* lisp/character-fold.el: New file (Bug#20887)

(character-fold-to-regexp): New function.

* lisp/replace.el (replace-search): Check value of
`character-fold-search'.

* lisp/isearch.el: Move character-folding code to
character-fold.el
(isearch-toggle-character-fold): New command.
(isearch-mode-map): Bind it to "\M-sf".
(isearch-mode): Check value of `character-fold-search'.

lisp/character-fold.el

@@ -0,0 +1,109 @@
+;;; chracter-fold.el --- matching unicode characters to their ascii similars -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2015 Free Software Foundation, Inc.
+
+;; Maintainer: emacs-devel@gnu.org
+;; Keywords: matching
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Code:
+
+
+;;;###autoload
+(defvar character-fold-search t
+  "Non-nil if searches should fold similar characters.
+This means some characters will match entire groups of charactes.
+For instance, \" will match all variants of double quotes, and
+the letter a will match all of its accented versions (and then
+some).")
+
+(defconst character-fold-table
+  (eval-when-compile
+    (let ((equiv (make-char-table 'character-fold-table)))
+      ;; Compile a list of all complex characters that each simple
+      ;; character should match.
+      (map-char-table
+       (lambda (i dec)
+         (when (consp dec)
+           ;; Discard a possible formatting tag.
+           (when (symbolp (car dec))
+             (setq dec (cdr dec)))
+           ;; Skip trivial cases lika ?a decomposing to (?a).
+           (unless (or (and (eq i (car dec))
+                            (not  (cdr dec))))
+             (let ((d dec) k found multiletter)
+               (while (and d (not found))
+                 (setq k (pop d))
+                 ;; Is k a number or letter, per unicode standard?
+                 (setq found (memq (get-char-code-property k 'general-category)
+                                   '(Lu Ll Lt Lm Lo Nd Nl No))))
+               (if found
+                   ;; Check if the decomposition has more than one letter,
+                   ;; because then we don't want the first letter to match
+                   ;; the decomposition.
+                   (dolist (k d)
+                     (when (memq (get-char-code-property k 'general-category)
+                                 '(Lu Ll Lt Lm Lo Nd Nl No))
+                       (setq multiletter t)))
+                 ;; If there's no number or letter on the
+                 ;; decomposition, take the first character in it.
+                 (setq found (car-safe dec)))
+               ;; Add i to the list of characters that k can
+               ;; represent. Also possibly add its decomposition, so we can
+               ;; match multi-char representations like (format "a%c" 769)
+               (when (and found (not (eq i k)))
+                 (let ((chars (cons (char-to-string i) (aref equiv k))))
+                   (aset equiv k
+                         (if multiletter chars
+                           (cons (apply #'string dec) chars)))))))))
+       (unicode-property-table-internal 'decomposition))
+      (dolist (it '((?\" "＂" "“" "”" "”" "„" "⹂" "〞" "‟" "‟" "❞" "❝" "❠" "“" "„" "〝" "〟" "🙷" "🙶" "🙸" "«" "»")
+                    (?' "❟" "❛" "❜" "‘" "’" "‚" "‛" "‚" "󠀢" "❮" "❯" "‹" "›")
+                    (?` "❛" "‘" "‛" "󠀢" "❮" "‹")
+                    (?\s "\t" "\r" "\n")))
+        (let ((idx (car it))
+              (chars (cdr it)))
+          (aset equiv idx (append chars (aref equiv idx)))))
+      (map-char-table
+       (lambda (i v) (let ((re (regexp-opt (cons (char-to-string i) v))))
+                  (if (consp i)
+                      (set-char-table-range equiv i re)
+                    (aset equiv i re))))
+       equiv)
+      equiv))
+  "Used for folding characters of the same group during search.")
+
+;;;###autoload
+(defun character-fold-to-regexp (string &optional lax)
+  "Return a regexp matching anything that character-folds into STRING.
+If `character-fold-search' is nil, `regexp-quote' string.
+Otherwise, any character in STRING that has an entry in
+`character-fold-table' is replaced with that entry (which is a
+regexp) and other characters are `regexp-quote'd.
+If LAX is non-nil, any single whitespace character is allowed to
+match any number of times."
+  (if character-fold-search
+      (apply #'concat
+        (mapcar (lambda (c) (let ((out (or (aref character-fold-table c)
+                                      (regexp-quote (string c)))))
+                         (if (and lax (memq c '(?\s ?\t ?\r ?\n )))
+                             (concat out "+")
+                           out)))
+                string))
+    (regexp-quote string)))
+
+;;; chracter-fold.el ends here

