-ready (man-buffer)
  "Notify the user when MAN-BUFFER is ready.
See the variable `Man-notify-method' for the different notification behaviors."
  (let ((saved-frame (save-excursion
                       (set-buffer man-buffer)
                       Man-original-frame)))
    (cond
     ((eq Man-notify-method 'newframe)
      ;; Since we run asynchronously, perhaps while Emacs is waiting
      ;; for input, we must not leave a different buffer current.  We
      ;; can't rely on the editor command loop to reselect the
      ;; selected window's buffer.
      (save-excursion
        (let ((frame (make-frame Man-frame-parameters)))
          (set-window-buffer (frame-selected-window frame) man-buffer)
          (set-window-dedicated-p (frame-selected-window frame) t)
          (or (display-multi-frame-p frame)
              (select-frame frame)))))
     ((eq Man-notify-method 'pushy)
      (switch-to-buffer man-buffer))
     ((eq Man-notify-method 'bully)
      (and (frame-live-p saved-frame)
           (select-frame saved-frame))
      (pop-to-buffer man-buffer)
      (delete-other-windows))
     ((eq Man-notify-method 'aggressive)
      (and (frame-live-p saved-frame)
           (select-frame saved-frame))
      (pop-to-buffer man-buffer))
     ((eq Man-notify-method 'friendly)
      (and (frame-live-p saved-frame)
           (select-frame saved-frame))
      (display-buffer man-buffer 'not-this-window))
     ((eq Man-notify-method 'polite)
      (beep)
      (message "Manual buffer %s is ready" (buffer-name man-buffer)))
     ((eq Man-notify-method 'quiet)
      (message "Manual buffer %s is ready" (buffer-name man-buffer)))
     ((or (eq Man-notify-method 'meek)
          t)
      (message ""))
     )))

(defun Man-softhyphen-to-minus ()
  ;; \255 is SOFT HYPHEN in Latin-N.  Versions of Debian man, at
  ;; least, emit it even when not in a Latin-N locale.
  (unless (eq t (compare-strings "latin-" 0 nil
                                 current-language-environment 0 6 t))
    (goto-char (point-min))
    (let ((str "\255"))
      (if enable-multibyte-characters
          (setq str (string-as-multibyte str)))
      (while (search-forward str nil t) (replace-match "-")))))

(defun Man-fontify-manpage ()
  "Convert overstriking and underlining to the correct fonts.
Same for the ANSI bold and normal escape sequences."
  (interactive)
  (message "Please wait: formatting the %s man page..." Man-arguments)
  (goto-char (point-min))
  ;; Fontify ANSI escapes.
  (let ((faces nil)
        (buffer-undo-list t)
        (start (point)))
    ;; http://www.isthe.com/chongo/tech/comp/ansi_escapes.html
    ;; suggests many codes, but we only handle:
    ;; ESC [ 00 m       reset to normal display
    ;; ESC [ 01 m       bold
    ;; ESC [ 04 m       underline
    ;; ESC [ 07 m       reverse-video
    ;; ESC [ 22 m       no-bold
    ;; ESC [ 24 m       no-underline
    ;; ESC [ 27 m       no-reverse-video
    (while (re-search-forward "\e\\[0?\\([1470]\\|2\\([247]\\)\\)m" nil t)
      (if faces (put-text-property start (match-beginning 0) 'face
                                   (if (cdr faces) faces (car faces))))
      (setq faces
            (cond
             ((match-beginning 2)
              (delq (case (char-after (match-beginning 2))
                      (?2 Man-overstrike-face)
                      (?4 Man-underline-face)
                      (?7 Man-reverse-face))
                    faces))
             ((eq (char-after (match-beginning 1)) ?0) nil)
             (t
              (cons (case (char-after (match-beginning 1))
                      (?1 Man-overstrike-face)
                      (?4 Man-underline-face)
                      (?7 Man-reverse-face))
                    faces))))
      (delete-region (match-beginning 0) (match-end 0))
      (setq start (point))))
  ;; Other highlighting.
  (let ((buffer-undo-list t))
    (if (< (buffer-size) (position-bytes (point-max)))
        ;; Multibyte characters exist.
        (progn
          (goto-char (point-min))
          (while (search-forward "__\b\b" nil t)
            (backward-delete-char 4)
            (put-text-property (point) (1+ (point)) 'face Man-underline-face))
          (goto-char (point-min))
          (while (search-forward "\b\b__" nil t)
            (backward-delete-char 4)
            (put-text-property (1- (point)) (point) 'face Man-underline-face))))
    (goto-char (point-min))
    (while (search-forward "_\b" nil t)
      (backward-delete-char 2)
      (put-text-property (point) (1+ (point)) 'face Man-underline-face))
    (goto-char (point-min))
    (while (search-forward "\b_" nil t)
      (backward-delete-char 2)
      (put-text-property (1- (point)) (point) 'face Man-underline-face))
    (goto-char (point-min))
    (while (re-search-forward "\\(.\\)\\(\b+\\1\\)+" nil t)
      (replace-match "\\1")
      (put-text-property (1- (point)) (point) 'face Man-overstrike-face))
    (goto-char (point-min))
    (while (re-search-forward "o\b\\+\\|\\+\bo" nil t)
      (replace-match "o")
      (put-text-property (1- (point)) (point) 'face 'bold))
    (goto-char (point-min))
    (while (re-search-forward "[-|]\\(\b[-|]\\)+" nil t)
      (replace-match "+")
      (put-text-property (1- (point)) (point) 'face 'bold))
    (goto-char (point-min))
    ;; Try to recognize common forms of cross references.
    (Man-highlight-references)
    (Man-softhyphen-to-minus)
    (goto-char (point-min))
    (while (re-search-forward Man-heading-regexp nil t)
      (put-text-property (match-beginning 0)
                         (match-end 0)
                         'face Man-overstrike-face)))
  (message "%s man page formatted" Man-arguments))

