source: trunk/prototype/app/plugins/when/When_Iterator.php @ 5341

<?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;
        }
}