Perform grep-mode's buffer modifications in a process filter (Bug#7952)

* progmodes/grep.el (grep-mode-font-lock-keywords): Remove
buffer-changing entries.
(grep-filter): New function.
(grep-mode): Add it to compilation-filter-hook.

* progmodes/compile.el (compilation-filter-hook)
(compilation-filter-start): New defvars.
(compilation-filter): Call compilation-filter-hook prior to
updating the process mark.

4 files changed, 53 insertions, 26 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 319f5f8c958..9e9778c6ac1 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -377,9 +377,15 @@ $ESHELL nor variable `explicit-shell-file-name' is set.
 
 ** comint and modes derived from it use the generic completion code.
 
-** The compile.el mode can be used without font-lock-mode.
+** Compilation mode
+
+*** Compilation mode can be used without font-lock-mode.
 `compilation-parse-errors-function' is now obsolete.
 
+*** `compilation-filter-start' is let-bound to the start of the text
+inserted by the compilation filter function, when calling
+compilation-filter-hook.
+
 ** The Landmark game is now invoked with `landmark', not `lm'.
 
 ** Prolog mode has been completely revamped, with lots of additional
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d50712503f2..3df4ba354eb 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,15 @@
+2011-05-08  Chong Yidong  <cyd@stupidchicken.com>
+
+        * progmodes/grep.el (grep-mode-font-lock-keywords): Remove
+        buffer-changing entries.
+        (grep-filter): New function.
+        (grep-mode): Add it to compilation-filter-hook.
+
+        * progmodes/compile.el (compilation-filter-hook)
+        (compilation-filter-start): New defvars.
+        (compilation-filter): Call compilation-filter-hook prior to
+        updating the process mark.
+
 2011-05-08  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         * emacs-lisp/eieio.el (defmethod): Fix typo in last change.
diff --git a/lisp/progmodes/compile.el b/lisp/progmodes/compile.el
index ec0830b3b1b..830de7d6244 100644
--- a/lisp/progmodes/compile.el
+++ b/lisp/progmodes/compile.el
@@ -64,6 +64,16 @@ the compilation to be killed, you can use this hook:
                  integer)
   :group 'compilation)
 
+(defvar compilation-filter-hook nil
+  "Hook run after `compilation-filter' has inserted a string into the buffer.
+It is called with the variable `compilation-filter-start' bound
+to the position of the start of the inserted text, and point at
+its end.")
+
+(defvar compilation-filter-start nil
+  "Start of the text inserted by `compilation-filter'.
+This is bound to a buffer position before running `compilation-filter-hook'.")
+
 (defvar compilation-first-column 1
   "*This is how compilers number the first column, usually 1 or 0.")
 
@@ -2038,11 +2048,12 @@ and runs `compilation-filter-hook'."
             ;; If we are inserting at the end of the accessible part of the
             ;; buffer, keep the inserted text visible.
             (min (point-min-marker))
-            (max (copy-marker (point-max) t)))
+            (max (copy-marker (point-max) t))
+            (compilation-filter-start (marker-position (process-mark proc))))
         (unwind-protect
             (progn
               (widen)
-              (goto-char (process-mark proc))
+              (goto-char compilation-filter-start)
               ;; We used to use `insert-before-markers', so that windows with
               ;; point at `process-mark' scroll along with the output, but we
               ;; now use window-point-insertion-type instead.
diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index 58f2ee98f3c..12295efc2d1 100644
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -1,4 +1,4 @@
-;;; grep.el --- run Grep as inferior of Emacs, parse match messages
+;;; grep.el --- run `grep' and display the results
 
 ;; Copyright (C) 1985-1987, 1993-1999, 2001-2011
 ;;   Free Software Foundation, Inc.
@@ -33,7 +33,7 @@
 
 
 (defgroup grep nil
-  "Run grep as inferior of Emacs, parse error messages."
+  "Run `grep' and display the results."
   :group 'tools
   :group 'processes)
 
@@ -399,26 +399,7 @@ Notice that using \\[next-error] or \\[compile-goto-error] modifies
       (0 '(face nil compilation-message nil help-echo nil mouse-face nil) t)
       (1 grep-error-face)
       (2 grep-error-face nil t))
-     ("^.+?-[0-9]+-.*\n" (0 grep-context-face))
-     ;; Highlight grep matches and delete markers.
-     ;; FIXME: Modifying the buffer text from font-lock is a bad idea!
-     ("\\(\033\\[01;31m\\)\\(.*?\\)\\(\033\\[[0-9]*m\\)"
-      ;; Refontification does not work after the markers have been
-      ;; deleted.  So we use the font-lock-face property here as Font
-      ;; Lock does not clear that.
-      (2 (list 'face nil 'font-lock-face grep-match-face))
-      ((lambda (bound))
-       (progn
-         ;; Delete markers with `replace-match' because it updates
-         ;; the match-data, whereas `delete-region' would render it obsolete.
-         (syntax-ppss-flush-cache (match-beginning 0))
-         (replace-match "" t t nil 3)
-         (replace-match "" t t nil 1))))
-     ("\033\\[[0-9;]*[mK]"
-      ;; Delete all remaining escape sequences
-      ((lambda (bound))
-       (syntax-ppss-flush-cache (match-beginning 0))
-       (replace-match "" t t))))
+     ("^.+?-[0-9]+-.*\n" (0 grep-context-face)))
    "Additional things to highlight in grep output.
 This gets tacked on the end of the generated expressions.")
 
@@ -491,6 +472,22 @@ Set up `compilation-exit-message-function' and run `grep-setup-hook'."
            (cons msg code))))
   (run-hooks 'grep-setup-hook))
 
+(defun grep-filter ()
+  "Handle match highlighting escape sequences inserted by the grep process.
+This function is called from `compilation-filter-hook'."
+  (save-excursion
+    (let ((end (point-marker)))
+      ;; Highlight grep matches and delete marking sequences.
+      (goto-char compilation-filter-start)
+      (while (re-search-forward "\033\\[01;31m\\(.*?\\)\033\\[[0-9]*m" end 1)
+        (replace-match (propertize (match-string 1)
+                                   'face nil 'font-lock-face grep-match-face)
+                       t t))
+      ;; Delete all remaining escape sequences
+      (goto-char compilation-filter-start)
+      (while (re-search-forward "\033\\[[0-9;]*[mK]" end 1)
+        (replace-match "" t t)))))
+
 (defun grep-probe (command args &optional func result)
   (let (process-file-side-effects)
     (equal (condition-case nil
@@ -697,7 +694,8 @@ Set up `compilation-exit-message-function' and run `grep-setup-hook'."
        grep-regexp-alist)
   (set (make-local-variable 'compilation-process-setup-function)
        'grep-process-setup)
-  (set (make-local-variable 'compilation-disable-input) t))
+  (set (make-local-variable 'compilation-disable-input) t)
+  (add-hook 'compilation-filter-hook 'grep-filter nil t))
 
 
 ;;;###autoload