git.r.bdr.sh - rbdr/serpentity/blob - lib/serpentity/node_collection.js

   1 /*
   2  * Node Collections contain nodes, in order to keep the lists of nodes
   3  * that belong to each type.
   4  *
   5  * It has a type which is the class name of the node, and an array of
   6  * instances of that class.
   7  */
   8
   9 export class NodeCollection extends EventTarget {
  10
  11   constructor(config) {
  12
  13     super();
  14
  15     this.nodes = [];
  16     this.type = null;
  17
  18     Object.assign(this, config);
  19   }
  20
  21   /*
  22    * Creates a node for an entity if it matches, and adds it to the
  23    * node list.
  24    *
  25    * Returns true if added, false otherwise.
  26    */
  27   add(entity) {
  28
  29     if (this.type.matches(entity) && !this._entityExists(entity)) {
  30
  31       const node = new this.type({});
  32       const types = this.type.types;
  33       const typeNames = Object.keys(types);
  34
  35       node.entity = entity;
  36
  37       for (const typeName of typeNames) {
  38         node[typeName] = entity.getComponent(types[typeName]);
  39       }
  40
  41       this.nodes.push(node);
  42       const event = new Event('nodeAdded');
  43       event.node = node;
  44       this.dispatchEvent(event);
  45
  46       return true;
  47     }
  48
  49     return false;
  50   }
  51
  52   /*
  53    * Removes an entity by removing its related node from the list of nodes
  54    *
  55    * returns true if it was removed, false otherwise.
  56    */
  57   remove(entity) {
  58
  59     let foundIndex = -1;
  60     let foundNode = null;
  61
  62     const found = this.nodes.some((node, i) => {
  63
  64       if (node.entity === entity) {
  65         foundIndex = i;
  66         foundNode = node;
  67         return true;
  68       }
  69     });
  70
  71     if (found) {
  72       this.nodes.splice(foundIndex, 1);
  73       const event = new Event('nodeRemoved');
  74       event.node = foundNode;
  75       this.dispatchEvent(event);
  76     }
  77
  78     return found;
  79   }
  80
  81   /*
  82    * Checks whether we already have nodes for this entity.
  83    */
  84   _entityExists(entity) {
  85
  86     return this.nodes.some((node) => node.entity === entity);
  87   }
  88 }
  89
  90
  91 /*
  92  * Make the node collection iterable without returning the array directly
  93  */
  94 NodeCollection.prototype[Symbol.iterator] = function * () {
  95
  96   yield* this.nodes;
  97 };