@end defun
@cindex optimize regexp
-@defun regexp-opt strings &optional paren keep-order
+@defun regexp-opt strings &optional paren
This function returns an efficient regular expression that will match
any of the strings in the list @var{strings}. This is useful when you
need to make matching or searching as fast as possible---for example,
it will apply to the whole expression.
@end table
-The optional argument @var{keep-order}, if non-@code{nil}, forces the
-match to be performed in the order given, as if the strings were made
-into a regexp by joining them with the @samp{\|} operator. If nil or
-omitted, the returned regexp will always match the longest string
-possible.
+The returned regexp is ordered in such a way that it will always match
+the longest string possible.
Up to reordering, the resulting regexp of @code{regexp-opt} is
equivalent to but usually more efficient than that of a simplified
This is currently supported on GNUish hosts and on modern versions of
MS-Windows.
-+++
-** The function 'regexp-opt' accepts an additional optional argument.
-By default, the regexp returned by 'regexp-opt' may match the strings
-in any order. If the new third argument is non-nil, the match is
-guaranteed to be performed in the order given, as if the strings were
-made into a regexp by joining them with '\|'.
-
+++
** The function 'regexp-opt', when given an empty list of strings, now
returns a regexp that never matches anything, which is an identity for
;;; Code:
;;;###autoload
-(defun regexp-opt (strings &optional paren keep-order)
+(defun regexp-opt (strings &optional paren)
"Return a regexp to match a string in the list STRINGS.
Each member of STRINGS is treated as a fixed string, not as a regexp.
Optional PAREN specifies how the returned regexp is surrounded by
necessary to ensure that a postfix operator appended to it will
apply to the whole expression.
-The optional argument KEEP-ORDER, if non-nil, forces the match to
-be performed in the order given, as if the strings were made into
-a regexp by joining them with the `\\|' operator. If nil or
-omitted, the returned regexp is will always match the longest
-string possible.
+The returned regexp is ordered in such a way that it will always
+match the longest string possible.
Up to reordering, the resulting regexp is equivalent to but
usually more efficient than that of a simplified version:
(completion-ignore-case nil)
(completion-regexp-list nil)
(open (cond ((stringp paren) paren) (paren "\\(")))
- (re
- (cond
- ;; No strings: return an unmatchable regexp.
- ((null strings)
- (concat (or open "\\(?:") regexp-unmatchable "\\)"))
-
- ;; The algorithm will generate a pattern that matches
- ;; longer strings in the list before shorter. If the
- ;; list order matters, then no string must come after a
- ;; proper prefix of that string. To check this, verify
- ;; that a straight or-pattern matches each string
- ;; entirely.
- ((and keep-order
- (let* ((case-fold-search nil)
- (alts (mapconcat #'regexp-quote strings "\\|")))
- (and (let ((s strings))
- (while (and s
- (string-match alts (car s))
- (= (match-end 0) (length (car s))))
- (setq s (cdr s)))
- ;; If we exited early, we found evidence that
- ;; regexp-opt-group cannot be used.
- s)
- (concat (or open "\\(?:") alts "\\)")))))
- (t
- (regexp-opt-group
- (delete-dups (sort (copy-sequence strings) 'string-lessp))
- (or open t) (not open))))))
+ (re (if strings
+ (regexp-opt-group
+ (delete-dups (sort (copy-sequence strings) 'string-lessp))
+ (or open t) (not open))
+ ;; No strings: return an unmatchable regexp.
+ (concat (or open "\\(?:") regexp-unmatchable "\\)"))))
(cond ((eq paren 'words)
(concat "\\<" re "\\>"))
((eq paren 'symbols)
(mapcar (lambda (i) (regexp-opt-test--permutation i list))
(number-sequence 0 (1- (regexp-opt-test--factorial (length list))))))
-(defun regexp-opt-test--match-all (words re)
- (mapcar (lambda (w) (and (string-match re w)
- (match-string 0 w)))
- words))
-
-(defun regexp-opt-test--check-perm (perm)
- (let* ((ref-re (mapconcat #'regexp-quote perm "\\|"))
- (opt-re (regexp-opt perm nil t))
- (ref (regexp-opt-test--match-all perm ref-re))
- (opt (regexp-opt-test--match-all perm opt-re)))
- (equal opt ref)))
-
-(defun regexp-opt-test--explain-perm (perm)
- (let* ((ref-re (mapconcat #'regexp-quote perm "\\|"))
- (opt-re (regexp-opt perm nil t))
- (ref (regexp-opt-test--match-all perm ref-re))
- (opt (regexp-opt-test--match-all perm opt-re)))
- (concat "\n"
- (format "Naïve regexp: %s\n" ref-re)
- (format "Optimized regexp: %s\n" opt-re)
- (format "Got: %s\n" opt)
- (format "Expected: %s\n" ref))))
-
-(put 'regexp-opt-test--check-perm 'ert-explainer 'regexp-opt-test--explain-perm)
-
-(ert-deftest regexp-opt-keep-order ()
- "Check that KEEP-ORDER works."
- (dolist (perm (regexp-opt-test--permutations '("abc" "bca" "cab")))
- (should (regexp-opt-test--check-perm perm)))
- (dolist (perm (regexp-opt-test--permutations '("abc" "ab" "bca" "bc")))
- (should (regexp-opt-test--check-perm perm)))
- (dolist (perm (regexp-opt-test--permutations '("abxy" "cdxy")))
- (should (regexp-opt-test--check-perm perm)))
- (dolist (perm (regexp-opt-test--permutations '("afgx" "bfgx" "afgy" "bfgy")))
- (should (regexp-opt-test--check-perm perm)))
- (dolist (perm (regexp-opt-test--permutations '("a" "ab" "ac" "abc")))
- (should (regexp-opt-test--check-perm perm))))
+(ert-deftest regexp-opt-longest-match ()
+ "Check that the regexp always matches as much as possible."
+ (let ((s "abcd"))
+ (dolist (perm (regexp-opt-test--permutations '("a" "ab" "ac" "abc")))
+ (should (equal (and (string-match (regexp-opt perm) s)
+ (match-string 0 s))
+ "abc")))))
(ert-deftest regexp-opt-charset ()
(should (equal (regexp-opt-charset '(?a ?b ?a)) "[ab]"))
projects / emacs.git / commitdiff