Re: Logic trouble parsing a formatted text file into hashes of hashes (of hashes, etc.)

[ambrus]

This is a tricky question, especially because some of the parenthisized entries in the input contain only a word, some both a word and :foo(...) pairs, some only :foo(...) pairs, so it's not obvious what data structure to use.

Here's my guess for interpreting it (you might want to tidy it a bit of course, like changing what's allowed in words and what's not, or adding my vars).

use Data::Dumper; $s = \%p; @s = (); while (<>) { while (/\G\s*(?:([-\
+w.]+)|:([-\w.]+)\s*\(|(\)))/gc) { if (defined($1)) { defined($$s{""})
+ and die "parse error: two"; $$s{""} = $1; } elsif (defined($2)) { pu
+sh @s, $s; $s = $$s{$2} = {}; } elsif (defined($3)) { @s or die "pars
+e error: close"; $s = pop @s; } } /(\S.*)/g and die "parse error: jun
+k: $1"; } $! and die "read error"; $s == \%p or die "parse error: ope
+n"; print Dumper(\%p);

Update 2006 jun 2: this works for the examples in the node only, not the full example int appears.

[idnopheq]

THX, ambrus!

I'm running with chromatic's idea for the moment.

I like yours as well at first glance, since it only requires Data::Dumper, which every perl-enabled machine has by dafault.

[ambrus]

Here's a corrected version that can parse the long sample on your scratchpad (which I also copy below so that it wouldn't disappear unexpextedly). The original script (that in the parent thread) couldn't parse the longer sample because of features it had that I couldn't have guessed from the small samples on the node, and by the time I wrote that you didn't give us the long sample. There are three differences: firstly, this script expects that the data starts with an opening parenthesis, secondly, it accepts a lone colon instead of a colon with a keyword after it, thirdly, it accepts double-quoted strings.

perl -we 'use Data::Dumper; $s = \%p; @s = (); while (<>) { our $f++ o
+r $_ = ": " . $_; while (/\G\s*(?:([-\w.]+|"[^"]*")|:([-\w.]*)\s*\(|(
+\)))/gc) { if (defined($1)) { defined($$s{""}) and die "parse error: 
+two"; $$s{"@"} = $1; } elsif (defined($2)) { push @s, $s; $s = $$s{$2
+} = {}; } elsif (defined($3)) { @s or die "parse error: close"; $s = 
+pop @s; } } /(\S.*)/g and die "parse error: junk: $1"; } $! and die "
+read error"; $s == \%p or die "parse error: open"; print Dumper(\%p);
+'

A historical note. I did the correction because someone has asked on an irc channel how to parse a file of this exact format.

Here's the long sample

Read more... (58 kB)

Update: a version of the above converted to a real script (not a one-liner using global variables) is here. This one also removes double-quotes from double-quoted strings and accepts multi-line strings. The file format has backslash-escaped double quotes in double-quoted strings it seems, and possibly other things this can't parse.

use warnings; use strict;
use Data::Dumper;
sub parse {
        my($f) = @_;
        my($s, %p, @s, $b);
        $s = \%p;
        while (<$f>) {
                $b++ or $_ = ": " . $_; 
                while (/\G\s*(?:([-\w.]+)|"([^"]*)"|("[^"]*$)|:([-\w.]
+*)\s*\(|(\)))/gc) {     
                        if (defined($1) || defined($2)) {
                                defined($$s{""}) and die "parse error:
+ two";
                                $$s{"@"} = defined($1) ? $1 : $2;
                        } elsif (defined($3)) { 
                                $_ = $+ . <$f>;  
                        } elsif (defined($4)) { 
                                push @s, $s; 
                                $s = $$s{$+} = {}; 
                        } elsif (defined($5)) { 
                                @s or die "parse error: close"; 
                                $s = pop @s; 
                        }
                } 
                /(\S.*)/g and die "parse error: junk: $1";
        } 
        $! and die "read error"; 
        $s == \%p or die "parse error: open";
        \%p;
}
my $p = parse(*ARGV);
print Dumper($p);
__END__

Update: defined($$s{""}) and die "parse error: two"; shoud be changed to defined($$s{"@"}) and die "parse error: two"; in both scripts I belive.