;;; character-fold.el --- match unicode to similar ASCII -*- 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 . ;;; Code: (eval-and-compile (put 'character-fold-table 'char-table-extra-slots 1)) (defconst character-fold-table (eval-when-compile (let ((equiv (make-char-table 'character-fold-table)) (equiv-multi (make-char-table 'character-fold-table)) (table (unicode-property-table-internal 'decomposition))) (set-char-table-extra-slot equiv 0 equiv-multi) ;; Ensure the table is populated. (let ((func (char-table-extra-slot table 1))) (map-char-table (lambda (char v) (when (consp char) (funcall func (car char) v table))) table)) ;; Compile a list of all complex characters that each simple ;; character should match. ;; In summary this loop does 3 things: ;; - A complex character might be allowed to match its decomp. ;; - The decomp is allowed to match the complex character. ;; - A single char of the decomp might be allowed to match the ;; character. ;; Some examples in the comments below. (map-char-table (lambda (char decomp) (when (consp decomp) ;; Skip trivial cases like ?a decomposing to (?a). (unless (and (not (cdr decomp)) (eq char (car decomp))) (if (symbolp (car decomp)) ;; Discard a possible formatting tag. (setq decomp (cdr decomp)) ;; If there's no formatting tag, ensure that char matches ;; its decomp exactly. This is because we want 'ä' to ;; match 'ä', but we don't want '¹' to match '1'. (aset equiv char (cons (apply #'string decomp) (aref equiv char)))) ;; Allow the entire decomp to match char. If decomp has ;; multiple characters, this is done by adding an entry ;; to the alist of the first character in decomp. This ;; allows 'ff' to match 'ff', 'ä' to match 'ä', and '1' to ;; match '¹'. (let ((make-decomp-match-char (lambda (decomp char) (if (cdr decomp) (aset equiv-multi (car decomp) (cons (cons (apply #'string (cdr decomp)) (regexp-quote (string char))) (aref equiv-multi (car decomp)))) (aset equiv (car decomp) (cons (char-to-string char) (aref equiv (car decomp)))))))) (funcall make-decomp-match-char decomp char) ;; Do it again, without the non-spacing characters. ;; This allows 'a' to match 'ä'. (let ((simpler-decomp nil) (found-one nil)) (dolist (c decomp) (if (> (get-char-code-property c 'canonical-combining-class) 0) (setq found-one t) (push c simpler-decomp))) (when (and simpler-decomp found-one) (funcall make-decomp-match-char simpler-decomp char) ;; Finally, if the decomp only had one spacing ;; character, we allow this character to match the ;; decomp. This is to let 'a' match 'ä'. (unless (cdr simpler-decomp) (aset equiv (car simpler-decomp) (cons (apply #'string decomp) (aref equiv (car simpler-decomp))))))))))) table) ;; Add some manual entries. (dolist (it '((?\" "＂" "“" "”" "”" "„" "⹂" "〞" "‟" "‟" "❞" "❝" "❠" "“" "„" "〝" "〟" "🙷" "🙶" "🙸" "«" "»") (?' "❟" "❛" "❜" "‘" "’" "‚" "‛" "‚" "󠀢" "❮" "❯" "‹" "›") (?` "❛" "‘" "‛" "󠀢" "❮" "‹"))) (let ((idx (car it)) (chars (cdr it))) (aset equiv idx (append chars (aref equiv idx))))) ;; Convert the lists of characters we compiled into regexps. (map-char-table (lambda (char dec-list) (let ((re (regexp-opt (cons (char-to-string char) dec-list)))) (if (consp char) (set-char-table-range equiv char re) (aset equiv char re)))) equiv) equiv)) "Used for folding characters of the same group during search. This is a char-table with the `character-fold-table' subtype. Let us refer to the character in question by char-x. Each entry is either nil (meaning char-x only matches literally) or a regexp. This regexp should match anything that char-x can match by itself \(including char-x). For instance, the default regexp for the ?+ character is \"[+⁺₊﬩﹢＋]\". This table also has one extra slot which is also a char-table. Each entry in the extra slot is an alist used for multi-character matching (which may be nil). The elements of the alist should have the form (SUFFIX . OTHER-REGEXP). If the characters after char-x are equal to SUFFIX, then this combination of char-x + SUFFIX is allowed to match OTHER-REGEXP. This is in addition to char-x being allowed to match REGEXP. For instance, the default alist for ?f includes: \((\"fl\" . \"ffl\") (\"fi\" . \"ffi\") (\"i\" . \"fi\") (\"f\" . \"ff\")) Exceptionally for the space character (32), ALIST is ignored.") (defun character-fold--make-space-string (n) "Return a string that matches N spaces." (format "\\(?:%s\\|%s\\)" (make-string n ?