Zero-width positive "look-behind"?

Ruby
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

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:

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

Note: you need Ruby 1.9.

Kind regards

robert

3

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