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bug#36251: Regex library doesn't recognize ']' in a character class
From: |
tomas |
Subject: |
bug#36251: Regex library doesn't recognize ']' in a character class |
Date: |
Sun, 16 Jun 2019 21:40:08 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Sun, Jun 16, 2019 at 08:16:29PM +0300, Abdulrahman Semrie wrote:
>
> I am using the pattern [\\[\\]a-zA-Z]+ to match a string with left or right
> bracket in it. However, the string-match function doesn’t match the ‘]’
> character. To demonstrate with an example, try the following funciton:
>
> (string-match "[\\[\\]a-zA-Z]+" "Text[ab]”)
>
> The result for the above function should have been a match structure with
> Text[ab] matched. However, the string-match returns #f which is incorrect. To
> test if the pattern I am using was right, I tried on regex101.com and it
> works. Here (https://regex101.com/r/VAl6aI/1) is the link that demonstrates
> that it works.
>
> Hence, the above leads me to believe there is a bug in the regex library that
> mishandles ] character in character-classes
If I understood you correctly, you are using POSIX regular
expressions. Within a bracket expression ([...]), you can't
escape ']' with a backslash. Just put the ] as first character,
like so:
[][a-zA-Z]
Quoting the man page (regex(7)):
A bracket expression is a list of characters enclosed in "[]".
It normally matches any single character from the list (but see
below). If the list begins with '^', it matches any single
character (but see below) not from the rest of the list. [...]
To include a literal ']' in the list, make it the first
character (following a possible '^'). To include a literal
'-', make it the first or last character, or the second endpoint
of a range [...]
See also [1], but the man page is more complete.
(I'm assuming your Guile is linked against some POSIX regex library).
Cheers
-- t
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