Fixes #3355. Added ElggPriorityList. Adapted the externals system to use it.

4 files changed, 241 insertions, 312 deletions

diff --git a/engine/classes/ElggPriorityList.php b/engine/classes/ElggPriorityList.php
index 931138106..17ce228bc 100644
--- a/engine/classes/ElggPriorityList.php
+++ b/engine/classes/ElggPriorityList.php
@@ -2,40 +2,11 @@
 /**
  * Iterate over elements in a specific priority.
  *
- * You can add, remove, and access elements using OOP or array interfaces:
- *
- * // OOP
  * $pl = new ElggPriorityList();
  * $pl->add('Element 0');
- * $pl->add('Element -5', -5);
  * $pl->add('Element 10', 10);
  * $pl->add('Element -10', -10);
  *
- * $pl->remove('Element -5');
- *
- * $elements = $pl->getElements();
- * var_dump($elements);
- *
- * Yields:
- *
- * array(
- *	-10 => 'Element -10',
- * 	0 => 'Element 0',
- * 	10 => 'Element 10',
- * )
- *
- *
- * // Array
- * 
- * $pl = new ElggPriorityList();
- * $pl[] = 'Element 0';
- * $pl[-5] = 'Element -5';
- * $pl[10] = 'Element 10';
- * $pl[-10] = 'Element -10';
- *
- * $priority = $pl->getPriority('Element -5');
- * unset($pl[$priority]);
- *
  * foreach ($pl as $priority => $element) {
  *	var_dump("$priority => $element");
  * }
@@ -45,52 +16,84 @@
  * 0 => Element 0
  * 10 => Element 10
  *
- *
- * Collisions with priority are handled by default differently in the OOP and the array interfaces.
- * 
- * If using the OOP interface, the default is to insert the element as close to the requested
- * priority as possible.
+ * Collisions on priority are handled by inserting the element at or as close to the
+ * requested priority as possible:
  *
  * $pl = new ElggPriorityList();
  * $pl->add('Element 5', 5);
  * $pl->add('Colliding element 5', 5);
  * $pl->add('Another colliding element 5', 5);
  *
- * var_dump($pl->getElements());
+ * foreach ($pl as $priority => $element) {
+ *	var_dump("$priority => $element");
+ * }
  *
  * Yields:
- * array(
  *	5 => 'Element 5',
  *	6 => 'Colliding element 5',
  *	7 => 'Another colliding element 5'
- * )
  *
- * If using the array interface, elements are added at exactly the priority, displacing other
- * elements if necessary. This behavior is also available by passing true as the 3rd argument to
- * ->add():
+ * You can do priority lookups by element:
  *
  * $pl = new ElggPriorityList();
- * $pl[5] = 'Element 5';
- * $pl[6] = 'Element 6';
- * $pl[5] = 'Colliding element 5'; // shifts the previous two up by one
- * $pl->add('Another colliding element 5', 5, true); // shifts the previous three up by one
+ * $pl->add('Element 0');
+ * $pl->add('Element -5', -5);
+ * $pl->add('Element 10', 10);
+ * $pl->add('Element -10', -10);
  *
- * var_dump($pl->getElements());
+ * $priority = $pl->getPriority('Element -5');
+ * 
+ * Or element lookups by priority.
+ * $element = $pl->getElement(-5);
  *
- * Yields:
- * array(
- *	5 => 'Another colliding element 5',
- *	6 => 'Colliding element 5',
- *	7 => 'Element 5',
- *	8 => 'Element 6'
- * )
+ * To remove elements, pass the element.
+ * $pl->remove('Element -10');
+ *
+ * To check if an element exists:
+ * $pl->contains('Element -5');
+ *
+ * To move an element:
+ * $pl->move('Element -5', -3);
+ *
+ * ElggPriorityList only tracks priority. No checking is done in ElggPriorityList for duplicates or
+ * updating. If you need to track this use objects and an external map:
+ *
+ * function elgg_register_something($id, $display_name, $location, $priority = 500) {
+ *	// $id => $element.
+ *	static $map = array();
+ *	static $list;
+ *
+ *	if (!$list) {
+ *		$list = new ElggPriorityList();
+ *	}
+ *
+ *	// update if already registered.
+ *	if (isset($map[$id])) {
+ *		$element = $map[$id];
+ *		// move it first because we have to pass the original element.
+ *		if (!$list->move($element, $priority)) {
+ *			return false;
+ *		}
+ *		$element->display_name = $display_name;
+ *		$element->location = $location;
+ *	} else {
+ *		$element = new stdClass();
+ *		$element->display_name = $display_name;
+ *		$element->location = $location;
+ *		if (!$list->add($element, $priority)) {
+ *			return false;
+ *		}
+ *		$map[$id] = $element;
+ *	}
+ *
+ *	return true;
+ * }
  *
  * @package Elgg.Core
  * @subpackage Helpers
  */
-
 class ElggPriorityList
-	implements Iterator, ArrayAccess, Countable {
+	implements Iterator, Countable {
 