\s) (apply #'concat (make-list n (or (aref character-fold-table ?\s) " "))))) ;;;###autoload (defun character-fold-to-regexp (string &optional _lax from) "Return a regexp matching anything that character-folds into STRING. 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. Note that this function can potentially return regexps too long for Emacs to handle. If STRING is longer than 30 characters, consider not using this function. FROM is for internal use. It specifies an index in the STRING from which to start." (let* ((spaces 0) (multi-char-table (char-table-extra-slot character-fold-table 0)) (lower-case-table (current-case-table)) (upper-case-table (char-table-extra-slot lower-case-table 0)) (i (or from 0)) (end (length string)) (out nil)) ;; When the user types a space, we want to match the table entry ;; for ?\s, which is generally a regexp like "[ ...]". However, ;; the `search-spaces-regexp' variable doesn't "see" spaces inside ;; these regexp constructs, so we need to use "\\( \\|[ ...]\\)" ;; instead (to manually expose a space). Furthermore, the lax ;; search engine acts on a bunch of spaces, not on individual ;; spaces, so if the string contains sequential spaces like " ", we ;; need to keep them grouped together like this: "\\( \\|[ ...][ ...]\\)". (while (< i end) (pcase (aref string i) (`?\s (setq spaces (1+ spaces))) (c (when (> spaces 0) (push (character-fold--make-space-string spaces) out) (setq spaces 0)) (let ((regexp (or (aref character-fold-table c) (regexp-quote (string c)))) (alist nil)) ;; Long string. The regexp would probably be too long. (unless (> end 50) (setq alist (aref multi-char-table c)) (when case-fold-search (let ((other-c (aref lower-case-table c))) (when (or (not other-c) (eq other-c c)) (setq other-c (aref upper-case-table c))) (when other-c (setq alist (append alist (aref multi-char-table other-c))) (setq regexp (concat "\\(?:" regexp "\\|" (or (aref character-fold-table other-c) (regexp-quote (string other-c))) "\\)")))))) (push (let ((alist-out '("\\)"))) (pcase-dolist (`(,suffix . ,out-regexp) alist) (let ((len-suf (length suffix))) (when (eq (compare-strings suffix 0 nil string (1+ i) (+ i 1 len-suf) nil) t) ;; FIXME: If N suffixes match, we "branch" ;; out into N+1 executions for the rest of ;; the string. This involves redundant ;; work and makes a huge regexp. (push (concat "\\|" out-regexp (character-fold-to-regexp string nil (+ i 1 len-suf))) alist-out)))) ;; If no suffixes matched, just go on. (if (not (cdr alist-out)) regexp ;; Otherwise, add a branch for the ;; no-suffix case, and stop the loop here. (prog1 (apply #'concat "\\(?:" regexp (character-fold-to-regexp string nil (1+ i)) alist-out) (setq i end)))) out)))) (setq i (1+ i))) (when (> spaces 0) (push (character-fold--make-space-string spaces) out)) (apply #'concat (nreverse out)))) ;;; Commands provided for completeness. (defun character-fold-search-forward (string &optional bound noerror count) "Search forward for a character-folded version of STRING. STRING is converted to a regexp with `character-fold-to-regexp', which is searched for with `re-search-forward'. BOUND NOERROR COUNT are passed to `re-search-forward'." (interactive "sSearch: ") (re-search-forward (character-fold-to-regexp string) bound noerror count)) (defun character-fold-search-backward (string &optional bound noerror count) "Search backward for a character-folded version of STRING. STRING is converted to a regexp with `character-fold-to-regexp', which is searched for with `re-search-backward'. BOUND NOERROR COUNT are passed to `re-search-backward'." (interactive "sSearch: ") (re-search-backward (character-fold-to-regexp string) bound noerror count)) (provide 'character-fold) ;;; character-fold.el ends here