(defun Man-highlight-references (&optional xref-man-type)
  "Highlight the references on mouse-over.
References include items in the SEE ALSO section,
header file (#include <foo.h>), and files in FILES.
If optional argument XREF-MAN-TYPE is non-nil, it used as the
button type for items in SEE ALSO section.  If it is nil, the
default type, `Man-xref-man-page' is used for the buttons."
  ;; `Man-highlight-references' is used from woman.el, too.
  ;; woman.el doesn't set `Man-arguments'.
  (unless Man-arguments
    (setq Man-arguments ""))
  (if (string-match "-k " Man-arguments)
      (progn
        (Man-highlight-references0 nil Man-reference-regexp 1
                                   'Man-default-man-entry
                                   (or xref-man-type 'Man-xref-man-page))
        (Man-highlight-references0 nil Man-apropos-regexp 1
                                   'Man-default-man-entry
                                   (or xref-man-type 'Man-xref-man-page)))
    (Man-highlight-references0 Man-see-also-regexp Man-reference-regexp 1 
                               'Man-default-man-entry
                               (or xref-man-type 'Man-xref-man-page))
    (Man-highlight-references0 Man-synopsis-regexp Man-header-regexp 0 2
                               'Man-xref-header-file)
    (Man-highlight-references0 Man-files-regexp Man-normal-file-regexp 0 0
                               'Man-xref-normal-file)))

(defun Man-highlight-references0 (start-section regexp button-pos target type)
  ;; Based on `Man-build-references-alist'
  (when (or (null start-section)
            (Man-find-section start-section))
    (let ((end (if start-section
                   (progn
                     (forward-line 1)
                     (back-to-indentation)
                     (save-excursion
                       (Man-next-section 1)
                       (point)))
                 (goto-char (point-min))
                 (point-max))))
      (while (re-search-forward regexp end t)
        (make-text-button
         (match-beginning button-pos)
         (match-end button-pos)
         'type type
         'Man-target-string (cond
                             ((numberp target) 
                              (match-string target))
                             ((functionp target)
                              target)
                             (t nil)))))))

(defun Man-cleanup-manpage (&optional interactive)
  "Remove overstriking and underlining from the current buffer.
Normally skip any jobs that should have been done by the sed script,
but when called interactively, do those jobs even if the sed
script would have done them."
  (interactive "p")
  (message "Please wait: cleaning up the %s man page..."
           Man-arguments)
  (if (or interactive (not Man-sed-script))
      (progn
        (goto-char (point-min))
        (while (search-forward "_\b" nil t) (backward-delete-char 2))
        (goto-char (point-min))
        (while (search-forward "\b_" nil t) (backward-delete-char 2))
        (goto-char (point-min))
        (while (re-search-forward "\\(.\\)\\(\b\\1\\)+" nil t)
          (replace-match "\\1"))
        (goto-char (point-min))
        (while (re-search-forward "\e\\[[0-9]+m" nil t) (replace-match ""))
        (goto-char (point-min))
        (while (re-search-forward "o\b\\+\\|\\+\bo" nil t) (replace-match "o"))
        ))
  (goto-char (point-min))
  (while (re-search-forward "[-|]\\(\b[-|]\\)+" nil t) (replace-match "+"))
  (Man-softhyphen-to-minus)
  (message "%s man page cleaned up" Man-arguments))

