mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-12-25 10:47:00 +00:00
22864a4875
(regexp-opt-not-groupie*-re): Remove. (regexp-opt): Properly handle inputs with duplicate entries.
290 lines
11 KiB
EmacsLisp
290 lines
11 KiB
EmacsLisp
;;; regexp-opt.el --- generate efficient regexps to match strings
|
||
|
||
;; Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2004
|
||
;; Free Software Foundation, Inc.
|
||
|
||
;; Author: Simon Marshall <simon@gnu.org>
|
||
;; Maintainer: FSF
|
||
;; Keywords: strings, regexps, extensions
|
||
|
||
;; 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 2, 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; see the file COPYING. If not, write to the
|
||
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
||
;; Boston, MA 02111-1307, USA.
|
||
|
||
;;; Commentary:
|
||
|
||
;; The "opt" in "regexp-opt" stands for "optim\\(al\\|i[sz]e\\)".
|
||
;;
|
||
;; This package generates a regexp from a given list of strings (which matches
|
||
;; one of those strings) so that the regexp generated by:
|
||
;;
|
||
;; (regexp-opt strings)
|
||
;;
|
||
;; is equivalent to, but more efficient than, the regexp generated by:
|
||
;;
|
||
;; (mapconcat 'regexp-quote strings "\\|")
|
||
;;
|
||
;; For example:
|
||
;;
|
||
;; (let ((strings '("cond" "if" "when" "unless" "while"
|
||
;; "let" "let*" "progn" "prog1" "prog2"
|
||
;; "save-restriction" "save-excursion" "save-window-excursion"
|
||
;; "save-current-buffer" "save-match-data"
|
||
;; "catch" "throw" "unwind-protect" "condition-case")))
|
||
;; (concat "(" (regexp-opt strings t) "\\>"))
|
||
;; => "(\\(c\\(atch\\|ond\\(ition-case\\)?\\)\\|if\\|let\\*?\\|prog[12n]\\|save-\\(current-buffer\\|excursion\\|match-data\\|restriction\\|window-excursion\\)\\|throw\\|un\\(less\\|wind-protect\\)\\|wh\\(en\\|ile\\)\\)\\>"
|
||
;;
|
||
;; Searching using the above example `regexp-opt' regexp takes approximately
|
||
;; two-thirds of the time taken using the equivalent `mapconcat' regexp.
|
||
|
||
;; Since this package was written to produce efficient regexps, not regexps
|
||
;; efficiently, it is probably not a good idea to in-line too many calls in
|
||
;; your code, unless you use the following trick with `eval-when-compile':
|
||
;;
|
||
;; (defvar definition-regexp
|
||
;; (eval-when-compile
|
||
;; (concat "^("
|
||
;; (regexp-opt '("defun" "defsubst" "defmacro" "defalias"
|
||
;; "defvar" "defconst") t)
|
||
;; "\\>")))
|
||
;;
|
||
;; The `byte-compile' code will be as if you had defined the variable thus:
|
||
;;
|
||
;; (defvar definition-regexp
|
||
;; "^(\\(def\\(alias\\|const\\|macro\\|subst\\|un\\|var\\)\\)\\>")
|
||
;;
|
||
;; Note that if you use this trick for all instances of `regexp-opt' and
|
||
;; `regexp-opt-depth' in your code, regexp-opt.el would only have to be loaded
|
||
;; at compile time. But note also that using this trick means that should
|
||
;; regexp-opt.el be changed, perhaps to fix a bug or to add a feature to
|
||
;; improve the efficiency of `regexp-opt' regexps, you would have to recompile
|
||
;; your code for such changes to have effect in your code.
|
||
|
||
;; Originally written for font-lock.el, from an idea from Stig's hl319.el, with
|
||
;; thanks for ideas also to Michael Ernst, Bob Glickstein, Dan Nicolaescu and
|
||
;; Stefan Monnier.
|
||
;; No doubt `regexp-opt' doesn't always produce optimal regexps, so code, ideas
|
||
;; or any other information to improve things are welcome.
|
||
;;
|
||
;; One possible improvement would be to compile '("aa" "ab" "ba" "bb")
|
||
;; into "[ab][ab]" rather than "a[ab]\\|b[ab]". I'm not sure it's worth
|
||
;; it but if someone knows how to do it without going through too many
|
||
;; contortions, I'm all ears.
|
||
|
||
;;; Code:
|
||
|
||
;;;###autoload
|
||
(defun regexp-opt (strings &optional paren)
|
||
"Return a regexp to match a string in STRINGS.
