[bpt/emacs.git] / lisp / add-log.el

;;; add-log.el --- change log maintenance commands for Emacs

;; Copyright (C) 1985, 86, 88, 93, 94, 97, 98, 2000 Free Software Foundation, Inc.

;; Maintainer: FSF
;; Keywords: tools

;; 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., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; This facility is documented in the Emacs Manual.

;;; Code:

(eval-when-compile
  (require 'timezone))

(defgroup change-log nil
  "Change log maintenance"
  :group 'tools
  :link '(custom-manual "(emacs)Change Log")
  :prefix "change-log-"
  :prefix "add-log-")


(defcustom change-log-default-name nil
  "*Name of a change log file for \\[add-change-log-entry]."
  :type '(choice (const :tag "default" nil)
		 string)
  :group 'change-log)

(defcustom change-log-mode-hook nil
  "Normal hook run by `change-log-mode'."
  :type 'hook
  :group 'change-log)

(defcustom add-log-current-defun-function nil
  "*If non-nil, function to guess name of surrounding function.
It is used by `add-log-current-defun' in preference to built-in rules.
Returns function's name as a string, or nil if outside a function."
  :type '(choice (const nil) function)
  :group 'change-log)

;;;###autoload
(defcustom add-log-full-name nil
  "*Full name of user, for inclusion in ChangeLog daily headers.
This defaults to the value returned by the function `user-full-name'."
  :type '(choice (const :tag "Default" nil)
		 string)
  :group 'change-log)

;;;###autoload
(defcustom add-log-mailing-address nil
  "*Electronic mail addresses of user, for inclusion in ChangeLog headers.
This defaults to the value of `user-mail-address'.  In addition to
being a simple string, this value can also be a list.  All elements
will be recognized as referring to the same user; when creating a new
ChangeLog entry, one element will be chosen at random."
  :type '(choice (const :tag "Default" nil)
		 (string :tag "String")
		 (repeat :tag "List of Strings" string))
  :group 'change-log)

(defcustom add-log-time-format 'add-log-iso8601-time-string
  "*Function that defines the time format.
For example, `add-log-iso8601-time-string', which gives the
date in international ISO 8601 format,
and `current-time-string' are two valid values."
  :type '(radio (const :tag "International ISO 8601 format"
		       add-log-iso8601-time-string)
		(const :tag "Old format, as returned by `current-time-string'"
		       current-time-string)
		(function :tag "Other"))
  :group 'change-log)

(defcustom add-log-keep-changes-together nil
  "*If non-nil, normally keep day's log entries for one file together.

Log entries for a given file made with \\[add-change-log-entry] or
\\[add-change-log-entry-other-window] will only be added to others \
for that file made
today if this variable is non-nil or that file comes first in today's
entries.  Otherwise another entry for that file will be started.  An
original log:

	* foo (...): ...
	* bar (...): change 1

in the latter case, \\[add-change-log-entry-other-window] in a \
buffer visiting `bar', yields:

	* bar (...): -!-
	* foo (...): ...
	* bar (...): change 1

and in the former:

	* foo (...): ...
	* bar (...): change 1
	(...): -!-

The NEW-ENTRY arg to `add-change-log-entry' can override the effect of
this variable."
  :version "20.3"
  :type 'boolean
  :group 'change-log)

(defcustom add-log-always-start-new-record nil
  "*If non-nil, `add-change-log-entry' will always start a new record."
  :version "21.4"
  :type 'boolean
  :group 'change-log)

(defcustom add-log-buffer-file-name-function nil
  "*If non-nil, function to call to identify the full filename of a buffer.
This function is called with no argument.  If this is nil, the default is to
use `buffer-file-name'."
  :type '(choice (const nil) function)
  :group 'change-log)

(defcustom add-log-file-name-function nil
  "*If non-nil, function to call to identify the filename for a ChangeLog entry.
This function is called with one argument, the value of variable
`buffer-file-name' in that buffer.  If this is nil, the default is to
use the file's name relative to the directory of the change log file."
  :type '(choice (const nil) function)
  :group 'change-log)


(defcustom change-log-version-info-enabled nil
  "*If non-nil, enable recording version numbers with the changes."
  :version "21.1"
  :type 'boolean
  :group 'change-log)

(defcustom change-log-version-number-regexp-list
  (let ((re    "\\([0-9]+\.[0-9.]+\\)"))
    (list
     ;;  (defconst ad-version "2.15"
     (concat "^(def[^ \t\n]+[ \t]+[^ \t\n][ \t]\"" re)
     ;; Revision: pcl-cvs.el,v 1.72 1999/09/05 20:21:54 monnier Exp
     (concat "^;+ *Revision: +[^ \t\n]+[ \t]+" re)))
  "*List of regexps to search for version number.
The version number must be in group 1.
Note: The search is conducted only within 10%, at the beginning of the file."
  :version "21.1"
  :type '(repeat regexp)
  :group 'change-log)