 	/**
 	 * The list of elements
@@ -123,15 +126,11 @@ class ElggPriorityList
 	 *                        maintains its priority and the new element is to the next available
 	 *                        slot, taking into consideration all previously registered elements.
 	 *                        Negative elements are accepted.
-	 * @param bool  $exact    If true, will put the element at exactly the priority specified, displacing
-	 *                        other elements.
 	 * @return int            The priority of the added element.
 	 */
 	public function add($element, $priority = null, $exact = false) {
 		if ($priority !== null && !is_numeric($priority)) {
 			return false;
-		} elseif ($exact) {
-			$this->shiftElementsSegment($priority);
 		} else {
 			$priority = $this->getNextPriority($priority);
 		}
@@ -163,16 +162,16 @@ class ElggPriorityList
 	/**
 	 * Move an existing element to a new priority.
 	 *
-	 * @param int  $current_priority
-	 * @param int  $new_priority
-	 * @param bool $exact
-	 * @return bool
+	 * @param mixed  $current_priority
+	 * @param int    $new_priority
+	 *
+	 * @return int The new priority.
 	 */
-	public function move($current_priority, $new_priority, $exact = false) {
-		$current_priority = (int) $current_priority;
+	public function move($element, $new_priority, $strict = false) {
 		$new_priority = (int) $new_priority;
-
-		if (!isset($this->elements[$current_priority])) {
+		
+		$current_priority = $this->getPriority($element, $strict);
+		if (!$current_priority) {
 			return false;
 		}
 
@@ -180,17 +179,16 @@ class ElggPriorityList
 			return true;
 		}
 
-		$element = $this->elements[$current_priority];
+		// move the actual element so strict operations still work
+		$element = $this->getElement($current_priority);
 		unset($this->elements[$current_priority]);
-
-		return $this->add($element, $new_priority, $exact);
+		return $this->add($element, $new_priority);
 	}
 
 	/**
 	 * Returns the elements
 	 *
-	 * @param type $elements
-	 * @param type $sort
+	 * @return array
 	 */
 	public function getElements() {
 		$this->sortIfUnsorted();
@@ -239,29 +237,6 @@ class ElggPriorityList
 	}
 
 	/**
-	 * Shift a segment of elements starting at $index up by one until the end of the array or
-	 * there's a gap in the indexes. This produces a space at $index to insert a new element.
-	 *
-	 * @param type $index The index to start
-	 * @return array
-	 */
-	private function shiftElementsSegment($index) {
-		$index = (int) $index;
-		// @todo probably a better way.
-		$replace_elements = array();
-		while (isset($this->elements[$index])) {
-			$replace_elements[$index + 1] = $this->elements[$index];
-			unset($this->elements[$index]);
-			$index++;
-		}
-
-		// insert old ones
-		foreach ($replace_elements as $index => $element) {
-			$this->elements[$index] = $element;
-		}
-	}
-
-	/**
 	 * Returns the next priority available.
 	 *
 	 * @param int $near Make the priority as close to $near as possible.
@@ -277,25 +252,45 @@ class ElggPriorityList
 		return $near;
 	}
 
-
 	/**
 	 * Returns the priority of an element if it exists in the list.
 	 * 
-	 * @warning This can return 0 if the element's priority is 0. Use identical operator (===) to
-	 * check for false if you want to know if an element exists.
+	 * @warning This can return 0 if the element's priority is 0.
 	 *
-	 * @param mixed $element
+	 * @param mixed $element The element to check for.
+	 * @param bool  $strict  Use strict checking?
 	 * @return mixed False if the element doesn't exists, the priority if it does.
 	 */
 	public function getPriority($element, $strict = false) {
 		return array_search($element, $this->elements, $strict);
 	}
 
