Added a swap function to FlxArrayUtil

flixel/util/FlxArrayUtil.hx

@@ -82,6 +82,61 @@ class FlxArrayUtil
 		return array;
 	}
 
+	/**
+	 * Swaps two elements of an array, which are located at indices `index1` and `index2`
+	 * @param array The array whose elements need to be swapped
+	 * @param index1 The index of one of the elements to be swapped
+	 * @param index2 The index of the other element to be swapped
+	 * @return The array
+	 */
+	public static inline function swapByIndex<T>(array:Array<T>, index1:Int, index2:Int):Array<T>
+	{
+		var temp = array[index1];
+		array[index1] = array[index2];
+		array[index2] = temp;
+		return array;
+	}
+
+	/**
+	 * Swaps two elements of an array, which are located at indices `index1` and `index2` and also checks if the indices are valid before swapping
+	 * @param array The array whose elements need to be swapped
+	 * @param index1 The index of one of the elements to be swapped
+	 * @param index2 The index of the other element to be swapped
+	 * @return The array
+	 */
+	public static inline function safeSwapByIndex<T>(array:Array<T>, index1:Int, index2:Int):Array<T>
+	{
+		if(index1 >= 0 && index1 < array.length && index2 >= 0 && index2 < array.length)
+		{
+			swapByIndex(array, index1, index2);
+		}
+		return array;
+	}
+
+	/**
+	 * Swaps two items, `item1` and `item2` which are in the array
+	 * @param array The array whose elements need to be swapped
+	 * @param item1 One of the elements of the array which needs to be swapped
+	 * @param item2 The other element of the array which needs to be swapped
+	 * @return The array
+	 */
+	public static inline function swap<T>(array:Array<T>, item1:T, item2:T):Array<T>
+	{
+		return swapByIndex(array, array.indexOf(item1), array.indexOf(item2));
+	}
+
+	/**
+	 * Swaps two items, `item1` and `item2` which are in the array, but only if both elements are present in the array
+	 * @param array The array whose elements need to be swapped
+	 * @param item1 One of the elements of the array which needs to be swapped
+	 * @param item2 The other element of the array which needs to be swapped
+	 * @return The array
+	 */
+	public static inline function safeSwap<T>(array:Array<T>, item1:T, item2:T):Array<T>
+	{
+		return safeSwapByIndex(array, array.indexOf(item1), array.indexOf(item2));
+	}
+
 	/**
 	 * Clears an array structure, but leaves the object data untouched
 	 * Useful for cleaning up temporary references to data you want to preserve.

tests/unit/src/flixel/util/FlxArrayUtilTest.hx

@@ -75,4 +75,31 @@ class FlxArrayUtilTest
 		Assert.areEqual(1, [1].last());
 		Assert.areEqual(3, [1, 2, 3].last());
 	}
+
+	@Test
+	function testSwapByIndex()
+	{
+		Assert.isTrue([0, 1, 2, 3, 4, 5].swapByIndex(2, 4).equals([0, 1, 4, 3, 2, 5]));
+	}
+
+	@Test
+	function testSafeSwapByIndex()
+	{
+		Assert.isTrue([0, 1, 2, 3].safeSwapByIndex(0, 3).equals([3, 1, 2, 0]));
+		Assert.isTrue([0, 1, 2, 3].safeSwapByIndex(2, 4).equals([0, 1, 2, 3]));
+		Assert.isTrue([0, 1, 2, 3].safeSwapByIndex(-1, 2).equals([0, 1, 2, 3]));
+	}
+
+	@Test
+	function testSwap()
+	{
+		Assert.isTrue([0, 1, 2, 3, 4, 5].swap(1, 3).equals([0, 3, 2, 1, 4, 5]));
+	}
+
+	@Test
+	function testSafeSwap()
+	{
+		Assert.isTrue([0, 1, 2, 3, 4, 5].safeSwap(0, 2).equals([2, 1, 0, 3, 4, 5]));
+		Assert.isTrue([0, 1, 2, 3, 4, 5].safeSwap(1, 6).equals([0, 1, 2, 3, 4, 5]));
+	}
 }