Use new faces isearch-group-odd and isearch-group-even (bug#43702)

* lisp/isearch.el (isearch-group-odd, isearch-group-even): New faces
instead of isearch-group-1 .. isearch-group-9.
(isearch-highlight): Use new faces.

3 files changed, 20 insertions, 90 deletions

diff --git a/doc/emacs/search.texi b/doc/emacs/search.texi
index d44d7bee2ac..d982a9e8787 100644
--- a/doc/emacs/search.texi
+++ b/doc/emacs/search.texi
@@ -1984,10 +1984,11 @@ the @code{search-highlight-submatches} variable.  If this variable's
 value is @code{nil}, no special highlighting is done, but if the value
 is non-@code{nil}, text that matches @samp{\( @dots{} \)} constructs
 (a.k.a.@: ``subexpressions'') in the regular expression will be
-highlighted with distinct faces, named @code{isearch-group-@var{n}}.
-For instance, when searching for @samp{foo-\([0-9]+\)}, the part
-matched by @samp{[0-9]+} will be highlighted with the
-@code{isearch-group-1} face.
+highlighted with distinct faces, named @code{isearch-group-odd}
+for the odd group matches, and @code{isearch-group-even}
+for the even group matches.  For instance, when searching for
+@samp{foo-\([0-9]+\)}, the part matched by @samp{[0-9]+} will be
+highlighted with the @code{isearch-group-odd} face.
 
 @cindex lazy highlighting customizations
 @vindex isearch-lazy-highlight
diff --git a/etc/NEWS b/etc/NEWS
index 43a99afafa3..3a176f22af4 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1097,8 +1097,9 @@ keystrokes.
 
 +++
 *** Interactive regular expression search now uses faces for sub-groups.
-E.g., 'C-M-s foo-\([0-9]+\)' will now use the 'isearch-group-1' face
+E.g., 'C-M-s foo-\([0-9]+\)' will now use the 'isearch-group-odd' face
 on the part of the regexp that matches the sub-expression "[0-9]+".
+The even group matches are highlighted with the 'isearch-group-even' face.
 This is controlled by the 'search-highlight-submatches' user option.
 This feature is available only on terminals that have enough colors to
 distinguish between sub-expression highlighting.
diff --git a/lisp/isearch.el b/lisp/isearch.el
index 4e964b325cd..781a8c5a93a 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -271,9 +271,8 @@ are `word-search-regexp' \(`\\[isearch-toggle-word]'), `isearch-symbol-regexp'
 
 (defcustom search-highlight-submatches t
   "Whether to highlight regexp subexpressions of the current regexp match.
-
-The faces used to do the highlights are named `isearch-group-1',
-`isearch-group-2', and so on."
+The faces used to do the highlights are named `isearch-group-odd' and
+`isearch-group-even'."
   :type 'boolean
   :version "28.1")
 
@@ -3664,97 +3663,26 @@ since they have special meaning in a regexp."
 (defvar isearch-overlay nil)
 (defvar isearch-submatches-overlays nil)
 
-(defface isearch-group-1
+(defface isearch-group-odd
   '((((class color) (min-colors 88) (background light))
      (:background "#ff00ff" :foreground "lightskyblue1"))
     (((class color) (min-colors 88) (background dark))
      (:background "palevioletred3" :foreground "brown4"))
     (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (first sub-group)."
-  :group 'isearch
-  :version "28.1")
-
-(defface isearch-group-2
-  '((((class color) (min-colors 88) (background light))
-     (:background "#d000d0" :foreground "lightskyblue1"))
-    (((class color) (min-colors 88) (background dark))
-     (:background "#be698f" :foreground "black"))
-    (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (second sub-group)."
-  :group 'isearch
-  :version "28.1")
-
-(defface isearch-group-3
-  '((((class color) (min-colors 88) (background light))
-     (:background "#a000a0" :foreground "lightskyblue1"))
-    (((class color) (min-colors 88) (background dark))
-     (:background "#a06080" :foreground "brown4"))
-    (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (third sub-group)."
+  "Face for highlighting Isearch the odd group matches."
   :group 'isearch
   :version "28.1")
 
-(defface isearch-group-4
+(defface isearch-group-even
   '((((class color) (min-colors 88) (background light))
      (:background "#800080" :foreground "lightskyblue1"))
     (((class color) (min-colors 88) (background dark))
      (:background "#905070" :foreground "brown4"))
     (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (fourth sub-group)."
-  :group 'isearch
-  :version "28.1")
-
-(defface isearch-group-5
-  '((((class color) (min-colors 88) (background light))
-     (:background "#600060" :foreground "lightskyblue1"))
-    (((class color) (min-colors 88) (background dark))
-     (:background "#804060" :foreground "black"))
-    (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (fifth sub-group)."
-  :group 'isearch
-  :version "28.1")
-
-(defface isearch-group-6
-  '((((class color) (min-colors 88) (background light))
-     (:background "#500050" :foreground "lightskyblue1"))
-    (((class color) (min-colors 88) (background dark))
-     (:background "#703050" :foreground "white"))
-    (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (sixth sub-group)."
-  :group 'isearch
-  :version "28.1")
-
-(defface isearch-group-7
-  '((((class color) (min-colors 88) (background light))
-     (:background "#400040" :foreground "lightskyblue1"))
-    (((class color) (min-colors 88) (background dark))
-     (:background "#602050" :foreground "white"))
-    (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (seventh sub-group)."
-  :group 'isearch
-  :version "28.1")
-
-(defface isearch-group-8
-  '((((class color) (min-colors 88) (background light))
-     (:background "#300030" :foreground "lightskyblue1"))
-    (((class color) (min-colors 88) (background dark))
-     (:background "#501050" :foreground "white"))
-    (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (eighth sub-group)."
+  "Face for highlighting Isearch the even group matches."
   :group 'isearch
   :version "28.1")
 
-(defface isearch-group-9
-  '((((class color) (min-colors 88) (background light))
-     (:background "#200020" :foreground "lightskyblue1"))
-    (((class color) (min-colors 88) (background dark))
-     (:background "#400040" :foreground "white"))
-    (t (:inherit isearch)))
-  "Face for highlighting Isearch sub-group matches (ninth sub-group)."
-  :group 'isearch
-  :version "28.1")
-
-
 (defun isearch-highlight (beg end)
   (if search-highlight
       (if isearch-overlay
@@ -3769,14 +3697,14 @@ since they have special meaning in a regexp."
              isearch-regexp)
     (mapc 'delete-overlay isearch-submatches-overlays)
     (setq isearch-submatches-overlays nil)
-    (let ((i 0) ov)
-      (while (<= i 9)
-        (when (match-beginning i)
-          (setq ov (make-overlay (match-beginning i) (match-end i)))
-          (overlay-put ov 'face (intern-soft (format "isearch-group-%d" i)))
+    (dotimes (i (/ (length (match-data)) 2))
+      (unless (zerop i)
+        (let ((ov (make-overlay (match-beginning i) (match-end i))))
+          (overlay-put ov 'face (if (zerop (mod i 2))
+                                    'isearch-group-even
+                                  'isearch-group-odd))
           (overlay-put ov 'priority 1002)
-          (push ov isearch-submatches-overlays))
-        (setq i (1+ i))))))
+          (push ov isearch-submatches-overlays))))))
 
 (defun isearch-dehighlight ()
   (when isearch-overlay