CODEWITHSUNDEEP
regex
shaun stewart
shaun stewart

Reputation: 293

regex, extract string NOT between two brackets

OK regex question , how to extract a character NOT between two characters, in this case brackets.

I have a string such as: word1 | {word2 | word3 } | word 4

I only want to get the first and last 'pipe', not the second which is between brackets. I have tried a myriad of attempts with negative carats and negative groupings and can't seem to get it to work.

Basically I am using this regex in a JavaScript split function to split this into an array containing: "word1", "{word2 | word3}", "word4".

Any assistance would be greatly appreciated!

Upvotes: 29

Views: 34648

Answers (2)

Diver
Diver

Reputation: 1608

Try using this pattern

/\|(?![^{]*})/g

with this text

word1 | {word2 | word3 } | word 4 | word 4 | {word2 | word3 }

This should match all of the Pipe symbols that are not inside {}.

*edit - removed link to dead site (Thanks Dennis)

Upvotes: 42

Andrew Cheong
Andrew Cheong

Reputation: 30273

Depends on the language/implementation you're using, but...

\|(?![^{]*})

This matches a pipe that is not followed by a } except in the case that a { comes first.

The (?! ... ) is known as a negative lookahead assertion. This is easier to understand if we start with a positive lookahead assertion:

\|(?=[^{]*})

The above only matches a pipe that is followed by a } without encountering a { first. When you negate that by replacing the = with a !, the match is now only successful if there's no way for the positive case to be true (also known as the complement).

Upvotes: 24

Related Questions