+	/**
+	 * Returns the element at $priority.
+	 *
+	 * @param int $priority
+	 * @return mixed The element or false on fail.
+	 */
+	public function getElement($priority) {
+		return (isset($this->elements[$priority])) ? $this->elements[$priority] : false;
+	}
+
+	/**
+	 * Returns if the list contains $element.
+	 *
+	 * @param mixed $element The element to check.
+	 * @param bool  $strict  Use strict checking?
+	 * @return bool
+	 */
+	public function contains($element, $strict = false) {
+		return $this->getPriority($element, $strict) !== false;
+	}
+
+	
 	/**********************
-	 * Interfaces methods *
+	 * Interface methods *
 	 **********************/
 
-
 	/**
 	 * Iterator
 	 */
@@ -356,29 +351,8 @@ class ElggPriorityList
 		return ($key !== NULL && $key !== FALSE);
 	}
 
-	// Coutable
+	// Countable
 	public function count() {
 		return count($this->elements);
 	}
-
-	// ArrayAccess
-	public function offsetExists($offset) {
-		return isset($this->elements[$offset]);
-	}
-
-	public function offsetGet($offset) {
-		return isset($this->elements[$offset]) ? $this->elements[$offset] : null;
-	}
-
-	public function offsetSet($offset, $value) {
-		// for $pl[] = 'New element'
-		$exact = ($offset !== null);
-		return $this->add($value, $offset, $exact);
-	}
-
-	public function offsetUnset($offset) {
-		if (isset($this->elements[$offset])) {
-			unset($this->elements[$offset]);
-		}
-	}
 }
\ No newline at end of file
diff --git a/engine/lib/elgglib.php b/engine/lib/elgglib.php
index b6b603e79..198ffe60c 100644
--- a/engine/lib/elgglib.php
+++ b/engine/lib/elgglib.php
@@ -167,7 +167,7 @@ function forward($location = "", $reason = 'system') {
  * @param string $name     An identifier for the JavaScript library
  * @param string $url      URL of the JavaScript file
  * @param string $location Page location: head or footer. (default: head)
- * @param int    $priority Priority of the CSS file (lower numbers load earlier)
+ * @param int    $priority Priority of the JS file (lower numbers load earlier)
  *
  * @return bool
  * @since 1.8.0
@@ -288,28 +288,24 @@ function elgg_register_external_file($type, $name, $url, $location, $priority =
 	$url = elgg_format_url($url);
 	$url = elgg_normalize_url($url);
 	
-	if (!isset($CONFIG->externals)) {
-		$CONFIG->externals = array();
-	}
-
-	if (!$CONFIG->externals[$type] instanceof ElggPriorityList) {
-		$CONFIG->externals[$type] = new ElggPriorityList();
-	}
+	elgg_bootstrap_externals_data_structure($type);
 
 	$name = trim(strtolower($name));
 	$priority = max((int)$priority, 0);
+	$item = elgg_extract($name, $CONFIG->externals_map[$type]);
 
-	$index = elgg_get_external_file_priority($name, $type);
-
-	if ($index !== false) {
+	if ($item) {
 		// updating a registered item
-		$item = $CONFIG->externals[$type][$index];
+		// don't update loaded because it could already be set
 		$item->url = $url;
 		$item->location = $location;
 
-		// remove old saved priority
-		elgg_remove_external_file_priority($name, $type);
-		$priority = $CONFIG->externals[$type]->move($index, $priority);
+		// if loaded before registered, that means it hasn't been added to the list yet
+		if ($CONFIG->externals[$type]->contains($item)) {
+			$priority = $CONFIG->externals[$type]->move($item, $priority);
+		} else {
+			$priority = $CONFIG->externals[$type]->add($item, $priority);
+		}
 	} else {
 		$item = new stdClass();
 		$item->loaded = false;
@@ -319,10 +315,9 @@ function elgg_register_external_file($type, $name, $url, $location, $priority =
 		$priority = $CONFIG->externals[$type]->add($item, $priority);
 	}
 
-	// save priority map so we can update if added again
-	elgg_save_external_file_priority($priority, $name, $type);
+	$CONFIG->externals_map[$type][$name] = $item;
 
