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     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
  61     const found = this.nodes.some((node, i) => {
  62
  63       if (node.entity === entity) {
  64         foundIndex = i;
  65         return true;
  66       }
  67     });
  68
  69     if (found) {
  70       this.nodes.splice(foundIndex, 1);
  71       this.emit('nodeRemoved', { node });
  72     }
  73
  74     return found;
  75   }
  76
  77   /*
  78    * Checks whether we already have nodes for this entity.
  79    */
  80   _entityExists(entity) {
  81
  82     let found = false;
  83
  84     for (const node of this.nodes) {
  85       if (node.entity === entity) {
  86         found = true;
  87       }
  88     }
  89
  90     return found;
  91   }
  92 };
  93
  94 module.exports = NodeCollection;