API CHANGE: Introduce SS_Limitable class for adding to SS_Lists that have limit capability.

API CHANGE: Deprecated SS_List::getRange() in favour of SS_Limitable::limit().
API CHANGE: Introduce SS_Limitable::limit($limit, $offset = 0) as the only modern way of specifying limits; deprecate all others.

core/PaginatedList.php

@@ -149,7 +149,7 @@ class PaginatedList extends SS_ListDecorator {
 	 */
 	public function getIterator() {
 		return new IteratorIterator(
-			$this->list->getRange($this->getPageStart(), $this->pageLength)
+			$this->list->limit($this->pageLength, $this->getPageStart())
 		);
 	}
 

forms/TableListField.php

@@ -430,7 +430,7 @@ JS
 			    $SQL_start = 0;
 		    }
 		
-		    $items = $items->getRange($SQL_start, $SQL_limit);
+		    $items = $items->limit($SQL_limit, $SQL_start);
 	    }
 
 		return $items;

forms/gridfield/GridFieldPaginator.php

@@ -64,14 +64,14 @@ class GridFieldPaginator implements GridField_HTMLProvider, GridField_DataManipu
 		if(!is_int($state->currentPage))
 			$state->currentPage = 1;
 
-		if(!$this->getListPaginatable($dataList)) {
+		if(!($dataList instanceof SS_Limitable)) {
 			return $dataList;
 		}
 		if(!$state->currentPage) {
-			return $dataList->getRange(0, (int)$this->itemsPerPage);
+			return $dataList->limit((int)$this->itemsPerPage);
 		}
 		$startRow = $this->itemsPerPage * ($state->currentPage - 1);
-		return $dataList->getRange((int)$startRow, (int)$this->itemsPerPage);
+		return $dataList->limit((int)$this->itemsPerPage, (int)$startRow);
 	}
 
 	/**
@@ -159,14 +159,4 @@ class GridFieldPaginator implements GridField_HTMLProvider, GridField_DataManipu
 		return $this->itemsPerPage;
 	}
 
-	/** Duck check to see if list support methods we need to paginate */
-	protected function getListPaginatable(SS_List $list) {
-		// If no list yet, not paginatable
-		if (!$list) return false;
-		// Check for methods we use
-		if(!method_exists($list, 'getRange')) return false;
-		if(!method_exists($list, 'limit')) return false;
-		// Default it true
-		return true;
-	}
 }

model/ArrayList.php

@@ -5,7 +5,7 @@
  * @package    sapphire
  * @subpackage model
  */
-class ArrayList extends ViewableData implements SS_List {
+class ArrayList extends ViewableData implements SS_List, SS_Limitable {
 
 	/**
 	 * Holds the items in the list
@@ -119,6 +119,18 @@ class ArrayList extends ViewableData implements SS_List {
 	 * @return ArrayList 
 	 */
 	public function getRange($offset, $length) {
+		Deprecation::notice("3.0", 'getRange($offset, $length) is deprecated.  Use limit($length, $offset) instead.  Note the new argument order.');
+		return $this->limit($length, $offset);
+	}
+
+	/**
+	 * Get a sub-range of this dataobjectset as an array
+	 * 
+	 * @param int $offset
+	 * @param int $length
+	 * @return ArrayList 
+	 */
+	public function limit($length, $offset = 0) {
 		return new ArrayList(array_slice($this->items, $offset, $length));
 	}
 
@@ -357,6 +369,15 @@ class ArrayList extends ViewableData implements SS_List {
 		call_user_func_array('array_multisort', $multisortArgs);
 		return $this;
 	}
+	
+	/**
+	 * Returns true if the given column can be used to filter the records.
+	 * 
+	 * It works by checking the fields available in the first record of the list.
+	 */
+	public function canFilterBy($by) {
+		return array_key_exists($by, $this->first());
+	}
 
