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# $Id: Constraint.pm,v 1.9 2007/03/05 09:12:49 cmungall Exp $
# -------------------------------------------------------
#
# Copyright (C) 2003 Chris Mungall <cjm@fruitfly.org>
#
# This module is free software.
# You may distribute this module under the same terms as perl itself
#---
# POD docs at end of file
#---
package DBIx::DBStag::Constraint;
use strict;
use vars qw($VERSION @ISA @EXPORT_OK %EXPORT_TAGS $DEBUG $AUTOLOAD);
use Carp;
use DBI;
use Data::Stag qw(:all);
use DBIx::DBStag;
$VERSION='0.12';
sub DEBUG {
$DBIx::DBStag::DEBUG = shift if @_;
return $DBIx::DBStag::DEBUG;
}
sub trace {
my ($priority, @msg) = @_;
return unless $ENV{DBSTAG_TRACE};
print "@msg\n";
}
sub dmp {
use Data::Dumper;
print Dumper shift;
}
sub new {
my $proto = shift;
my $class = ref($proto) || $proto;
my $self = {};
bless $self, $class;
$self->bindings({});
$self->children([]);
$self;
}
# takes a simple hash of bindings
# and makes an ANDed set of constraints
sub from_hash {
my $class = shift;
my $h = shift;
my $cons = $class->new;
$cons->bool('and');
$cons->children([
map {
my $sc = $class->new;
$sc->bindings({$_ => $h->{$_}});
$sc;
} keys %$h
]);
return $cons;
}
sub throw {
my $self = shift;
my $fmt = shift;
print STDERR "\nERROR:\n";
printf STDERR $fmt, @_;
print STDERR "\n";
confess;
}
#AND, OR, NOT
sub bool {
my $self = shift;
$self->{_bool} = shift if @_;
return $self->{_bool};
}
# eg AND(cons1, cons2, cons3)
sub children {
my $self = shift;
$self->{_children} = shift if @_;
return $self->{_children};
}
sub is_leaf {
my $self = shift;
return !scalar(@{$self->children});
}
# value to replace => in option block with
sub op {
my $self = shift;
$self->{_op} = shift if @_;
return $self->{_op};
}
# variable bindings - hash of varname => varval
sub bindings {
my $self = shift;
$self->{_bindings} = shift if @_;
return $self->{_bindings};
}
1;
__END__
=head1 NAME
DBIx::DBStag::Constraint - recursive structure for representing query constraints
=head1 SYNOPSIS
=cut
=head1 DESCRIPTION
A constraint is a recursive structure for representing query constraints;
AND --- x=1
\
\---- OR --- y>2
\
\----- boolfunc(z)
A constraint is either a bool (AND, OR, NOT) with >0 children,
or it can be a leaf node representing an atomic constraint
the constraint corresponds to a SQLTemplate option block; eg
[ name LIKE &name& ]
[ name => &name& ]
[ start > &min_start& ]
[ start => &start& ]
[ somefunc(&x&) ]
[ somefunc(&x&, &y&) ]
[ somefunc(t.col, &x&, &y&) => &z& ]
the constraint consists of an operator (represented by => in the
option block). If no => is present, then it is a simple variable binding.
A constraint can consist of multiple variable bindings
=head1 WEBSITE
L<http://stag.sourceforge.net>
=head1 AUTHOR
Chris Mungall <F<cjm@fruitfly.org>>
=head1 COPYRIGHT
Copyright (c) 2003 Chris Mungall
This module is free software.
You may distribute this module under the same terms as perl itself
=cut
1;
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