Nits/Diff command that doesn't req regex

Author: goldsteinn

clang/tools/clang-format/clang-format.el

@@ -146,20 +146,6 @@ is a zero-based file offset, assuming ‘utf-8-unix’ coding."
     (lambda (byte &optional _quality _coding-system)
       (byte-to-position (1+ byte)))))
 
-(defun clang-format--vc-diff-match-diff-line (line)
-  ;; We are matching something like:
-  ;; "@@ -80 +80 @@" or "@@ -80,2 +80,2 @@"
-  ;; Return as "<LineStart>:<LineEnd>"
-  (when (string-match "^@@\s-[0-9,]+\s\\+\\([0-9]+\\)\\(,\\([0-9]+\\)\\)?\s@@$" line)
-    ;; If we have multi-line diff
-    (if (match-string 3 line)
-        (concat (match-string 1 line)
-                ":"
-                (number-to-string
-                 (+ (string-to-number (match-string 1 line))
-                    (string-to-number (match-string 3 line)))))
-      (concat (match-string 1 line) ":" (match-string 1 line)))))
-
 (defun clang-format--vc-diff-get-diff-lines (file-orig file-new)
   "Return all line regions that contain diffs between FILE-ORIG and
 FILE-NEW.  If there is no diff ‘nil’ is returned. Otherwise the
@@ -169,7 +155,7 @@ which can be passed directly to ‘clang-format’."
   (with-temp-buffer
     ;; We could use diff.el:diff-no-select here. The reason we don't
     ;; is diff-no-select requires extra copies on the buffers which
-    ;; induces noticable slowdowns, especially on larger files.
+    ;; induces noticeable slowdowns, especially on larger files.
     (let ((status (call-process
                    diff-command
                    nil
@@ -178,35 +164,32 @@ which can be passed directly to ‘clang-format’."
                    ;; Binary diff has different behaviors that we
                    ;; aren't interested in.
                    "-a"
-                   ;; Get minimal diff (copy diff config for git-clang-format).
-                   "-U0"
+                   ;; Print new lines in file-new formatted as
+                   ;; "--lines=<StartDiff:EndDiff> "
+                   "--changed-group-format=%(N=0?:--lines=%dF:%dM )"
+                   ;; Don't print anything for unchanged lines
+                   "--unchanged-group-format="
                    file-orig
                    file-new))
           (stderr (concat (if (zerop (buffer-size)) "" ": ")
                           (buffer-substring-no-properties
-                           (point-min) (line-end-position))))
-          (diff-lines '()))
+                           (point-min) (line-end-position)))))
       (cond
        ((stringp status)
         (error "(diff killed by signal %s%s)" status stderr))
        ;; Return of 0 indicates no diff.
        ((= status 0) nil)
        ;; Return of 1 indicates found diffs and no error.
        ((= status 1)
-        ;; Iterate through all lines in diff buffer and collect all
-        ;; lines in current buffer that have a diff.
-        (goto-char (point-min))
-        (while (not (eobp))
-          (let ((diff-line (clang-format--vc-diff-match-diff-line
-                            (buffer-substring-no-properties
-                             (line-beginning-position)
-                             (line-end-position)))))
-            (when diff-line
-              ;; Create list line regions with diffs to pass to
-              ;; clang-format.
-              (push (concat "--lines=" diff-line) diff-lines)))
-          (forward-line 1))
-        (reverse diff-lines))
+        ;; We had our diff command printout all diffs as
+        ;; "--lines=S0:E0 --lines=S1:E1 ... --lines=SN:EN " so just
+        ;; split the output into a list to pass to clang-format.
+        (split-string
+         (buffer-substring-no-properties (point-min) (point-max))
+         ;; All whitespace (practically only spaces).
+         "[ \f\t\n\r\v]"
+         ;; Don't create empty entries.
+         t))
        ;; Any return != 0 && != 1 indicates some level of error.
        (t
         (error "(diff returned unsuccessfully %s%s)" status stderr))))))
@@ -235,7 +218,7 @@ supported vc."
         (let ((status (call-process
                        vc-git-program
                        nil
-                       `(:file, tmpfile-vc-head)
+                       `(:file ,tmpfile-vc-head)
                        nil
                        "show" (concat "HEAD:" vc-file-name)))
               (stderr (with-temp-buffer