When_Iterator.php

<?php
/**
 * Name: When_Iterator
 * Author: Thomas Planer <tplaner@gmail.com>
 * Location: http://github.com/tplaner/When
 * Created: November 2010
 * Description: Implements PHP's Object Iteration Interface (http://us.php.net/Iterator & http://php.net/manual/en/class.iterator.php) so you can use the object within a foreach loop.
 * 
 * Thanks to Andrew Collington for suggesting the implementation of an Iterator and supplying the base code for it.
 */

require_once('When.php');

class When_Iterator extends When implements Iterator 
{
	// store the current position in the array
	protected $position = 0;

	// store an individual result if caching is disabled
	protected $result;

	// store all of the results
	protected $results = array();

	protected $cache = false;

	// caching the results will cause the script to
	// use more memory but less cpu (should also perform quicker)
	// 
	// results should always be the same regardless of cache
	public function __construct($cache = false) 
	{
		parent::__construct();

		$this->position = 0;
		$this->results = array();
		$this->cache = $cache;
	}

	public function rewind()
	{
		if($this->cache)
		{
			$this->position = 0;
		}
		else
		{
			// reset the counter and try_date in the parent class
			$this->counter = 0;
			$this->try_date = clone $this->start_date;
		}
	}

	public function current()
	{
		if($this->cache === true)
		{
			return $this->results[$this->position];
		}
		else
		{
			return $this->result;
		}
	}

	// only used if caching is enabled
	public function key()
	{
		return $this->position;
	}

	// only used of caching is enabled
	public function next()
	{
		++$this->position;
	}

	public function valid()
	{
		if($this->cache === true)
		{
			// check to see if the current position has already been stored
			if(!empty($this->results[$this->position]))
			{
				return isset($this->results[$this->position]);
			}
			// if it hasn't been found, check to see if there are more dates
			elseif($next_date = parent::next())
			{
				$this->results[] = $next_date;
				return isset($next_date);
			}
		}
		else
		{
			// check to see if there is another result and set that as the result
			if($next_date = parent::next())
			{
				$this->result = $next_date;
				return isset($this->result);
			}
		}

		// end the foreach loop when all options are exhausted
		return false;
	}

	public function enable_cache($cache)
	{
		$this->cache = $cache;
	}
}