<?php

class ArrayList implements ArrayAccess, IteratorAggregate, Countable {

    private $list = array();

    function add($value, $index=null) {
        $this->offsetSet($index, $value);
    }

    function addAll(array &$values) {
        foreach($values as &$value) {
            $this->add($value);
        }
    }

    function clear() {
        $this->list = array();
    }

    function contains($value) {
        return in_array($this->list);
    }

    function indexOf($value) {
        foreach($this->list as $index=>$sValue) {
            if($value===$sValue) {
                return $index;
            }
        }

        return -1;
    }

    function isEmpty() {
        return $this->count() == 0;
    }

    function count() {
        return count($this->list);
    }

    function get($index) {
        if (!is_numeric($offset) || $offset!=(int)$offset) {
            throw new InvalidArgumentException(
                "Index to ".get_class($this)." must be an integer."
            );
        }

        $this->offsetGet($index);

    }

    function remove($index) {
        $this->offsetUnset($index);
    }

    function set($index, $value) {
        $this->offsetSet($index, $value);
    }

    function size() {
        return $this->count();
    }

    function toArray() {
        return $this->list;
    }

    function offsetExists($offset) {
        if (!is_numeric($offset) || $offset!=(int)$offset) {
            throw new InvalidArgumentException(
                "Index to ".get_class($this)." must be an integer."
            );
        }

        return array_key_exists($offset, $this->list);
    }
    function offsetGet($offset) {
        if (!is_numeric($offset) || $offset!=(int)$offset) {
            throw new InvalidArgumentException(
                "Index to ".get_class($this)." must be an integer."
            );
        }

        if (offsetExists($offset))
            return $this->list[$offset];

        throw new OutOfBoundsException("Index '$offset' does not exist.");
    }
    function offsetSet($offset, $value) {
        if ($offset==null) {
            $this->list[] = $value;
        } else{
            if (!is_numeric($offset) || $offset!=(int)$offset) {
                throw new InvalidArgumentException(
                    "Index to ".get_class($this)." must be an integer."
                );
            }

            if ($offset<0 || $offset>=$this->size())
                throw new OutOfBoundsException("Index '$offset' does not exist.");

            $this->list[$offset] = $value;
        }

    }
    function offsetUnset($offset) {
        if (!is_numeric($offset) || $offset!=(int)$offset) {
            throw new InvalidArgumentException(
                "Index to ".get_class($this)." must be an integer."
            );
        }
        unset($this->list[$offset]);
        $this->list = array_values($this->list);
    }
    function getIterator() {
        return new ArrayIterator($this->list);
    }

}

$list = new ArrayList();

$list->add(1);

try {
    $list[1] = 2;

    echo "'\$list[1] = 2' should have thrown an OutOfBoundsError(), did not");
    exit(1);
} catch (OutOfBoundsException $error) {}

$list[] = 2;

if($list->get(1)!=2)
    echo "'\$list->get(1)' did not return '2', returned '{$list->get(1)}'";

if($list->size()!=2)
    echo "'\$list->size()' did not return '2', returned '{$list->size()}'";


?>