Restore the point in grep buffers when traversing the history

* lisp/progmodes/grep.el (grep-process-setup): Allow moving
point to a specific place after finishing the grep command.
(grep-mode): Use it to restore point after traversing the history.
(grep--history-point): New internal variable.
(grep--save-history, grep-forward-history): Use it to restore
the point.

diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index 7ce787e72848228a6f928b807cdf129f540b25fa..fd55576e13513458d3957c5e1aceb749f144299a 100644 (file)
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -472,9 +472,12 @@ This variable's value takes effect when `grep-compute-defaults' is called.")
 (defvar grep-files-history nil)
 
 ;;;###autoload
-(defun grep-process-setup ()
+(defun grep-process-setup (&optional point)
   "Setup compilation variables and buffer for `grep'.
-Set up `compilation-exit-message-function' and run `grep-setup-hook'."
+Set up `compilation-exit-message-function' and run
+`grep-setup-hook'.  If the optional parameter POINT is given,
+point will be moved to this vicinity when the grep command has
+finished."
   (when (eq grep-highlight-matches 'auto-detect)
     (grep-compute-defaults))
   (unless (or (eq grep-highlight-matches 'auto-detect)
@@ -495,12 +498,14 @@ Set up `compilation-exit-message-function' and run `grep-setup-hook'."
             ;; This relies on the fact that `compilation-start'
             ;; sets buffer-modified to nil before running the command,
             ;; so the buffer is still unmodified if there is no output.
-            (cond ((and (zerop code) (buffer-modified-p))
-                   '("finished (matches found)\n" . "matched"))
-                  ((not (buffer-modified-p))
-                   '("finished with no matches found\n" . "no match"))
-                  (t
-                   (cons msg code)))
+             (progn
+               (goto-char (min point (point-max)))
+               (cond ((and (zerop code) (buffer-modified-p))
+                      '("finished (matches found)\n" . "matched"))
+                     ((not (buffer-modified-p))
+                      '("finished with no matches found\n" . "no match"))
+                     (t
+                      (cons msg code))))
           (cons msg code))))
   (run-hooks 'grep-setup-hook))
 
@@ -732,6 +737,10 @@ This function is called from `compilation-filter-hook'."
       ;; Now replace the pattern with the default tag.
       (replace-match tag-default t t grep-default 1))))
 
+(defvar grep--command-history nil)
+(defvar grep--history-inhibit nil)
+(defvar grep--history-place 0)
+(defvar grep--history-point 0)
 
 ;;;###autoload
 (define-compilation-mode grep-mode "Grep"
@@ -746,19 +755,19 @@ This function is called from `compilation-filter-hook'."
   ;; can never match.
   (set (make-local-variable 'compilation-directory-matcher) '("\\`a\\`"))
   (set (make-local-variable 'compilation-process-setup-function)
-       'grep-process-setup)
+       (lambda ()
+         (grep-process-setup grep--history-point)))
   (set (make-local-variable 'compilation-disable-input) t)
   (set (make-local-variable 'compilation-error-screen-columns)
        grep-error-screen-columns)
   (add-hook 'compilation-filter-hook 'grep-filter nil t))
 
-(defvar grep--command-history nil)
-(defvar grep--history-inhibit nil)
-(defvar grep--history-place 0)
-
 (defun grep--save-history (command)
   (unless grep--history-inhibit
-    (push (cons default-directory command) grep--command-history)
+    (when grep--command-history
+      (setcar (cdr (car grep--command-history)) (point)))
+    (push (list default-directory 0 command)
+          grep--command-history)
     (setq grep--history-place 0)
     ;; Don't let the history grow without bounds.
     (when (> (length grep--command-history) 100)
@@ -773,9 +782,11 @@ Also see `grep-backward-history'."
         (grep--history-inhibit t))
     (unless elem
       (error "Nothing further in the command history"))
+    (setcar (cdr (nth grep--history-place grep--command-history)) (point))
     (cl-decf grep--history-place)
-    (let ((default-directory (car elem)))
-      (grep (cdr elem)))))
+    (let ((default-directory (car elem))
+          (grep--history-point (nth 1 elem)))
+      (grep (nth 2 elem)))))
 
 (defun grep-backward-history ()
   "Go to the previous result in the grep command history.
@@ -785,9 +796,11 @@ Also see `grep-forward-history'."
         (grep--history-inhibit t))
     (unless elem
       (error "Nothing further in the command history"))
+    (setcar (cdr (nth grep--history-place grep--command-history)) (point))
     (cl-incf grep--history-place)
-    (let ((default-directory (car elem)))
-      (grep (cdr elem)))))
+    (let ((default-directory (car elem))
+          (grep--history-point (nth 1 elem)))
+      (grep (nth 2 elem)))))
 
 (defun grep--save-buffers ()
   (when grep-save-buffers