 	/**
 	 * Filter the list to include items with these charactaristics

model/DataList.php

@@ -6,7 +6,7 @@
  * @package    sapphire
  * @subpackage model
  */
-class DataList extends ViewableData implements SS_List {
+class DataList extends ViewableData implements SS_List, SS_Limitable {
 	/**
 	 * The DataObject class name that this data list is querying
 	 * 
@@ -145,8 +145,11 @@ class DataList extends ViewableData implements SS_List {
 	 * 
 	 * @param string $limit
 	 */
-	public function limit($limit) {
+	public function limit($limit, $offset = 0) {
-		$this->dataQuery->limit($limit);
+		if(!is_numeric($limit)) {
+			Deprecation::notice('3.0', 'Please pass limits as 2 arguments, rather than an array or SQL fragment.');
+		}
+		$this->dataQuery->limit($limit, $offset);
 		return $this;
 	}
 	
@@ -545,7 +548,8 @@ class DataList extends ViewableData implements SS_List {
 	 * @return DataList
 	 */
 	public function getRange($offset, $length) {
-		return $this->limit(array('start' => $offset, 'limit' => $length));
+		Deprecation::notice("3.0", 'getRange($offset, $length) is deprecated.  Use limit($length, $offset) instead.  Note the new argument order.');
+		return $this->limit($length, $offset);
 	}
 	
 	/**
@@ -813,7 +817,7 @@ class DataList extends ViewableData implements SS_List {
 	 * @return bool
 	 */
 	public function offsetExists($key) {
-	    return ($this->getRange($key, 1)->First() != null);
+	    return ($this->limit(1,$key)->First() != null);
 	}
 
 	/**
@@ -823,7 +827,7 @@ class DataList extends ViewableData implements SS_List {
 	 * @return DataObject
 	 */
 	public function offsetGet($key) {
-	    return $this->getRange($key, 1)->First();
+	    return $this->limit(1, $key)->First();
 	}
 	
 	/**

model/DataQuery.php

@@ -373,9 +373,9 @@ class DataQuery {
 	/**
 	 * Set the limit of this query
 	 */
-	function limit($limit) {
+	function limit($limit, $offset = 0) {
 		$clone = $this;
-		$clone->query->limit($limit);
+		$clone->query->limit($limit, $offset);
 		return $clone;
 	}
 

model/Limitable.php

@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * Additional interface for {@link SS_List} classes that are limitable - able to have a subset of the list extracted.
+ * 
+ * @see SS_List, SS_Sortable, SS_Filterable
+ */
+interface SS_Limitable {
+
+	/**
+	 * Returns a filtered version of this where no more than $limit records are included.
+	 * If $offset is specified, then that many records at the beginning of the list will be skipped.
+	 * This matches the behaviour of the SQL LIMIT clause.
+	 * 
+	 * @return SS_List
+	 */
+	public function limit($limit, $offset = 0);
+
+}

model/List.php

@@ -21,15 +21,6 @@ interface SS_List extends ArrayAccess, Countable, IteratorAggregate {
 	 */
 	public function toNestedArray();
 
-	/**
-	 * Returns a subset of the items within the list.
-	 *
-	 * @param  int $offset
-	 * @param  int $length
-	 * @return SS_List
-	 */
-	public function getRange($offset, $length);
-
 	/**
 	 * Adds an item to the list, making no guarantees about where it will
 	 * appear.

model/ListDecorator.php

@@ -7,7 +7,7 @@
  * @package    sapphire
  * @subpackage model
  */
-abstract class SS_ListDecorator extends ViewableData implements SS_List {
+abstract class SS_ListDecorator extends ViewableData implements SS_List, S_Limitable {
 
 	protected $list;
 
@@ -61,10 +61,6 @@ abstract class SS_ListDecorator extends ViewableData implements SS_List {
 		$this->list->remove($itemObject);
 	}
 
-	public function getRange($offset, $length) {
-		return $this->list->getRange($offset, $length);
-	}
-
 	public function getIterator() {
 		return $this->list->getIterator();
 	}
@@ -136,6 +132,10 @@ abstract class SS_ListDecorator extends ViewableData implements SS_List {
 		return call_user_func_array(array($this->list, 'filter'), $args);
 	}
 
