coercion happens during obj construction too

[gitmo/Moose.git] / lib / Moose / Util / TypeConstraints.pm

package Moose::Util::TypeConstraints;

use strict;
use warnings;

use Carp         'confess';
use Sub::Name    'subname';
use Scalar::Util 'blessed';

our $VERSION = '0.02';

sub import {
	shift;
	my $pkg = shift || caller();
	return if $pkg eq ':no_export';
	no strict 'refs';
	foreach my $export (qw(type subtype as where coerce from via)) {
		*{"${pkg}::${export}"} = \&{"${export}"};
	}	
}

{
    my %TYPES;
    sub find_type_constraint { 
        my $type_name = shift;
        $TYPES{$type_name}; 
    }

    sub register_type_constraint { 
        my ($type_name, $type_constraint) = @_;
        $TYPES{$type_name} = $type_constraint;
    }
    
    sub dump_type_constraints {
        require Data::Dumper;
        $Data::Dumper::Deparse = 1;
        Data::Dumper::Dumper(\%TYPES);
    }
    
    sub export_type_contstraints_as_functions {
        my $pkg = caller();
	    no strict 'refs';
    	foreach my $constraint (keys %TYPES) {
    		*{"${pkg}::${constraint}"} = $TYPES{$constraint};
    	}        
    }
}

{
    my %COERCIONS;
    sub find_type_coercion { 
        my $type_name = shift;
        $COERCIONS{$type_name}; 
    }

    sub register_type_coercion { 
        my ($type_name, $type_coercion) = @_;
        $COERCIONS{$type_name} = $type_coercion;
    }
}


sub type ($$) {
	my ($name, $check) = @_;
	my $full_name = caller() . "::${name}";
	register_type_constraint($name => subname $full_name => sub { 
		local $_ = $_[0];
		return undef unless $check->($_[0]);
		$_[0];
	});
}

sub subtype ($$;$) {
	my ($name, $parent, $check) = @_;
	if (defined $check) {
	    my $full_name = caller() . "::${name}";
		$parent = find_type_constraint($parent) 
		    unless $parent && ref($parent) eq 'CODE';
		register_type_constraint($name => subname $full_name => sub { 			
			local $_ = $_[0];
			return undef unless defined $parent->($_[0]) && $check->($_[0]);
			$_[0];
		});	
	}
	else {
		($parent, $check) = ($name, $parent);
		$parent = find_type_constraint($parent) 
		    unless $parent && ref($parent) eq 'CODE';		
		return subname '__anon_subtype__' => sub { 			
			local $_ = $_[0];
			return undef unless defined $parent->($_[0]) && $check->($_[0]);
			$_[0];
		};		
	}
}

sub coerce ($@) {
    my ($type_name, @coercion_map) = @_;
    #use Data::Dumper;
    #warn Dumper \@coercion_map;    
    my @coercions;
    while (@coercion_map) {
        my ($constraint_name, $action) = splice(@coercion_map, 0, 2);
        my $constraint = find_type_constraint($constraint_name);
        (defined $constraint)
            || confess "Could not find the type constraint ($constraint_name)";
        push @coercions => [  $constraint, $action ];
    }
    register_type_coercion($type_name, sub { 
        my $thing = shift;
        foreach my $coercion (@coercions) {
            my ($constraint, $converter) = @$coercion;
            if (defined $constraint->($thing)) {
                return $converter->($thing);
            }
        }
        return $thing;
    });
}

sub as    ($) { $_[0] }
sub from  ($) { $_[0] }
sub where (&) { $_[0] }
sub via   (&) { $_[0] }

# define some basic types

type Any => where { 1 };

type Value => where { !ref($_) };
type Ref   => where {  ref($_) };

subtype Int => as Value => where {  Scalar::Util::looks_like_number($_) };
subtype Str => as Value => where { !Scalar::Util::looks_like_number($_) };

subtype ScalarRef => as Ref => where { ref($_) eq 'SCALAR' };	
subtype ArrayRef  => as Ref => where { ref($_) eq 'ARRAY'  };
subtype HashRef   => as Ref => where { ref($_) eq 'HASH'   };	
subtype CodeRef   => as Ref => where { ref($_) eq 'CODE'   };
subtype RegexpRef => as Ref => where { ref($_) eq 'Regexp' };	

# NOTE: 
# blessed(qr/.../) returns true,.. how odd
subtype Object => as Ref => where { blessed($_) && blessed($_) ne 'Regexp' };

1;

__END__

=pod

=head1 NAME

Moose::Util::TypeConstraints - Type constraint system for Moose

=head1 SYNOPSIS

  use Moose::Util::TypeConstraints;

  type Num => where { Scalar::Util::looks_like_number($_) };
  
  subtype Natural 
      => as Num 
      => where { $_ > 0 };
  
  subtype NaturalLessThanTen 
      => as Natural
      => where { $_ < 10 };
      
  coerce Num 
      => from Str
        => via { 0+$_ }; 

=head1 DESCRIPTION

This module provides Moose with the ability to create type contraints 
to be are used in both attribute definitions and for method argument 
validation. 

This is B<NOT> a type system for Perl 5.

This module also provides a simple hierarchy for Perl 5 types, this 
could probably use some work, but it works for me at the moment.

  Any
      Value
          Int
          Str
      Ref
          ScalarRef
          ArrayRef
          HashRef
          CodeRef
          RegexpRef
          Object	

Suggestions for improvement are welcome.	
    
=head1 FUNCTIONS

=head2 Type Constraint Registry

=over 4

=item B<find_type_constraint ($type_name)>

=item B<register_type_constraint ($type_name, $type_constraint)>

=item B<find_type_coercion>

=item B<register_type_coercion>

=item B<export_type_contstraints_as_functions>

=item B<dump_type_constraints>

=back

=head2 Type Constraint Constructors

=over 4

=item B<type>

=item B<subtype>

=item B<as>

=item B<where>

=item B<coerce>

=item B<from>

=item B<via>

=back

=head2 Built-in Type Constraints

=over 4

=item B<Any>

=item B<Value>

=item B<Int>

=item B<Str>

=item B<Ref>

=item B<ArrayRef>

=item B<CodeRef>

=item B<HashRef>

=item B<RegexpRef>

=item B<ScalarRef>

=item B<Object>

=back

=head1 BUGS

All complex software has bugs lurking in it, and this module is no 
exception. If you find a bug please either email me, or add the bug
to cpan-RT.

=head1 AUTHOR

Stevan Little E<lt>stevan@iinteractive.comE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright 2006 by Infinity Interactive, Inc.

L<http://www.iinteractive.com>

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself. 

=cut