Implemented Layers and LayerStack

GlitchyEngine/src/LayerStack.bf

@@ -0,0 +1,61 @@
+using System.Collections;
+
+namespace GlitchyEngine
+{
+	public class LayerStack
+	{
+		private List<Layer> _layers = new List<Layer>() ~ DeleteContainerAndItems!(_);
+
+		/*
+		 * Marks the index of the last layer.
+		 * Used to insert new layers before overlays.
+		 */
+		private int _insertIndex = 0;
+
+		/**
+		 * Pushes the provided layer onto the layer stack.
+		 * @param ownLayer The layer that will be pushed onto the layerstack.
+		 * @remarks The layerstack takes ownership of ownLayer.
+		 */
+		public void PushLayer(Layer ownLayer)
+		{
+			_layers.Insert(_insertIndex++, ownLayer);
+		}
+		
+		/**
+		 * Pushes the provided overlay onto the layer stack.
+		 * @param ownLayer The overlay that will be pushed onto the layerstack.
+		 * @remarks The layerstack takes ownership of ownOverlay.
+		 */
+		public void PushOverlay(Layer ownOverlay)
+		{
+			_layers.Add(ownOverlay);
+		}
+		
+		/**
+		 * Removes the given overlay from the layer stack.
+		 * @param layer The layer to pop from the LayerStack.
+		 */
+		public void PopLayer(Layer layer)
+		{
+			if(_layers.Remove(layer))
+			{
+				_insertIndex--;
+			}
+		}
+		
+		/**
+		 * Removes the given overlay from the layer stack.
+		 * @param overlay The overlay to pop from the LayerStack.
+		 */
+		public void PopOverlay(Layer overlay)
+		{
+			_layers.Remove(overlay);
+		}
+
+		/**
+		 * Returns an enumerator for enumerating the layers.
+		 */
+		public List<Layer>.Enumerator GetEnumerator() => _layers.GetEnumerator();
+	}
+}