How to move pieces with Games_Chess

There are two basic methods for performing moves with Games_Chess, moveSAN and moveSquare. Both of these methods either return TRUE or a PEAR_Error class upon error, so the proper way to handle for a return value is:

<?php
require_once 'Games/Chess/Standard.php';
$standard = new Games_Chess_Standard;
$err = $standard->moveSAN('Nf9');
if ($standard->isError($err)) {
    echo $err->getMessage();
    die;
}
?>

The example below demonstrates the two ways that Games_Chess should be called to make moves on the chess board, including the way to represent a placement move in the Crazyhouse variant:

<?php
require_once 'PEAR.php'; // for the PEAR_Error class
function showerror($err)
{
    echo $err->getMessage();
    exit;
}
require_once 'Games/Chess/Standard.php';
require_once 'Games/Chess/Crazyhouse.php';
PEAR::setErrorHandling(PEAR_ERROR_CALLBACK, 'showerror');
$standard = new Games_Chess_Standard;
$crazyhouse = new Games_Chess_Crazyhouse;
$standard->resetGame();
$crazyhouse->resetGame();

$standard->moveSAN('e4'); // 'e2' to 'e4' if using moveSquare
$standard->moveSquare('d7', 'd5'); // 'd5' if using moveSAN
$standard->moveSAN('exd5');

$crazyhouse->moveSquare('e2', 'e4'); // same as moveSAN() above
$crazyhouse->moveSAN('d5'); // save as moveSquare above
$crazyhouse->moveSAN('exd5');
$crazyhouse->moveSAN('Qxd5');
$crazyhouse->moveSAN('P@d7'); // dumb move, but demonstrates piece placement
?>

<?php
require_once 'PEAR.php'; // for the PEAR_Error class
function showerror($err)
{
    echo $err->getMessage();
    exit;
}
require_once 'Games/Chess/Crazyhouse.php';
PEAR::setErrorHandling(PEAR_ERROR_CALLBACK, 'showerror');
$crazyhouse = new Games_Chess_Crazyhouse;
$crazyhouse->resetGame();
$crazyhouse->moveSAN('e4');
$crazyhouse->moveSAN('d5');
$crazyhouse->moveSAN('exd5');
$crazyhouse->moveSAN('Qxd5');
$crazyhouse->moveSAN('d3');
$crazyhouse->moveSAN('Kd7');
$crazyhouse->moveSAN('d4');
$crazyhouse->moveSAN('Ke6');
$crazyhouse->moveSAN('P@d7');
$crazyhouse->moveSAN('Qd6');
// $crazyhouse->moveSAN('d8=Q'); // normal way to do this
$crazyhouse->moveSquare('d7', 'd8', 'Q'); // using moveSquare to do this
// dumb moves, but demonstrates pawn promotion to queen
?>

Retrieving information on the game in progress

To retrieve necessary information such as the current move list, current FEN, list of captured pieces (Crazyhouse only), determine whether the game is over and so on, you'll want to use one of the following methods:

• gameOver(). This method can be used to determine if the game has concluded, and simply returns an abbreviation of W if the white pieces have won (checkmate), B if the black pieces have won (checkmate), D if there is a draw, or false if the game is still in progress.

• renderFen().

  This method returns a Forsyth-Edwards Notation (FEN) representation of the current game state. Note that the FEN standard does not contain a way to represent captured pieces, and so cannot be used to exactly replicate a Crazyhouse game in progress, although it can be close.

• toArray().

  For the Standard and Loser's chess drivers, this returns an associative array of algebraic square name (a1 to h8) mapped to its contents. If the square is unoccupied, it will contain its algebraic square name (a1 will map to a1), otherwise it will contain the piece name, one of P, R, N, B, Q or K. If the piece is a white piece, it will be in upper case, like P, and if the piece is a black piece, it will be in lower case like p.

  For the Crazyhouse driver, this returns an associative array with two indices, board and captured. The board element is identical to the return for Standard/Loser's chess drivers described in the previous paragraph. The captured sub-array contains an array of this format:

  <?php $captured = array( 'W' => array( 'P' => 6, // 6 black pawns captured by white 'R' => 0, 'N' => 0, 'B' => 0, 'Q' => 0, ), 'B' => array( 'P' => 4, // 4 white pawns captured by black 'R' => 0, 'N' => 0, 'B' => 0, 'Q' => 0, ), ); ?>

  Each segment represents white's or black's pieces (W and B), and each sub-element represents the number of captured pieces of that type. In the example above, white can choose to place a pawn for up to the next 6 moves in a row, whereas black can choose to place a pawn for up to the next 4 moves in a row.

• toMove().

  This methods simply returns the color of the pieces that have the next move. W is returned for white, B is returned for black.