CODEWITHSUNDEEP
rubyregex
DeX3
DeX3

Reputation: 5539

Ruby regular expressions: negative matching

I was wondering if it was possible to use negative matching on whole words, so that something like [^(<em>.*?<\/em>)] would match everything but text between (and including) <em>...</em>.

I was thinking about using negative lookahead, but I don't think this will work, as I need to check for the opening <em> as well.

Of course, I could just use the positive regex and then subtract the matches from the original text, but I'm looking for a more 'elegant' solution.

thx for any help

Upvotes: 2

Views: 2509

Answers (2)

sawa
sawa

Reputation: 168091

String#split works as negative match. It returns you an array of whatever part that does not match the regex.

'XXXXXXXX<em>YYYYYYY</em>ZZZZZZZZ'.split(%r|<em>.*?</em>|)
# => ['XXXXXXX', 'ZZZZZZZZ']

And if want it back into a string, just do join.

'XXXXXXXX<em>YYYYYYY</em>ZZZZZZZZ'.split(%r|<em>.*?</em>|).join
 # => 'XXXXXXXZZZZZZZZ'

Upvotes: 4

Staffan N&#246;teberg
Staffan N&#246;teberg

Reputation: 4145

The whole thing with lookaround is that it doesn't consume any of the input. If you want to match everything but a pattern, it means that you want to match the prefix and the suffix of that pattern. To match the suffix, you probably want to consume --- and throw away -- the pattern that you don't want. But negative lookahead doesn't consume.

Upvotes: 0

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