-	return true;
+	return $priority !== false;
 }
 
 /**
@@ -337,22 +332,14 @@ function elgg_register_external_file($type, $name, $url, $location, $priority =
 function elgg_unregister_external_file($type, $name) {
 	global $CONFIG;
 
-	if (!isset($CONFIG->externals)) {
-		return false;
-	}
-
-	if (!$CONFIG->externals[$type] instanceof ElggPriorityList) {
-		return false;
-	}
+	elgg_bootstrap_externals_data_structure($type);
 
 	$name = trim(strtolower($name));
-	
-	$priority = elgg_get_external_file_priority($name, $type);
+	$item = elgg_extract($name, $CONFIG->externals_map[$type]);
 
-	if ($priority !== false) {
-		elgg_remove_external_file_priority($name, $type);
-		unset($CONFIG->externals[$type][$priority]);
-		return true;
+	if ($item) {
+		unset($CONFIG->externals_map[$type][$name]);
+		return $CONFIG->externals[$type]->remove($item);
 	}
 
 	return false;
@@ -370,21 +357,15 @@ function elgg_unregister_external_file($type, $name) {
 function elgg_load_external_file($type, $name) {
 	global $CONFIG;
 
-	if (!isset($CONFIG->externals)) {
-		$CONFIG->externals = array();
-	}
-
-	if (!$CONFIG->externals[$type] instanceof ElggPriorityList) {
-		$CONFIG->externals[$type] = new ElggPriorityList();
-	}
+	elgg_bootstrap_externals_data_structure($type);
 
 	$name = trim(strtolower($name));
 
-	$priority = elgg_get_external_file_priority($name, $type);
+	$item = elgg_extract($name, $CONFIG->externals_map[$type]);
 
-	if ($priority !== false) {
+	if ($item) {
 		// update a registered item
-		$CONFIG->externals[$type][$priority]->loaded = true;
+		$item->loaded = true;
 	} else {
 		$item = new stdClass();
 		$item->loaded = true;
@@ -392,60 +373,11 @@ function elgg_load_external_file($type, $name) {
 		$item->location = '';
 
 		$priority = $CONFIG->externals[$type]->add($item);
-		elgg_save_external_file_priority($priority, $name, $type);
+		$CONFIG->externals_map[$type][$name] = $item;
 	}
 }
 
 /**
- * Gets the priority of an external by name and type.
- *
- * @param type $name
- * @param type $type
- * @return type 
- */
-function elgg_get_external_file_priority($name, $type) {
-	global $CONFIG;
-
-	if (!isset($CONFIG->externals_priorities[$type][$name])) {
-		return false;
-	}
-
-	return $CONFIG->externals_priorities[$type][$name];
-}
-
-function elgg_save_external_file_priority($priority, $name, $type) {
-	global $CONFIG;
-
-	if (!isset($CONFIG->externals_priorities)) {
-		$CONFIG->externals_priorities = array();
-	}
-	
-	if (!isset($CONFIG->externals_priorities[$type])) {
-		$CONFIG->externals_priorities[$type] = array();
-	}
-
-	$CONFIG->externals_priorities[$type][$name] = $priority;
-
-	return true;
-}
-
-function elgg_remove_external_file_priority($name, $type) {
-	global $CONFIG;
-	
-	if (!isset($CONFIG->externals_priorities)) {
-		$CONFIG->externals_priorities = array();
-	}
-
-	if (!isset($CONFIG->externals_priorities[$type])) {
-		$CONFIG->externals_priorities[$type] = array();
-	}
-
-	unset($CONFIG->externals_priorities[$type][$name]);
-
-	return true;
-}
-
-/**
  * Get external resource descriptors
  *
  * @param string $type     Type of file: js or css
@@ -471,6 +403,31 @@ function elgg_get_loaded_external_files($type, $location) {
 }
 
