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55535639 | 1 | ;;; regexp-opt.el --- generate efficient regexps to match strings |
56329bc5 | 2 | |
ba318903 | 3 | ;; Copyright (C) 1994-2014 Free Software Foundation, Inc. |
56329bc5 | 4 | |
5762abec | 5 | ;; Author: Simon Marshall <simon@gnu.org> |
34dc21db | 6 | ;; Maintainer: emacs-devel@gnu.org |
370893a1 | 7 | ;; Keywords: strings, regexps, extensions |
56329bc5 RS |
8 | |
9 | ;; This file is part of GNU Emacs. | |
10 | ||
d6cba7ae | 11 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
56329bc5 | 12 | ;; it under the terms of the GNU General Public License as published by |
d6cba7ae GM |
13 | ;; the Free Software Foundation, either version 3 of the License, or |
14 | ;; (at your option) any later version. | |
56329bc5 RS |
15 | |
16 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
17 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 | ;; GNU General Public License for more details. | |
20 | ||
21 | ;; You should have received a copy of the GNU General Public License | |
d6cba7ae | 22 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
56329bc5 RS |
23 | |
24 | ;;; Commentary: | |
25 | ||
b02b54a8 | 26 | ;; The "opt" in "regexp-opt" stands for "optim\\(al\\|i[sz]e\\)". |
56329bc5 | 27 | ;; |
25544ce1 SM |
28 | ;; This package generates a regexp from a given list of strings (which matches |
29 | ;; one of those strings) so that the regexp generated by: | |
56329bc5 | 30 | ;; |
25544ce1 SM |
31 | ;; (regexp-opt strings) |
32 | ;; | |
33 | ;; is equivalent to, but more efficient than, the regexp generated by: | |
34 | ;; | |
35 | ;; (mapconcat 'regexp-quote strings "\\|") | |
56329bc5 RS |
36 | ;; |
37 | ;; For example: | |
38 | ;; | |
39 | ;; (let ((strings '("cond" "if" "when" "unless" "while" | |
40 | ;; "let" "let*" "progn" "prog1" "prog2" | |
41 | ;; "save-restriction" "save-excursion" "save-window-excursion" | |
42 | ;; "save-current-buffer" "save-match-data" | |
43 | ;; "catch" "throw" "unwind-protect" "condition-case"))) | |
44 | ;; (concat "(" (regexp-opt strings t) "\\>")) | |
45 | ;; => "(\\(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\\)\\)\\>" | |
46 | ;; | |
25544ce1 SM |
47 | ;; Searching using the above example `regexp-opt' regexp takes approximately |
48 | ;; two-thirds of the time taken using the equivalent `mapconcat' regexp. | |
49 | ||
56329bc5 RS |
50 | ;; Since this package was written to produce efficient regexps, not regexps |
51 | ;; efficiently, it is probably not a good idea to in-line too many calls in | |
52 | ;; your code, unless you use the following trick with `eval-when-compile': | |
53 | ;; | |
54 | ;; (defvar definition-regexp | |
55 | ;; (eval-when-compile | |
56 | ;; (concat "^(" | |
57 | ;; (regexp-opt '("defun" "defsubst" "defmacro" "defalias" | |
58 | ;; "defvar" "defconst") t) | |
59 | ;; "\\>"))) | |
60 | ;; | |
61 | ;; The `byte-compile' code will be as if you had defined the variable thus: | |
62 | ;; | |
63 | ;; (defvar definition-regexp | |
64 | ;; "^(\\(def\\(alias\\|const\\|macro\\|subst\\|un\\|var\\)\\)\\>") | |
65 | ;; | |
25544ce1 SM |
66 | ;; Note that if you use this trick for all instances of `regexp-opt' and |
67 | ;; `regexp-opt-depth' in your code, regexp-opt.el would only have to be loaded | |
68 | ;; at compile time. But note also that using this trick means that should | |
69 | ;; regexp-opt.el be changed, perhaps to fix a bug or to add a feature to | |
70 | ;; improve the efficiency of `regexp-opt' regexps, you would have to recompile | |
