Improving the efficiency of your regular expressions

abseil.io

19 pointsEntICOnc3 comments

> Using RE2::FullMatch() with leading or trailing .* is an antipattern. Instead, change it to RE2::PartialMatch() and remove the .*.

This is something the compiler should do for me.

Do what? PartialMatch inserts them for you. FullMatch doesn't. The compiler can't guess your intent.

The author actually touches on why it couldn't optimise this away: .* doesn't match any character sequence, it is equivalent to [^\n]* by default

Also, assuming RE2 works like other engines, it also couldn't convert to a partial match without the .* prefix+suffix even if .* matched any char, because you might then ask for capture group 0

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