<?php

/* Basic Queue Class
 * Asher Holley ( http://www.wolfoxinc.com/opensource/ )
 * Based on the Stack class ( http://www.phpclasses.org/browse/package/3442.html )
 * Released under the GNU General Public License ( http://www.opensource.org/licenses/gpl-license.html )
 * Copyright © 2006 Asher Holley
 *
 * This queue is based on the "ps stack" class available at PHP Classes
 *   that I have authored. */

require_once( 'list.abstr.php' );

class Queue extends List_abstr implements Countable, ArrayAccess {
	private $fifo;

	function __construct( $data = null ) {
		if ( is_array( $data ) ) {
			$this->fifo = $data;
		} else if ( is_a( $data, 'Queue' ) ) {
			$this->fifo = $data->fifo;
		} else if ( $data ) {
			$this->fifo = array();
			$this->fifo[] = $data;
		} else {
			$this->fifo = array();
		}

		return;
	}
	
	public function offsetSet( $key, $value ) {
		if ( is_numeric( $key ) ) {
			if ( $this->index( $key ) ) {
				$r =& $this->index_ref( $key );
				$r = $value;
				return $value;
			}
		}
		
		if ( $key = '' ) {
			$this->push( $value );
		}
		
		return null;
	}
	
	public function offsetGet( $key ) {
		if ( is_numeric( $key ) ) {
			return $this->index( $key );
		}
		
		return null;
	}
	
	public function offsetUnset( $key ) {
		if ( is_numeric( $key ) ) {
			if ( $offset > count( $this->fifo ) - 1 || $offset < 0 ) {
				return false;
			} else {
				unset( $this->fifo[ $offset ] );
				return true;
			}
		}
		
		return false;
	}
	
	public function offsetExists( $offset ) {
		if ( is_numeric( $key ) ) {
			if ( $offset > count( $this->fifo ) || $offset < 0 ) {
				return false;
			} else {
				return array_key_exists( $offset, $this->fifo );
			}
		}
	}
	
	public function top() {
		if ( !empty( $this->fifo ) ) {
			return $this->fifo[0];
		} else {
			return null;
		}
	}
	
	public function &top_ref() {
		if ( !empty( $this->fifo ) ) {
			return $this->fifo[0];
		} else {
			return null;
		}
	}

	public function push() {
		$args = func_get_args();
		$exec = 'array_push( $this->fifo';
		for ( $a = 0; $a < count( $args ); $a++ ) {
			$exec .= ', $args[' . $a . ']';
		}
		
		$exec .= ' );';
		return eval( $exec );
	}

	public function pop() {
		return array_shift( $this->fifo );
	}
	
	public function &pop_ref() {
		$e =& $this->top_ref();
		array_shift( $this->fifo );
		return $e;
	}
	
	public function index( $i ) {
		if ( $i > count( $this->fifo ) - 1 || $i < 0 ) {
			return null;
		} else {
			return $this->fifo[ $i ];
		}
	}
	
	public function &index_ref( $i ) {
		if ( $i > count( $this->fifo ) - 1 || $i < 0 ) {
			return null;
		} else {
			return $this->fifo[ $i ];
		}
	}
	
	public function count() {
		return count( $this->fifo );
	}
	
	public function is_empty() {
		return empty( $this->fifo );
	}

	public function clear() {
		$this->fifo = array();
		return;
	}

	public function get_queue() {
		return $this->fifo;
	}
	
	public function get_list() {
		return get_queue();
	}
	
	public function exch() {
		$m0 = $this->pop_ref();
		$m1 = $this->pop_ref();
		$this->fifo[1] =& $m0;
		$this->fifo[0] =& $m1;
		return;
	}
	
	public function dup() {
		array_unshift( $this->fifo, $this->top() );
		return;
	}
	
	public function roll( $c ) {
		if ( is_int( $c ) ) {
			if ( abs( $c ) > ( $l = $this->count() ) ) {
				if ( $c < 0 ) {
					$c = ( abs( $c ) % $l ) * -1;
				} else {
					$c %= $l;
				}
			}
			
			if ( $c > 0 ) { // rotate right
				$this->fifo = array_merge( array_slice( $this->fifo, $c ),
										array_slice( $this->fifo, 0, $c ) );
			} else if ( $c < 0 ) { // rotate left
				$c = abs( $c );
				$this->fifo = array_merge( array_slice( $this->fifo, $l - $c ),
										array_slice( $this->fifo, 0, $l - $c ) );
			}
		}

		return;
	}
}

?>