ArrayList

<?php
 
/**
 * @name    ArrayList
 * @author  Michael Scribellito
 * @version 1.0 (10/12/2011)
 */
class ArrayList {
 
    /**
     * The array into which the elements of the ArrayList are stored.
     *
     * @var array 
     */
    private $data;
 
    /**
     * The size of the ArrayList (the number of elements it contains).
     *
     * @var integer 
     */
    private $size;
 
    /**
     * Constructs an empty list.
     */
    public function __construct() {
 
        $this->initialize();
 
    }
 
    /**
     * Appends the specified element to the end of this list.
     *
     * @param   mixed $element  element to be appended to this list
     * 
     * @return  boolean  true
     */
    public function add($element) {
 
        $this->data[] = $element;
 
        $this->size++;
 
        return true;
 
    }
 
    /**
     * Checks if the given index is in range. If not, throws an exception.
     * 
     * @param   integer $index  index to check
     * 
     * @throws  Exception
     */
    private function rangeCheck($index) {
 
        if (is_int($index) == false) {
 
            throw new Exception("Index must be numeric");   
 
        }
 
        if ($index < 0 || $index >= $this->size) {
 
            throw new Exception(sprintf("Index out of bounds: Index: %d, Size: %s", $this->size(), $index));
 
        }
 
    }
 
    /**
     * Removes all of the elements from this list. The list will be empty after
     * this call returns.
     * 
     * @return  void
     */
    public function clear() {
 
        $this->initialize();
 
    }
 
    /**
     * Returns the element at the specified position in this list.
     *
     * @param   integer $index  index of the element to return
     * 
     * @return  mixed  the element at the specified position in this list
     * 
     * @throws  Exception
     */
    public function get($index) {
 
        $this->rangeCheck($index);
 
        return $this->data[$index];
 
    }
 
    /**
     * Initializes this list.
     * 
     * @return  void
     */
    private function initialize() {
 
        $this->data = array();
 
        $this->size = 0;
 
    }
 
    /**
     * Returns true if this list contains no elements
     * 
     * @return boolean  true if this list contains no elements
     */
    public function isEmpty() {
 
        return $this->size == 0;
 
    }
 
    /**
     *
     * @return ArrayIterator 
     */
    public function iterator() {
 
        return new ArrayIterator($this->data);
 
    }
 
    /**
     * Removes the element at the specified position in this list. Shifts any
     * subsequent elements to the left (subtracts one from their indices).
     *
     * @param   integer $index  the index of the element to be removed
     * 
     * @return  mixed  the element that was removed from the list
     * 
     * @throws  Exception
     */
    public function remove($index) {
 
        $temp = null;
 
        $this->rangeCheck($index);
 
        $old = $this->get($index);
 
        for ($i = $index; $i < $this->size() - 1; $i++) {
 
            $this->set($i, $this->get($i + 1));
 
        }
 
        unset($this->data[$i]);
 
        $this->size--;
 
        return $old;
 
    }
 
    /**
     * Replaces the element at the specified position in this list with the specified element.
     * 
     * @param   integer $index  index of the element to replace
     * @param   mixed $element  element to be stored at the specified position
     * 
     * @return  mixed  the element previously at the specified position
     * 
     * @throws  Exception
     */
    public function set($index, $element) {
 
        $this->rangeCheck($index);
 
        $old = $this->get($index);
 
        $this->data[$index] = $element;
 
        return $old;
 
    }
 
    /**
     * Returns the number of elements in this list.
     * 
     * @return  int  the number of elements in this list
     */
    public function size() {
 
        return $this->size;
 
    }
 
    /**
     * Returns an array of this list.
     *
     * @return  array  an array of this list
     */
    public function toArray() {
 
        return $this->data;
 
    }
 
    /**
     * Returns a string representation of this list.
     *
     * @return  string  string representation of this list
     */
    public function toString() {
 
        return "[ " . implode(", ", $this->data) . " ]";
 
    }
 
}