(defun Man-bgproc-sentinel (process msg)
  "Manpage background process sentinel.
When manpage command is run asynchronously, PROCESS is the process
object for the manpage command; when manpage command is run
synchronously, PROCESS is the name of the buffer where the manpage
command is run.  Second argument MSG is the exit message of the
manpage command."
  (let ((Man-buffer (if (stringp process) (get-buffer process)
                      (process-buffer process)))
        (delete-buff nil)
        (err-mess nil))

    (if (null (buffer-name Man-buffer)) ;; deleted buffer
        (or (stringp process)
            (set-process-buffer process nil))

      (save-excursion
        (set-buffer Man-buffer)
        (let ((case-fold-search nil))
          (goto-char (point-min))
          (cond ((or (looking-at "No \\(manual \\)*entry for")
                     (looking-at "[^\n]*: nothing appropriate$"))
                 (setq err-mess (buffer-substring (point)
                                                  (progn
                                                    (end-of-line) (point)))
                       delete-buff t))
                ((or (stringp process)
                     (not (and (eq (process-status process) 'exit)
                               (= (process-exit-status process) 0))))
                 (or (zerop (length msg))
                     (progn
                       (setq err-mess
                             (concat (buffer-name Man-buffer)
                                     ": process "
                                     (let ((eos (1- (length msg))))
                                       (if (= (aref msg eos) ?\n)
                                           (substring msg 0 eos) msg))))
                       (goto-char (point-max))
                       (insert (format "\nprocess %s" msg))))
                 ))
        (if delete-buff
            (kill-buffer Man-buffer)
          (if Man-fontify-manpage-flag
              (Man-fontify-manpage)
            (Man-cleanup-manpage))

          (run-hooks 'Man-cooked-hook)
          (Man-mode)

          (if (not Man-page-list)
              (let ((args Man-arguments))
                (kill-buffer (current-buffer))
                (error "Can't find the %s manpage" args)))

          (set-buffer-modified-p nil)
          ))
        ;; Restore case-fold-search before calling
        ;; Man-notify-when-ready because it may switch buffers.

        (if (not delete-buff)
            (Man-notify-when-ready Man-buffer))

        (if err-mess
            (error err-mess))
        ))))

\f
;; ======================================================================
;; set up manual mode in buffer and build alists

(put 'Man-mode 'mode-class 'special)

(defun Man-mode ()
  "A mode for browsing Un*x manual pages.

The following man commands are available in the buffer.  Try
\"\\[describe-key] <key> RET\" for more information:

\\[man]       Prompt to retrieve a new manpage.
\\[Man-follow-manual-reference]       Retrieve reference in SEE ALSO section.
\\[Man-next-manpage]   Jump to next manpage in circular list.
\\[Man-previous-manpage]   Jump to previous manpage in circular list.
\\[Man-next-section]       Jump to next manpage section.
\\[Man-previous-section]       Jump to previous manpage section.
\\[Man-goto-section]       Go to a manpage section.
\\[Man-goto-see-also-section]       Jumps to the SEE ALSO manpage section.
\\[Man-quit]       Deletes the manpage window, bury its buffer.
\\[Man-kill]       Deletes the manpage window, kill its buffer.
\\[describe-mode]       Prints this help text.

The following variables may be of some use.  Try
\"\\[describe-variable] <variable-name> RET\" for more information:

`Man-notify-method'             What happens when manpage formatting is done.
`Man-downcase-section-letters-flag' Force section letters to lower case.
`Man-circular-pages-flag'       Treat multiple manpage list as circular.
`Man-section-translations-alist' List of section numbers and their Un*x equiv.
`Man-filter-list'               Background manpage filter command.
`Man-mode-map'                  Keymap bindings for Man mode buffers.
`Man-mode-hook'                 Normal hook run on entry to Man mode.
`Man-section-regexp'            Regexp describing manpage section letters.
`Man-heading-regexp'            Regexp describing section headers.
`Man-see-also-regexp'           Regexp for SEE ALSO section (or your equiv).
`Man-first-heading-regexp'      Regexp for first heading on a manpage.
`Man-reference-regexp'          Regexp matching a references in SEE ALSO.
`Man-switches'                  Background `man' command switches.

