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

   1 import Events from 'events';
   2
   3 /*
   4  * Node Collections contain nodes, in order to keep the lists of nodes
   5  * that belong to each type.
   6  *
   7  * It has a type which is the class name of the node, and an array of
   8  * instances of that class.
   9  */
  10
  11 export class NodeCollection extends Events {
  12
  13   constructor(config) {
  14
  15     super();
  16
  17     this.nodes = [];
  18     this.type = null;
  19
  20     Object.assign(this, config);
  21   }
  22
  23   /*
  24    * Creates a node for an entity if it matches, and adds it to the
  25    * node list.
  26    *
  27    * Returns true if added, false otherwise.
  28    */
  29   add(entity) {
  30
  31     if (this.type.matches(entity) && !this._entityExists(entity)) {
  32
  33       const node = new this.type({});
  34       const types = this.type.types;
  35       const typeNames = Object.keys(types);
  36
  37       node.entity = entity;
  38
  39       for (const typeName of typeNames) {
  40         node[typeName] = entity.getComponent(types[typeName]);
  41       }
  42
  43       this.nodes.push(node);
  44       this.emit('nodeAdded', { node });
  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       this.emit('nodeRemoved', { node: foundNode });
  74     }
  75
  76     return found;
  77   }
  78
  79   /*
  80    * Checks whether we already have nodes for this entity.
  81    */
  82   _entityExists(entity) {
  83
  84     let found = false;
  85
  86     for (const node of this.nodes) {
  87       if (node.entity === entity) {
  88         found = true;
  89       }
  90     }
  91
  92     return found;
  93   }
  94 }
  95
  96
  97 /*
  98  * Make the node collection iterable without returning the array directly
  99  */
 100 NodeCollection.prototype[Symbol.iterator] = function * () {
 101
 102   yield* this.nodes;
 103 };