71 | ;; your code for such changes to have effect in your code. | |
72 | ||
73 | ;; Originally written for font-lock.el, from an idea from Stig's hl319.el, with | |
b02b54a8 GM |
74 | ;; thanks for ideas also to Michael Ernst, Bob Glickstein, Dan Nicolaescu and |
75 | ;; Stefan Monnier. | |
76 | ;; No doubt `regexp-opt' doesn't always produce optimal regexps, so code, ideas | |
77 | ;; or any other information to improve things are welcome. | |
c0056275 SM |
78 | ;; |
79 | ;; One possible improvement would be to compile '("aa" "ab" "ba" "bb") | |
80 | ;; into "[ab][ab]" rather than "a[ab]\\|b[ab]". I'm not sure it's worth | |
81 | ;; it but if someone knows how to do it without going through too many | |
82 | ;; contortions, I'm all ears. | |
56329bc5 | 83 | \f |
c0056275 | 84 | ;;; Code: |
56329bc5 RS |
85 | |
86 | ;;;###autoload | |
87 | (defun regexp-opt (strings &optional paren) | |
784c9f3c | 88 | "Return a regexp to match a string in the list STRINGS. |
582305b0 RS |
89 | Each string should be unique in STRINGS and should not contain any regexps, |
90 | quoted or not. If optional PAREN is non-nil, ensure that the returned regexp | |
91 | is enclosed by at least one regexp grouping construct. | |
56329bc5 RS |
92 | The returned regexp is typically more efficient than the equivalent regexp: |
93 | ||
908bb42f SM |
94 | (let ((open (if PAREN \"\\\\(\" \"\")) (close (if PAREN \"\\\\)\" \"\"))) |
95 | (concat open (mapconcat 'regexp-quote STRINGS \"\\\\|\") close)) | |
96 | ||
97 | If PAREN is `words', then the resulting regexp is additionally surrounded | |
07ff7702 MB |
98 | by \\=\\< and \\>. |
99 | If PAREN is `symbols', then the resulting regexp is additionally surrounded | |
100 | by \\=\\_< and \\_>." | |
56329bc5 RS |
101 | (save-match-data |
102 | ;; Recurse on the sorted list. | |
dbf3ef78 CY |
103 | (let* ((max-lisp-eval-depth 10000) |
104 | (max-specpdl-size 10000) | |
908bb42f | 105 | (completion-ignore-case nil) |
08cf00d8 | 106 | (completion-regexp-list nil) |
908bb42f | 107 | (open (cond ((stringp paren) paren) (paren "\\("))) |
22864a48 SM |
108 | (sorted-strings (delete-dups |
109 | (sort (copy-sequence strings) 'string-lessp))) | |
9cc236e0 | 110 | (re (regexp-opt-group sorted-strings (or open t) (not open)))) |
07ff7702 MB |
111 | (cond ((eq paren 'words) |
112 | (concat "\\<" re "\\>")) | |
113 | ((eq paren 'symbols) | |
114 | (concat "\\_<" re "\\_>")) | |
115 | (t re))))) | |
56329bc5 RS |
116 | |
117 | ;;;###autoload | |
118 | (defun regexp-opt-depth (regexp) | |
119 | "Return the depth of REGEXP. | |
22864a48 | 120 | This means the number of non-shy regexp grouping constructs |
8665b2b6 | 121 | \(parenthesized expressions) in REGEXP." |
56329bc5 RS |
122 | (save-match-data |
123 | ;; Hack to signal an error if REGEXP does not have balanced parentheses. | |
124 | (string-match regexp "") | |
125 | ;; Count the number of open parentheses in REGEXP. | |
22864a48 | 126 | (let ((count 0) start last) |
cf38dd42 | 127 | (while (string-match "\\\\(\\(\\?[0-9]*:\\)?" regexp start) |
22864a48 SM |
128 | (setq start (match-end 0)) ; Start of next search. |
129 | (when (and (not (match-beginning 1)) | |
130 | (subregexp-context-p regexp (match-beginning 0) last)) | |
131 | ;; It's not a shy group and it's not inside brackets or after | |
132 | ;; a backslash: it's really a group-open marker. | |
133 | (setq last start) ; Speed up next regexp-opt-re-context-p. | |
134 | (setq count (1+ count)))) | |
56329bc5 RS |
135 | count))) |
136 | \f | |
137 | ;;; Workhorse functions. | |
138 | ||