The following key bindings are currently in effect in the buffer:
\\{Man-mode-map}"
  (interactive)
  (kill-all-local-variables)
  (setq major-mode 'Man-mode
        mode-name "Man"
        buffer-auto-save-file-name nil
        mode-line-buffer-identification
        (list (default-value 'mode-line-buffer-identification)
              " {" 'Man-page-mode-string "}")
        truncate-lines t
        buffer-read-only t)
  (buffer-disable-undo)
  (auto-fill-mode -1)
  (use-local-map Man-mode-map)
  (set-syntax-table man-mode-syntax-table)
  (setq imenu-generic-expression (list (list nil Man-heading-regexp 0)))
  (set (make-local-variable 'outline-regexp) Man-heading-regexp)
  (set (make-local-variable 'outline-level) (lambda () 1))
  (Man-build-page-list)
  (Man-strip-page-headers)
  (Man-unindent)
  (Man-goto-page 1 t)
  (run-mode-hooks 'Man-mode-hook))

(defsubst Man-build-section-alist ()
  "Build the association list of manpage sections."
  (setq Man-sections-alist nil)
  (goto-char (point-min))
  (let ((case-fold-search nil))
    (while (re-search-forward Man-heading-regexp (point-max) t)
      (aput 'Man-sections-alist (match-string 1))
      (forward-line 1))))

(defsubst Man-build-references-alist ()
  "Build the association list of references (in the SEE ALSO section)."
  (setq Man-refpages-alist nil)
  (save-excursion
    (if (Man-find-section Man-see-also-regexp)
        (let ((start (progn (forward-line 1) (point)))
              (end (progn
                     (Man-next-section 1)
                     (point)))
              hyphenated
              (runningpoint -1))
          (save-restriction
            (narrow-to-region start end)
            (goto-char (point-min))
            (back-to-indentation)
            (while (and (not (eobp)) (/= (point) runningpoint))
              (setq runningpoint (point))
              (if (re-search-forward Man-hyphenated-reference-regexp end t)
                  (let* ((word (match-string 0))
                         (len (1- (length word))))
                    (if hyphenated
                        (setq word (concat hyphenated word)
                              hyphenated nil
                              ;; Update len, in case a reference spans
                              ;; more than two lines (paranoia).
                              len (1- (length word))))
                    (if (memq (aref word len) '(?- ?­))
                        (setq hyphenated (substring word 0 len)))
                    (if (string-match Man-reference-regexp word)
                        (aput 'Man-refpages-alist word))))
              (skip-chars-forward " \t\n,"))))))
  (setq Man-refpages-alist (nreverse Man-refpages-alist)))

(defun Man-build-page-list ()
  "Build the list of separate manpages in the buffer."
  (setq Man-page-list nil)
  (let ((page-start (point-min))
        (page-end (point-max))
        (header ""))
    (goto-char page-start)
    ;; (switch-to-buffer (current-buffer))(debug)
    (while (not (eobp))
      (setq header
            (if (looking-at Man-page-header-regexp)
                (match-string 1)
              nil))
      ;; Go past both the current and the next Man-first-heading-regexp
      (if (re-search-forward Man-first-heading-regexp nil 'move 2)
          (let ((p (progn (beginning-of-line) (point))))
            ;; We assume that the page header is delimited by blank
            ;; lines and that it contains at most one blank line.  So
            ;; if we back by three blank lines we will be sure to be
            ;; before the page header but not before the possible
            ;; previous page header.
            (search-backward "\n\n" nil t 3)
            (if (re-search-forward Man-page-header-regexp p 'move)
                (beginning-of-line))))
      (setq page-end (point))
      (setq Man-page-list (append Man-page-list
                                  (list (list (copy-marker page-start)
                                              (copy-marker page-end)
                                              header))))
      (setq page-start page-end)
      )))

