bug#29360: 26.0; Add full-buffer choice for `isearch-lazy-highlight'

[Juri Linkov <juri@linkov.net>]

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> In any case, yes, your suggestion of first doing what we do now
> (highlight the immediate area, using the current algorith), and
> then following that with highlighting the rest of the buffer,
> could be a good idea. Dunno how much that might change
> the existing code.

In the patch attached below, a new function isearch-lazy-highlight-buffer-update
is a copy of isearch-lazy-highlight-update with some changes specific
to highlighting the full buffer.  It seems making a duplicate function
is necessary because adding more full-buffer specific conditions to
the existing function isearch-lazy-highlight-update will make it
unmaintainable.

Only a part of the function (that highlights the match) is extracted
into a new function isearch-lazy-highlight-match and shared among these
aforementioned two functions.


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[-- Attachment #2: isearch-lazy-highlight-buffer.1.patch --]
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diff --git a/lisp/isearch.el b/lisp/isearch.el
index 1e785a44c5..cb9e72526b 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -304,7 +304,7 @@ isearch-fail
 
 (defcustom isearch-lazy-highlight t
   "Controls the lazy-highlighting during incremental search.
-When non-nil, all text in the buffer matching the current search
+When non-nil, all text on the screen matching the current search
 string is highlighted lazily (see `lazy-highlight-initial-delay'
 and `lazy-highlight-interval').
 
@@ -316,6 +316,15 @@ isearch-lazy-highlight
   :group 'lazy-highlight
   :group 'isearch)
 
+(defcustom isearch-lazy-highlight-buffer nil
+  "Controls the lazy-highlighting of the whole buffer.
+When non-nil, all text in the buffer matching the current search
+string is highlighted lazily (see `lazy-highlight-initial-delay',
+`lazy-highlight-interval' and `lazy-highlight-buffer-max-at-a-time')."
+  :type 'boolean
+  :group 'lazy-highlight
+  :group 'isearch)
+
 ;;; Lazy highlight customization.
 
 (defgroup lazy-highlight nil
@@ -351,6 +360,15 @@ lazy-highlight-max-at-a-time
 		 (integer :tag "Some"))
   :group 'lazy-highlight)
 
+(defcustom lazy-highlight-buffer-max-at-a-time 20
+  "Maximum matches to highlight at a time (for `isearch-lazy-highlight-buffer').
+Larger values may reduce Isearch's responsiveness to user input;
+smaller values make matches highlight slowly.
+A value of nil means highlight all matches shown in the buffer."
+  :type '(choice (const :tag "All" nil)
+		 (integer :tag "Some"))
+  :group 'lazy-highlight)
+
 (defface lazy-highlight
   '((((class color) (min-colors 88) (background light))
      (:background "paleturquoise"))
@@ -3290,13 +3308,13 @@ isearch-lazy-highlight-search
 				(+ isearch-lazy-highlight-start
 				   ;; Extend bound to match whole string at point
 				   (1- (length isearch-lazy-highlight-last-string)))
-			      (window-group-end)))
+			      (if isearch-lazy-highlight-buffer (point-max) (window-group-end))))
 		     (max (or isearch-lazy-highlight-start-limit (point-min))
 			  (if isearch-lazy-highlight-wrapped
 			      (- isearch-lazy-highlight-end
 				 ;; Extend bound to match whole string at point
 				 (1- (length isearch-lazy-highlight-last-string)))
-			    (window-group-start))))))
+			    (if isearch-lazy-highlight-buffer (point-min) (window-group-start)))))))
 	;; Use a loop like in `isearch-search'.
 	(while retry
 	  (setq success (isearch-search-string
@@ -3317,6 +3335,20 @@ isearch-lazy-highlight-start
   (lazy-highlight-cleanup t) ;remove old overlays
   (isearch-lazy-highlight-update))
 
