Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.lang.perl
Subject: Re: Simplifying paths.  A hairy regex
Message-ID: <19249:Mar223:57:2891@kramden.acf.nyu.edu>
Date: 2 Mar 91 23:57:28 GMT
References: <11249@cae780.csi.com> <1991Mar2.202521.29658@iwarp.intel.com>
Organization: IR
Lines: 15
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In article <1991Mar2.202521.29658@iwarp.intel.com> merlyn@iwarp.intel.com (Randal L. Schwartz) writes:
> Hmm.  after writing this code, I know it breaks on "../..".  Yuck.
> But I'm late for my next appointment.  The flash I just had (if
> someone wants to make it work) is to have an inviolate "prefix string"
> consisting of all the null and ".." entries from the head of the
> string as in /^((\.\.)?\/)+/, and then push and pop the rest as above.

No, that fails. foo/../../bar. You'll have to keep track of the number
of leading ..'s, then apply your solution, increasing the number of ..'s
by one every time you pop an empty stack.

I think the regexp version is more natural; I basically did it that way
when I wrote the same routine in C a month back.

---Dan