(defun Man-strip-page-headers ()
  "Strip all the page headers but the first from the manpage."
  (let ((buffer-read-only nil)
        (case-fold-search nil)
        (page-list Man-page-list)
        (page ())
        (header ""))
    (while page-list
      (setq page (car page-list))
      (and (nth 2 page)
           (goto-char (car page))
           (re-search-forward Man-first-heading-regexp nil t)
           (setq header (buffer-substring (car page) (match-beginning 0)))
           ;; Since the awk script collapses all successive blank
           ;; lines into one, and since we don't want to get rid of
           ;; the fast awk script, one must choose between adding
           ;; spare blank lines between pages when there were none and
           ;; deleting blank lines at page boundaries when there were
           ;; some.  We choose the first, so we comment the following
           ;; line.
           ;; (setq header (concat "\n" header)))
           (while (search-forward header (nth 1 page) t)
             (replace-match "")))
      (setq page-list (cdr page-list)))))

(defun Man-unindent ()
  "Delete the leading spaces that indent the manpage."
  (let ((buffer-read-only nil)
        (case-fold-search nil)
        (page-list Man-page-list))
    (while page-list
      (let ((page (car page-list))
            (indent "")
            (nindent 0))
        (narrow-to-region (car page) (car (cdr page)))
        (if Man-uses-untabify-flag
            (untabify (point-min) (point-max)))
        (if (catch 'unindent
              (goto-char (point-min))
              (if (not (re-search-forward Man-first-heading-regexp nil t))
                  (throw 'unindent nil))
              (beginning-of-line)
              (setq indent (buffer-substring (point)
                                             (progn
                                               (skip-chars-forward " ")
                                               (point))))
              (setq nindent (length indent))
              (if (zerop nindent)
                  (throw 'unindent nil))
              (setq indent (concat indent "\\|$"))
              (goto-char (point-min))
              (while (not (eobp))
                (if (looking-at indent)
                    (forward-line 1)
                  (throw 'unindent nil)))
              (goto-char (point-min)))
            (while (not (eobp))
              (or (eolp)
                  (delete-char nindent))
              (forward-line 1)))
        (setq page-list (cdr page-list))
        ))))

\f
;; ======================================================================
;; Man mode commands

(defun Man-next-section (n)
  "Move point to Nth next section (default 1)."
  (interactive "p")
  (let ((case-fold-search nil))
    (if (looking-at Man-heading-regexp)
        (forward-line 1))
    (if (re-search-forward Man-heading-regexp (point-max) t n)
        (beginning-of-line)
      (goto-char (point-max)))))

(defun Man-previous-section (n)
  "Move point to Nth previous section (default 1)."
  (interactive "p")
  (let ((case-fold-search nil))
    (if (looking-at Man-heading-regexp)
        (forward-line -1))
    (if (re-search-backward Man-heading-regexp (point-min) t n)
        (beginning-of-line)
      (goto-char (point-min)))))

(defun Man-find-section (section)
  "Move point to SECTION if it exists, otherwise don't move point.
Returns t if section is found, nil otherwise."
  (let ((curpos (point))
        (case-fold-search nil))
    (goto-char (point-min))
    (if (re-search-forward (concat "^" section) (point-max) t)
        (progn (beginning-of-line) t)
      (goto-char curpos)
      nil)
    ))

(defun Man-goto-section ()
  "Query for section to move point to."
  (interactive)
  (aput 'Man-sections-alist
        (let* ((default (aheadsym Man-sections-alist))
               (completion-ignore-case t)
               chosen
               (prompt (concat "Go to section (default " default "): ")))
          (setq chosen (completing-read prompt Man-sections-alist))
          (if (or (not chosen)
                  (string= chosen ""))
              default
            chosen)))
  (Man-find-section (aheadsym Man-sections-alist)))

(defun Man-goto-see-also-section ()
  "Move point to the \"SEE ALSO\" section.
Actually the section moved to is described by `Man-see-also-regexp'."
  (interactive)
  (if (not (Man-find-section Man-see-also-regexp))
      (error (concat "No " Man-see-also-regexp
                     " section found in the current manpage"))))

(defun Man-possibly-hyphenated-word ()
  "Return a possibly hyphenated word at point.
If the word starts at the first non-whitespace column, and the
previous line ends with a hyphen, return the last word on the previous
line instead.  Thus, if a reference to \"tcgetpgrp(3V)\" is hyphenated
as \"tcgetp-grp(3V)\", and point is at \"grp(3V)\", we return
\"tcgetp-\" instead of \"grp\"."
  (save-excursion
    (skip-syntax-backward "w()")
    (skip-chars-forward " \t")
    (let ((beg (point))
          (word (current-word)))
      (when (eq beg (save-excursion
                      (back-to-indentation)
                      (point)))
        (end-of-line 0)
        (if (eq (char-before) ?-)
            (setq word (current-word))))
      word)))

