Supplant the "while case ... break ;; esac" idiom

diff --git a/contrib/emacs/vc-git.el b/contrib/emacs/vc-git.el
index 8b6361922fd6e6a2fcd9acb20fd54f5b645b36f0..b8f6be5c0af64dfbe7e136f984404f22aea68130 100644 (file)
--- a/contrib/emacs/vc-git.el
+++ b/contrib/emacs/vc-git.el
@@ -58,8 +58,9 @@
   (with-temp-buffer
     (let* ((dir (file-name-directory file))
            (name (file-relative-name file dir)))
-      (when dir (cd dir))
-      (and (ignore-errors (eq 0 (call-process "git" nil '(t nil) nil "ls-files" "-c" "-z" "--" name)))
+      (and (ignore-errors
+             (when dir (cd dir))
+             (eq 0 (call-process "git" nil '(t nil) nil "ls-files" "-c" "-z" "--" name)))
            (let ((str (buffer-string)))
              (and (> (length str) (length name))
                   (string= (substring str 0 (1+ (length name))) (concat name "\0"))))))))
@@ -80,6 +81,71 @@
         (match-string 2 str)
       str)))
 
+(defun vc-git-symbolic-commit (commit)
+  "Translate COMMIT string into symbolic form.
+Returns nil if not possible."
+  (and commit
+       (with-temp-buffer
+        (and
+         (zerop
+          (call-process "git" nil '(t nil) nil "name-rev"
+                        "--name-only" "--tags"
+                        commit))
+         (goto-char (point-min))
+         (= (forward-line 2) 1)
+         (bolp)
+         (buffer-substring-no-properties (point-min) (1- (point-max)))))))
+
+(defun vc-git-previous-version (file rev)
+  "git-specific version of `vc-previous-version'."
+  (let ((default-directory (file-name-directory (expand-file-name file)))
+       (file (file-name-nondirectory file)))
+    (vc-git-symbolic-commit
+     (with-temp-buffer
+       (and
+       (zerop
+        (call-process "git" nil '(t nil) nil "rev-list"
+                      "-2" rev "--" file))
+       (goto-char (point-max))
+       (bolp)
+       (zerop (forward-line -1))
+       (not (bobp))
+       (buffer-substring-no-properties
+          (point)
+          (1- (point-max))))))))
+
+(defun vc-git-next-version (file rev)
+  "git-specific version of `vc-next-version'."
+  (let* ((default-directory (file-name-directory
+                            (expand-file-name file)))
+       (file (file-name-nondirectory file))
+       (current-rev
+        (with-temp-buffer
+          (and
+           (zerop
+            (call-process "git" nil '(t nil) nil "rev-list"
+                          "-1" rev "--" file))
+           (goto-char (point-max))
+           (bolp)
+           (zerop (forward-line -1))
+           (bobp)
+           (buffer-substring-no-properties
+            (point)
+            (1- (point-max)))))))
+    (and current-rev
+        (vc-git-symbolic-commit
+         (with-temp-buffer
+           (and
+            (zerop
+             (call-process "git" nil '(t nil) nil "rev-list"
+                           "HEAD" "--" file))
+            (goto-char (point-min))
+            (search-forward current-rev nil t)
+            (zerop (forward-line -1))
+            (buffer-substring-no-properties
+             (point)
+             (progn (forward-line 1) (1- (point))))))))))
+
 (defun vc-git-revert (file &optional contents-done)
   "Revert FILE to the version stored in the git repository."
   (if contents-done
@@ -119,7 +185,16 @@
     (vc-git--run-command file "commit" "-m" comment "--only" "--")))
 
 (defun vc-git-checkout (file &optional editable rev destfile)
-  (vc-git--run-command file "checkout" (or rev "HEAD")))
+  (if destfile
+      (let ((fullname (substring
+                       (vc-git--run-command-string file "ls-files" "-z" "--full-name" "--")
+                       0 -1))
+            (coding-system-for-read 'no-conversion)
+            (coding-system-for-write 'no-conversion))
+        (with-temp-file destfile
+          (eq 0 (call-process "git" nil t nil "cat-file" "blob"
+                              (concat (or rev "HEAD") ":" fullname)))))
+    (vc-git--run-command file "checkout" (or rev "HEAD"))))
 
 (defun vc-git-annotate-command (file buf &optional rev)
   ; FIXME: rev is ignored