(defface change-log-date-face
  '((t (:inherit font-lock-string-face)))
  "Face used to highlight dates in date lines."
  :version "21.1"
  :group 'change-log)

(defface change-log-name-face
  '((t (:inherit font-lock-constant-face)))
  "Face for highlighting author names."
  :version "21.1"
  :group 'change-log)

(defface change-log-email-face
  '((t (:inherit font-lock-variable-name-face)))
  "Face for highlighting author email addresses."
  :version "21.1"
  :group 'change-log)

(defface change-log-file-face
  '((t (:inherit font-lock-function-name-face)))
  "Face for highlighting file names."
  :version "21.1"
  :group 'change-log)

(defface change-log-list-face
  '((t (:inherit font-lock-keyword-face)))
  "Face for highlighting parenthesized lists of functions or variables."
  :version "21.1"
  :group 'change-log)

(defface change-log-conditionals-face
  '((t (:inherit font-lock-variable-name-face)))
  "Face for highlighting conditionals of the form `[...]'."
  :version "21.1"
  :group 'change-log)

(defface change-log-function-face
  '((t (:inherit font-lock-variable-name-face)))
  "Face for highlighting items of the form `<....>'."
  :version "21.1"
  :group 'change-log)

(defface change-log-acknowledgement-face
  '((t (:inherit font-lock-comment-face)))
  "Face for highlighting acknowledgments."
  :version "21.1"
  :group 'change-log)

(defvar change-log-font-lock-keywords
  '(;;
    ;; Date lines, new and old styles.
    ("^\\sw.........[0-9:+ ]*"
     (0 'change-log-date-face)
     ;; Name and e-mail; some people put e-mail in parens, not angles.
     ("\\([^<(]+?\\)[ \t]*[(<]\\([A-Za-z0-9_.-]+@[A-Za-z0-9_.-]+\\)[>)]" nil nil
      (1 'change-log-name-face)
      (2 'change-log-email-face)))
    ;;
    ;; File names.
    ("^\t\\* \\([^ ,:([\n]+\\)"
     (1 'change-log-file-face)
     ;; Possibly further names in a list:
     ("\\=, \\([^ ,:([\n]+\\)" nil nil (1 'change-log-file-face))
     ;; Possibly a parenthesized list of names:
     ("\\= (\\([^) ,:\n]+\\)" nil nil (1 'change-log-list-face))
     ("\\=, *\\([^) ,:\n]+\\)" nil nil (1 'change-log-list-face)))
    ;;
    ;; Function or variable names.
    ("^\t(\\([^) ,:\n]+\\)"
     (1 'change-log-list-face)
     ("\\=, *\\([^) ,:\n]+\\)" nil nil (1 'change-log-list-face)))
    ;;
    ;; Conditionals.
    ("\\[!?\\([^]\n]+\\)\\]\\(:\\| (\\)" (1 'change-log-conditionals-face))
    ;;
    ;; Function of change.
    ("<\\([^>\n]+\\)>\\(:\\| (\\)" (1 'change-log-function-face))
    ;;
    ;; Acknowledgements.
    ("\\(^\t\\|  \\)\\(From\\|Patch\\(es\\)? by\\|Report\\(ed by\\| from\\)\\|Suggest\\(ed by\\|ion from\\)\\)"
     2 'change-log-acknowledgement-face))
  "Additional expressions to highlight in Change Log mode.")

(defvar change-log-mode-map (make-sparse-keymap)
  "Keymap for Change Log major mode.")

(defvar change-log-time-zone-rule nil
  "Time zone used for calculating change log time stamps.
It takes the same format as the TZ argument of `set-time-zone-rule'.
If nil, use local time.")

(defun add-log-iso8601-time-zone (time)
  (let* ((utc-offset (or (car (current-time-zone time)) 0))
	 (sign (if (< utc-offset 0) ?- ?+))
	 (sec (abs utc-offset))
	 (ss (% sec 60))
	 (min (/ sec 60))
	 (mm (% min 60))
	 (hh (/ min 60)))
    (format (cond ((not (zerop ss)) "%c%02d:%02d:%02d")
		  ((not (zerop mm)) "%c%02d:%02d")
		  (t "%c%02d"))
	    sign hh mm ss)))