|
||
Each string should be unique in STRINGS and should not contain any regexps,
|
||
quoted or not. If optional PAREN is non-nil, ensure that the returned regexp
|
||
is enclosed by at least one regexp grouping construct.
|
||
The returned regexp is typically more efficient than the equivalent regexp:
|
||
|
||
(let ((open (if PAREN \"\\\\(\" \"\")) (close (if PAREN \"\\\\)\" \"\")))
|
||
(concat open (mapconcat 'regexp-quote STRINGS \"\\\\|\") close))
|
||
|
||
If PAREN is `words', then the resulting regexp is additionally surrounded
|
||
by \\=\\< and \\>."
|
||
(save-match-data
|
||
;; Recurse on the sorted list.
|
||
(let* ((max-lisp-eval-depth (* 1024 1024))
|
||
(max-specpdl-size (* 1024 1024))
|
||
(completion-ignore-case nil)
|
||
(completion-regexp-list nil)
|
||
(words (eq paren 'words))
|
||
(open (cond ((stringp paren) paren) (paren "\\(")))
|
||
(sorted-strings (delete-dups
|
||
(sort (copy-sequence strings) 'string-lessp)))
|
||
(re (regexp-opt-group sorted-strings open)))
|
||
(if words (concat "\\<" re "\\>") re))))
|
||
|
||
;;;###autoload
|
||
(defun regexp-opt-depth (regexp)
|
||
"Return the depth of REGEXP.
|
||
This means the number of non-shy regexp grouping constructs
|
||
\(parenthesised expressions) in REGEXP."
|
||
(save-match-data
|
||
;; Hack to signal an error if REGEXP does not have balanced parentheses.
|
||
(string-match regexp "")
|
||
;; Count the number of open parentheses in REGEXP.
|
||
(let ((count 0) start last)
|
||
(while (string-match "\\\\(\\(\\?:\\)?" regexp start)
|
||
(setq start (match-end 0)) ; Start of next search.
|
||
(when (and (not (match-beginning 1))
|
||
(subregexp-context-p regexp (match-beginning 0) last))
|
||
;; It's not a shy group and it's not inside brackets or after
|
||
;; a backslash: it's really a group-open marker.
|
||
(setq last start) ; Speed up next regexp-opt-re-context-p.
|
||
(setq count (1+ count))))
|
||
count)))
|
||
|
||
;;; Workhorse functions.
|
||
|
||
(eval-when-compile
|
||
(require 'cl))
|
||
|
||
(defun regexp-opt-group (strings &optional paren lax)
|
||
;; Return a regexp to match a string in the sorted list STRINGS.
|
||
;; If PAREN non-nil, output regexp parentheses around returned regexp.
|
||
;; If LAX non-nil, don't output parentheses if it doesn't require them.
|
||
;; Merges keywords to avoid backtracking in Emacs' regexp matcher.
|
||
|
||
;; The basic idea is to find the shortest common prefix or suffix, remove it
|
||
;; and recurse. If there is no prefix, we divide the list into two so that
|
||
;; \(at least) one half will have at least a one-character common prefix.
|
||
|
||
;; Also we delay the addition of grouping parenthesis as long as possible
|
||
;; until we're sure we need them, and try to remove one-character sequences
|
||
;; so we can use character sets rather than grouping parenthesis.
|
||
(let* ((open-group (cond ((stringp paren) paren) (paren "\\(?:") (t "")))
|
||
(close-group (if paren "\\)" ""))
|
||
(open-charset (if lax "" open-group))
|
||
(close-charset (if lax "" close-group)))
|
||
(cond
|
||
;;
|
||
;; If there are no strings, just return the empty string.
|
||
((= (length strings) 0)
|
||
"")
|
||
;;
|
||
;; If there is only one string, just return it.
|
||
((= (length strings) 1)
|
||
(if (= (length (car strings)) 1)
|
||
(concat open-charset (regexp-quote (car strings)) close-charset)
|
||
(concat open-group (regexp-quote (car strings)) close-group)))
|
||
;;
|
||
;; If there is an empty string, remove it and recurse on the rest.
|
||
((= (length (car strings)) 0)
|
||
(concat open-charset
|
||
(regexp-opt-group (cdr strings) t t) "?"
