Chess::Game::MoveListEntry - a read-only class containing move data, used by

Chess documentation Contained in the Chess distribution.

Index

Code Index:

NAME

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Chess::Game::MoveListEntry - a read-only class containing move data, used by Chess::Game::MoveList to record a game.

SYNOPSIS

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$entry = Chess::Game::MoveListEntry->new(1, $pawn, "e2", "e4", 0); $one = $entry->get_move_num(); $pawn = $entry->get_piece(); $e2 = $entry->get_start_square(); $e4 = $entry->get_dest_square(); $false = $entry->is_capture(); $false = $entry->is_short_castle(); $false = $entry->is_long_castle(); $false = $entry->is_en_passant();

DESCRIPTION

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The Chess module provides a framework for writing chess programs with Perl. This class forms part of that framework, containing object data about a single move.

METHODS

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Construction

Constructs a new MoveListEntry with the provided parameters. Requires four scalar parameters containing move number, piece, start square and destination square. Optionally takes a fifth parameter containing flags for the entry. The following flags are recognized (but there are no exported constants for them):

    MOVE_CAPTURE == 0x01
    MOVE_CASTLE_SHORT == 0x02
    MOVE_CASTLE_LONG == 0x04
    MOVE_EN_PASSANT == 0x08

    $entry = Chess::Game::MoveListEntry->new(1, $pawn, "e2", "e4", 0);

Class methods

There are no class methods for this class.

Object methods

Takes no parameters. Returns the move number this entry was constructed with.

Takes no parameters. Returns the piece reference this entry was constructed with.

Takes no parameters. Returns the start square this entry was constructed with.

Takes no parameters. Returns the destination square this entry was constructed with.

Takes no parameters. Returns true if the entry was recorded as a capture

Takes no parameters. Returns true if the entry was recorded as a short (kingside) castle.

Takes no parameters. Returns true if the entry was recorded as a long (queenside) castle.

Takes no parameters. Returns true if the entry was recorded as an 'en passant' capture. "is_capture()" will also return true in this case.

DIAGNOSTICS

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The program uses a reference to a MoveListEntry that was not obtained by calling "new()". Ensure that all MoveListEntries in the program were obtained either in this fashion, or through the container class, Chess::Game::MoveList, and that the reference refers to a defined value.

BUGS

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Please report any bugs to the author.

AUTHOR

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Brian Richardson <bjr@cpan.org>

COPYRIGHT

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Copyright (c) 2002, 2005 Brian Richardson. All rights reserved. This module is Free Software. It may be modified and redistributed under the same terms as Perl itself.

Chess documentation Contained in the Chess distribution. 
package Chess::Game::MoveListEntry;

use Carp;
use strict;

use constant OBJECT_FIELDS => (
    move_num => 0,
    piece_ref => undef,
    from_sq => '',
    dest_sq => '', 
    flags => 0x0,
    promoted_to => undef
);

# Chess::Game uses these flags as well
use constant MOVE_CAPTURE => 0x01;
use constant MOVE_CASTLE_SHORT => 0x02;
use constant MOVE_CASTLE_LONG => 0x04;
use constant MOVE_EN_PASSANT => 0x08;
use constant MOVE_PROMOTE => 0x10;

{
    my @_move_list_entries = ( );
    my %_object_fields = OBJECT_FIELDS;

    sub _get_entry {
	my ($i) = @_;
	return $_move_list_entries[$i];
    }

    sub new {
	my ($caller, $move_num, $r_piece, $from, $dest, $flags) = @_;
	my $class = ref($caller) || $caller;
	my $obj_data = { %_object_fields };
	$obj_data->{move_num} = $move_num;
	croak "Invalid Chess::Piece reference" unless ($r_piece);
	$obj_data->{piece_ref} = $r_piece;
	$obj_data->{from_sq} = $from;
	$obj_data->{dest_sq} = $dest;
	$obj_data->{flags} = defined($flags) ? $flags & 0x1f : 0x0;
	push @_move_list_entries, $obj_data;
	my $i = $#_move_list_entries;
	return bless \$i, $class;
    }

    sub clone {
	my ($self) = @_;
	my $class = ref($self) || croak "Invalid Chess::Game::MoveListEntry reference";
	my $obj_data = { %{$_move_list_entries[$$self]} } || croak "Invalid Chess:Game::MoveListEntry reference";
	if (my $r_piece = $obj_data->{piece_ref}) {
	    $r_piece = $r_piece->clone() if ($r_piece->can('clone'));
	    $obj_data->{piece_ref} = $r_piece;
	}
	push @_move_list_entries, $obj_data;
	my $i = $#_move_list_entries;
	return bless \$i, $class;
    }

    sub DESTROY {
	my ($self) = @_;
	$_move_list_entries[$$self] = undef if (ref($self));
    }
}

sub get_move_num {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless ($obj_data);
    return $obj_data->{move_num}; 
}

sub get_piece {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless ($obj_data);
    return $obj_data->{piece_ref}; 
}

sub get_start_square {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless ($obj_data);
    return $obj_data->{from_sq}; 
}

sub get_dest_square {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless ($obj_data);
    return $obj_data->{dest_sq}; 
}

sub is_capture {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    return $obj_data->{flags} & MOVE_CAPTURE;
}

sub is_short_castle {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    return $obj_data->{flags} & MOVE_CASTLE_SHORT;
}

sub is_long_castle {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    return $obj_data->{flags} & MOVE_CASTLE_LONG;
}

sub is_en_passant {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    return $obj_data->{flags} & MOVE_EN_PASSANT;
}

sub is_promotion {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    return $obj_data->{flags} & MOVE_PROMOTE;
}

sub get_promoted_to {
    my ($self) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    return $obj_data->{promoted_to};
}

sub set_promoted_to {
    my ($self, $new_piece) = @_;
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    my $obj_data = _get_entry($$self);
    croak "Invalid Chess::Game::MoveListEntry reference" unless (ref($self));
    $obj_data->{promoted_to} = $new_piece;
}

1;