(defun Man-follow-manual-reference (reference)
  "Get one of the manpages referred to in the \"SEE ALSO\" section.
Specify which REFERENCE to use; default is based on word at point."
  (interactive
   (if (not Man-refpages-alist)
       (error "There are no references in the current man page")
     (list (let* ((default (or
                            (car (all-completions
                                  (let ((word
                                         (or (Man-possibly-hyphenated-word)
                                             "")))
                                    ;; strip a trailing '-':
                                    (if (string-match "-$" word)
                                        (substring word 0
                                                   (match-beginning 0))
                                      word))
                                  Man-refpages-alist))
                            (aheadsym Man-refpages-alist)))
                   chosen
                   (prompt (concat "Refer to (default " default "): ")))
              (setq chosen (completing-read prompt Man-refpages-alist))
              (if (or (not chosen)
                      (string= chosen ""))
                  default
                chosen)))))
  (if (not Man-refpages-alist)
      (error "Can't find any references in the current manpage")
    (aput 'Man-refpages-alist reference)
    (Man-getpage-in-background
     (Man-translate-references (aheadsym Man-refpages-alist)))))

(defun Man-kill ()
  "Kill the buffer containing the manpage."
  (interactive)
  (quit-window t))

(defun Man-quit ()
  "Bury the buffer containing the manpage."
  (interactive)
  (quit-window))

(defun Man-goto-page (page &optional noerror)
  "Go to the manual page on page PAGE."
  (interactive
   (if (not Man-page-list)
       (error "Not a man page buffer")
     (if (= (length Man-page-list) 1)
         (error "You're looking at the only manpage in the buffer")
       (list (read-minibuffer (format "Go to manpage [1-%d]: "
                                      (length Man-page-list)))))))
  (if (and (not Man-page-list) (not noerror))
      (error "Not a man page buffer"))
  (when Man-page-list
    (if (or (< page 1)
            (> page (length Man-page-list)))
        (error "No manpage %d found" page))
    (let* ((page-range (nth (1- page) Man-page-list))
           (page-start (car page-range))
           (page-end (car (cdr page-range))))
      (setq Man-current-page page
            Man-page-mode-string (Man-make-page-mode-string))
      (widen)
      (goto-char page-start)
      (narrow-to-region page-start page-end)
      (Man-build-section-alist)
      (Man-build-references-alist)
      (goto-char (point-min)))))


(defun Man-next-manpage ()
  "Find the next manpage entry in the buffer."
  (interactive)
  (if (= (length Man-page-list) 1)
      (error "This is the only manpage in the buffer"))
  (if (< Man-current-page (length Man-page-list))
      (Man-goto-page (1+ Man-current-page))
    (if Man-circular-pages-flag
        (Man-goto-page 1)
      (error "You're looking at the last manpage in the buffer"))))

(defun Man-previous-manpage ()
  "Find the previous manpage entry in the buffer."
  (interactive)
  (if (= (length Man-page-list) 1)
      (error "This is the only manpage in the buffer"))
  (if (> Man-current-page 1)
      (Man-goto-page (1- Man-current-page))
    (if Man-circular-pages-flag
        (Man-goto-page (length Man-page-list))
      (error "You're looking at the first manpage in the buffer"))))

;; Header file support
(defun Man-view-header-file (file)
  "View a header file specified by FILE from `Man-header-file-path'."
  (let ((path Man-header-file-path)
        complete-path)
    (while path
      (setq complete-path (concat (car path) "/" file)
            path (cdr path))
      (if (file-readable-p complete-path)
          (progn (view-file complete-path)
                 (setq path nil))
        (setq complete-path nil)))
    complete-path))
\f
;; Init the man package variables, if not already done.
(Man-init-defvars)

(add-to-list 'debug-ignored-errors "^No manpage [0-9]* found$")
(add-to-list 'debug-ignored-errors "^Can't find the .* manpage$")

(provide 'man)

;; arch-tag: 587cda76-8e23-4594-b1f3-89b6b09a0d47
;;; man.el ends here