Search code examples
perl

perl regex - pattern matching

Can anyone explain what is being done below?

 $name=~m,common/([^/]+)/run.*/([^/]+)/([^/]+)$,;
Solution
    • common, run and / are match themselves.
    • () captures.
    • [^/]+ matches 1 or more characters that aren't /.
    • .* matches 0 or more characters that aren't Line Feeds.[1]
    • $ is equivalent to (\n?\z).[2]
    • \n optionally matches a Line Feed.
    • \z matches the end of the string.

    I think it's trying to match a path of one or both of the following forms:

    • .../common/XXX/runYYY/XXX/XXX
    • common/XXX/runYYY/XXX/XXX

    Where

    • XXX is a sequence of at least one character that doesn't contain /.
    • YYY is a sequence of any number of characters (incl zero) that doesn't contain /.

    It matches more than that, however.

    • It matches uncommon/XXX/runYYY/XXX/XXX
    • It matches common/XXX/runYYY/XXX/XXX/XXX/XXX/XXX/XXX

    The parts in bold are captured (available to the caller).

    1. When the s flag isn't used.
    2. When the m flag isn't used.