(defun add-log-iso8601-time-string ()
  (if change-log-time-zone-rule
      (let ((tz (getenv "TZ"))
	    (now (current-time)))
	(unwind-protect
	    (progn
	      (set-time-zone-rule change-log-time-zone-rule)
	      (concat
	       (format-time-string "%Y-%m-%d " now)
	       (add-log-iso8601-time-zone now)))
	  (set-time-zone-rule tz)))
    (format-time-string "%Y-%m-%d")))

(defun change-log-name ()
  "Return (system-dependent) default name for a change log file."
  (or change-log-default-name
      (if (eq system-type 'vax-vms)
	  "$CHANGE_LOG$.TXT"
	"ChangeLog")))

;;;###autoload
(defun prompt-for-change-log-name ()
  "Prompt for a change log name."
  (let* ((default (change-log-name))
	 (name (expand-file-name
		(read-file-name (format "Log file (default %s): " default)
				nil default))))
    ;; Handle something that is syntactically a directory name.
    ;; Look for ChangeLog or whatever in that directory.
    (if (string= (file-name-nondirectory name) "")
	(expand-file-name (file-name-nondirectory default)
			  name)
      ;; Handle specifying a file that is a directory.
      (if (file-directory-p name)
	  (expand-file-name (file-name-nondirectory default)
			    (file-name-as-directory name))
	name))))

(defun change-log-version-number-search ()
  "Return version number of current buffer's file.
This is the value returned by `vc-workfile-version' or, if that is
nil, by matching `change-log-version-number-regexp-list'."
  (let* ((size (buffer-size))
	 (end
	  ;; The version number can be anywhere in the file, but
	  ;; restrict search to the file beginning: 10% should be
	  ;; enough to prevent some mishits.
	  ;;
	  ;; Apply percentage only if buffer size is bigger than
	  ;; approx 100 lines.
	  (if (> size (* 100 80))
	      (/ size 10)
	    size))
	 version)
    (or (and buffer-file-name (vc-workfile-version buffer-file-name))
	(save-restriction
	  (widen)
	  (let ((regexps change-log-version-number-regexp-list))
	    (while regexps
	      (save-excursion
		(goto-char (point-min))
		(when (re-search-forward (pop regexps) end t)
		  (setq version (match-string 1)
			regexps nil)))))))))


;;;###autoload
(defun find-change-log (&optional file-name buffer-file)
  "Find a change log file for \\[add-change-log-entry] and return the name.

Optional arg FILE-NAME specifies the file to use.
If FILE-NAME is nil, use the value of `change-log-default-name'.
If 'change-log-default-name' is nil, behave as though it were 'ChangeLog'
\(or whatever we use on this operating system).

If 'change-log-default-name' contains a leading directory component, then
simply find it in the current directory.  Otherwise, search in the current
directory and its successive parents for a file so named.

Once a file is found, `change-log-default-name' is set locally in the
current buffer to the complete file name.
Optional arg BUFFER-FILE overrides `buffer-file-name'."
  ;; If user specified a file name or if this buffer knows which one to use,
  ;; just use that.
  (or file-name
      (setq file-name (and change-log-default-name
			   (file-name-directory change-log-default-name)
			   change-log-default-name))
      (progn
	;; Chase links in the source file
	;; and use the change log in the dir where it points.
	(setq file-name (or (and (or buffer-file buffer-file-name)
				 (file-name-directory
				  (file-chase-links
				   (or buffer-file buffer-file-name))))
			    default-directory))
	(if (file-directory-p file-name)
	    (setq file-name (expand-file-name (change-log-name) file-name)))
	;; Chase links before visiting the file.
	;; This makes it easier to use a single change log file
	;; for several related directories.
	(setq file-name (file-chase-links file-name))
	(setq file-name (expand-file-name file-name))
	;; Move up in the dir hierarchy till we find a change log file.
	(let ((file1 file-name)
	      parent-dir)
	  (while (and (not (or (get-file-buffer file1) (file-exists-p file1)))
		      (progn (setq parent-dir
				   (file-name-directory
				    (directory-file-name
				     (file-name-directory file1))))
			     ;; Give up if we are already at the root dir.
			     (not (string= (file-name-directory file1)
					   parent-dir))))
	    ;; Move up to the parent dir and try again.
	    (setq file1 (expand-file-name
			 (file-name-nondirectory (change-log-name))
			 parent-dir)))
	  ;; If we found a change log in a parent, use that.
	  (if (or (get-file-buffer file1) (file-exists-p file1))
	      (setq file-name file1)))))
  ;; Make a local variable in this buffer so we needn't search again.
  (set (make-local-variable 'change-log-default-name) file-name)
  file-name)

