(require 'compile)
(defgroup diff nil
"Comparing files with `diff'."
:group 'tools)
(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)
(defcustom diff-command "diff"
"*The command to use to run diff."
:type 'string
:group 'diff)
(defvar diff-regexp-alist
'(
("^@@ -\\([0-9]+\\),[0-9]+ \\+\\([0-9]+\\),[0-9]+ @@$" 1 2)
("^\\*\\*\\* \\([0-9]+\\),[0-9]+ \\*\\*\\*\\*$" 1 nil)
("^--- \\([0-9]+\\),[0-9]+ ----$" nil 1)
("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]\\([0-9]+\\)\\(,[0-9]+\\)?$" 1 3)
("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]$" 1)
("^[adc]\\([0-9]+\\)\\( [0-9]+\\)?$" 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.")
(defun diff-parse-differences (limit-search find-at-least)
(setq compilation-error-list nil)
(message "Parsing differences...")
(if compilation-parsing-end (goto-char compilation-parsing-end))
(let ((regexp (mapconcat (lambda (elt)
(concat "\\(" (car elt) "\\)"))
diff-regexp-alist
"\\|"))
(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
(goto-char
(match-beginning subexpr))
(beginning-of-line)
(point-marker))
(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)
(re-search-forward regexp nil t))
(setq g groups)
(while (and g (null (match-beginning (car (car g)))))
(setq g (cdr g)))
(setq g (car g))
(if (nth 1 g) (funcall new-error diff-old-file (nth 1 g)))
(if (nth 2 g) (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)))
(setq found-desired t)))
(set-marker compilation-parsing-end
(if found-desired (point)
(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'."
(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))))))
(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)
(if switches
(if (consp switches)
switches (list switches))
(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)))))
(or (fboundp 'start-process)
(funcall compilation-finish-function nil nil))
buf))))
(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) "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)
(setq fn (file-chase-links (expand-file-name fn)))
(or
(let ((bak (make-backup-file-name fn)))
(if (file-exists-p bak) bak))
(let* ((backupname (car (find-backup-file-name fn)))
(dir (file-name-directory backupname))
(base-versions (concat (file-name-sans-versions
(file-name-nondirectory backupname))
".~"))
(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)