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

   1 'use strict';
   2
   3 const Events = require('events');
   4
   5 /*
   6  * Node Collections contain nodes, in order to keep the lists of nodes
   7  * that belong to each type.
   8  *
   9  * It has a type which is the class name of the node, and an array of
  10  * instances of that class.
  11  */
  12
  13 const NodeCollection = class NodeCollection extends Events {
  14
  15   constructor(config) {
  16
  17     super();
  18
  19     this.nodes = [];
  20     this.type = null;
  21
  22     Object.assign(this, config);
  23   }
  24
  25   /*
  26    * Creates a node for an entity if it matches, and adds it to the
  27    * node list.
  28    *
  29    * Returns true if added, false otherwise.
  30    */
  31   add(entity) {
  32
  33     if (this.type.matches(entity) && !this._entityExists(entity)) {
  34
  35       const node = new this.type({});
  36       const types = this.type.types;
  37       const typeNames = Object.keys(types);
  38
  39       node.entity = entity;
  40
  41       for (const typeName of typeNames) {
  42         node[typeName] = entity.getComponent(types[typeName]);
  43       }
  44
  45       this.nodes.push(node);
  46       this.emit('nodeAdded', { node });
  47
  48       return true;
  49     }
  50
  51     return false;
  52   }
  53
  54   /*
  55    * Removes an entity by removing its related node from the list of nodes
  56    *
  57    * returns true if it was removed, false otherwise.
  58    */
  59   remove(entity) {
  60
  61     let foundIndex = -1;
  62     let foundNode = null;
  63
  64     const found = this.nodes.some((node, i) => {
  65
  66       if (node.entity === entity) {
  67         foundIndex = i;
  68         foundNode = node;
  69         return true;
  70       }
  71     });
  72
  73     if (found) {
  74       this.nodes.splice(foundIndex, 1);
  75       this.emit('nodeRemoved', { foundNode });
  76     }
  77
  78     return found;
  79   }
  80
  81   /*
  82    * Checks whether we already have nodes for this entity.
  83    */
  84   _entityExists(entity) {
  85
  86     let found = false;
  87
  88     for (const node of this.nodes) {
  89       if (node.entity === entity) {
  90         found = true;
  91       }
  92     }
  93
  94     return found;
  95   }
  96 };
  97
  98
  99 /*
 100  * Make the node collection iterable without returning the array directly
 101  */
 102 NodeCollection.prototype[Symbol.iterator] = function * () {
 103
 104   yield* this.nodes;
 105 };
 106
 107 module.exports = NodeCollection;