PHP-Collection类

PHP在类中存在集合类型的成员时只能存array，这样非常不安全，也不符合面向对象原则，有了下面这个collection类就可以解决这些问题了

/**
 * Generic Collection class
 *
 * Based on: http://codeutopia.net/code/library/CU/Collection.php
 *
 * My additions are marked with "--aaron"
 */
class CU_Collection implements Countable, IteratorAggregate, ArrayAccess
{
	protected $_valueType;

	// --aaron
	/**
	 * Whether or not the members or this collection are of a "basic" type
	 *
	 * Basic types are anything that has a matching "is_*" function listed
	 * in {@link http://us2.php.net/manual/en/ref.var.php}. Anything else is
	 * assumed to be the name of a class or interface.
	 *
	 * @var boolean
	 */
	protected $_isBasicType = false;

	// --aaron
	/**
	 * The "is_*" function that validates {@link $_valueType}
	 *
	 * This property is only used if {@link $_isBasicType} == true
	 * @var string
	 */
	protected $_validateFunc;

	protected $_collection = array();

	/**
	 * Construct a new typed collection
	 * @param string valueType collection value type
	 */
	public function __construct($valueType)
	{
		$this->_valueType = $valueType;
		// --aaron
		if(function_exists("is_$valueType")) {
			$this->_isBasicType = true;
			$this->_validateFunc = "is_$valueType";
		}
	}

	/**
	 * Add a value into the collection
	 * @param string $value
	 * @throws InvalidArgumentException when wrong type
	 */
	public function add($value)
	{
		if(!$this->isValidType($value))
			throw new InvalidArgumentException("Trying to add a value of wrong type");

		$this->_collection[] = $value;
	}

	/**
	 * Set index"s value
	 * @param integer $index
	 * @param mixed $value
	 * @throws OutOfRangeException
	 * @throws InvalidArgumentException
	 */
	public function set($index, $value)
	{
		if($index >= $this->count())
			throw new OutOfRangeException("Index out of range");

		if(!$this->isValidType($value))
			throw new InvalidArgumentException("Trying to add a value of wrong type");

		$this->_collection[$index] = $value;
	}

	/**
	 * Remove a value from the collection
	 * @param integer $index index to remove
	 * @throws OutOfRangeException if index is out of range
	 */
	public function remove($index)
	{
		if($index >= $this->count())
			throw new OutOfRangeException("Index out of range");

		array_splice($this->_collection, $index, 1);
	}

	/**
	 * Return value at index
	 * @param integer $index
	 * @return mixed
	 * @throws OutOfRangeException
	 */
	public function get($index)
	{
		if($index >= $this->count())
			throw new OutOfRangeException("Index out of range");

		return $this->_collection[$index];
	}

	/**
	 * Determine if index exists
	 * @param integer $index
	 * @return boolean
	 */
	public function exists($index)
	{
		if($index >= $this->count())
			return false;

		return true;
	}
	/**
	 * Return count of items in collection
	 * Implements countable
	 * @return integer
	 */
	public function count()
	{
		return count($this->_collection);
	}

	/**
	 * Determine if this value can be added to this collection
	 * @param string $value
	 * @return boolean
	 */
	public function isValidType($value)
	{
		// --aaron
		if($this->_isBasicType) {
			$validateFunc = $this->_validateFunc;
			return $validateFunc($value);
		} else {
			// instanceof works on interfaces as well as classes.
			// It also checks the entire inheritance chain
			return $value instanceof $this->_valueType;
		}
	}

	/**
	 * Return an iterator
	 * Implements IteratorAggregate
	 * @return ArrayIterator
	 */
	public function getIterator()
	{
		return new ArrayIterator($this->_collection);
	}

	/**
	 * Set offset to value
	 * Implements ArrayAccess
	 * @see set
	 * @param integer $offset
	 * @param mixed $value
	 */
	public function offsetSet($offset, $value)
	{
		$this->set($offset, $value);
	}

	/**
	 * Unset offset
	 * Implements ArrayAccess
	 * @see remove
	 * @param integer $offset
	 */
	public function offsetUnset($offset)
	{
		$this->remove($offset);
	}

	/**
	 * get an offset"s value
	 * Implements ArrayAccess
	 * @see get
	 * @param integer $offset
	 * @return mixed
	 */
	public function offsetGet($offset)
	{
		return $this->get($offset);
	}

	/**
	 * Determine if offset exists
	 * Implements ArrayAccess
	 * @see exists
	 * @param integer $offset
	 * @return boolean
	 */
	public function offsetExists($offset)
	{
		return $this->exists($offset);
	}
}