lisp/isearch.el

@@ -272,79 +272,6 @@ Default value, nil, means edit the string instead."
   :version "23.1"
   :group 'isearch)
 
-(defvar isearch-character-fold-search t
-  "Non-nil if isearch should fold similar characters.
-This means some characters will match entire groups of charactes.
-For instance, \" will match all variants of double quotes, and
-the letter a will match all of its accented versions (and then
-some).")
-
-(defconst isearch--character-fold-extras
-  '((?\" "＂" "“" "”" "”" "„" "⹂" "〞" "‟" "‟" "❞" "❝" "❠" "“" "„" "〝" "〟" "🙷" "🙶" "🙸" "«" "»")
-    (?' "❟" "❛" "❜" "‘" "’" "‚" "‛" "‚" "󠀢" "❮" "❯" "‹" "›")
-    (?` "❛" "‘" "‛" "󠀢" "❮" "‹")
-    ;; `isearch-character-fold-search' doesn't interact with
-    ;; `isearch-lax-whitespace' yet.  So we need to add this here.
-    (?\s "	" "\r" "\n"))
-  "Extra entries to add to `isearch--character-fold-table'.
-Used to specify character folding not covered by unicode
-decomposition.  Each car is a character and each cdr is a list of
-strings that it should match (itself excluded).")
-
-(defvar isearch--character-fold-table
-  (eval-when-compile
-    (require 'subr-x)
-    (let ((equiv (make-char-table 'character-fold-table)))
-      ;; Compile a list of all complex characters that each simple
-      ;; character should match.
-      (dotimes (i (length equiv))
-        (let ((dd (get-char-code-property i 'decomposition))
-              d k found)
-          ;; Skip trivial cases (?a decomposes to (?a)).
-          (unless (and (eq i (car dd)))
-            ;; Discard a possible formatting tag.
-            (when (symbolp (car-safe dd))
-              (setq dd (cdr dd)))
-            ;; Is k a number or letter, per unicode standard?
-            (setq d dd)
-            (while (and d (not found))
-              (setq k (pop d))
-              (setq found (and (characterp k)
-                               (memq (get-char-code-property k 'general-category)
-                                     '(Lu Ll Lt Lm Lo Nd Nl No)))))
-            ;; If there's no number or letter on the
-            ;; decomposition, find the first character in it.
-            (setq d dd)
-            (while (and d (not found))
-              (setq k (pop d))
-              (setq found (characterp k)))
-            ;; Add i to the list of characters that k can
-            ;; represent. Also add its decomposition, so we can
-            ;; match multi-char representations like (format "a%c" 769)
-            (when (and found (not (eq i k)))
-              (aset equiv k (cons (apply #'string dd)
-                                  (cons (char-to-string i)
-                                        (aref equiv k))))))))
-      (dotimes (i (length equiv))
-        (when-let ((chars (append (cdr (assq i isearch--character-fold-extras))
-                                  (aref equiv i))))
-          (aset equiv i (regexp-opt (cons (char-to-string i) chars)))))
-      equiv))
-  "Used for folding characters of the same group during search.")
-
-(defun isearch--character-folded-regexp (string)
-  "Return a regexp matching anything that character-folds into STRING.
-If `isearch-character-fold-search' is nil, `regexp-quote' string.
-Otherwise, any character in STRING that has an entry in
-`isearch--character-fold-table' is replaced with that entry
-\(which is a regexp) and other characters are `regexp-quote'd."
-  (if isearch-character-fold-search
-      (apply #'concat
-        (mapcar (lambda (c) (or (aref isearch--character-fold-table c)
-                           (regexp-quote (string c))))
-                string))
-    (regexp-quote string)))
-
 (defcustom isearch-lazy-highlight t
   "Controls the lazy-highlighting during incremental search.
 When non-nil, all text in the buffer matching the current search
@@ -592,6 +519,7 @@ This is like `describe-bindings', but displays only Isearch keys."
     (define-key map "\M-sw" 'isearch-toggle-word)
     (define-key map "\M-s_" 'isearch-toggle-symbol)
     (define-key map "\M-s " 'isearch-toggle-lax-whitespace)
+    (define-key map "\M-s'" #'isearch-toggle-character-fold)
 
