API CHANGE: Added SS_Sortable, an extra interface to apply to SS_Lists.

model/ArrayList.php

@@ -5,7 +5,7 @@
  * @package    sapphire
  * @subpackage model
  */
-class ArrayList extends ViewableData implements SS_List, SS_Filterable, SS_Limitable {
+class ArrayList extends ViewableData implements SS_List, SS_Filterable, SS_Sortable, SS_Limitable {
 
 	/**
 	 * Holds the items in the list

model/DataList.php

@@ -6,7 +6,7 @@
  * @package    sapphire
  * @subpackage model
  */
-class DataList extends ViewableData implements SS_List, SS_Filterable, SS_Limitable {
+class DataList extends ViewableData implements SS_List, SS_Filterable, SS_Sortable, SS_Limitable {
 	/**
 	 * The DataObject class name that this data list is querying
 	 * 

model/ListDecorator.php

@@ -7,7 +7,7 @@
  * @package    sapphire
  * @subpackage model
  */
-abstract class SS_ListDecorator extends ViewableData implements SS_List, SS_Filterable, SS_Limitable {
+abstract class SS_ListDecorator extends ViewableData implements SS_List, SS_Sortable, SS_Filterable, SS_Limitable {
 
 	protected $list;
 

model/Sortable.php

@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * Additional interface for {@link SS_List} classes that are sortable.
+ * 
+ * @see SS_List, SS_Filterable, SS_Limitable
+ */
+interface SS_Sortable {
+
+	/**
+	 * Returns TRUE if the list can be sorted by a field.
+	 *
+	 * @param  string $by
+	 * @return bool
+	 */
+	public function canSortBy($by);
+
+	/**
+	 * Sorts this list by one or more fields. You can either pass in a single
+	 * field name and direction, or a map of field names to sort directions.
+	 *
+	 * @example $list->sort('Name'); // default ASC sorting
+	 * @example $list->sort('Name DESC'); // DESC sorting
+	 * @example $list->sort('Name', 'ASC');
+	 * @example $list->sort(array('Name'=>'ASC,'Age'=>'DESC'));
+	 */
+	public function sort();
+
+}