(defun add-log-file-name (buffer-file log-file)
  ;; Never want to add a change log entry for the ChangeLog file itself.
  (unless (or (null buffer-file) (string= buffer-file log-file))
    (if add-log-file-name-function
	(funcall add-log-file-name-function buffer-file)
      (setq buffer-file
	    (if (string-match
		 (concat "^" (regexp-quote (file-name-directory log-file)))
		 buffer-file)
		(substring buffer-file (match-end 0))
	      (file-name-nondirectory buffer-file)))
      ;; If we have a backup file, it's presumably because we're
      ;; comparing old and new versions (e.g. for deleted
      ;; functions) and we'll want to use the original name.
      (if (backup-file-name-p buffer-file)
	  (file-name-sans-versions buffer-file)
	buffer-file))))

;;;###autoload
(defun add-change-log-entry (&optional whoami file-name other-window new-entry)
  "Find change log file, and add an entry for today and an item for this file.
Optional arg WHOAMI (interactive prefix) non-nil means prompt for user
name and site.

Second arg FILE-NAME is file name of the change log.
If nil, use the value of `change-log-default-name'.

Third arg OTHER-WINDOW non-nil means visit in other window.

Fourth arg NEW-ENTRY non-nil means always create a new entry at the front;
never append to an existing entry.  Option `add-log-keep-changes-together'
otherwise affects whether a new entry is created.

Option `add-log-always-start-new-record' non-nil means always create a
new record, even when the last record was made on the same date and by
the same person.

The change log file can start with a copyright notice and a copying
permission notice.  The first blank line indicates the end of these
notices.

Today's date is calculated according to `change-log-time-zone-rule' if
non-nil, otherwise in local time."
  (interactive (list current-prefix-arg
		     (prompt-for-change-log-name)))
  (or add-log-full-name
      (setq add-log-full-name (user-full-name)))
  (or add-log-mailing-address
      (setq add-log-mailing-address user-mail-address))
  (if whoami
      (progn
	(setq add-log-full-name (read-input "Full name: " add-log-full-name))
	 ;; Note that some sites have room and phone number fields in
	 ;; full name which look silly when inserted.  Rather than do
	 ;; anything about that here, let user give prefix argument so that
	 ;; s/he can edit the full name field in prompter if s/he wants.
	(setq add-log-mailing-address
	      (read-input "Mailing address: " add-log-mailing-address))))

  (let* ((defun (add-log-current-defun))
	 (version (and change-log-version-info-enabled
		       (change-log-version-number-search)))
	 (buf-file-name (if add-log-buffer-file-name-function
			    (funcall add-log-buffer-file-name-function)
			  buffer-file-name))
	 (buffer-file (if buf-file-name (expand-file-name buf-file-name)))
	 (file-name (expand-file-name
		     (or file-name (find-change-log file-name buffer-file))))
	 ;; Set ITEM to the file name to use in the new item.
	 (item (add-log-file-name buffer-file file-name))
	 bound)

    (unless (equal file-name buffer-file-name)
      (if (or other-window (window-dedicated-p (selected-window)))
	  (find-file-other-window file-name)
	(find-file file-name)))
    (or (eq major-mode 'change-log-mode)
	(change-log-mode))
    (undo-boundary)
    (goto-char (point-min))

    ;; If file starts with a copyright and permission notice, skip them.
    ;; Assume they end at first blank line.
    (when (looking-at "Copyright")
      (search-forward "\n\n")
      (skip-chars-forward "\n"))

    ;; Advance into first entry if it is usable; else make new one.
    (let ((new-entries (mapcar (lambda (addr)
				 (concat (funcall add-log-time-format)
					 "  " add-log-full-name
					 "  <" addr ">"))
			       (if (consp add-log-mailing-address)
				   add-log-mailing-address
				 (list add-log-mailing-address)))))
      (if (and (not add-log-always-start-new-record)
               (let ((hit nil))
		 (dolist (entry new-entries hit)
		   (when (looking-at (regexp-quote entry))
		     (setq hit t)))))
	  (forward-line 1)
	(insert (nth (random (length new-entries))
		     new-entries)
		"\n\n")
	(forward-line -1)))

    ;; Determine where we should stop searching for a usable
    ;; item to add to, within this entry.
    (setq bound
	  (save-excursion
            (if (looking-at "\n*[^\n* \t]")
                (skip-chars-forward "\n")
	      (if add-log-keep-changes-together
		  (forward-page)	; page delimits entries for date
		(forward-paragraph)))	; paragraph delimits entries for file
	    (point)))