     (define-key map [?\M-%] 'isearch-query-replace)
     (define-key map [?\C-\M-%] 'isearch-query-replace-regexp)
@@ -907,6 +835,9 @@ See the command `isearch-forward-symbol' for more information."
 ;;			     isearch-forward-regexp isearch-backward-regexp)
 ;;  "List of commands for which isearch-mode does not recursive-edit.")
 
+(autoload 'character-fold-to-regexp "character-fold")
+(put 'character-fold-to-regexp 'isearch-message-prefix "char-fold ")
+(defvar character-fold-search)
 
 (defun isearch-mode (forward &optional regexp op-fun recursive-edit word)
   "Start Isearch minor mode.
@@ -931,7 +862,8 @@ convert the search string to a regexp used by regexp search functions."
   ;; Initialize global vars.
   (setq isearch-forward forward
 	isearch-regexp regexp
-	isearch-word word
+	isearch-word (or word (and character-fold-search
+                                   'character-fold-to-regexp))
 	isearch-op-fun op-fun
 	isearch-last-case-fold-search isearch-case-fold-search
 	isearch-case-fold-search case-fold-search
@@ -1581,6 +1513,15 @@ Use `isearch-exit' to quit without signaling."
   (setq isearch-success t isearch-adjusted t)
   (isearch-update))
 
+(defun isearch-toggle-character-fold ()
+  "Toggle character folding in searching on or off."
+  (interactive)
+  (setq isearch-word (unless (eq isearch-word #'character-fold-to-regexp)
+                       #'character-fold-to-regexp))
+  (if isearch-word (setq isearch-regexp nil))
+  (setq isearch-success t isearch-adjusted t)
+  (isearch-update))
+
 (defun isearch-toggle-lax-whitespace ()
   "Toggle whitespace matching in searching on or off.
 In ordinary search, toggles the value of the variable
@@ -2680,11 +2621,6 @@ Can be changed via `isearch-search-fun-function' for special needs."
       're-search-backward-lax-whitespace))
    (isearch-regexp
     (if isearch-forward 're-search-forward 're-search-backward))
-   (isearch-character-fold-search
-    (lambda (string &optional bound noerror count)
-      (funcall (if isearch-forward #'re-search-forward #'re-search-backward)
-        (isearch--character-folded-regexp string)
-        bound noerror count)))
    ((and isearch-lax-whitespace search-whitespace-regexp)
     (if isearch-forward
 	'search-forward-lax-whitespace

lisp/replace.el

@@ -2012,8 +2012,9 @@ It is called with three arguments, as if it were
   ;; outside of this function because then another I-search
   ;; used after `recursive-edit' might override them.
   (let* ((isearch-regexp regexp-flag)
-	 (isearch-word delimited-flag)
-         (isearch-character-fold-search replace-character-fold)
+	 (isearch-word (or delimited-flag
+                           (and replace-character-fold
+                                #'character-fold-to-regexp)))
 	 (isearch-lax-whitespace
 	  replace-lax-whitespace)
 	 (isearch-regexp-lax-whitespace