bug#6227: Color isearch regexp submatches differently

[Juri Linkov <juri@jurta.org>]

>> I agree, your approach is probably better. But check for more
>> submatches. Maybe upto the value of some variable, say
>> isearch-max-submatch-num.
>
> Good idea.

Maybe something like this:

=== modified file 'lisp/isearch.el'
--- lisp/isearch.el	2010-06-10 14:32:41 +0000
+++ lisp/isearch.el	2010-06-10 20:51:43 +0000
@@ -223,6 +223,15 @@ (defcustom search-highlight t
   :type 'boolean
   :group 'isearch)
 
+(defcustom search-highlight-submatches 0
+  "Highlight regexp subexpressions of the current regexp match.
+An integer means highlight regexp subexpressions up to the
+specified maximal number.
+When 0, do not highlight regexp subexpressions."
+  :type 'integer
+  :version "24.1"
+  :group 'isearch)
+
 (defface isearch
   '((((class color) (min-colors 88) (background light))
      ;; The background must not be too dark, for that means
@@ -2526,6 +2535,23 @@ (defun isearch-unread (&rest char-or-eve
 ;; Highlighting
 
 (defvar isearch-overlay nil)
+(defvar isearch-submatches-overlays nil)
+
+(defface isearch-1
+  '((((class color) (min-colors 88) (background light))
+     :background "magenta2" :foreground "lightskyblue1")
+    (((class color) (min-colors 88) (background dark))
+     :background "palevioletred3" :foreground "brown4"))
+  "Used for displaying the first matching subexpression."
+  :group 'isearch)
+
+(defface isearch-2
+  '((((class color) (min-colors 88) (background light))
+     :background "magenta1" :foreground "lightskyblue1")
+    (((class color) (min-colors 88) (background dark))
+     :background "palevioletred4" :foreground "brown4"))
+  "Used for displaying the second matching subexpression."
+  :group 'isearch)
 
 (defun isearch-highlight (beg end)
   (if search-highlight
@@ -2536,11 +2562,28 @@ (defun isearch-highlight (beg end)
 	(setq isearch-overlay (make-overlay beg end))
 	;; 1001 is higher than lazy's 1000 and ediff's 100+
 	(overlay-put isearch-overlay 'priority 1001)
-	(overlay-put isearch-overlay 'face isearch))))
+	(overlay-put isearch-overlay 'face isearch)))
+  (when (and (integerp search-highlight-submatches)
+	     (> search-highlight-submatches 0)
+	     isearch-regexp)
+    (mapc 'delete-overlay isearch-submatches-overlays)
+    (setq isearch-submatches-overlays nil)
+    (let ((i 0) ov)
+      (while (<= i search-highlight-submatches)
+	(when (match-beginning i)
+	  (setq ov (make-overlay (match-beginning i) (match-end i)))
+	  (overlay-put ov 'face (intern-soft (format "isearch-%d" i)))
+	  (overlay-put ov 'priority 1002)
+	  (push ov isearch-submatches-overlays))
+	(setq i (1+ i))))))
 
 (defun isearch-dehighlight ()
   (when isearch-overlay
-    (delete-overlay isearch-overlay)))
+    (delete-overlay isearch-overlay))
+  (when search-highlight-submatches
+    (mapc 'delete-overlay isearch-submatches-overlays)
+    (setq isearch-submatches-overlays nil)))
+
 \f
 ;; isearch-lazy-highlight feature
 ;; by Bob Glickstein <http://www.zanshin.com/~bobg/>

-- 
Juri Linkov
http://www.jurta.org/emacs/