Problem with quantifiers and look-behind

Question

### Ruby 1.8.7 ###

require \'rubygems\'
require \'oniguruma\' # for look-behind

Oniguruma::ORegexp.new(\'h(?=\\w*)\')
# => /h(?=\\w*)/

Oniguruma::ORegexp.new(\         


        

Answer 1

I was banging my head against the same problem, and Borealid's answer helped explain the issue well.

However, that got me thinking. Maybe the quantifier does not need to be inside the lookbehind, but can be applied on the lookbehind itself?

"hello".match(/(?<=\w*)o/)
# => SyntaxError: (irb):3: invalid pattern in look-behind: /(?<=\w*)o/

"hello".match(/(?<=\w)*o/)
# => #

So now we have a variable number of constant-length lookbehinds. Seems to bypass the issue for me. :)