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Re: Re-define Word Boundary?

by thelenm (Vicar)
on Nov 20, 2003 at 23:27 UTC ( #308753=note: print w/ replies, xml ) Need Help??


in reply to Re-define Word Boundary?

\w matches alphanumerics and underscore. \b is effectively the same as using lookbehinds and lookaheads like this:

(?:(?<=\w)(?=\W|\z)|(?:(?<=\W)|(?<=\A))(?=\w)

Update: Hmm, or even nicer, as merlyn posted in •Re: Why do zero width assertions care about lookahead/behind? (code examples also updated),

(?:(?<!\w)(?=\w)|(?<=\w)(?!\w))

So to make a specialized version of \b that views "-" and "/" as "word characters" (sort of), you might use something like this:

(?:(?<![\w/-])(?=[\w/-])|(?<=[\w/-])(?![\w/-]))

So maybe something like this will suit you?

my $w = '\w/-'; my $b = "(?:(?<![$w])(?=[$w])|(?<=[$w])(?![$w]))"; my @words = ($rec =~ /${b}[$w]+${b}/g);

I've tested this a little but not a lot, and it seems all right. You'll want to verify it yourself before you go using it for anything important :-)

-- Mike

--
XML::Simpler does not require XML::Parser or a SAX parser. It does require File::Slurp.
-- grantm, perldoc XML::Simpler


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