regex parsing brainteaser

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

I have a simple solution for this. Just wondering if there's a cool regex trick to do it in one shot.

Given data like this:

<%def .errors>
missing_name: You must provide your name.
missing_email: You must provide your email address.
</%def>
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I want to end up with a hash containing the keys and values implied by this format. This was my first try:

my %errors =
  ( $data =~ m|<\%def \.errors>.*?(?:(^\w+):(.*?)$)+.*?</\%def>|sgm );
[download]

But of course that only gets the first one. Is there a way to get them all without first trimming the text?

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Re: regex parsing brainteaser by Roy Johnson (Monsignor) on Apr 01, 2008 at 20:35 UTC
`my %errors = ( $data =~ m#(?:<\%def \.errors>\|\G).?(?:(^\w+):(.?)$)(?=.?</\%de +f>)#sgm );` [download] It's not immune to matching before or after the tags, though. That gets uglier: `my %errors = ( $data =~ m#(?:<\%def \.errors>\|(?<=.)\G)(?:(?!</\%def>).)?(?:(^\w ++):([^\n]))(?=.?</\%def>)#sgm );` [download] Caution: Contents may have been coded under pressure.	[reply] [d/l] [select]
Re: regex parsing brainteaser by ikegami (Patriarch) on Apr 01, 2008 at 22:32 UTC
You really need a parser. Using extended regexp features, you can write a parser in a regexp. use strict; use warnings; my $text = <<'__EOI__'; <%def .errors> missing_name: You must provide your name. missing_email: You must provide your email address. </%def> __EOI__ # Perl code in regexps close over lexicals when # the regexp is compiled. It's best to avoid # using lexical variables declared outside the # regexp in Perl code in regexps. local our %errors; $text =~ / (?{ +{} }) <%def\ \.errors> \n (?: (\w+): \s* (.) \n (?{ +{ %{$^R}, $1 => $2 } }) ) <\/%def> \n (?{ %errors = %{$^R} }) /x or die("Bad text\n"); for (keys %errors) { print("$_ => $errors{$_}\n"); } [download] 5.10 has features that make this even easier, but I haven't taken the time to look at them yet.	[reply] [d/l]
Re: regex parsing brainteaser by FunkyMonk (Bishop) on Apr 01, 2008 at 22:58 UTC
I'm all for simplicity, so I'd split this into two steps: `my $data = '<%def .errors> missing_name: You must provide your name. missing_email: You must provide your email address. </%def>'; my ( $errors ) = $data =~ m[\Q<%def .errors>\E\n (.\n) \Q</%def>\E ]sx; my %errors = $errors =~ m{(\w+):\s(.*?)\n}g; print Dumper \%errors;` [download] Output: `$VAR1 = { 'missing_email' => 'You must provide your email address.', 'missing_name' => 'You must provide your name.' };` [download]	[reply] [d/l] [select]
Re: regex parsing brainteaser by poolpi (Hermit) on Apr 02, 2008 at 13:32 UTC
`#!/usr/bin/perl use strict; use warnings; use Data::Dumper; $_= q{<%def .errors> missing_name: You must provide your name. missing_email: You must provide your email address. </%def>}; my %errors; my $start = q{<%def .errors>}; my $end = q{</%def>}; /$start/ .. /$end/ and %errors = ( $_ =~/ (.+) [:] (.+) [.] /gx ); print Dumper \%errors;` [download] `Output: $VAR1 = { 'missing_email' => ' You must provide your email address', 'missing_name' => ' You must provide your name' };` [download] hth, PooLpi 'Ebry haffa hoe hab im tik a bush'. Jamaican proverb	[reply] [d/l] [select]