--- /dev/null
+'use strict';
+
+/*
+Serpentity is a simple entity framework inspired by Ash.
+
+Usage:
+
+ let Serpentity = require('serpentity');
+
+## Instantiating an engine
+
+ let engine = Serpentity();
+
+Add entities or systems, systems are added with a priority (the smaller
+the number, the earlier it will be called):
+
+ engine.addEntity(entityFactory());
+ engine.addSystem(new GameSystem(), priority);
+
+Update all systems:
+
+ engine.update(dt);
+
+Remove entities or systems:
+
+ engine.removeEntity(entityReference);
+ engine.removeSystem(systemReference);
+
+## Creating Entities
+
+Entities are the basic object of Serpentity, and they do nothing.
+
+ let entity = new Serpentity.Entity();
+
+All the behavior is added through components
+
+## Creating Components
+
+Components define data that we can add to an entity. This data will
+eventually be consumed by "Systems"
+
+ let PositionComponent = class PositionComponent extends Serpentity.Component {
+ constructor (config) {
+ this.x = 0;
+ this.y = 0;
+
+ super(config);
+ }
+ };
+
+You can add components to entities by using the add method:
+
+ entity.addComponent(new PositionComponent());
+
+
+Systems can refer to entities by requesting nodes.
+
+## Working with Nodes
+
+Nodes are sets of components that you define, so your system can require
+entities that always follow the API defined in the node.
+
+ let MovementNode = class MovementNode extends Serpentity.Node;
+ MovementNode.position = PositionComponent;
+ MovementNode.motion = MotionComponent;
+
+You can then request an array of all the nodes representing entities
+that comply with that API
+
+ engine.getNodes(MovementNode);
+
+## Creating Systems
+
+Systems are called on every update, and they use components through nodes.
+
+ let TestSystem = class TestSystem extends Serpentity.System {
+ added (engine){
+ this.nodeList = engine.getNodes(MovementNode);
+ },
+ removed (engine){
+ this.nodeList = undefined;
+ }
+ update (dt){
+ let node;
+ for (node of this.nodeList) {
+ console.log(`Current position is: ${node.position.x},${node.position.y}`);
+ }
+ }
+ };
+
+## That's it
+
+Just run `engine.update(dt)` in your game loop :D
+
+*/
+let Serpentity = class Serpentity {
+
+ constructor (config) {
+ this.systems = [];
+ this.entities = [];
+ this._nodeCollections = [];
+ this._nodeCollectionKeys = [];
+
+ Object.assign(this, config || {});
+ }
+
+ /*
+ * Adds a system to the engine, so its update method will be called
+ * with the others. Triggers added hook.
+ *
+ * returns true if added succesfully, false if already added
+ */
+ addSystem (system, priority) {
+ let lastIndex, found;
+
+ if (this.systems.indexOf(system) >= 0) {
+ return false;
+ }
+
+ system.priority = priority;
+
+ found = false;
+ lastIndex = 0;
+
+ this.systems.some(function findPriority(existingSystem, i) {
+ lastIndex = i;
+ if (existingSystem.priority >= system.priority) {
+ found = true;
+ return true;
+ }
+ });
+
+ if (!found) {
+ lastIndex += 1;
+ }
+
+ this.systems.splice(lastIndex, 0, system);
+ system.added(this);
+ return true;
+ }
+
+ /*
+ * Removes a system from the engine, so its update method will no
+ * longer will be called. Triggers the removed hook.
+ *
+ * returns true if removed succesfully, false if already added
+ */
+ removeSystem (system) {
+ let position;
+
+ position = this.systems.indexOf(system);
+ if (position >= 0) {
+ this.systems[position].removed(this);
+ this.systems.splice(position, 1);
+ return true;
+ }
+
+ return false;
+ }
+
+ /*
+ * Adds an entity to the engine, adds to existing node collections
+ *
+ * returns true if added, false if already there
+ */
+ addEntity (entity) {
+ if (this.entities.indexOf(entity) >= 0) {
+ return false;
+ }
+ this.entities.push(entity);
+
+ this._nodeCollections.forEach(function (collection) {
+ collection.add(entity);
+ });
+
+ return true;
+ }
+
+ /*
+ * Removes entity from system, removing from all node collections
+ *
+ * returns true if removed, false if not present
+ */
+ removeEntity (entity) {
+ let position;
+
+ position = this.entities.indexOf(entity);
+ if (position >= 0) {
+ this._nodeCollections.forEach(function (collection) {
+ collection.remove(entity);
+ });
+
+ this.entities.splice(position, 1);
+ return true;
+ }
+
+ return false;
+ }
+
+ /*
+ * Given a Node Class, retrieves a list of all the nodes for each
+ * applicable entity.
+ */
+ getNodes (nodeType) {
+ let position, nodeCollection;
+
+ position = this._nodeCollectionKeys.indexOf(nodeType);
+
+ if (position >= 0) {
+ return this._nodeCollections[position].nodes;
+ }
+
+ nodeCollection = new Serpentity.NodeCollection({
+ type : nodeType
+ });
+
+ this._nodeCollectionKeys.push(nodeType);
+ this._nodeCollections.push(nodeCollection);
+
+ this.entities.forEach(function (entity) {
+ nodeCollection.add(entity);
+ });
+
+ return nodeCollection.nodes;
+ }
+
+ /*
+ * Calls update for every loaded system.
+ */
+ update (dt) {
+ this.systems.forEach(function (system) {
+ system.update(dt);
+ });
+ }
+};
+
+// Add namespaced objects.
+if (typeof module !== 'undefined' && this.module !== module) {
+ Serpentity.Component = require('./serpentity/component.js');
+ Serpentity.Entity = require('./serpentity/entity.js');
+ Serpentity.Node = require('./serpentity/node.js');
+ Serpentity.NodeCollection = require('./serpentity/node_collection.js');
+ Serpentity.System = require('./serpentity/system.js');
+
+ module.exports = Serpentity;
+} else {
+ window.Serpentity = Serpentity;
+}