(comint-output-filter):

[emacs.git] / lisp / diff.el

;;; diff.el --- Run `diff' in compilation-mode.

;; Copyright (C) 1992, 1994, 1996 Free Software Foundation, Inc.

;; Keywords: unix, 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 package helps you explore differences between files, using the
;; UNIX command diff(1).  The commands are `diff' and `diff-backup'.
;; You can specify options with `diff-switches'.

;;; Code:

(require 'compile)

(defgroup diff nil
  "Comparing files with `diff'."
  :group 'tools)

;;;###autoload
(defcustom diff-switches "-c"
  "*A string or list of strings specifying switches to be be passed to diff."
  :type '(choice string (repeat string))
  :group 'diff)

;;;###autoload
(defcustom diff-command "diff"
  "*The command to use to run diff."
  :type 'string
  :group 'diff)

(defvar diff-regexp-alist
  '(
    ;; -u format: @@ -OLDSTART,OLDEND +NEWSTART,NEWEND @@
    ("^@@ -\\([0-9]+\\),[0-9]+ \\+\\([0-9]+\\),[0-9]+ @@$" 1 2)

    ;; -c format: *** OLDSTART,OLDEND ****
    ("^\\*\\*\\* \\([0-9]+\\),[0-9]+ \\*\\*\\*\\*$" 1 nil)
    ;;            --- NEWSTART,NEWEND ----
    ("^--- \\([0-9]+\\),[0-9]+ ----$" nil 1)

    ;; plain diff format: OLDSTART[,OLDEND]{a,d,c}NEWSTART[,NEWEND]
    ("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]\\([0-9]+\\)\\(,[0-9]+\\)?$" 1 3)

    ;; -e (ed) format: OLDSTART[,OLDEND]{a,d,c}
    ("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]$" 1)

    ;; -f format: {a,d,c}OLDSTART[ OLDEND]
    ;; -n format: {a,d,c}OLDSTART LINES-CHANGED
    ("^[adc]\\([0-9]+\\)\\( [0-9]+\\)?$" 1)
    )
  "Alist (REGEXP OLD-IDX NEW-IDX) of regular expressions to match difference
sections in \\[diff] output.  If REGEXP matches, the OLD-IDX'th
subexpression gives the line number in the old file, and NEW-IDX'th
subexpression gives the line number in the new file.  If OLD-IDX or NEW-IDX
is nil, REGEXP matches only half a section.")

(defvar diff-old-file nil
  "This is the old file name in the comparison in this buffer.")
(defvar diff-new-file nil
  "This is the new file name in the comparison in this buffer.")
(defvar diff-old-temp-file nil
  "This is the name of a temp file to be deleted after diff finishes.")
(defvar diff-new-temp-file nil
  "This is the name of a temp file to be deleted after diff finishes.")

;; See compilation-parse-errors-function (compile.el).
(defun diff-parse-differences (limit-search find-at-least)
  (setq compilation-error-list nil)
  (message "Parsing differences...")

  ;; Don't reparse diffs already seen at last parse.
  (if compilation-parsing-end (goto-char compilation-parsing-end))

  ;; Construct in REGEXP a regexp composed of all those in dired-regexp-alist.
  (let ((regexp (mapconcat (lambda (elt)
                             (concat "\\(" (car elt) "\\)"))
                           diff-regexp-alist
                           "\\|"))
        ;; (GROUP-IDX OLD-IDX NEW-IDX)
        (groups (let ((subexpr 1))
                  (mapcar (lambda (elt)
                            (prog1
                                (cons subexpr
                                      (mapcar (lambda (n)
                                                (and n
                                                     (+ subexpr n)))
                                              (cdr elt)))
                              (setq subexpr (+ subexpr 1
                                               (count-regexp-groupings
                                                (car elt))))))
                          diff-regexp-alist)))

        (new-error
         (function (lambda (file subexpr)
                     (setq compilation-error-list
                           (cons
                            (cons (save-excursion
                                    ;; Report location of message
                                    ;; at beginning of line.
                                    (goto-char
                                     (match-beginning subexpr))
                                    (beginning-of-line)
                                    (point-marker))
                                  ;; Report location of corresponding text.
                                  (let ((line (string-to-int
                                               (buffer-substring
                                                (match-beginning subexpr)
                                                (match-end subexpr)))))
                                    (save-excursion
                                      (save-match-data
                                        (set-buffer (find-file-noselect file)))
                                      (save-excursion
                                        (goto-line line)
                                        (point-marker)))))
                            compilation-error-list)))))

        (found-desired nil)
        (num-loci-found 0)
        g)

    (while (and (not found-desired)
                ;; We don't just pass LIMIT-SEARCH to re-search-forward
                ;; because we want to find matches containing LIMIT-SEARCH
                ;; but which extend past it.
                (re-search-forward regexp nil t))

      ;; Find which individual regexp matched.
      (setq g groups)
      (while (and g (null (match-beginning (car (car g)))))
        (setq g (cdr g)))
      (setq g (car g))

      (if (nth 1 g)                     ;OLD-IDX
          (funcall new-error diff-old-file (nth 1 g)))
      (if (nth 2 g)                     ;NEW-IDX
          (funcall new-error diff-new-file (nth 2 g)))

      (setq num-loci-found (1+ num-loci-found))
      (if (or (and find-at-least
                   (>= num-loci-found find-at-least))
              (and limit-search (>= (point) limit-search)))
              ;; We have found as many new loci as the user wants,
              ;; or the user wanted a specific diff, and we're past it.
          (setq found-desired t)))
    (set-marker compilation-parsing-end
                (if found-desired (point)
                  ;; Set to point-max, not point, so we don't perpetually
                  ;; parse the last bit of text when it isn't a diff header.
                  (point-max)))
    (message "Parsing differences...done"))
  (setq compilation-error-list (nreverse compilation-error-list)))

