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;;; diffview.el --- View diffs in side-by-side format
;; Copyright (C) 2013-2015, Mitchel Humpherys
;; Author: Mitchel Humpherys <mitch.special@gmail.com>
;; Keywords: convenience, diff
;; Version: 1.0
;; URL: https://github.com/mgalgs/diffview-mode
;; This program 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 3 of the License, or
;; (at your option) any later version.
;; This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Render a unified diff (top/bottom) in an easy-to-comprehend side-by-side
;; format. This comes in handy for reading patches from mailing lists (or
;; from whencever you might acquire them).
;;
;;; Installation:
;;
;; M-x package-install diffview
;;
;;; Usage:
;;
;; The following functions are provided for launching a side-by-side diff:
;;
;; o `diffview-current' : View the current diff buffer side-by-side
;; o `diffview-region' : View the current diff region side-by-side
;; o `diffview-message' : View the current email message (which presumably
;; contains a patch) side-by-side
;;
;;
;;; Screenshots:
;;
;; Before:<br>
;; <img src="https://raw.github.com/mgalgs/diffview-mode/master/screenshots/diffview-before.png"><br>
;; After:<br>
;; <img src="https://raw.github.com/mgalgs/diffview-mode/master/screenshots/diffview-after.png"><br>
;;
;;; Code:
(require 'message)
(defun diffview--print-all-lines-to-buffer (lines buffer-name)
"Prints each line in `LINES' to a buffer named `BUFFER-NAME'."
(let ((old-temp-buffer (get-buffer buffer-name)))
;; (with-output-to-temp-buffer buffer-name
(when old-temp-buffer
(kill-buffer old-temp-buffer))
(with-current-buffer (get-buffer-create buffer-name)
(erase-buffer)
(dolist (line lines)
(insert line "\n")))))
(defvar diffview--minus-bufname "*side-by-side-1*")
(defvar diffview--plus-bufname "*side-by-side-2*")
(defvar diffview--saved-wincfg nil)
(defvar diffview--regexp-is-plus-line "^\\+\\([^+]\\{1\\}\\|$\\)"
"A + followed by one non + or the end of the line.")
(defvar diffview--regexp-is-minus-line "^-\\([^-]\\{1\\}\\|$\\)"
"A - followed by one non - or the end of the line.")
(defun diffview--view-string (input-string)
"Displays `INPUT-STRING' (a diff) in a side-by-side view."
(setq diffview--saved-wincfg (current-window-configuration))
(delete-other-windows)
(let (plus-lines
minus-lines
tmp-line
(current-state 'in-common)
(last-state 'in-common)
(current-lines-in-plus 0)
(current-lines-in-minus 0)
(total-lines 0)
(all-lines (split-string input-string "\n")))
(dolist (line all-lines)
(cond
((string-match diffview--regexp-is-plus-line line)
(push line plus-lines)
(setq current-state 'in-plus)
(setq current-lines-in-plus (1+ current-lines-in-plus)))
((string-match diffview--regexp-is-minus-line line)
(push line minus-lines)
(setq current-state 'in-minus)
(setq current-lines-in-minus (1+ current-lines-in-minus)))
;; everything else must be common
(t
(push line plus-lines)
(push line minus-lines)
(setq current-state 'in-common)))
(setq total-lines (1+ total-lines))
;; Process hunk state transitions
(when (not (equal current-state last-state))
;; there's been a state change
(when (equal current-state 'in-common)
;; we're transitioning out the +/- part of a hunk. We would
;; like both sides to have the same number lines for this
;; hunk, so we might need to fill one side or the other with
;; empty lines.
(cond
((> current-lines-in-plus current-lines-in-minus)
;; need to fill minus
(setq tmp-line (pop minus-lines))
(dotimes (i (- current-lines-in-plus current-lines-in-minus))
(push "" minus-lines))
(push tmp-line minus-lines))
((< current-lines-in-plus current-lines-in-minus)
;; need to fill plus
(setq tmp-line (pop plus-lines))
(dotimes (i (- current-lines-in-minus current-lines-in-plus))
(push "" plus-lines))
(push tmp-line plus-lines)))
(setq current-lines-in-plus 0
current-lines-in-minus 0)))
(setq last-state current-state))
(diffview--print-all-lines-to-buffer (reverse minus-lines) diffview--minus-bufname)
(diffview--print-all-lines-to-buffer (reverse plus-lines) diffview--plus-bufname)
(switch-to-buffer diffview--minus-bufname nil t)
(goto-char (point-min))
(diffview-mode)
(split-window-right)
(other-window 1)
(switch-to-buffer diffview--plus-bufname nil t)
(goto-char (point-min))
(diffview-mode)
(scroll-all-mode)))
;;;###autoload
(defun diffview-current ()
"Show current diff buffer in a side-by-side view."
(interactive)
(diffview--view-string (buffer-string)))
;;;###autoload
(defun diffview-region ()
"Show current diff region in a side-by-side view."
(interactive)
(diffview--view-string (buffer-substring (point) (mark))))
;;;###autoload
(defun diffview-message ()
"Show `message-mode' buffer in a side-by-side view.
This is useful for reading patches from mailing lists."
(interactive)
(let (beg end)
(save-excursion
(message-goto-body)
(search-forward-regexp "^---$")
(setq beg (1+ (point)))
(search-forward-regexp "^-- $")
(setq end (1+ (point)))
(diffview--view-string (buffer-substring beg end)))))
;;; You probably don't want to invoke `diffview-mode' directly. Just use
;;; one of the autoload functions above.
(define-derived-mode diffview-mode special-mode "Diffview"
"Mode for viewing diffs side-by-side"
(setq font-lock-defaults '(diff-font-lock-keywords t nil nil nil (font-lock-multiline . nil))))
(defun diffview--quit ()
"Quit diffview and clean up diffview buffers."
(interactive)
(delete-other-windows)
(scroll-all-mode 0)
(let ((plusbuf (get-buffer diffview--plus-bufname))
(minusbuf (get-buffer diffview--minus-bufname)))
(if plusbuf (kill-buffer plusbuf))
(if minusbuf (kill-buffer minusbuf)))
(set-window-configuration diffview--saved-wincfg))
(define-key diffview-mode-map (kbd "q") 'diffview--quit)
(provide 'diffview)
;;; diffview.el ends here
;;
|