    ;; Now insert the new line for this item.
    (cond ((re-search-forward "^\\s *\\*\\s *$" bound t)
	   ;; Put this file name into the existing empty item.
	   (if item
	       (insert item)))
	  ((and (not new-entry)
		(let (case-fold-search)
		  (re-search-forward
		   (concat (regexp-quote (concat "* " item))
			   ;; Don't accept `foo.bar' when
			   ;; looking for `foo':
			   "\\(\\s \\|[(),:]\\)")
		   bound t)))
	   ;; Add to the existing item for the same file.
	   (re-search-forward "^\\s *$\\|^\\s \\*")
	   (goto-char (match-beginning 0))
	   ;; Delete excess empty lines; make just 2.
	   (while (and (not (eobp)) (looking-at "^\\s *$"))
	     (delete-region (point) (line-beginning-position 2)))
	   (insert-char ?\n 2)
	   (forward-line -2)
	   (indent-relative-maybe))
	  (t
	   ;; Make a new item.
	   (while (looking-at "\\sW")
	     (forward-line 1))
	   (while (and (not (eobp)) (looking-at "^\\s *$"))
	     (delete-region (point) (line-beginning-position 2)))
	   (insert-char ?\n 3)
	   (forward-line -2)
	   (indent-to left-margin)
	   (insert "* ")
	   (if item (insert item))))
    ;; Now insert the function name, if we have one.
    ;; Point is at the item for this file,
    ;; either at the end of the line or at the first blank line.
    (if (not defun)
	;; No function name, so put in a colon unless we have just a star.
	(unless (save-excursion
		  (beginning-of-line 1)
		  (looking-at "\\s *\\(\\*\\s *\\)?$"))
	  (insert ": ")
	  (if version (insert version ?\ )))
      ;; Make it easy to get rid of the function name.
      (undo-boundary)
      (unless (save-excursion
		(beginning-of-line 1)
		(looking-at "\\s *$"))
	(insert ?\ ))
      ;; See if the prev function name has a message yet or not.
      ;; If not, merge the two items.
      (let ((pos (point-marker)))
	(skip-syntax-backward " ")
	(skip-chars-backward "):")
	(if (and (looking-at "):")
		 (> fill-column (+ (current-column) (length defun) 4)))
	    (progn (delete-region (point) pos) (insert ", "))
	  (if (looking-at "):")
	      (delete-region (+ 1 (point)) (line-end-position)))
	  (goto-char pos)
	  (insert "("))
	(set-marker pos nil))
      (insert defun "): ")
      (if version (insert version ?\ )))))

;;;###autoload
(defun add-change-log-entry-other-window (&optional whoami file-name)
  "Find change log file in other window and add entry and item.
This is just like `add-change-log-entry' except that it displays
the change log file in another window."
  (interactive (if current-prefix-arg
		   (list current-prefix-arg
			 (prompt-for-change-log-name))))
  (add-change-log-entry whoami file-name t))
;;;###autoload (define-key ctl-x-4-map "a" 'add-change-log-entry-other-window)

;;;###autoload
(define-derived-mode change-log-mode text-mode "Change Log"
  "Major mode for editing change logs; like Indented Text Mode.
Prevents numeric backups and sets `left-margin' to 8 and `fill-column' to 74.
New log entries are usually made with \\[add-change-log-entry] or \\[add-change-log-entry-other-window].
Each entry behaves as a paragraph, and the entries for one day as a page.
Runs `change-log-mode-hook'."
  (setq left-margin 8
	fill-column 74
	indent-tabs-mode t
	tab-width 8)
  (set (make-local-variable 'fill-paragraph-function)
       'change-log-fill-paragraph)
  (set (make-local-variable 'indent-line-function) 'indent-to-left-margin)
  ;; We really do want "^" in paragraph-start below: it is only the
  ;; lines that begin at column 0 (despite the left-margin of 8) that
  ;; we are looking for.  Adding `* ' allows eliding the blank line
  ;; between entries for different files.
  (set (make-local-variable 'paragraph-start) "\\s *$\\|\f\\|^\\<")
  (set (make-local-variable 'paragraph-separate) paragraph-start)
  ;; Match null string on the date-line so that the date-line
  ;; is grouped with what follows.
  (set (make-local-variable 'page-delimiter) "^\\<\\|^\f")
  (set (make-local-variable 'version-control) 'never)
  (set (make-local-variable 'smerge-resolve-function)
       'change-log-resolve-conflict)
  (set (make-local-variable 'adaptive-fill-regexp) "\\s *")
  (set (make-local-variable 'font-lock-defaults)
       '(change-log-font-lock-keywords t nil nil backward-paragraph)))