|
||
close-charset))
|
||
;;
|
||
;; If there are several one-char strings, use charsets
|
||
((and (= (length (car strings)) 1)
|
||
(let ((strs (cdr strings)))
|
||
(while (and strs (/= (length (car strs)) 1))
|
||
(pop strs))
|
||
strs))
|
||
(let (letters rest)
|
||
;; Collect one-char strings
|
||
(dolist (s strings)
|
||
(if (= (length s) 1) (push (string-to-char s) letters) (push s rest)))
|
||
|
||
(if rest
|
||
;; several one-char strings: take them and recurse
|
||
;; on the rest (first so as to match the longest).
|
||
(concat open-group
|
||
(regexp-opt-group (nreverse rest))
|
||
"\\|" (regexp-opt-charset letters)
|
||
close-group)
|
||
;; all are one-char strings: just return a character set.
|
||
(concat open-charset
|
||
(regexp-opt-charset letters)
|
||
close-charset))))
|
||
;;
|
||
;; We have a list of different length strings.
|
||
(t
|
||
(let ((prefix (try-completion "" strings)))
|
||
(if (> (length prefix) 0)
|
||
;; common prefix: take it and recurse on the suffixes.
|
||
(let* ((n (length prefix))
|
||
(suffixes (mapcar (lambda (s) (substring s n)) strings)))
|
||
(concat open-group
|
||
(regexp-quote prefix)
|
||
(regexp-opt-group suffixes t t)
|
||
close-group))
|
||
|
||
(let* ((sgnirts (mapcar (lambda (s)
|
||
(concat (nreverse (string-to-list s))))
|
||
strings))
|
||
(xiffus (try-completion "" sgnirts)))
|
||
(if (> (length xiffus) 0)
|
||
;; common suffix: take it and recurse on the prefixes.
|
||
(let* ((n (- (length xiffus)))
|
||
(prefixes
|
||
;; Sorting is necessary in cases such as ("ad" "d").
|
||
(sort (mapcar (lambda (s) (substring s 0 n)) strings)
|
||
'string-lessp)))
|
||
(concat open-group
|
||
(regexp-opt-group prefixes t t)
|
||
(regexp-quote
|
||
(concat (nreverse (string-to-list xiffus))))
|
||
close-group))
|
||
|
||
;; Otherwise, divide the list into those that start with a
|
||
;; particular letter and those that do not, and recurse on them.
|
||
(let* ((char (char-to-string (string-to-char (car strings))))
|
||
(half1 (all-completions char strings))
|
||
(half2 (nthcdr (length half1) strings)))
|
||
(concat open-group
|
||
(regexp-opt-group half1)
|
||
"\\|" (regexp-opt-group half2)
|
||
close-group))))))))))
|
||
|
||
|
||
(defun regexp-opt-charset (chars)
|
||
;;
|
||
;; Return a regexp to match a character in CHARS.
|
||
;;
|
||
;; The basic idea is to find character ranges. Also we take care in the
|
||
;; position of character set meta characters in the character set regexp.
|
||
;;
|
||
(let* ((charmap (make-char-table 'case-table))
|
||
(start -1) (end -2)
|
||
(charset "")
|
||
(bracket "") (dash "") (caret ""))
|
||
;;
|
||
;; Make a character map but extract character set meta characters.
|
||
(dolist (char chars)
|
||
(case char
|
||
(?\]
|
||
(setq bracket "]"))
|
||
(?^
|
||
(setq caret "^"))
|
||
(?-
|
||
(setq dash "-"))
|
||
(otherwise
|
||
(aset charmap char t))))
|
||
;;
|
||
;; Make a character set from the map using ranges where applicable.
|
||
(map-char-table
|
||
(lambda (c v)
|
||
(when v
|
||
(if (= (1- c) end) (setq end c)
|
||
(if (> end (+ start 2))
|
||
(setq charset (format "%s%c-%c" charset start end))
|
||
(while (>= end start)
|
||
(setq charset (format "%s%c" charset start))
|
||
(incf start)))
|
||
(setq start c end c))))
|
||
charmap)
|
||
(when (>= end start)
|
||
(if (> end (+ start 2))
|
||
(setq charset (format "%s%c-%c" charset start end))
|
||
(while (>= end start)
|
||
(setq charset (format "%s%c" charset start))
|
||
(incf start))))
|
||
;;
|
||
;; Make sure a caret is not first and a dash is first or last.
|
||
(if (and (string-equal charset "") (string-equal bracket ""))
|
||
(concat "[" dash caret "]")
|
||
(concat "[" bracket charset caret dash "]"))))
|
||
|
||
(provide 'regexp-opt)
|
||
|
||
;; arch-tag: 6c5a66f4-29af-4fd6-8c3b-4b554d5b4370
|
||
;;; regexp-opt.el ends here
|