mirror of
git://git.sv.gnu.org/emacs.git
synced 2026-01-16 08:10:43 -08:00
6dc6b0079e
The regex engine tries to optimise Kleene star by avoiding backtracking
when it can detect that star’s operand cannot match what follows it in
the pattern.
For example, when ‘[[:alpha:]]*1’ tries to match a ‘foo’, the engine
will test the longest match for ‘[[:alpha:]]*’, namely ’foo’ which is
the entire string. Literal digit one still present in the pattern will
however not match the remaining empty string.
Normally, backtracking would be performed trying a shorter match for the
character class (namely ‘fo’ leaving ‘o’ in the string), but since the
engine knows whatever would be put back into the string cannot possibly
match literal digit one so no backtracking will be attempted.
In the regexes of the form ‘[[:CC:]]*X’, the optimisation can be applied
if the character class CC does not match character X. In the above
example, this holds because digit one is not in alpha character class.
This test is performed by mutually_exclusive_p function but it did not
check class bits of a charset opcode. This resulted in an assumption
that character classes do not match multibyte characters. For example,
it would incorrectly conclude that [[:alpha:]] doesn’t match ‘ż’.
This, in turn, led to the aforementioned Kleene star optimisation being
incorrectly applied in patterns such as ‘[[:graph:]]*☠’ (which should
match ‘☠’ but doesn’t as can be tested by executing
(string-match-p "[[:graph:]]*☠" "☠")
which should return 0 but instead yields nil.
This issue affects any class witch matches multibyte characters, i.e.
if ‘[[:cc:]]’ matches a multibyte character X then ‘[[:cc:]]*X’ will
fail to match ‘X’.
* src/regex.c (executing_charset): A new function for executing the
charset and charset_not opcodes. It performs check on the character
taking into consideration existing bitmap, range table and class bits.
It also advances the pointer in the regex bytecode past the parsed
opcode.
(CHARSET_LOOKUP_RANGE_TABLE_RAW, CHARSET_LOOKUP_RANGE_TABLE): Removed.
Code now included in executing_charset.
(mutually_exclusive_p, re_match_2_internal): Changed to take advantage
of executing_charset function.
* test/src/regex-tests.el: New file with tests for the character class
matching.
|
||
|---|---|---|
| .. | ||
| data | ||
| etags | ||
| lisp | ||
| manual | ||
| src | ||
| ChangeLog.1 | ||
| file-organisation.org | ||
| make-test-deps.emacs-lisp | ||
| Makefile.in | ||
| README | ||
Copyright (C) 2008-2016 Free Software Foundation, Inc. See the end of the file for license conditions. This directory contains files intended to test various aspects of Emacs's functionality. Please help add tests! Emacs uses ERT, Emacs Lisp Regression Testing, for testing. See (info "(ert)") or https://www.gnu.org/software/emacs/manual/html_node/ert/ for more information on writing and running tests. The Makefile in this directory supports the following targets: * make check Run all tests as defined in the directory. Expensive tests are suppressed. The result of the tests for <filename>.el is stored in <filename>.log. * make check-maybe Like "make check", but run only the tests for files which have unresolved prerequisites. * make check-expensive Like "make check", but run also the tests marked as expensive. * make <filename> or make <filename>.log Run all tests declared in <filename>.el. This includes expensive tests. In the former case the output is shown on the terminal, in the latter case the output is written to <filename>.log. ERT offers selectors, which make it possible to filter out which test cases shall run. The make variable $(SELECTOR) gives you a simple mean to use your own selectors. The ERT manual describes how selectors are constructed, see (info "(ert)Test Selectors") or https://www.gnu.org/software/emacs/manual/html_node/ert/Test-Selectors.html You could use predefined selectors of the Makefile. "make <filename> SELECTOR='$(SELECTOR_DEFAULT)'" runs all tests for <filename>.el except the tests tagged as expensive. If your test file contains the tests "test-foo", "test2-foo" and "test-foo-remote", and you want to run only the former two tests, you could use a selector regexp: "make <filename> SELECTOR='\"foo$$\"'". (Also, see etc/compilation.txt for compilation mode font lock tests.) 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 <http://www.gnu.org/licenses/>.