Zero-width positive "look-behind"?

ruby-talk
1

"tttttattttt".match(/ttt(?=a)/) # Rubular: ttt(?=a)

=> ["ttt"]

"tttttattttt".match(/(?=a)ttt/) # Rubular: (?=a)ttt

=> nil

Why? And how can I get this effect?

2

It seems you have just demonstrated how to get the effect you described.

For more info:

http://www.geocities.jp/kosako3/oniguruma/doc/RE.txt

Note: you need Ruby 1.9.

Kind regards

  robert

···

On 04/09/2010 10:40 AM, Nathan wrote:

"tttttattttt".match(/ttt(?=a)/) # Rubular: ttt(?=a)

=> ["ttt"]

"tttttattttt".match(/(?=a)ttt/) # Rubular: (?=a)ttt

=> nil

Why? And how can I get this effect?

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

3

Ah (?<=a)ttt is what I was after. Thanks for the link.

···

On Apr 9, 11:10 am, Robert Klemme <shortcut...@googlemail.com> wrote:

On 04/09/2010 10:40 AM, Nathan wrote:

>> "tttttattttt".match(/ttt(?=a)/) #Rubular: ttt(?=a)
> => ["ttt"]
>> "tttttattttt".match(/(?=a)ttt/) #Rubular: (?=a)ttt
> => nil

> Why? And how can I get this effect?

It seems you have just demonstrated how to get the effect you described.

For more info:

サービス終了のお知らせ

Note: you need Ruby 1.9.

Kind regards

    robert

--
remember.guy do |as, often| as.you_can - without endhttp://blog.rubybestpractices.com/