[Asterisk-Dev] better pattern matcher

Reini Urban r.urban at inode.at
Fri Jun 6 05:23:38 MST 2003

John Todd wrote:
> This has been discussed before on the list.  Someone correct me if I'm 
> wrong on this: The issue is that there are no regular expression 
> libraries that can be used in the way that the Asterisk license is 
> written.  All of them are licensed such that they cannot be bundled into 
> a larger package which _optionally_ may not be open-sourced under the 
> same license as the library.  Asterisk is such a package, so most other 
> inclusion libraries are not viable.
> If you want to write one, and sign over the rights to the software to 
> Digium, we'd all be thrilled to see it!  A better and more extensible 
> pattern-match engine is sorely needed.  While you're at it, make sure it 
> understands alphanumerics as well as just numerics; I'd like to see * 
> eventually support "real" SIP addresses which incorporate letters as 
> well as numbers.  :)

well, for the beginning I added support to continue to match after a "."
to be able to add extensions after the dialed number and not only before. :)

e.g "_0N.8500" matches my voicemail extension for all dialed numbers.

I'll commit this short patch on Tuesday, because I have to do more 
testing and the weekend is free.

But maybe I add quantifiers also and support
   "." for any char,
   "+" for "one or more"
   "*" for zero or more chars.
This will break existing extensions.

BTW: character classes (alphanumerics) are already supported by [].
[a-z0-9] for example.

I'm not good in interpreting licenses. Can somebody look at the PCRE 
license. I always use this in my projects and it should be able to use 
this commercially.

>> I have to match against an ending pattern.
>> Something like _09nnnn.8500
>> The problem is that . immediately returns.
>> My suggestion is to use a better matcher like
>> glob or regex or pcre which supports this.
>> Or at least check if there are still characters behind the "." in the 
>> pattern to match against.
>> So "." will relate to ".*" in regex or "*" in glob.
>> Will such a patch be considered useful?
Reini Urban - Entwicklung - http://inode.at

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