+(defvar isearch-lazy-highlight-match-function #'isearch-lazy-highlight-match
+  "Function that highlights the found match.
+The function accepts two arguments: the beginning and the end of the match.")
+
+(defun isearch-lazy-highlight-match (mb me)
+  (let ((ov (make-overlay mb me)))
+    (push ov isearch-lazy-highlight-overlays)
+    ;; 1000 is higher than ediff's 100+,
+    ;; but lower than isearch main overlay's 1001
+    (overlay-put ov 'priority 1000)
+    (overlay-put ov 'face 'lazy-highlight)
+    (unless (eq isearch-lazy-highlight 'all-windows)
+      (overlay-put ov 'window (selected-window)))))
+
 (defun isearch-lazy-highlight-update ()
   "Update highlighting of other matches for current search."
   (let ((max lazy-highlight-max-at-a-time)
@@ -3353,16 +3385,8 @@ isearch-lazy-highlight-update
 					(window-group-start)))
 				(setq found nil)
 			      (forward-char -1)))
-
 			;; non-zero-length match
-			(let ((ov (make-overlay mb me)))
-			  (push ov isearch-lazy-highlight-overlays)
-			  ;; 1000 is higher than ediff's 100+,
-			  ;; but lower than isearch main overlay's 1001
-			  (overlay-put ov 'priority 1000)
-			  (overlay-put ov 'face 'lazy-highlight)
-			  (unless (eq isearch-lazy-highlight 'all-windows)
-                            (overlay-put ov 'window (selected-window)))))
+			(funcall isearch-lazy-highlight-match-function mb me))
 		      ;; Remember the current position of point for
 		      ;; the next call of `isearch-lazy-highlight-update'
 		      ;; when `lazy-highlight-max-at-a-time' is too small.
@@ -3384,11 +3408,75 @@ isearch-lazy-highlight-update
 			(setq isearch-lazy-highlight-start (window-group-end))
 			(goto-char (min (or isearch-lazy-highlight-end-limit (point-max))
 					(window-group-end))))))))
-	    (unless nomore
+	    (if nomore
+                (when isearch-lazy-highlight-buffer
+                  (setq isearch-lazy-highlight-start (window-group-start))
+                  (setq isearch-lazy-highlight-end (window-group-end))
+                  (setq isearch-lazy-highlight-wrapped nil)
+                  (run-at-time lazy-highlight-interval nil
+			       'isearch-lazy-highlight-buffer-update))
 	      (setq isearch-lazy-highlight-timer
 		    (run-at-time lazy-highlight-interval nil
 				 'isearch-lazy-highlight-update)))))))))
 
+(defun isearch-lazy-highlight-buffer-update ()
+  "Update highlighting of other matches in the whole buffer."
+  (let ((max lazy-highlight-buffer-max-at-a-time)
+        (looping t)
+        nomore)
+    (with-local-quit
+      (save-excursion
+	(save-match-data
+	  (goto-char (if isearch-lazy-highlight-forward
+			 isearch-lazy-highlight-end
+		       isearch-lazy-highlight-start))
+	  (while looping
+	    (let ((found (isearch-lazy-highlight-search)))
+	      (when max
+		(setq max (1- max))
+		(if (<= max 0)
+		    (setq looping nil)))
+	      (if found
+		  (let ((mb (match-beginning 0))
+			(me (match-end 0)))
+		    (if (= mb me)	;zero-length match
+			(if isearch-lazy-highlight-forward
+			    (if (= mb (if isearch-lazy-highlight-wrapped
+					  (window-group-start)
+				        (point-max)))
+				(setq found nil)
+			      (forward-char 1))
+			  (if (= mb (if isearch-lazy-highlight-wrapped
+					(window-group-end)
+				      (point-min)))
+			      (setq found nil)
+			    (forward-char -1)))
+		      ;; non-zero-length match
+		      (funcall isearch-lazy-highlight-match-function mb me))
+		    ;; Remember the current position of point for
+		    ;; the next call of `isearch-lazy-highlight-update'
+		    ;; when `lazy-highlight-max-at-a-time' is too small.
+		    (if isearch-lazy-highlight-forward
+			(setq isearch-lazy-highlight-end (point))
+		      (setq isearch-lazy-highlight-start (point)))))
+	      ;; not found or zero-length match at the search bound
+	      (if (not found)
+		  (if isearch-lazy-highlight-wrapped
+		      (setq looping nil
+			    nomore  t)
+		    (setq isearch-lazy-highlight-wrapped t)
+		    (if isearch-lazy-highlight-forward
+			(progn
+			  (setq isearch-lazy-highlight-end (point-min))
+			  (goto-char (point-min)))
+		      (setq isearch-lazy-highlight-start (point-max))
+		      (goto-char (point-max)))))))
+	  (if nomore
+              (message "Finished lazy-highlighting the buffer")
+	    (setq isearch-lazy-highlight-timer
+		  (run-at-time lazy-highlight-interval nil
+			       'isearch-lazy-highlight-buffer-update))))))))
+
 (defun isearch-resume (string regexp word forward message case-fold)
   "Resume an incremental search.
 STRING is the string or regexp searched for.