Standard Library

[Thierry Douez]

> Yes, but just having a more complete implementation of PCRE regex would make a big difference.
> For example, LC's regex does not include back references.
> Having the ability to use (PCRE compliant) back references would, I believe, in many case, eliminate the need for that array of matches.
> For example....

>> The dictionary says "LiveCode implements regular expressions compatible with the PCRE library." Without back references the LC implementation is a rather limited subset of that library.

Sorry to be a bit more precise, but actually back references *are*
implemented. You can use them in the pattern matching, as:
  " (.)\1"
I let the reader find what's for :)

A regex engine needs 2 input: a text and a pattern matching
and it returns true or false plus a list (generic word)
of index if any captures. That's it. Everything else is *not* part
of the regex engine.

That said, implementing back references in the replacement text
is and only is the responsability of Livecode engine! (see below)


>> Example:
>> I would expect to be able to do this in the message box:
>> put replaceText("abcd","(ab)(cd)","$2$1")
>> and get this:
>> "cdab"

Well, change $1 $2 by \1 and \2 and it will be less Perlish
plus this syntax is already in use.

What a pity you didn't manifest yourself here and at this time:

http://forums.livecode.com/viewtopic.php?f=66&t=17412

I dropped all, feeling a bit lonely on this path..


>> Instead I have to do this:
>> if matchText("abcd","(ab)(cd)",var1,var2) then put var2 & var1
>>
>> But this is a trivial example. If either my string to search or my pattern is slightly more complex, then what would be a trivial task with full PCRE compliant regex becomes comparatively complicated in LC.

Yes, speaking from experience, Perl and Regex are just "Wow"
and they are fast; yes, fast!
Why do you think I spent so much time developping a
Perl external for Livecode some years ago.

And if you don't believe a French guy, check how geneticians
work  with huge databases and DNA files..

Regards,

Thierry


------------------------------------------------
Thierry Douez - http://sunny-tdz.com
Maker of sunnYperl - sunnYmidi - sunnYmage