longjumps
asked on
C++ how to profile code for regex lib?
I have a small test program that is testing regex library.
2 major lines are:
...
if(xregcomp(preg,pattern,R
int ret = xregexec(preg, buffer, 1, &pmatch, 0);
std::cout << "ret=" << ret << " pmatch.rm_so=" << pmatch.rm_so << ", pmatch..rm_eo=" << pmatch.rm_eo << std::endl;
}
for some reason xregexec is taking some extra seconds that shouldn't at all!
In my project I have a reference to project xregex that is using regex.c lib from
Extended regular expression matching and search library,
version 0.12.
...
The question: How can I profile and find out where the time is wasting here?
regex.c
xregex.h
2 major lines are:
...
if(xregcomp(preg,pattern,R
int ret = xregexec(preg, buffer, 1, &pmatch, 0);
std::cout << "ret=" << ret << " pmatch.rm_so=" << pmatch.rm_so << ", pmatch..rm_eo=" << pmatch.rm_eo << std::endl;
}
for some reason xregexec is taking some extra seconds that shouldn't at all!
In my project I have a reference to project xregex that is using regex.c lib from
Extended regular expression matching and search library,
version 0.12.
...
The question: How can I profile and find out where the time is wasting here?
regex.c
xregex.h
ozo
what is in pattern and buffer when it takes extra seconds?
ASKER
ozo, I attached both
Regex
(OR|[|][|]|AND|[&][&]|HAVI
and buffer attached.
rule122-regex.txt
toparsw.txt
Regex
(OR|[|][|]|AND|[&][&]|HAVI
and buffer attached.
rule122-regex.txt
toparsw.txt
There can be exponentially many ways for
([[:space:]]*|/[*].*[*]/)*
to match. It may take a lot of time to check all of them.
([[:space:]]*|/[*].*[*]/)*
to match. It may take a lot of time to check all of them.
ASKER
Yes. But why this slowness happens for this buffer?
Once I take any other it is not happening?
Once I take any other it is not happening?
does changing
([[:space:]]*|/[*].*[*]/)*
to
([[:space:]]|/[*][^*]*[*]+
make a difference?
([[:space:]]*|/[*].*[*]/)*
to
([[:space:]]|/[*][^*]*[*]+
make a difference?
ASKER
I am checking your regex substitution proposal.
However why the attached specific buffer is slowing down significantly performance?
Same expression with other buffers, including MBs of the things is working super fast. Why?
However why the attached specific buffer is slowing down significantly performance?
Same expression with other buffers, including MBs of the things is working super fast. Why?
With REG_ICASE,
beland
matches (OR|[|][|]|AND|[&][&]|HAVI
We then match ([[:space:]]*|/[*].*[*]/)*
When the
[('\"]*[[:space:]]*([^('\"
fails to match, a human or sufficiently clever match engine may realize that
backtracking to find a different way to match the ([[:space:]]*|/[*].*[*]/)*
won't make a difference to the success of the entire match,
but a more naive match engine
(such as one optimized for tight loops without extra complicated checks)
would go back to try them all.
(And, in theory, it could even find an infinite number of ways to match it)
would
beland
matches (OR|[|][|]|AND|[&][&]|HAVI
We then match ([[:space:]]*|/[*].*[*]/)*
When the
[('\"]*[[:space:]]*([^('\"
fails to match, a human or sufficiently clever match engine may realize that
backtracking to find a different way to match the ([[:space:]]*|/[*].*[*]/)*
won't make a difference to the success of the entire match,
but a more naive match engine
(such as one optimized for tight loops without extra complicated checks)
would go back to try them all.
(And, in theory, it could even find an infinite number of ways to match it)
would
ASKER CERTIFIED SOLUTION
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ASKER
checking solution
ASKER
workaround solution for changes in Regex and not code.