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Allow empty argument to `regexp-opt-charset'

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* test/lisp/emacs-lisp/regexp-opt-tests.el (regexp-opt-charset):
Handle nil argument, and use regexp-quote for singletons.
* lisp/emacs-lisp/regexp-opt.el (regexp-opt-charset): Expand tests.
This commit is contained in:
Mattias Engdegård 2019-06-29 11:10:36 +02:00
parent 1dfb2f3615
commit f1d414b98f
2 changed files with 36 additions and 13 deletions
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20
lisp/emacs-lisp/regexp-opt.el
View file

@ -279,7 +279,9 @@ Merges keywords to avoid backtracking in Emacs's regexp matcher."
(defun regexp-opt-charset (chars)
"Return a regexp to match a character in CHARS.
CHARS should be a list of characters."
CHARS should be a list of characters.
If CHARS is the empty list, the return value is a regexp that
never matches anything."
;; 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.
;;
@ -326,13 +328,15 @@ CHARS should be a list of characters."
(while (>= end start)
(setq charset (format "%s%c" charset start))
(setq start (1+ start)))))
;;
;; Make sure a caret is not first and a dash is first or last.
(if (and (string-equal charset "") (string-equal bracket ""))
(if (string-equal dash "")
"\\^" ; [^] is not a valid regexp
(concat "[" dash caret "]"))
(concat "[" bracket charset caret dash "]"))))
;; Make sure that ] is first, ^ is not first, - is first or last.
(let ((all (concat bracket charset caret dash)))
(pcase (length all)
(0 regexp-unmatchable)
(1 (regexp-quote all))
(_ (if (string-equal all "^-")
"[-^]"
(concat "[" all "]")))))))
(defun regexp-opt--contains-prefix (strings)

29
test/lisp/emacs-lisp/regexp-opt-tests.el
View file

@ -1,4 +1,4 @@
;;; regexp-tests.el --- Test suite for regular expression handling.
;;; regexp-opt-tests.el --- Tests for regexp-opt.el
;; Copyright (C) 2013-2019 Free Software Foundation, Inc.
@ -25,9 +25,28 @@
(require 'regexp-opt)
(ert-deftest regexp-test-regexp-opt ()
"Test the `compilation-error-regexp-alist' regexps.
The test data is in `compile-tests--test-regexps-data'."
(should (string-match (regexp-opt-charset '(?^)) "a^b")))
(ert-deftest regexp-opt-charset ()
(should (equal (regexp-opt-charset '(?a ?b ?a)) "[ab]"))
(should (equal (regexp-opt-charset '(?D ?d ?B ?a ?b ?C ?7 ?a ?c ?A))
"[7A-Da-d]"))
(should (equal (regexp-opt-charset '(?a)) "a"))
(should (equal (regexp-opt-charset '(?^)) "\\^"))
(should (equal (regexp-opt-charset '(?-)) "-"))
(should (equal (regexp-opt-charset '(?\])) "]"))
(should (equal (regexp-opt-charset '(?^ ?\])) "[]^]"))
(should (equal (regexp-opt-charset '(?^ ?-)) "[-^]"))
(should (equal (regexp-opt-charset '(?- ?\])) "[]-]"))
(should (equal (regexp-opt-charset '(?- ?\] ?^)) "[]^-]"))
(should (equal (regexp-opt-charset '(?^ ?a)) "[a^]"))
(should (equal (regexp-opt-charset '(?- ?a)) "[a-]"))
(should (equal (regexp-opt-charset '(?\] ?a)) "[]a]"))
(should (equal (regexp-opt-charset '(?^ ?\] ?a)) "[]a^]"))
(should (equal (regexp-opt-charset '(?^ ?- ?a)) "[a^-]"))
(should (equal (regexp-opt-charset '(?- ?\] ?a)) "[]a-]"))
(should (equal (regexp-opt-charset '(?- ?\] ?^ ?a)) "[]a^-]"))
(should (equal (regexp-opt-charset '()) regexp-unmatchable)))
;;; regexp-tests.el ends here.