silverstripe-framework/ORM/Map_Iterator.php

<?php

namespace SilverStripe\ORM;

use Iterator;

/**
 * Builds a map iterator around an Iterator.  Called by Map
 */
class Map_Iterator implements Iterator
{

	/**
	 * @var Iterator
	 **/
	protected $items;

	protected $keyField, $titleField;

	protected $firstItemIdx = 0;

	protected $endItemIdx;

	protected $firstItems = array();
	protected $lastItems = array();

	protected $excludedItems = array();

	/**
	 * @param Iterator $items The iterator to build this map from
	 * @param string $keyField The field to use for the keys
	 * @param string $titleField The field to use for the values
	 * @param array $firstItems An optional map of items to show first
	 * @param array $lastItems An optional map of items to show last
	 */
	public function __construct(Iterator $items, $keyField, $titleField, $firstItems = null, $lastItems = null)
	{
		$this->items = $items;
		$this->keyField = $keyField;
		$this->titleField = $titleField;
		$this->endItemIdx = null;

		if ($firstItems) {
			foreach ($firstItems as $k => $v) {
				$this->firstItems[] = array($k, $v);
				$this->excludedItems[] = $k;
			}
		}

		if ($lastItems) {
			foreach ($lastItems as $k => $v) {
				$this->lastItems[] = array($k, $v);
				$this->excludedItems[] = $k;
			}
		}

	}

	/**
	 * Rewind the Iterator to the first element.
	 *
	 * @return mixed
	 */
	public function rewind()
	{
		$this->firstItemIdx = 0;
		$this->endItemIdx = null;

		$rewoundItem = $this->items->rewind();

		if (isset($this->firstItems[$this->firstItemIdx])) {
			return $this->firstItems[$this->firstItemIdx][1];
		} else {
			if ($rewoundItem) {
				return $this->extractValue($rewoundItem, $this->titleField);
			} else {
				if (!$this->items->valid() && $this->lastItems) {
					$this->endItemIdx = 0;

					return $this->lastItems[0][1];
				}
			}
		}
	}

	/**
	 * Return the current element.
	 *
	 * @return mixed
	 */
	public function current()
	{
		if (($this->endItemIdx !== null) && isset($this->lastItems[$this->endItemIdx])) {
			return $this->lastItems[$this->endItemIdx][1];
		} else {
			if (isset($this->firstItems[$this->firstItemIdx])) {
				return $this->firstItems[$this->firstItemIdx][1];
			}
		}
		return $this->extractValue($this->items->current(), $this->titleField);
	}

	/**
	 * Extracts a value from an item in the list, where the item is either an
	 * object or array.
	 *
	 * @param  array|object $item
	 * @param  string $key
	 * @return mixed
	 */
	protected function extractValue($item, $key)
	{
		if (is_object($item)) {
			if (method_exists($item, 'hasMethod') && $item->hasMethod($key)) {
				return $item->{$key}();
			}
			return $item->{$key};
		} else {
			if (array_key_exists($key, $item)) {
				return $item[$key];
			}
		}
	}

	/**
	 * Return the key of the current element.
	 *
	 * @return string
	 */
	public function key()
	{
		if (($this->endItemIdx !== null) && isset($this->lastItems[$this->endItemIdx])) {
			return $this->lastItems[$this->endItemIdx][0];
		} else {
			if (isset($this->firstItems[$this->firstItemIdx])) {
				return $this->firstItems[$this->firstItemIdx][0];
			} else {
				return $this->extractValue($this->items->current(), $this->keyField);
			}
		}
	}

	/**
	 * Move forward to next element.
	 *
	 * @return mixed
	 */
	public function next()
	{
		$this->firstItemIdx++;

		if (isset($this->firstItems[$this->firstItemIdx])) {
			return $this->firstItems[$this->firstItemIdx][1];
		} else {
			if (!isset($this->firstItems[$this->firstItemIdx - 1])) {
				$this->items->next();
			}

			if ($this->excludedItems) {
				while (($c = $this->items->current()) && in_array($c->{$this->keyField}, $this->excludedItems, true)) {
					$this->items->next();
				}
			}
		}

		if (!$this->items->valid()) {
			// iterator has passed the preface items, off the end of the items
			// list. Track through the end items to go through to the next
			if ($this->endItemIdx === null) {
				$this->endItemIdx = -1;
			}

			$this->endItemIdx++;

			if (isset($this->lastItems[$this->endItemIdx])) {
				return $this->lastItems[$this->endItemIdx];
			}

			return false;
		}
	}

	/**
	 * Checks if current position is valid.
	 *
	 * @return boolean
	 */
	public function valid()
	{
		return (
			(isset($this->firstItems[$this->firstItemIdx])) ||
			(($this->endItemIdx !== null) && isset($this->lastItems[$this->endItemIdx])) ||
			$this->items->valid()
		);
	}
}