bliako has asked for the wisdom of the Perl Monks concerning the following question:

Esteemed Monks,

I am trying to translate the following Node.js fragment to Perl (it takes a URL and sort of chdir to it, clever enough to remove endpoint if a file and query):

const url = require('url'); const x = 'http:/'; const y = '../../../'; console.log(url.resolve(x, y));

result is : http:/

Now, if x='http:/'; (i.e. the path points to a "directory" rather than to a "file") the result is http:/ (as expected IMO)

I tried to do this with URI but failed:

use URI; my $x = 'http:/'; my $y = '../../../'; my $u = URI->new($x); my $p = $u->path().'/'.$y; $u->path($p); print $u; <c> <p>With this result: <c>http:/

The Node.js version seems to be able to understand that the last segment before the query is a "file" and removes it. Then it does the merging of the two paths including successful relative operations (../). What is the safest way to achieve that behaviour in Perl? The last resort would be to shell-out to Node.js ...

bw, bliako

Replies are listed 'Best First'.
Re: URL resolve (operations on path etc.)
by haukex (Archbishop) on Jul 31, 2022 at 07:52 UTC
    use warnings; use strict; use URI; my $x = ''; my $y = '../../../'; my $u = URI->new($y); print $u->abs($x), "\n"; __END__

      Thanks haukex++ (I swear last night abs was not working!!!!!!)

      EDIT!: ouchhhh I was doing the reverse!!!!!:

      # this is wrong, note new($x)!! abs($y) it should be the reverse my $u = URI->new($x); # this is wrong print $u->abs($y), "\n"; # this is wrong

      Edit2: that's definetely an X-Y problem hehe

      Could this be resolved with a regex maybe? Like for example:

      #!/usr/bin/perl use strict; use warnings; my $PATH = '' . '/' . '/../../../ +'; $PATH =~ tr|/||s; my $PREV = 0; my $LEN; for (;;) { $PATH =~ s/\/[^\/]+\/\.\.//; $LEN = length($PATH); last if ($PREV == $LEN); $PREV = $LEN; } print $PATH;

      I put the regex in a for(;;) loop, because adding global flag didn't do what I want:

      $PATH =~ s/\/[^\/]+\/\.\.//g;

Re: URL resolve (operations on path etc.)
by Your Mother (Archbishop) on Jul 31, 2022 at 17:27 UTC

    haukex already solved it but this is the way I generally handle these. It lends itself to bulk changes; URI.

    ~>perl -MURI -E '$x = ""; $y = "../ +../../"; say URI->new_abs($y,$x);'