+	public function limit($length, $offset) {
+		return $this->list->getRange($length, $offset);
+	}
+
 	/**
 	 * Exclude the list to not contain items with these charactaristics
 	 *

model/SQLQuery.php

@@ -252,10 +252,10 @@ class SQLQuery {
 	 * @param string|array $limit
 	 * @return SQLQuery This instance
 	 */
-	public function limit($limit) {
+	public function limit($limit, $offset = 0) {
 		if($limit && is_numeric($limit)) {
 			$this->limit = array(
-				'start' => 0,
+				'start' => $offset,
 				'limit' => $limit,
 			);
 		} else if($limit && is_string($limit)) {
@@ -667,7 +667,7 @@ class SQLQuery {
 	function firstRow() {
 		$query = clone $this;
 		$offset = $this->limit ? $this->limit['start'] : 0;
-		$query->limit(array('start' => $offset, 'limit' => 1));
+		$query->limit(1, $offset);
 		return $query;
 	}
 
@@ -677,7 +677,7 @@ class SQLQuery {
 	function lastRow() {
 		$query = clone $this;
 		$offset = $this->limit ? $this->limit['start'] : 0;
-		$query->limit(array('start' => $this->count() + $offset - 1, 'limit' => 1));
+		$query->limit(1, $this->count() + $offset - 1);
 		return $query;
 	}
 

tests/model/ArrayListTest.php

@@ -61,11 +61,11 @@ class ArrayListTest extends SapphireTest {
 		));
 	}
 
-	public function testGetRange() {
+	public function testLimit() {
 		$list = new ArrayList(array(
 			array('Key' => 1), array('Key' => 2), array('Key' => 3)
 		));
-		$this->assertEquals($list->getRange(1, 2)->toArray(), array(
+		$this->assertEquals($list->limit(2,1)->toArray(), array(
 			array('Key' => 2), array('Key' => 3)
 		));
 	}

tests/model/DataListTest.php

@@ -50,7 +50,7 @@ class DataListTest extends SapphireTest {
 		$this->assertEquals(array('Bob', 'Joe', 'Phil'), $list->column('Name'));
 		
 		// We can also restrict the output to a range
-		$this->assertEquals(array('Joe', 'Phil'), $list->getRange(1,2)->column('Name'));
+		$this->assertEquals(array('Joe', 'Phil'), $list->limit(2, 1)->column('Name'));
 	}
 	
 	function testDataClass() {

tests/model/DataObjectTest.php

@@ -197,18 +197,12 @@ class DataObjectTest extends SapphireTest {
 		// There's 4 records in total
 		$this->assertEquals(4, $players->count());
 
-		// Testing "## offset ##" syntax
-		$this->assertEquals(4, $players->limit("20 OFFSET 0")->count());
-		$this->assertEquals(0, $players->limit("20 OFFSET 20")->count());
-		$this->assertEquals(2, $players->limit("2 OFFSET 0")->count());
-		$this->assertEquals(1, $players->limit("5 OFFSET 3")->count());
-
 		// Testing "##, ##" syntax
-		$this->assertEquals(4, $players->limit("20")->count());
+		$this->assertEquals(4, $players->limit(20)->count());
-		$this->assertEquals(4, $players->limit("0, 20")->count());
+		$this->assertEquals(4, $players->limit(20, 0)->count());
-		$this->assertEquals(0, $players->limit("20, 20")->count());
+		$this->assertEquals(0, $players->limit(20, 20)->count());
-		$this->assertEquals(2, $players->limit("0, 2")->count());
+		$this->assertEquals(2, $players->limit(2, 0)->count());
-		$this->assertEquals(1, $players->limit("3, 5")->count());
+		$this->assertEquals(1, $players->limit(5, 3)->count());
 	}
 
 	/**

tests/model/SQLQueryTest.php

@@ -87,19 +87,13 @@ class SQLQueryTest extends SapphireTest {
 			// numeric limit
 			$query = new SQLQuery();
 			$query->from[] = "MyTable";
-			$query->limit("99");
+			$query->limit(99);
 			$this->assertEquals("SELECT * FROM MyTable LIMIT 99", $query->sql());
 		
-			// array limit
-			$query = new SQLQuery();
-			$query->from[] = "MyTable";
-			$query->limit(array('limit'=>99));
-			$this->assertEquals("SELECT * FROM MyTable LIMIT 99", $query->sql());
-
 			// array limit with start (MySQL specific)
 			$query = new SQLQuery();
 			$query->from[] = "MyTable";
-			$query->limit(array('limit'=>99, 'start'=>97));
+			$query->limit(99, 97);
 			$this->assertEquals("SELECT * FROM MyTable LIMIT 99 OFFSET 97", $query->sql());
 		}
 	}