 /**
+ * Bootstraps the externals data structure in $CONFIG.
+ *
+ * @param string $type The type of external, js or css.
+ */
+function elgg_bootstrap_externals_data_structure($type) {
+	global $CONFIG;
+
+	if (!isset($CONFIG->externals)) {
+		$CONFIG->externals = array();
+	}
+
+	if (!$CONFIG->externals[$type] instanceof ElggPriorityList) {
+		$CONFIG->externals[$type] = new ElggPriorityList();
+	}
+
+	if (!isset($CONFIG->externals_map)) {
+		$CONFIG->externals_map = array();
+	}
+
+	if (!isset($CONFIG->externals_map[$type])) {
+		$CONFIG->externals_map[$type] = array();
+	}
+}
+
+/**
  * Returns a list of files in $directory.
  *
  * Only returns files.  Does not recurse into subdirs.
diff --git a/engine/lib/views.php b/engine/lib/views.php
index 7686a8bef..fe3265347 100644
--- a/engine/lib/views.php
+++ b/engine/lib/views.php
@@ -1480,21 +1480,6 @@ function autoregister_views($view_base, $folder, $base_location_path, $viewtype)
 }
 
 /**
- * Add the core Elgg head elements that could be cached
- *
- * @return void
- */
-function elgg_views_register_core_head_elements() {
-	$url = elgg_get_simplecache_url('js', 'elgg');
-	elgg_register_js('elgg', $url, 'head', 10);
-	elgg_load_js('elgg');
-
-	$url = elgg_get_simplecache_url('css', 'elgg');
-	elgg_register_css('elgg', $url, 10);
-	elgg_load_css('elgg');
-}
-
-/**
  * Add the rss link to the extras when if needed
  *
  * @return void
@@ -1548,12 +1533,17 @@ function elgg_views_boot() {
 	elgg_register_simplecache_view('css/ie6');
 	elgg_register_simplecache_view('js/elgg');
 
-	elgg_register_js('jquery', '/vendors/jquery/jquery-1.6.2.min.js', 'head', 1);
-	elgg_register_js('jquery-ui', '/vendors/jquery/jquery-ui-1.8.16.min.js', 'head', 2);
+	elgg_register_js('jquery', '/vendors/jquery/jquery-1.6.2.min.js', 'head');
+	elgg_register_js('jquery-ui', '/vendors/jquery/jquery-ui-1.8.16.min.js', 'head');
 	elgg_register_js('jquery.form', '/vendors/jquery/jquery.form.js');
+	
+	$elgg_js_url = elgg_get_simplecache_url('js', 'elgg');
+	elgg_register_js('elgg', $elgg_js_url, 'head');
+
 	elgg_load_js('jquery');
 	elgg_load_js('jquery-ui');
 	elgg_load_js('jquery.form');
+	elgg_load_js('elgg');
 
 	elgg_register_simplecache_view('js/lightbox');
 	$lightbox_js_url = elgg_get_simplecache_url('js', 'lightbox');
@@ -1561,7 +1551,10 @@ function elgg_views_boot() {
 	$lightbox_css_url = 'vendors/jquery/fancybox/jquery.fancybox-1.3.4.css';
 	elgg_register_css('lightbox', $lightbox_css_url);
 
-	elgg_register_event_handler('ready', 'system', 'elgg_views_register_core_head_elements');
+	$elgg_css_url = elgg_get_simplecache_url('css', 'elgg');
+	elgg_register_css('elgg', $elgg_css_url, 1);
+	elgg_load_css('elgg');
+
 	elgg_register_event_handler('pagesetup', 'system', 'elgg_views_add_rss_link');
 
 	// discover the built-in view types
diff --git a/engine/tests/api/helpers.php b/engine/tests/api/helpers.php
index cceb762be..ee2e64cfe 100644
--- a/engine/tests/api/helpers.php
+++ b/engine/tests/api/helpers.php
@@ -31,7 +31,7 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 
 		global $CONFIG;
 		unset($CONFIG->externals);
-		unset($CONFIG->externals_priorities);
+		unset($CONFIG->externals_map);
 	}
 
 	/**
@@ -107,9 +107,16 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 		// specify name
 		$result = elgg_register_js('key', 'http://test1.com', 'footer');
 		$this->assertTrue($result);
-		$this->assertTrue(isset($CONFIG->externals_priorities['js']['key']));
-		$index = $CONFIG->externals_priorities['js']['key'];
-		$this->assertIdentical('http://test1.com', $CONFIG->externals['js'][$index]->url);
+		$this->assertTrue(isset($CONFIG->externals_map['js']['key']));
+
+		$item = $CONFIG->externals_map['js']['key'];
+		$this->assertTrue($CONFIG->externals['js']->contains($item));
+
+		$priority = $CONFIG->externals['js']->getPriority($item);
+		$this->assertTrue($priority !== false);
+
+		$item = $CONFIG->externals['js']->getElement($priority);
+		$this->assertIdentical('http://test1.com', $item->url);
 
