http://www.perlmonks.org?node_id=728756


in reply to In search of an efficient query abstractor

The regexes do a lot of backtracking and stuff.

Which one? I don't see anywhere that backtracking could occur. Everything there's a choice, only one path can possibly match.

$query =~ s{ (?<![\w.+-]) [+-]? (?: \d+ (?:[.]\d*)? |[.]\d+ ) (?:e[+-]?\d+)? \b } {N}gx; # Float/real into N

The trailing \b is buggy.

"12345 " -> "N " "12345. " -> "N. "

It matched "12345." until the "\b" was reached, then it backtracked to release the "." from the match. Oops, I guess there is backtracking, but only because of the bug.