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Re: regex alternation

by keszler (Priest)
on Sep 30, 2011 at 10:24 UTC ( #928737=note: print w/ replies, xml ) Need Help??


in reply to regex alternation

Why capture the closing single-quote? If you don't need it the alternation is unnecessary overhead. qr<^in directory '/directory/tmp(/\..*)?'$> would be better in that case. Also, if you're not planning to do anything with $1 after the match then there's no need to capture at all: qr<^in directory '/directory/tmp(?:/\..*)?'$>

For overall regex performance it's hard - for me anyway - to determine without knowing what the non-matching data looks like. In general you want the non-matching tests to fail as quickly as possible. (Your anchoring "in directory" to the start of the string is good for that.)

update - moritz's prefix method is even better


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