Question

I have the following string:

<SEM>electric</SEM> cu <SEM>hello</SEM> rent <SEM>is<I>love</I>, <PARTITION />mind 

I want to find the last ‘SEM’ start tag before the ‘PARTITION’ tag. not the SEM end tag but the start tag. The result should be:

<SEM>is <Im>love</Im>, <PARTITION /> 

I have tried this regular expression:

<SEM>[^<]*<PARTITION[ ]/> 

but it only works if the final ‘SEM’ and ‘PARTITION’ tags do not have any other tag between them. Any ideas?

Answer 1

And here’s your goofy Regex!!!

(?=[\s\S]*?\<PARTITION)(?![\s\S]+?\<SEM\>)\<SEM\> 

What that says is ‘While ahead somewhere is a PARTITION tag… but while ahead is NOT another SEM tag… match a SEM tag.’

Enjoy!

Here’s that regex broken down:

(?=[\s\S]*?\<PARTITION) means 'While ahead somewhere is a PARTITION tag' (?![\s\S]+?\<SEM\>) means 'While ahead somewhere is not a SEM tag' \<SEM\> means 'Match a SEM tag'