;; It might be nice to have a general feature to replace this.  The idea I
;; have is a variable giving a regexp matching text which should not be
;; moved from bol by filling.  change-log-mode would set this to "^\\s *\\s(".
;; But I don't feel up to implementing that today.
(defun change-log-fill-paragraph (&optional justify)
  "Fill the paragraph, but preserve open parentheses at beginning of lines.
Prefix arg means justify as well."
  (interactive "P")
  (let ((end (progn (forward-paragraph) (point)))
	(beg (progn (backward-paragraph) (point)))
	(paragraph-start (concat paragraph-start "\\|\\s *\\s(")))
    (fill-region beg end justify)
    t))
\f
(defcustom add-log-current-defun-header-regexp
  "^\\([[:upper:]][[:upper:]_ ]*[[:upper:]_]\\|[-_[:alpha:]]+\\)[ \t]*[:=]"
  "*Heuristic regexp used by `add-log-current-defun' for unknown major modes."
  :type 'regexp
  :group 'change-log)

;;;###autoload
(defvar add-log-lisp-like-modes
    '(emacs-lisp-mode lisp-mode scheme-mode dsssl-mode lisp-interaction-mode)
  "*Modes that look like Lisp to `add-log-current-defun'.")

;;;###autoload
(defvar add-log-c-like-modes
    '(c-mode c++-mode c++-c-mode objc-mode)
  "*Modes that look like C to `add-log-current-defun'.")

;;;###autoload
(defvar add-log-tex-like-modes
    '(TeX-mode plain-TeX-mode LaTeX-mode plain-tex-mode latex-mode)
  "*Modes that look like TeX to `add-log-current-defun'.")

;;;###autoload
(defun add-log-current-defun ()
  "Return name of function definition point is in, or nil.

Understands C, Lisp, LaTeX (\"functions\" are chapters, sections, ...),
Texinfo (@node titles) and Perl.

Other modes are handled by a heuristic that looks in the 10K before
point for uppercase headings starting in the first column or
identifiers followed by `:' or `='.  See variables
`add-log-current-defun-header-regexp' and
`add-log-current-defun-function'.

Has a preference of looking backwards."
  (condition-case nil
      (save-excursion
	(let ((location (point)))
	  (cond (add-log-current-defun-function
		 (funcall add-log-current-defun-function))
		((memq major-mode add-log-lisp-like-modes)
		 ;; If we are now precisely at the beginning of a defun,
		 ;; make sure beginning-of-defun finds that one
		 ;; rather than the previous one.
		 (or (eobp) (forward-char 1))
		 (beginning-of-defun)
		 ;; Make sure we are really inside the defun found,
		 ;; not after it.
		 (when (and (looking-at "\\s(")
			    (progn (end-of-defun)
				   (< location (point)))
			    (progn (forward-sexp -1)
				   (>= location (point))))
		   (if (looking-at "\\s(")
		       (forward-char 1))
		   ;; Skip the defining construct name, typically "defun"
		   ;; or "defvar".
		   (forward-sexp 1)
		   ;; The second element is usually a symbol being defined.
		   ;; If it is not, use the first symbol in it.
		   (skip-chars-forward " \t\n'(")
		   (buffer-substring-no-properties (point)
						   (progn (forward-sexp 1)
							  (point)))))
		((and (memq major-mode add-log-c-like-modes)
		      (save-excursion
			(beginning-of-line)
			;; Use eq instead of = here to avoid
			;; error when at bob and char-after
			;; returns nil.
			(while (eq (char-after (- (point) 2)) ?\\)
			  (forward-line -1))
			(looking-at "[ \t]*#[ \t]*define[ \t]")))
		 ;; Handle a C macro definition.
		 (beginning-of-line)
		 (while (eq (char-after (- (point) 2)) ?\\) ;not =; note above
		   (forward-line -1))
		 (search-forward "define")
		 (skip-chars-forward " \t")
		 (buffer-substring-no-properties (point)
						 (progn (forward-sexp 1)
							(point))))
		((memq major-mode add-log-c-like-modes)
		 (beginning-of-line)
		 ;; See if we are in the beginning part of a function,
		 ;; before the open brace.  If so, advance forward.
		 (while (not (looking-at "{\\|\\(\\s *$\\)"))
		   (forward-line 1))
		 (or (eobp)
		     (forward-char 1))
		 (beginning-of-defun)
		 (when (progn (end-of-defun)
			      (< location (point)))
		   (backward-sexp 1)
		   (let (beg tem)

