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Posted to dev@cocoon.apache.org by Nathaniel Alfred <Al...@swx.com> on 2006/09/20 10:39:11 UTC
Wildcard matcher matching wild things
The head of 2.1 contains a new WildcardMatcherHelper [1] to replace the
rather obscure WildcardHelper [2] implementation. WMH is now used for
matching wildcard patterns in map:match.
Although the code is a lot clearer than WH, it is still very complex
logic. A number of bugs in the original WMH code have been fixed in the
meantime, but a few more seem to be lurking..
I recently fixed two bugs but now I am facing yet another one. This
time it is a false positive where "*" matches what should be matched
only by "**". Rather than submerging myself into the WMH code for
fixing it I am inclined to rewrite the stuff one more time.
Along the lines already discussed in the thread following [1] I would
use the regexp library to do the heavy lifting. Since map:match is the
most frequently executed pipeline instruction, speed is an issue. That
can be mastered by a) caching the compiled regexps and b) handling the
simple pattern with a single * or ** as special cases without using
regexps.
At the same time regexps would also remove the known limitation that
"**/*/*" cannot match because "**" is over-greedy in the current WMH
implementation.
WDYT?
Cheers, Alfred.
[1] http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=115096562921641&w=2
[2] http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=114915395328845&w=2
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Re: Wildcard matcher matching wild things
Posted by Reinhard Poetz <re...@apache.org>.
Nathaniel Alfred wrote:
> The head of 2.1 contains a new WildcardMatcherHelper [1] to replace the
> rather obscure WildcardHelper [2] implementation. WMH is now used for
> matching wildcard patterns in map:match.
>
> Although the code is a lot clearer than WH, it is still very complex
> logic. A number of bugs in the original WMH code have been fixed in the
> meantime, but a few more seem to be lurking..
>
> I recently fixed two bugs but now I am facing yet another one. This
> time it is a false positive where "*" matches what should be matched
> only by "**". Rather than submerging myself into the WMH code for
> fixing it I am inclined to rewrite the stuff one more time.
>
> Along the lines already discussed in the thread following [1] I would
> use the regexp library to do the heavy lifting. Since map:match is the
> most frequently executed pipeline instruction, speed is an issue. That
> can be mastered by a) caching the compiled regexps and b) handling the
> simple pattern with a single * or ** as special cases without using
> regexps.
>
> At the same time regexps would also remove the known limitation that
> "**/*/*" cannot match because "**" is over-greedy in the current WMH
> implementation.
>
> WDYT?
As you and Bertrand said, speed and compatibility are very important. If your
new implementation takes care of both and is proved by tests, I don't see a problem.
--
Reinhard Pötz Independent Consultant, Trainer & (IT)-Coach
{Software Engineering, Open Source, Web Applications, Apache Cocoon}
web(log): http://www.poetz.cc
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Re: Wildcard matcher matching wild things
Posted by Bertrand Delacretaz <bd...@apache.org>.
On 9/20/06, Nathaniel Alfred <Al...@swx.com> wrote:
> ...WDYT?..
Using the regexp library makes sense, but backwards compatiblity is
very important in this case, as subtle differences in matching might
break a lot of things in existing apps.
As long as test cases are plenty (I haven't checked), what you suggest
shouldn't be a problem.
-Bertrand
Re: Wildcard matcher matching wild things
Posted by Joerg Heinicke <jo...@gmx.de>.
On 20.09.2006 10:39, Nathaniel Alfred wrote:
> Since map:match is the
> most frequently executed pipeline instruction, speed is an issue. That
> can be mastered by a) caching the compiled regexps and b) handling the
> simple pattern with a single * or ** as special cases without using
> regexps.
Just wondering, did you actually do some performance comparisons?
Regards,
Jörg