From: Logan Capaldo <logancapaldo@...>
Date: 2006-07-13T09:25:18+09:00
Subject: Re: Ruby regexp spec.


On Jul 11, 2006, at 2:12 PM, Daniel Martin wrote:

> "Simon Strandgaard" <neoneye@gmail.com> writes:
>
>> Have a look here:
>>
>> http://www.geocities.jp/kosako3/oniguruma/doc/RE.txt
>
> That's nice, but it doesn't document ruby's Regexp engine, at least
> not the one in Ruby 1.8.4; the document says:
>
> (?<=subexp)        look-behind
>
> But:
>
> irb(main):032:0> Regexp.new('(?<=abc)')
> RegexpError: undefined (?...) sequence: /(?<=abc)/
>         from (irb):32:in `initialize'
>         from (irb):32
>         from :0
>
> I suspect that this documents what will be, in the Ruby 2.0 that's
> going to have easy built-in support for unicode in all its glory.
>
> That still leaves the current engine undocumented.
>

Section A-4 of the above document tells you the differences between  
the new regexp engine and the current one. You could do a mental diff  
<g>