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#
# Copyright (C) 2000 Benjamin Drieu
#
# 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, or (at your option) any
# later version.
#
# 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.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
#
#
# $Header: /cvsroot/TextQuery/Text-Query-SQL/lib/Text/Query/BuildSQLPg.pm,v 1.1 2000/03/21 14:10:48 benj2 Exp $
#
package Text::Query::BuildSQLPg;
use strict;
use vars qw(@ISA $VERSION);
use Text::Query::BuildSQL;
use Carp;
@ISA = qw(Text::Query::BuildSQL);
sub build_near {
my($self, $l, $r) = @_;
if($$l[0] ne 'literal' || $$r[0] ne 'literal') {
croak("cannot use near on non literal");
} elsif($$l[1] ne $$r[1]) {
croak("cannot use near with literals that does not belong to the same scope");
} else {
my($t);
# if(!$self->{parseopts}{-encoding} =~ /^big5$/io) {
# $t = "$$l[2]%$$r[2]";
# } else {
my($max) = $self->{parseopts}{-near};
my($op) = "[^a-z0-9]{0,$max}";
$t = "$$l[2]$op$$r[2]";
# }
return [ 'literal', $$l[1], $t ];
}
}
sub resolve {
my($self, $scope, $t) = @_;
#
# If the scope is not the scope of the enclosing
# expression, the field must be explicitly specified.
#
my($fill_fields) = ( @{$scope} > 0 ) ? $$t[1] ne $scope->[0] : 1;
if(!ref($$t[2]) || $$t[0] eq 'true') {
return $self->resolve_literal($t, $fill_fields);
} else {
my(@operands);
unshift(@{$scope}, $$t[1]);
foreach (@{$t}[2..$#{$t}]) {
push(@operands, $self->resolve($scope, $_));
}
shift(@{$scope});
my(%opmap) = (
'and' => 'and',
'or' => 'or'
);
my($expr);
#
# If there is an homogenous scope, use compact form
#
if($$t[1]) {
if($opmap{$$t[0]}) {
$expr = " ( " . join(" $opmap{$$t[0]} ", @operands) . " ) ";
} elsif($$t[0] eq 'not') {
$expr = "not (@operands)";
} elsif($$t[0] eq 'near') {
my($max) = $self->{parseopts}{-near};
$expr = "( " . join(" & ", @operands ) . " ) ";
}
#
# If this expression is not enclosed in an homogenous form
# resolve to explicit syntax
#
if($fill_fields) {
return $self->fill_fields($expr, $$t[1]);
} else {
#
# Otherwise just return the compact form
#
return $expr;
}
} else {
#
# We are not in homogenous scope, use explicit form
#
if($$t[0] eq 'or' or $$t[0] eq 'and') {
return " ( " . join(" $$t[0] ", @operands) . " ) ";
} elsif($$t[0] eq 'not') {
return "not (@operands) ";
}
}
}
}
sub has_relevance {
shift->SUPER::has_relevance();
return 1;
}
sub resolve_literal {
my($self, $t, $fill_fields) = @_;
my($true_value) = $$t[0] eq 'true';
my($weight) = '';
if($self->relevance_needed()) {
#
# At present relevance ranking is only needed for simple requests
#
if($true_value) {
#
# The 'true' value term has default weight (1)
#
$t = $$t[2];
} else {
#
# All search terms have a 10 weight
#
# $weight = ' weight 10';
}
}
my($value) = "'[[:<:]]" . $self->quote($$t[2]) . "[[:>:]]'";
# if($fill_fields) {
return $self->fill_fields("__FIELD__ ~* $value", $$t[1]);
# } else {
#
# If the enclosing expression has the same scope, the distribution
# is delayed.
#
# return $value;
# }
}
sub fill_fields {
my($self, $t, $fields) = @_;
return $t if($t !~ /__FIELD__/o);
my(@t);
my($scope);
foreach $scope (split(',', $fields)) {
my($tmp) = $t;
$tmp =~ s/__FIELD__/$scope/g;
push(@t, $tmp);
}
return @t == 1 ? $t[0] : "( ( " . join(" ) or ( ", @t) . " ) )";
}
1;
__END__
=head1 NAME
Text::Query::BuildSQLPg - Builder for Postgres
=head1 SYNOPSIS
use Text::Query;
my $q=new Text::Query('hello and world',
-parse => 'Text::Query::ParseAdvanced',
-solve => 'Text::Query::SolveSQL',
-build => 'Text::Query::BuildSQLPg');
=head1 DESCRIPTION
Generates a well formed C<where> clause for Text::Query::ParseAdvanced or
Text::Query::ParseSimple suitable for query with Postgres.
Code is mainly based on Text:Query::BuildSQLMySQL.
=head1 SEE ALSO
Text::Query(3)
Text::Query::BuildSQL(3)
=head1 AUTHORS
Benjamin Drieu (bdrieu@april.org)
Loic Dachary (loic@senga.org)
=cut
# Local Variables: ***
# mode: perl ***
# End: ***
|
