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RE: Regex optimizations

by dchetlin (Friar)
on Oct 25, 2000 at 01:13 UTC ( #38223=note: print w/replies, xml ) Need Help??

in reply to Regex optimizations

This is a good question. The answer is that the REx engine does not optimize \d{2} into \d\d.

Here's how to check:

[~] $ perl -Mre=debug -e'qr/\d{2}/' Freeing REx: `,' Compiling REx `\d{2}' size 4 first at 3 1: CURLY {2,2}(4) 3: DIGIT(0) 4: END(0) stclass `DIGIT' minlen 2 Freeing REx: `\d{2}' [~] $ perl -Mre=debug -e'qr/\d\d/' Freeing REx: `,' Compiling REx `\d\d' size 3 first at 1 1: DIGIT(2) 2: DIGIT(3) 3: END(0) stclass `DIGIT' minlen 2 Freeing REx: `\d\d'

Why doesn't it? I don't know. But as the Benchmarks above have noted, I can't imagine that difference being notable enough to really worry about.


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