The regex engine won't backtrack to validate a variable width assertion, and that's what would be necessary to make variable width work, from what I understand.

perlre suggests a workaround with \K, and I've seen people suggest that one of the most effective variable width lookbehinds is reverse (process the reversed string instead).


Dave

In reply to Re: Why is variable length lookahead implemented while lookbehind is not? by davido
in thread Why is variable length lookahead implemented while lookbehind is not? by Kc12349

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