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package SWISH::ParseQuery;
# Module to parse the "Parsed Words:" header returned by swish
#
# Copyright (C) 2003 Bill Moseley
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version
# 2 of the License, or (at your option) any later version.
# The full text of the GNU General Public License is at URL
# http://www.fsf.org/copyleft/gpl.html and this software is
# licensed as specified there.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
use strict;
require Exporter;
use vars qw/$VERSION @ISA @EXPORT/;
@ISA = qw(Exporter);
$VERSION = '0.01';
@EXPORT = 'parse_query';
sub parse_query {
my ( $query, $phraseDelimiter ) = @_;
return {} unless $query;
s/^\s+//, s/\s+$// for $query;
my @tokens = split /\s+/, $query;
my %p = (
query => [ split /\s+/, $query ],
phrase => $phraseDelimiter || '"',
metas => {},
);
process_query( \%p );
# sort in reverse phrase length order
$_ = [ sort { @$b <=> @$a } @$_ ] for values %{$p{metas}};
return $p{metas};
}
sub process_query {
my ( $p, $current_meta, $end_char, $single_token ) = @_;
$current_meta ||= 'swishdefault';
my $query = $p->{query};
my $phrase = $p->{phrase};
my $metas = $p->{metas};
while ( my $next_token = shift @$query ) {
last if $end_char && $next_token eq $end_char;
# check for sub query
if ( $next_token eq '(' ) {
process_query( $p, $current_meta, ')' );
# check for start of a phrase
} elsif ( @$query > 1 && $next_token eq $phrase ) {
push @{$metas->{$current_meta}}, fetch_words( $query, $phrase );
# check for metaname
} elsif ( @$query > 1 && $query->[0] eq '=' ) {
shift @$query;
warn "nested metaname '$next_token' inside meta '$current_meta'" if $single_token;
process_query( $p, $next_token, undef, 1 ); # fetch one word, phrase, or sub-query
# ignore operators outside of quotes
} elsif ( $next_token =~ /^(?:and|or|not)$/ ) {
next;
# just a regular word
} else {
push @{$metas->{$current_meta}}, [$next_token];
}
last if $single_token; # use for meta names
}
}
sub fetch_words {
my ( $tokens, $end_char ) = @_;
my @words;
while ( my $word = shift @$tokens ) {
last if $word eq $end_char;
push @words, $word;
}
return \@words;
}
1;
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