You need look-around assertions, not non-capturing groups. See perlre, search for positive look-ahead assertion and zero-width positive look-behind assertion.

A substitution substitutions not only the captured part of the string, but the matched part of the string. Using zero-width assertion you can reduce the matched part of the string to the captured part.

In reply to Re: regexp: non-capturing grouping in replacement possible? by moritz
in thread regexp: non-capturing grouping in replacement possible? by diweooy

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