(defun diff-process-setup ()
  "Set up \`compilation-exit-message-function' for \`diff'."
  ;; Avoid frightening people with "abnormally terminated"
  ;; if diff finds differences.
  (set (make-local-variable 'compilation-exit-message-function)
       (lambda (status code msg)
         (cond ((not (eq status 'exit))
                (cons msg code))
               ((zerop code)
                '("finished (no differences)\n" . "no differences"))
               ((= code 1)
                '("finished\n" . "differences found"))
               (t
                (cons msg code))))))

;;;###autoload
(defun diff (old new &optional switches)
  "Find and display the differences between OLD and NEW files.
Interactively the current buffer's file name is the default for NEW
and a backup file for NEW is the default for OLD.
With prefix arg, prompt for diff switches."
  (interactive
   (nconc
    (let (oldf newf)
      (nreverse
       (list
        (setq newf (buffer-file-name)
              newf (if (and newf (file-exists-p newf))
                       (read-file-name
                        (concat "Diff new file: ("
                                (file-name-nondirectory newf) ") ")
                        nil newf t)
                     (read-file-name "Diff new file: " nil nil t)))
        (setq oldf (file-newest-backup newf)
              oldf (if (and oldf (file-exists-p oldf))
                       (read-file-name
                        (concat "Diff original file: ("
                                (file-name-nondirectory oldf) ") ")
                        (file-name-directory oldf) oldf t)
                     (read-file-name "Diff original file: "
                                     (file-name-directory newf) nil t))))))
    (if current-prefix-arg
        (list (read-string "Diff switches: "
                           (if (stringp diff-switches)
                               diff-switches
                             (mapconcat 'identity diff-switches " "))))
      nil)))
  (setq new (expand-file-name new)
        old (expand-file-name old))
  (let ((old-alt (file-local-copy old))
        (new-alt (file-local-copy new))
        buf)
    (save-excursion
        (let ((compilation-process-setup-function 'diff-process-setup)
              (command
               (mapconcat 'identity
                          (append (list diff-command)
                                  ;; Use explicitly specified switches
                                  (if switches
                                      (if (consp switches)
                                          switches (list switches))
                                    ;; If not specified, use default.
                                    (if (consp diff-switches)
                                        diff-switches
                                      (list diff-switches)))
                                  (if (or old-alt new-alt)
                                      (list "-L" old "-L" new))
                                  (list
                                   (shell-quote-argument (or old-alt old)))
                                  (list
                                   (shell-quote-argument (or new-alt new))))
                          " ")))
          (setq buf
                (compile-internal command
                                  "No more differences" "Diff"
                                  'diff-parse-differences))
          (set-buffer buf)
          (set (make-local-variable 'diff-old-file) old)
          (set (make-local-variable 'diff-new-file) new)
          (set (make-local-variable 'diff-old-temp-file) old-alt)
          (set (make-local-variable 'diff-new-temp-file) new-alt)
          (set (make-local-variable 'compilation-finish-function)
               (function (lambda (buff msg)
                           (if diff-old-temp-file
                               (delete-file diff-old-temp-file))
                           (if diff-new-temp-file
                               (delete-file diff-new-temp-file)))))
          ;; When async processes aren't available, the compilation finish
          ;; function doesn't get chance to run.  Invoke it by hand.
          (or (fboundp 'start-process)
              (funcall compilation-finish-function nil nil))
          buf))))

;;;###autoload
(defun diff-backup (file &optional switches)
  "Diff this file with its backup file or vice versa.
Uses the latest backup, if there are several numerical backups.
If this file is a backup, diff it with its original.
The backup file is the first file given to `diff'."
  (interactive (list (read-file-name "Diff (file with backup): ")
                     (if current-prefix-arg
                         (read-string "Diff switches: "
                                      (if (stringp diff-switches)
                                          diff-switches
                                        (mapconcat 'identity
                                                   diff-switches " ")))
                       nil)))
  (let (bak ori)
    (if (backup-file-name-p file)
        (setq bak file
              ori (file-name-sans-versions file))
      (setq bak (or (diff-latest-backup-file file)
                    (error "No backup found for %s" file))
            ori file))
    (diff bak ori switches)))

(defun diff-latest-backup-file (fn)     ; actually belongs into files.el
  "Return the latest existing backup of FILE, or nil."
  (let ((handler (find-file-name-handler fn 'diff-latest-backup-file)))
    (if handler
        (funcall handler 'diff-latest-backup-file fn)
      ;; First try simple backup, then the highest numbered of the
      ;; numbered backups.
      ;; Ignore the value of version-control because we look for existing
      ;; backups, which maybe were made earlier or by another user with
      ;; a different value of version-control.
      (setq fn (file-chase-links (expand-file-name fn)))
      (or
       (let ((bak (make-backup-file-name fn)))
         (if (file-exists-p bak) bak))
       ;; We use BACKUPNAME to cope with backups stored in a different dir.
       (let* ((backupname (car (find-backup-file-name fn)))
              (dir (file-name-directory backupname))
              (base-versions (concat (file-name-sans-versions
                                      (file-name-nondirectory backupname))
                                     ".~"))
              ;; This is a fluid var for backup-extract-version.
              (backup-extract-version-start (length base-versions)))
         (concat dir
                 (car (sort
                       (file-name-all-completions base-versions dir)
                       (function
                        (lambda (fn1 fn2)
                          (> (backup-extract-version fn1)
                             (backup-extract-version fn2))))))))))))

(provide 'diff)

;;; diff.el ends here