Add 'packages/diff-hl/' from commit '80abec80ea5c060470a34e2d2ed593f1bb9dc5eb'

[gnu-emacs-elpa] / packages / diff-hl / diff-hl-amend.el

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+;; Copyright (C) 2012-2013  Free Software Foundation, Inc.
+
+;; Author:   Dmitry Gutov <dgutov@yandex.ru>
+;; URL:      https://github.com/dgutov/diff-hl
+
+;; 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Toggle in the current buffer with `M-x diff-hl-amend-mode'.
+;; Toggle in all buffers with `M-x global-diff-hl-amend-mode'.
+
+;;; Code:
+
+(require 'diff-hl)
+
+;;;###autoload
+(define-minor-mode diff-hl-amend-mode
+  "Show changes against the second-last revision in `diff-hl-mode'.
+Most useful with backends that support rewriting local commits,
+and most importantly, 'amending' the most recent one.
+Currently only supports Git, Mercurial and Bazaar."
+  :lighter " Amend"
+  (if diff-hl-amend-mode
+      (progn
+        (diff-hl-amend-setup)
+        (add-hook 'after-revert-hook 'diff-hl-amend-setup nil t))
+    (remove-hook 'after-revert-hook 'diff-hl-amend-setup t)
+    (setq-local diff-hl-reference-revision nil))
+  (when diff-hl-mode
+    (diff-hl-update)))
+
+(defun diff-hl-amend-setup ()
+  (let ((backend (vc-backend buffer-file-name)))
+    (when backend
+      (setq-local diff-hl-reference-revision
+                  (cl-case backend
+                    (Git
+                     "HEAD^")
+                    (Hg
+                     "-2")
+                    (Bzr
+                     "revno:-2"))))))
+
+;;;###autoload
+(define-globalized-minor-mode global-diff-hl-amend-mode diff-hl-amend-mode
+  turn-on-diff-hl-amend-mode)
+
+(defun turn-on-diff-hl-amend-mode ()
+  "Turn on `diff-hl-amend-mode' in a buffer if appropriate."
+  (and buffer-file-name (diff-hl-amend-mode 1)))
+
+(provide 'diff-hl-amend)
+
+;;; diff-hl-amend.el ends here