Re: [Rd] grep problem in R-devel 2.14 r57004

From: Simon Urbanek <simon.urbanek_at_r-project.org>
Date: Fri, 16 Sep 2011 09:42:24 -0400

I forgot to mention the more obvious ;) - yes, it is a known issue in PCRE 8.13 which is hitting more people. After re-reading the standard I think the problem was that PCRE did not require enclosing [ to treat [. as special. This has been addressed in the PCRE trunk since and it also has a comment on what happened. I have ported that fix into R-devel.

Cheers,
Simon

On Sep 16, 2011, at 9:01 AM, Simon Urbanek wrote:

> Mark, quick googling gives the answer - [.] is not what you think it is, you probably meant [\.]. Bracket expressions starting with [. are collating symbols which is unsupported by PCRE (only [:xxx:] is supported, neither [=xxx=] nor [.xxx.] is) but that's probably not what you intended. See POSIX:
> 
> 9.3.5 RE Bracket Expression
> [...]
> 1. [..] The character sequences "[.", "[=", and "[:" (left-bracket followed by a period, equals-sign, or colon) shall be special inside a bracket expression and are used to delimit collating symbols, equivalence class expressions, and character class expressions.
> 
> Cheers,
> Simon
> 
> 
> 
> On Sep 16, 2011, at 12:45 AM, <Mark.Bravington_at_csiro.au> <Mark.Bravington_at_csiro.au> wrote:
> 

>> Problem below with PCRE grep in R-devel; works fine in R-patched. (Unless there's been an absolutely massive change in rules for updated PCRE version 8.13; jeez I hope not)
>>
>>> grep( '[.][.]', '', perl=TRUE)

>> Error in grep("[.][.]", "", perl = TRUE) :
>> invalid regular expression '[.][.]'
>> In addition: Warning message:
>> In grep("[.][.]", "", perl = TRUE) : PCRE pattern compilation error
>> 'POSIX collating elements are not supported'
>> at '[.][.]'
>>
>>> sessionInfo()

>> R Under development (unstable) (2011-09-13 r57004)
>> Platform: i386-pc-mingw32/i386 (32-bit)
>>
>> locale:
>> [1] LC_COLLATE=English_Australia.1252 LC_CTYPE=English_Australia.1252
>> [3] LC_MONETARY=English_Australia.1252 LC_NUMERIC=C
>> [5] LC_TIME=English_Australia.1252
>>
>> attached base packages:
>> [1] stats graphics grDevices utils datasets methods base
>>
>> NB I'm sending to R-devel rather than posting a bug report because (i) I have a dim recollection that's what we're supposed to do for bugs in R-devel, and (ii) Bugzilla doesn't include an R-devel version and (iii) couldn't find any guidance on these matters.
>>
>> Mark
>>
>> --
>> Mark Bravington
>> CSIRO Mathematical & Information Sciences
>> Marine Laboratory
>> Castray Esplanade
>> Hobart 7001
>> TAS
>>
>> ph (+61) 3 6232 5118
>> fax (+61) 3 6232 5012
>> mob (+61) 438 315 623
>>
>> ______________________________________________
>> R-devel_at_r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>
> 
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