 		// send a bad url
 		$result = @elgg_register_js('bad');
@@ -121,13 +128,20 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 	 */
 	public function testElggRegisterCSS() {
 		global $CONFIG;
-
+		
 		// specify name
 		$result = elgg_register_css('key', 'http://test1.com');
 		$this->assertTrue($result);
-		$this->assertTrue(isset($CONFIG->externals_priorities['css']['key']));
-		$index = elgg_get_external_file_priority('css', 'key');
-		$this->assertIdentical('http://test1.com', $CONFIG->externals['css'][$index]->url);
+		$this->assertTrue(isset($CONFIG->externals_map['css']['key']));
+
+		$item = $CONFIG->externals_map['css']['key'];
+		$this->assertTrue($CONFIG->externals['css']->contains($item));
+
+		$priority = $CONFIG->externals['css']->getPriority($item);
+		$this->assertTrue($priority !== false);
+
+		$item = $CONFIG->externals['css']->getElement($priority);
+		$this->assertIdentical('http://test1.com', $item->url);
 	}
 
 	/**
@@ -139,6 +153,7 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 		$base = trim(elgg_get_site_url(), "/");
 
 		$urls = array('id1' => "$base/urla", 'id2' => "$base/urlb", 'id3' => "$base/urlc");
+		
 		foreach ($urls as $id => $url) {
 			elgg_register_js($id, $url);
 		}
@@ -148,26 +163,33 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 
 		$js = $CONFIG->externals['js'];
 		$elements = $js->getElements();
-		$this->assertFalse(isset($CONFIG->externals_priorities['js']['id1']));
+		$this->assertFalse(isset($CONFIG->externals_map['js']['id1']));
+		
 		foreach ($elements as $element) {
 			$this->assertFalse($element->name == 'id1');
 		}
 
 		$result = elgg_unregister_js('id1');
 		$this->assertFalse($result);
+
 		$result = elgg_unregister_js('', 'does_not_exist');
 		$this->assertFalse($result);
 
 		$result = elgg_unregister_js('id2');
 		$elements = $js->getElements();
-		$this->assertFalse(isset($CONFIG->externals_priorities['js']['id2']));
+
+		$this->assertFalse(isset($CONFIG->externals_map['js']['id2']));
 		foreach ($elements as $element) {
 			$this->assertFalse($element->name == 'id2');
 		}
 
-		$this->assertTrue(isset($CONFIG->externals_priorities['js']['id3']));
-		$priority = $CONFIG->externals_priorities['js']['id3'];
-		$this->assertIdentical($urls['id3'], $CONFIG->externals['js'][$priority]->url);
+		$this->assertTrue(isset($CONFIG->externals_map['js']['id3']));
+
+		$priority = $CONFIG->externals['js']->getPriority($CONFIG->externals_map['js']['id3']);
+		$this->assertTrue($priority !== false);
+
+		$item = $CONFIG->externals['js']->getElement($priority);
+		$this->assertIdentical($urls['id3'], $item->url);
 	}
 
 	/**
@@ -180,6 +202,7 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 		elgg_load_js('key');
 		$result = elgg_register_js('key', 'http://test1.com', 'footer');
 		$this->assertTrue($result);
+		
 		$js_urls = elgg_get_loaded_js('footer');
 		$this->assertIdentical(array('http://test1.com'), $js_urls);
 	}
@@ -192,7 +215,12 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 
 		$base = trim(elgg_get_site_url(), "/");
 
-		$urls = array('id1' => "$base/urla", 'id2' => "$base/urlb", 'id3' => "$base/urlc");
+		$urls = array(
+			'id1' => "$base/urla",
+			'id2' => "$base/urlb",
+			'id3' => "$base/urlc"
+		);
+		
 		foreach ($urls as $id => $url) {
 			elgg_register_js($id, $url);
 			elgg_load_js($id);
@@ -315,6 +343,28 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 		$this->assertIdentical($elements[2], $test_elements[2]);
 	}
 
