From 4fd6ec538e4e1b73645569283ed1431bbf3a3a98 Mon Sep 17 00:00:00 2001
From: Davis Herring <herring@lanl.gov>
Date: Thu, 18 Feb 2016 07:47:45 -0700
Subject: [PATCH 1/6] Clean up context diff header regexps

* lisp/vc/diff-mode.el (diff-hunk-header-re-context): New const.
(diff-hunk-header-re,diff-context->unified,diff-reverse-direction,
diff-sanity-check-hunk): Use it.
(diff-context-mid-hunk-header-re): Add missing ^.
---
 lisp/vc/diff-mode.el |   34 +++++++++++++++++++++++-----------
 1 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 58498cb..10a2734 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -359,8 +359,10 @@ well."
 
 (defconst diff-hunk-header-re-unified
   "^@@ -\\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? \\+\\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? @@")
+(defconst diff-hunk-header-re-context
+  "\\*\\{15\\}\\(?: .*\\)?\n\\*\\*\\* \\(\\([0-9]+\\)\\(?:,\\(-?[0-9]+\\)\\)?\\) \\*\\*\\*\\*")
 (defconst diff-context-mid-hunk-header-re
-  "--- \\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? ----$")
+  "^--- \\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? ----$")
 
 (defvar diff-use-changed-face (and (face-differs-from-default-p 'diff-changed)
 				   (not (face-equal 'diff-changed 'diff-added))
@@ -435,7 +437,9 @@ empty lines.  This makes the format less robust, but is tolerated.
 See http://lists.gnu.org/archive/html/emacs-devel/2007-11/msg01990.html")
 
 (defconst diff-hunk-header-re
-  (concat "^\\(?:" diff-hunk-header-re-unified ".*\\|\\*\\{15\\}.*\n\\*\\*\\* .+ \\*\\*\\*\\*\\|[0-9]+\\(,[0-9]+\\)?[acd][0-9]+\\(,[0-9]+\\)?\\)$"))
+  (concat "^\\(?:" diff-hunk-header-re-unified ".*\\|"
+          diff-hunk-header-re-context
+          "\\|[0-9]+\\(,[0-9]+\\)?[acd][0-9]+\\(,[0-9]+\\)?\\)$"))
 (defconst diff-file-header-re (concat "^\\(--- .+\n\\+\\+\\+ \\|\\*\\*\\* .+\n--- \\|[^-+!<>0-9@* \n]\\).+\n" (substring diff-hunk-header-re 1)))
 (defvar diff-narrowed-to nil)
 
@@ -1028,7 +1032,11 @@ With a prefix argument, convert unified format to context format."
           (inhibit-read-only t))
       (save-excursion
         (goto-char start)
-        (while (and (re-search-forward "^\\(\\(\\*\\*\\*\\) .+\n\\(---\\) .+\\|\\*\\{15\\}.*\n\\*\\*\\* \\([0-9]+\\),\\(-?[0-9]+\\) \\*\\*\\*\\*\\)\\(?: \\(.*\\)\\|$\\)" nil t)
+        (while (and (re-search-forward
+                     (concat "^\\(\\(\\*\\*\\*\\) .+\n\\(---\\) .+\\|"
+                             diff-hunk-header-re-context
+                             "\\)\\(?: \\(.*\\)\\|$\\)")
+                     nil t)
                     (< (point) end))
           (combine-after-change-calls
             (if (match-beginning 2)
@@ -1038,15 +1046,15 @@ With a prefix argument, convert unified format to context format."
                   (replace-match "+++" t t nil 3)
                   (replace-match "---" t t nil 2))
               ;; we matched a hunk header
-              (let ((line1s (match-string 4))
-                    (line1e (match-string 5))
+              (let ((line1s (match-string 5))
+                    (line1e (match-string 6))
                     (pt1 (match-beginning 0))
                     ;; Variables to use the special undo function.
                     (old-undo buffer-undo-list)
                     (old-end (marker-position end))
                     ;; We currently throw away the comment that can follow
                     ;; the hunk header.  FIXME: Preserve it instead!
-                    (reversible (not (match-end 6))))
+                    (reversible (not (match-end 7))))
                 (replace-match "")
                 (unless (re-search-forward
                          diff-context-mid-hunk-header-re nil t)
@@ -1124,7 +1132,11 @@ else cover the whole buffer."
 	(inhibit-read-only t))
     (save-excursion
       (goto-char start)
-      (while (and (re-search-forward "^\\(\\([-*][-*][-*] \\)\\(.+\\)\n\\([-+][-+][-+] \\)\\(.+\\)\\|\\*\\{15\\}.*\n\\*\\*\\* \\(.+\\) \\*\\*\\*\\*\\|@@ -\\([0-9,]+\\) \\+\\([0-9,]+\\) @@.*\\)$" nil t)
+      (while (and (re-search-forward
+                   (concat "^\\(\\([-*][-*][-*] \\)\\(.+\\)\n\\([-+][-+][-+] \\)\\(.+\\)\\|"
+                           diff-hunk-header-re-context
+                           "\\|@@ -\\([0-9,]+\\) \\+\\([0-9,]+\\) @@.*\\)$")
+                   nil t)
 		  (< (point) end))
 	(combine-after-change-calls
 	  (cond
@@ -1477,13 +1489,13 @@ Only works for unified diffs."
 
        ;; A context diff.
        ((eq (char-after) ?*)
-        (if (not (looking-at "\\*\\{15\\}\\(?: .*\\)?\n\\*\\*\\* \\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? \\*\\*\\*\\*"))
+        (if (not (looking-at diff-hunk-header-re-context))
             (error "Unrecognized context diff first hunk header format")
           (forward-line 2)
           (diff-sanity-check-context-hunk-half
-	   (if (match-end 2)
-	       (1+ (- (string-to-number (match-string 2))
-		      (string-to-number (match-string 1))))
+           (if (match-end 3)
+               (1+ (- (string-to-number (match-string 3))
+                      (string-to-number (match-string 2))))
 	     1))
           (if (not (looking-at diff-context-mid-hunk-header-re))
               (error "Unrecognized context diff second hunk header format")
-- 
1.7.1