A theoretical question which piqued my interest.

my $str = "tar a rat at ararat";

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A match:

$str =~ /at(.*)at/; # captures " at arar"

The same, but non-greedy:

$str =~ /at(.*?)at/; # captures just" "

You might call this "right-non-greedy". Where it matches, it matches, and grabs as little as possible to the right of that.

So what would be the best (shortest, most comprehensible and complete) way to write a "left-non-greedy" match? I.e.

$str =~ /at($magic_match)at/; # matches " arar"

where $magic_match matches at the last place possible, so that it has to grab as little as possible?

Head spinning now... how about a regex that is both right-and-left-non-greedy. I.e. it tries to grab as little as possible, both by matching minimally, and by trying to match as late as possible - and compares all the possibilities to find the shortest?

(I'm looking for generic solutions here - a regex, or at least a way to write regexes, that would work for left- or both- non-greedy matching on any string.)

andramoiennepemousapolutropon

In reply to left-non-greedy regex? by dash2

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