+	public function testElggPriorityListMove() {
+		$pl = new ElggPriorityList();
+
+		$elements = array(
+			-5 => 'Test Element -5',
+			0 => 'Test Element 0',
+			5 => 'Test Element 5',
+		);
+
+		foreach ($elements as $priority => $element) {
+			$pl->add($element, $priority);
+		}
+
+		$this->assertTrue($pl->move($elements[-5], 10));
+		
+		// check it's at the new place
+		$this->assertIdentical($elements[-5], $pl->getElement(10));
+
+		// check it's not at the old
+		$this->assertFalse($pl->getElement(-5));
+	}
+
 	public function testElggPriorityListConstructor() {
 		$elements = array(
 			10 => 'Test Element 10',
@@ -358,6 +408,25 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 		$this->assertIdentical(2, $pl->getPriority($elements[2]));
 	}
 
+	public function testElggPriorityListGetElement() {
+		$pl = new ElggPriorityList();
+		$priorities = array();
+
+		$elements = array(
+			'Test element 0',
+			'Test element 1',
+			'Test element 2',
+		);
+
+		foreach ($elements as $element) {
+			$priorities[] = $pl->add($element);
+		}
+
+		$this->assertIdentical($elements[0], $pl->getElement($priorities[0]));
+		$this->assertIdentical($elements[1], $pl->getElement($priorities[1]));
+		$this->assertIdentical($elements[2], $pl->getElement($priorities[2]));
+	}
+
 	public function testElggPriorityListPriorityCollision() {
 		$pl = new ElggPriorityList();
 		
@@ -378,31 +447,6 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 		$this->assertEqual(7, $pl->getPriority('Colliding element'));
 	}
 
-	public function testElggPriorityListArrayAccess() {
-		$pl = new ElggPriorityList();
-		
-		$pl[] = 'Test element 0';
-		$pl[-10] = 'Test element -10';
-		$pl[-1] = 'Test element -1';
-		$pl[] = 'Test element 1';
-		$pl[5] = 'Test element 5';
-		$pl[0] = 'Test element collision with 0';
-
-		$elements = array(
-			-1 => 'Test element -1',
-			0 => 'Test element collision with 0',
-			1 => 'Test element 0',
-			2 => 'Test element 1',
-			5 => 'Test element 5',
-		);
-
-		$priority = $pl->getPriority('Test element -10');
-		unset($pl[$priority]);
-
-		$test_elements = $pl->getElements();
-		$this->assertIdentical($elements, $test_elements);
-	}
-
 	public function testElggPriorityListIterator() {
 		$elements = array(
 			-5 => 'Test element -5',
@@ -422,13 +466,13 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 
 		$this->assertEqual(0, count($pl));
 
-		$pl[] = 'Test element 0';
+		$pl->add('Test element 0');
 		$this->assertEqual(1, count($pl));
 
-		$pl[] = 'Test element 1';
+		$pl->add('Test element 1');
 		$this->assertEqual(2, count($pl));
 
-		$pl[] = 'Test element 2';
+		$pl->add('Test element 2');
 		$this->assertEqual(3, count($pl));
 	}
 
@@ -461,43 +505,4 @@ class ElggCoreHelpersTest extends ElggCoreUnitTest {
 
 		$this->assertIdentical($elements_sorted_string, $test_elements);
 	}
-
-	function testElggPriorityListShiftElementsSegment() {
-		$elements = array(
-			0 => 'Element 0',
-			1 => 'Element 1',
-			2 => 'Element 2',
-			4 => 'Element 4',
-		);
-
-		$pl = new ElggPriorityList($elements);
-
-		// add a new element directly at 1.
-		$pl->add('New Element', 1, true);
-
-		$elements_sorted = array(
-			0 => 'Element 0',
-			1 => 'New Element',
-			2 => 'Element 1',
-			3 => 'Element 2',
-			4 => 'Element 4',
-		);
-
-		$test_elements = $pl->getElements();
-		$this->assertIdentical($elements_sorted, $test_elements);
-
-		$pl->add('New Element 10', 10, true);
-
-		$elements_sorted = array(
-			0 => 'Element 0',
-			1 => 'New Element',
-			2 => 'Element 1',
-			3 => 'Element 2',
-			4 => 'Element 4',
-			10 => 'New Element 10'
-		);
-
-		$test_elements = $pl->getElements();
-		$this->assertIdentical($elements_sorted, $test_elements);
-	}
 }
\ No newline at end of file