		     (forward-line -1)
		     ;; Skip back over typedefs of arglist.
		     (while (and (not (bobp))
				 (looking-at "[ \t\n]"))
		       (forward-line -1))
		     ;; See if this is using the DEFUN macro used in Emacs,
		     ;; or the DEFUN macro used by the C library.
		     (if (condition-case nil
			     (and (save-excursion
				    (end-of-line)
				    (while (= (preceding-char) ?\\)
				      (end-of-line 2))
				    (backward-sexp 1)
				    (beginning-of-line)
				    (setq tem (point))
				    (looking-at "DEFUN\\b"))
				  (>= location tem))
			   (error nil))
			 (progn
			   (goto-char tem)
			   (down-list 1)
			   (if (= (char-after (point)) ?\")
			       (progn
				 (forward-sexp 1)
				 (skip-chars-forward " ,")))
			   (buffer-substring-no-properties
			    (point)
			    (progn (forward-sexp 1)
				   (point))))
		       (if (looking-at "^[+-]")
			   (change-log-get-method-definition)
			 ;; Ordinary C function syntax.
			 (setq beg (point))
			 (if (and
			      ;; Protect against "Unbalanced parens" error.
			      (condition-case nil
				  (progn
				    (down-list 1) ; into arglist
				    (backward-up-list 1)
				    (skip-chars-backward " \t")
				    t)
				(error nil))
			      ;; Verify initial pos was after
			      ;; real start of function.
			      (save-excursion
				(goto-char beg)
				;; For this purpose, include the line
				;; that has the decl keywords.  This
				;; may also include some of the
				;; comments before the function.
				(while (and (not (bobp))
					    (save-excursion
					      (forward-line -1)
					      (looking-at "[^\n\f]")))
				  (forward-line -1))
				(>= location (point)))
			      ;; Consistency check: going down and up
			      ;; shouldn't take us back before BEG.
			      (> (point) beg))
			     (let (end middle)
			       ;; Don't include any final whitespace
			       ;; in the name we use.
			       (skip-chars-backward " \t\n")
			       (setq end (point))
			       (backward-sexp 1)
			       ;; Now find the right beginning of the name.
			       ;; Include certain keywords if they
			       ;; precede the name.
			       (setq middle (point))
			       (forward-word -1)
			       ;; Ignore these subparts of a class decl
			       ;; and move back to the class name itself.
			       (while (looking-at "public \\|private ")
				 (skip-chars-backward " \t:")
				 (setq end (point))
				 (backward-sexp 1)
				 (setq middle (point))
				 (forward-word -1))
			       (and (bolp)
				    (looking-at
				     "enum \\|struct \\|union \\|class ")
				    (setq middle (point)))
			       (goto-char end)
			       (when (eq (preceding-char) ?=)
				 (forward-char -1)
				 (skip-chars-backward " \t")
				 (setq end (point)))
			       (buffer-substring-no-properties
				middle end))))))))
		((memq major-mode add-log-tex-like-modes)
		 (if (re-search-backward
		      "\\\\\\(sub\\)*\\(section\\|paragraph\\|chapter\\)"
		      nil t)
		     (progn
		       (goto-char (match-beginning 0))
		       (buffer-substring-no-properties
			(1+ (point))	; without initial backslash
			(line-end-position)))))
		((eq major-mode 'texinfo-mode)
		 (if (re-search-backward "^@node[ \t]+\\([^,\n]+\\)" nil t)
		     (match-string-no-properties 1)))
		((memq major-mode '(perl-mode cperl-mode))
		 (if (re-search-backward "^sub[ \t]+\\([^({ \t\n]+\\)" nil t)
		     (match-string-no-properties 1)))
		;; Emacs's autoconf-mode installs its own
		;; `add-log-current-defun-function'.  This applies to
		;; a different mode apparently for editing .m4
		;; autoconf source.
                ((eq major-mode 'autoconf-mode)
                 (if (re-search-backward
		      "^\\(\\(m4_\\)?define\\|A._DEFUN\\)(\\[?\\([A-Za-z0-9_]+\\)" nil t)
                     (match-string-no-properties 3)))
		(t
		 ;; If all else fails, try heuristics
		 (let (case-fold-search
		       result)
		   (end-of-line)
		   (when (re-search-backward
			  add-log-current-defun-header-regexp
			  (- (point) 10000)
			  t)
		     (setq result (or (match-string-no-properties 1)
				      (match-string-no-properties 0)))
		     ;; Strip whitespace away
		     (when (string-match "\\([^ \t\n\r\f].*[^ \t\n\r\f]\\)"
					 result)
		       (setq result (match-string-no-properties 1 result)))
		     result))))))
    (error nil)))

(defvar change-log-get-method-definition-md)

;; Subroutine used within change-log-get-method-definition.
;; Add the last match in the buffer to the end of `md',
;; followed by the string END; move to the end of that match.
(defun change-log-get-method-definition-1 (end)
  (setq change-log-get-method-definition-md
	(concat change-log-get-method-definition-md
		(match-string 1)
		end))
  (goto-char (match-end 0)))