56329bc5 | 139 | (defun regexp-opt-group (strings &optional paren lax) |
a7769c30 SM |
140 | "Return a regexp to match a string in the sorted list STRINGS. |
141 | If PAREN non-nil, output regexp parentheses around returned regexp. | |
142 | If LAX non-nil, don't output parentheses if it doesn't require them. | |
44e97401 | 143 | Merges keywords to avoid backtracking in Emacs's regexp matcher." |
94abe30b SM |
144 | ;; The basic idea is to find the shortest common prefix or suffix, remove it |
145 | ;; and recurse. If there is no prefix, we divide the list into two so that | |
146 | ;; \(at least) one half will have at least a one-character common prefix. | |
147 | ||
148 | ;; Also we delay the addition of grouping parenthesis as long as possible | |
149 | ;; until we're sure we need them, and try to remove one-character sequences | |
150 | ;; so we can use character sets rather than grouping parenthesis. | |
c0056275 | 151 | (let* ((open-group (cond ((stringp paren) paren) (paren "\\(?:") (t ""))) |
56329bc5 RS |
152 | (close-group (if paren "\\)" "")) |
153 | (open-charset (if lax "" open-group)) | |
c0056275 | 154 | (close-charset (if lax "" close-group))) |
56329bc5 | 155 | (cond |
b02b54a8 GM |
156 | ;; |
157 | ;; If there are no strings, just return the empty string. | |
158 | ((= (length strings) 0) | |
159 | "") | |
160 | ;; | |
56329bc5 RS |
161 | ;; If there is only one string, just return it. |
162 | ((= (length strings) 1) | |
163 | (if (= (length (car strings)) 1) | |
164 | (concat open-charset (regexp-quote (car strings)) close-charset) | |
165 | (concat open-group (regexp-quote (car strings)) close-group))) | |
166 | ;; | |
167 | ;; If there is an empty string, remove it and recurse on the rest. | |
168 | ((= (length (car strings)) 0) | |
169 | (concat open-charset | |
170 | (regexp-opt-group (cdr strings) t t) "?" | |
171 | close-charset)) | |
172 | ;; | |
c0056275 SM |
173 | ;; If there are several one-char strings, use charsets |
174 | ((and (= (length (car strings)) 1) | |
175 | (let ((strs (cdr strings))) | |
176 | (while (and strs (/= (length (car strs)) 1)) | |
177 | (pop strs)) | |
178 | strs)) | |
179 | (let (letters rest) | |
180 | ;; Collect one-char strings | |
181 | (dolist (s strings) | |
5cda4b07 | 182 | (if (= (length s) 1) (push (string-to-char s) letters) (push s rest))) |
c0056275 SM |
183 | |
184 | (if rest | |
185 | ;; several one-char strings: take them and recurse | |
186 | ;; on the rest (first so as to match the longest). | |
187 | (concat open-group | |
188 | (regexp-opt-group (nreverse rest)) | |
189 | "\\|" (regexp-opt-charset letters) | |
190 | close-group) | |
191 | ;; all are one-char strings: just return a character set. | |
192 | (concat open-charset | |
193 | (regexp-opt-charset letters) | |
194 | close-charset)))) | |
56329bc5 RS |
195 | ;; |
196 | ;; We have a list of different length strings. | |
197 | (t | |
91fc05b1 | 198 | (let ((prefix (try-completion "" strings))) |
c0056275 SM |
199 | (if (> (length prefix) 0) |
200 | ;; common prefix: take it and recurse on the suffixes. | |
201 | (let* ((n (length prefix)) | |
202 | (suffixes (mapcar (lambda (s) (substring s n)) strings))) | |
bba6564c | 203 | (concat open-group |
c0056275 SM |
204 | (regexp-quote prefix) |
205 | (regexp-opt-group suffixes t t) | |
bba6564c | 206 | close-group)) |
c0056275 SM |
207 | |
208 | (let* ((sgnirts (mapcar (lambda (s) | |
209 | (concat (nreverse (string-to-list s)))) | |
210 | strings)) | |
91fc05b1 | 211 | (xiffus (try-completion "" sgnirts))) |
c0056275 SM |
212 | (if (> (length xiffus) 0) |
