(perform-replace): When matching regexps, if the next match is

adjacent to this one, record the next match before replacing this one.
This fixes a bug where (replace-regexp "\\ba " "c") replaced "a a a "
with "ca c" instead of "ccc".

diff --git a/lisp/replace.el b/lisp/replace.el
index 99e8921a26c5be79d676693dad5c3fe4280bac77..2f3fb9a6fe62e82a8b6e164fe2ec0af7488d1baa 100644 (file)
--- a/lisp/replace.el
+++ b/lisp/replace.el
@@ -576,8 +576,12 @@ which will run faster and probably do exactly what you want."
        (stack nil)
        (next-rotate-count 0)
        (replace-count 0)
-       (lastrepl nil)                  ;Position after last match considered.
+       (nonempty-match nil)
+
+       ;; Data for the next match.  If a cons, it has the same format as
+       ;; (match-data); otherwise it is t if a match is possible at point.
        (match-again t)
+
        (message
         (if query-flag
             (substitute-command-keys
@@ -597,30 +601,37 @@ which will run faster and probably do exactly what you want."
        ;; Loop finding occurrences that perhaps should be replaced.
        (while (and keep-going
                    (not (eobp))
-                   (funcall search-function search-string nil t)
-                   ;; If the search string matches immediately after
-                   ;; the previous match, but it did not match there
-                   ;; before the replacement was done, ignore the match.
-                   (if (or (eq lastrepl (point))
-                           (and regexp-flag
-                                (eq lastrepl (match-beginning 0))
-                                (not match-again)))
-                       (if (eobp)
-                           nil
-                         ;; Don't replace the null string 
-                         ;; right after end of previous replacement.
-                         (forward-char 1)
-                         (funcall search-function search-string nil t))
-                     t))
-
-         ;; Save the data associated with the real match.
-         ;; For speed, use only integers and reuse the list used last time.
-         (setq real-match-data (match-data t real-match-data))
-
-         ;; Before we make the replacement, decide whether the search string
-         ;; can match again just after this match.
-         (if regexp-flag
-             (setq match-again (looking-at search-string)))
+                   ;; Use the next match if it is already known;
+                   ;; otherwise, search for a match after moving forward
+                   ;; one char if progress is required.
+                   (setq real-match-data
+                         (if (consp match-again)
+                             (progn (goto-char (nth 1 match-again))
+                                    match-again)
+                           (and (or match-again
+                                    (progn
+                                      (forward-char 1)
+                                      (not (eobp))))
+                                (funcall search-function search-string nil t)
+                                ;; For speed, use only integers and
+                                ;; reuse the list used last time.
+                                (match-data t real-match-data)))))
+
+         ;; Record whether the match is nonempty, to avoid an infinite loop
+         ;; repeatedly matching the same empty string.
+         (setq nonempty-match
+               (/= (nth 0 real-match-data) (nth 1 real-match-data)))
+
+         ;; If the match is empty, record that the next one can't be adjacent.
+         ;; Otherwise, if matching a regular expression, do the next
+         ;; match now, since the replacement for this match may
+         ;; affect whether the next match is adjacent to this one.
+         (setq match-again
+               (and nonempty-match
+                    (or (not regexp-flag)
+                        (and (looking-at search-string)
+                             (match-data t)))))
+
          ;; If time for a change, advance to next replacement string.
          (if (and (listp replacements)
                   (= next-rotate-count replace-count))
@@ -714,8 +725,9 @@ which will run faster and probably do exactly what you want."
                       ;; Before we make the replacement,
                       ;; decide whether the search string
                       ;; can match again just after this match.
-                      (if regexp-flag
-                          (setq match-again (looking-at search-string))))
+                      (if (and regexp-flag nonempty-match)
+                          (setq match-again (and (looking-at search-string)
+                                                 (match-data t)))))
                      ((eq def 'delete-and-edit)
                       (delete-region (match-beginning 0) (match-end 0))
                       (store-match-data
@@ -738,8 +750,7 @@ which will run faster and probably do exactly what you want."
              (setq stack
                    (cons (cons (point)
                                (or replaced (match-data t)))
-                         stack))))
-         (setq lastrepl (point)))
+                         stack)))))
       (replace-dehighlight))
     (or unread-command-events
        (message "Replaced %d occurrence%s"