From: bojohan+mail@dd.chalmers.se (Johan Bockgård)
Subject: [BUG] Regexp compiler, problem with character classes
Date: Sat, 03 Jun 2006 03:14:15 +0200 [thread overview]
Message-ID: <yoijejupnugv.fsf@gamma02.me.chalmers.se> (raw)
[I'm resending this because I think it's a serious bug. It makes
character classes totally unreliable.]
Character classes are translated to character alternatives during the
regexp compile phase. This is wrong, since the syntax table should be
taken into account during the actual matching. This may be non-trivial
to fix.
(with-temp-buffer
(list
(progn (modify-syntax-entry ?a " ")
(string-match "x[[:space:]]" "xa"))
(progn (modify-syntax-entry ?a "w")
(string-match "x[[:space:]]" "xa"))))
=> (0 0)
0: /exactn/1/x
3: /charset [\t\f a\302\200-\303\277]
37: /succeed
38: end of pattern.
Compiling pattern: x[[:space:]]
Compiled pattern:
38 bytes used/174 bytes allocated.
fastmap: x
re_nsub: 0 regs_alloc: 0 can_be_null: 0 no_sub: 0 not_bol: 0 not_eol: 0 syntax: 340204
0: /exactn/1/x
3: /charset [\t\f a\302\200-\303\277]
37: /succeed
38: end of pattern.
0: /exactn/1/x
3: /charset [\t\f a\302\200-\303\277]
37: /succeed
38: end of pattern.
As an effect you get the behavior below, since the compiler takes no
care to setup the syntax in the first place:
1)
emacs -Q
(with-temp-buffer
(string-match "x[[:space:]]" "x\n"))
=> nil
(exit Emacs)
2)
emacs -Q
(with-temp-buffer
(char-syntax ?\n)
(string-match "x[[:space:]]" "x\n"))
=> 0
(Fchar_syntax does
gl_state.current_syntax_table = current_buffer->syntax_table;)
--
This is bad.
next reply other threads:[~2006-06-03 1:14 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-03 1:14 Johan Bockgård [this message]
2006-09-07 21:15 ` [BUG] Regexp compiler, problem with character classes Richard Stallman
2006-09-13 9:50 ` Johan Bockgård
2006-09-13 19:25 ` Richard Stallman
2006-09-07 21:15 ` Richard Stallman
2006-09-14 23:20 ` Chong Yidong
2006-09-15 14:29 ` Richard Stallman
2006-09-15 15:13 ` Chong Yidong
2006-09-18 8:43 ` Johan Bockgård
2006-09-18 12:53 ` Chong Yidong
2006-09-18 13:03 ` Stefan Monnier
2006-09-18 13:12 ` Johan Bockgård
2006-09-15 3:14 ` Richard Stallman
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