I'm trying to create a regular expression that makes sure that there are no other tags outside a certain tag.
The following should fail:
This <F>is</F> a test <ID><F>sentence</F></ID> for stackoverflow.This <ID><M>is</M></ID> a test <F>sentence</F> for stackoverflow.
This one should pass:
This is a test <ID><F>sentence</F></ID> for stackoverflow.This is a test <ID><F>sentence</F></ID> for <ID>stackoverflow.</ID>
This is what I have tried so far:
- Match the correct tag:
(<ID>.+?<\/ID>) - Make sure that there are no tags before the matched tag:
(?<![<>].+?)(<ID>.+?<\/ID>) - Make sure that there are no tags after the matched tag:
(?<![<>].+?)(<ID>.+?<\/ID>)(?!.+?[<>])
Part 3 is where the problem relies. When I add this part the match just expands to the last tag in order to satisfy the negative lookahead as you can see in the following screenshots:
No negative lookahead:
Negative lookahead:
