2010/3/2 ????? ???????????? <olga.kryzhanovska at gmail.com>:
> On Tue, Mar 2, 2010 at 10:44 PM, Glenn Skinner <glenn.skinner at covad.net>
> wrote:
>> On Mar 2, 2010, at 12:55 PM, Garrett D'Amore - sun microsystems wrote:
>>
>>> This project is an amendment to the Korn Shell 93 Integration project
>>> (PSARC/2006/550 and PSARC/2007/035, PSARC/2008/094, PSARC/2008/344
>>> and PSARC/2008/589) specifying the following additional
>>> interfaces:
>>> Addition of /usr/bin/xgrep
>>>
>>> Bug/RFE Number(s):
>>>
>>> 6929154 RFE: Add /usr/bin/xgrep (Augmented regular expressions
>>> (conjunction, negation.))
>>>
>>>
>>> Interface Stability Description
>>> --------- --------- -----------
>>> /usr/bin/xgrep Committed xgrep command
>>> ksh93 'xgrep' built in Committed xgrep command
>>
>> Before I give this case my +1, I have some questions:
>>
>> The case's specification should define the syntax of the regular expressions
>> the utility accepts. I suspect that the variants requested by the -E, -F,
>> -G, and -P flags can be handled with references to the corresponding man
>> pages. But what is the specification for -X mode REs (including the
>> semantics of alternation and conjunction)?
>
> -X is like POSIX grep -E (egrep) but adds & as AND operator and ! as
> NOT operator.
>
>>
>> What is the difference between lenient and strict pattern interpretation?
>
> Strict will print syntax errors if the pattern does not match the
> standard exactly. I leave the exact explanation to Glenn Fowler.
Glenn's replied this:
--------------------------------
-O, --lenient sets the regcomp(3) REG_LENIENT flag
in general if REG_LENIENT is on then certain constructs marked
"unspecified" in the standard will be accepted, otherwise they
may produce regcomp(3) errors
e.g.
invalid \char escape
grep -S '\#' <<<'#'
invalid [...] range endpoint
grep -S '[a-q-z]' <<<'a'
the intention (theory) is that RE's that make it through -S, --strict
will make it through all conformant implementations
as counterexamples roll in I tweak libast/reg*.c to make pratice match theory
--------------------------------
'lenient' mode by default may be an option (i.e. look at Garrett
D'Amore proposal for moving /usr/xpg4/bin to /usr/bin, AST grep would
keep strong backwards compatibility sans the dreaded i18n bugs in the
current /usr/bin/grep) if we replace /usr/bin/grep and friends with
this grep implementation and use 'strict' mode for /usr/xpg4/bin/grep.
Olga
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`'-..-| / Solaris/BSD//C/C++ programmer \ |-..-'`
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