(defun change-log-get-method-definition ()
"For objective C, return the method name if we are in a method."
  (let ((change-log-get-method-definition-md "["))
    (save-excursion
      (if (re-search-backward "^@implementation\\s-*\\([A-Za-z_]*\\)" nil t)
	  (change-log-get-method-definition-1 " ")))
    (save-excursion
      (cond
       ((re-search-forward "^\\([-+]\\)[ \t\n\f\r]*\\(([^)]*)\\)?\\s-*" nil t)
	(change-log-get-method-definition-1 "")
	(while (not (looking-at "[{;]"))
	  (looking-at
	   "\\([A-Za-z_]*:?\\)\\s-*\\(([^)]*)\\)?[A-Za-z_]*[ \t\n\f\r]*")
	  (change-log-get-method-definition-1 ""))
	(concat change-log-get-method-definition-md "]"))))))
\f
(defun change-log-sortable-date-at ()
  "Return date of log entry in a consistent form for sorting.
Point is assumed to be at the start of the entry."
  (require 'timezone)
  (if (looking-at "^\\sw.........[0-9:+ ]*")
      (let ((date (match-string-no-properties 0)))
	(if date
	    (if (string-match "\\(....\\)-\\(..\\)-\\(..\\)\\s-+" date)
		(concat (match-string 1 date) (match-string 2 date)
			(match-string 3 date))
	      (condition-case nil
		  (timezone-make-date-sortable date)
		(error nil)))))
    (error "Bad date")))

(defun change-log-resolve-conflict ()
  "Function to be used in `smerge-resolve-function'."
  (let ((buf (current-buffer)))
    (with-temp-buffer
      (insert-buffer-substring buf (match-beginning 1) (match-end 1))
      (save-match-data (change-log-mode))
      (let ((other-buf (current-buffer)))
	(with-current-buffer buf
	  (save-excursion
	    (save-restriction
	      (narrow-to-region (match-beginning 0) (match-end 0))
	      (replace-match (match-string 3) t t)
	      (change-log-merge other-buf))))))))

;;;###autoload
(defun change-log-merge (other-log)
  "Merge the contents of ChangeLog file OTHER-LOG with this buffer.
Both must be found in Change Log mode (since the merging depends on
the appropriate motion commands).  OTHER-LOG can be either a file name
or a buffer.

Entries are inserted in chronological order.  Both the current and
old-style time formats for entries are supported."
  (interactive "*fLog file name to merge: ")
  (if (not (eq major-mode 'change-log-mode))
      (error "Not in Change Log mode"))
  (let ((other-buf (if (bufferp other-log) other-log
		     (find-file-noselect other-log)))
	(buf (current-buffer))
	date1 start end)
    (save-excursion
      (goto-char (point-min))
      (set-buffer other-buf)
      (goto-char (point-min))
      (if (not (eq major-mode 'change-log-mode))
	  (error "%s not found in Change Log mode" other-log))
      ;; Loop through all the entries in OTHER-LOG.
      (while (not (eobp))
	(setq date1 (change-log-sortable-date-at))
	(setq start (point)
	      end (progn (forward-page) (point)))
	;; Look for an entry in original buffer that isn't later.
	(with-current-buffer buf
	  (while (and (not (eobp))
		      (string< date1 (change-log-sortable-date-at)))
	    (forward-page))
	  (if (not (eobp))
	      (insert-buffer-substring other-buf start end)
	    ;; At the end of the original buffer, insert a newline to
	    ;; separate entries and then the rest of the file being
	    ;; merged.
	    (unless (or (bobp)
			(and (= ?\n (char-before))
			     (or (<= (1- (point)) (point-min))
				 (= ?\n (char-before (1- (point)))))))
	      (insert "\n"))
	    ;; Move to the end of it to terminate outer loop.
	    (with-current-buffer other-buf
	      (goto-char (point-max)))
	    (insert-buffer-substring other-buf start)))))))

;;;###autoload
(defun change-log-redate ()
  "Fix any old-style date entries in the current log file to default format."
  (interactive)
  (require 'timezone)
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward "^\\sw.........[0-9:+ ]*" nil t)
      (unless (= 12 (- (match-end 0) (match-beginning 0)))
	(let* ((date (save-match-data
		       (timezone-fix-time (match-string 0) nil nil)))
	       (zone (if (consp (aref date 6))
			 (nth 1 (aref date 6)))))
	  (replace-match (format-time-string
			  "%Y-%m-%d  "
			  (encode-time (aref date 5)
				       (aref date 4)
				       (aref date 3)
				       (aref date 2)
				       (aref date 1)
				       (aref date 0)
				       zone))))))))

(provide 'add-log)

;;; add-log.el ends here