213 | ;; common suffix: take it and recurse on the prefixes. | |
214 | (let* ((n (- (length xiffus))) | |
7e1d6bdb SM |
215 | (prefixes |
216 | ;; Sorting is necessary in cases such as ("ad" "d"). | |
217 | (sort (mapcar (lambda (s) (substring s 0 n)) strings) | |
218 | 'string-lessp))) | |
bba6564c | 219 | (concat open-group |
c0056275 SM |
220 | (regexp-opt-group prefixes t t) |
221 | (regexp-quote | |
222 | (concat (nreverse (string-to-list xiffus)))) | |
bba6564c | 223 | close-group)) |
a1506d29 | 224 | |
c0056275 SM |
225 | ;; Otherwise, divide the list into those that start with a |
226 | ;; particular letter and those that do not, and recurse on them. | |
75407435 | 227 | (let* ((char (substring-no-properties (car strings) 0 1)) |
91fc05b1 | 228 | (half1 (all-completions char strings)) |
94abe30b | 229 | (half2 (nthcdr (length half1) strings))) |
c0056275 SM |
230 | (concat open-group |
231 | (regexp-opt-group half1) | |
232 | "\\|" (regexp-opt-group half2) | |
233 | close-group)))))))))) | |
234 | ||
56329bc5 RS |
235 | |
236 | (defun regexp-opt-charset (chars) | |
55802e4a CY |
237 | "Return a regexp to match a character in CHARS. |
238 | CHARS should be a list of characters." | |
56329bc5 RS |
239 | ;; The basic idea is to find character ranges. Also we take care in the |
240 | ;; position of character set meta characters in the character set regexp. | |
241 | ;; | |
5cda4b07 SM |
242 | (let* ((charmap (make-char-table 'case-table)) |
243 | (start -1) (end -2) | |
56329bc5 RS |
244 | (charset "") |
245 | (bracket "") (dash "") (caret "")) | |
246 | ;; | |
247 | ;; Make a character map but extract character set meta characters. | |
5cda4b07 | 248 | (dolist (char chars) |
c505aaeb CY |
249 | (cond |
250 | ((eq char ?\]) | |
251 | (setq bracket "]")) | |
252 | ((eq char ?^) | |
253 | (setq caret "^")) | |
254 | ((eq char ?-) | |
255 | (setq dash "-")) | |
256 | (t | |
257 | (aset charmap char t)))) | |
56329bc5 RS |
258 | ;; |
259 | ;; Make a character set from the map using ranges where applicable. | |
5cda4b07 SM |
260 | (map-char-table |
261 | (lambda (c v) | |
262 | (when v | |
6466bb34 KH |
263 | (if (consp c) |
264 | (if (= (1- (car c)) end) (setq end (cdr c)) | |
265 | (if (> end (+ start 2)) | |
266 | (setq charset (format "%s%c-%c" charset start end)) | |
267 | (while (>= end start) | |
268 | (setq charset (format "%s%c" charset start)) | |
c505aaeb | 269 | (setq start (1+ start)))) |
6466bb34 KH |
270 | (setq start (car c) end (cdr c))) |
271 | (if (= (1- c) end) (setq end c) | |
272 | (if (> end (+ start 2)) | |
5cda4b07 SM |
273 | (setq charset (format "%s%c-%c" charset start end)) |
274 | (while (>= end start) | |
275 | (setq charset (format "%s%c" charset start)) | |
c505aaeb | 276 | (setq start (1+ start)))) |
6466bb34 | 277 | (setq start c end c))))) |
5cda4b07 SM |
278 | charmap) |
279 | (when (>= end start) | |
280 | (if (> end (+ start 2)) | |
281 | (setq charset (format "%s%c-%c" charset start end)) | |
282 | (while (>= end start) | |
283 | (setq charset (format "%s%c" charset start)) | |
c505aaeb | 284 | (setq start (1+ start))))) |
56329bc5 RS |
285 | ;; |
286 | ;; Make sure a caret is not first and a dash is first or last. | |
287 | (if (and (string-equal charset "") (string-equal bracket "")) | |
bf4906d7 CD |
288 | (if (string-equal dash "") |
289 | "\\^" ; [^] is not a valid regexp | |
290 | (concat "[" dash caret "]")) | |
56329bc5 RS |
291 | (concat "[" bracket charset caret dash "]")))) |
292 | ||
293 | (provide 'regexp-opt) | |
294 | ||
295 | ;;; regexp-opt.el ends here |