Entity Components

ec.js

import R from 'ramda';
import * as Perf from '../cpcs/performance';
import fast from '../../node_modules/fast.js/index';

/**
 * @return {string}
 */
function newId(){
  let d = new Date().getTime();
  let uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    const r = (d + Math.random()*16)%16 | 0;
    d = Math.floor(d/16);
    return (c=='x' ? r : (r&0x3|0x8)).toString(16);
  });
  return uuid;
}

/**
 * @return {object}
 */
export const newWorld = () => ({});

/**
 * @return {Entity}
 */
export const newEntity = () => ({});

/**
 *
 * @param {object} entities
 * @param {Entity} entity
 */
export const addEntity = function( entities, entity ){
  const id = newId();
  entities[ id ] = entity;
  entity._id = id;
  return entity;
};

/**
 *
 * @param {object} entities
 * @param {Entity} entity
 * @return {Entity}
 */
export const removeEntity = function( entities, entity ){
  delete entities[ entity._id ];
  return entity;
};

/**
 *
 * @param {object} entities
 * @param {string} id
 * @return {Entity}
 */
export const getEntityById =function( entities, id ){
  return entities[ id ];
};

/**
 *
 * @param {object} entities
 * @param {Entity} entity
 * @return {string}
 */
export const lookupEntityId = function( entities, entity ){
  for( let id in entities ){
    if( entities[ id ] === entity ){
      return id;
    }
  }
};

export const createComponent = function( componentType, componentData = {} ){
  const component = new componentType( componentData );
  return component;
};

/**
 *
 * @param {Entity} entity
 * @param {Component.BaseComponent} component
 */
export const addComponent = function( entity, component ){
  entity[ component.name ] = component;
  return component;
};

/**
 *
 * @param {Entity} entity
 * @param {Component.BaseComponent} component
 */
export const removeComponent = function( entity, component ){
  delete entity[ component.name ];
  return component;
};

export const getEntities = function( entities, ...components ){
  //Perf.start('EC: Get Entities');
  const list = fast.filter( Object.values( entities ), function( entity ){
    return hasKeys( components, entity )
  }, this );
  //Perf.endByName('EC: Get Entities');
  return list;
};

/**
 *
 * @param {object} entities
 * @return {Entity[]}
 */
export const getEntityList = function( entities ){
  return Object.values( entities );
};

/**
 *
 * @param {string[]} keys
 * @param {object} object
 */
export const hasKeys = function( keys, object ){
  const objectKeys = Object.keys( object );
  return keys.every( function( keyName ){
    if( keyName.charAt( 0 ) === '!' ){
      return ( object[ keyName.slice(1,keyName.length) ] === undefined );
    }
    else{
      return ( object[ keyName ] !== undefined );
    }
  });
};

/**
 *
 * @param {*} componentTemplate
 */
export const defineComponent = function( componentTemplate ){
  const componentType = function( data ){
    const initializer = componentTemplate.init.bind( this );
    initializer( data );
  };
  componentType.prototype.name = componentTemplate.name;
  return componentType;
};

/**
 *
 * @param {object} entities
 * @return {CPCS.World}
 */
export const world = function( entities ){

  /**
   *
   * @param {Entity} entity
   */
  function addEntityIn( entity ){
    return addEntity( entities, entity );
  }

  /**
   *
   * @param {Entity} entity
   */
  function removeEntityIn( entity ){
    return removeEntity( entities, entity );
  }

  function getEntitiesIn(...args){
    return getEntities( entities, ...args )
  }

  /**
   *
   * @param {string} id
   * @return {Entity}
   */
  function getEntityByIdIn( id ){
    return getEntityById( entities, id );
  }

  /**
   *
   * @param {Entity} entity
   * @return {string}
   */
  function lookupEntityByIdIn( entity ){
    return lookupEntityId( entities, entity );
  }

  /**
   * @type {CPCS.World}
   */
  const w = {
    addEntity: addEntityIn,
    removeEntity: removeEntityIn,
    getEntities: getEntitiesIn,
    get: () => entities,
    clone: () => R.clone( entities ),
    getEntityById: getEntityByIdIn,
    lookupEntityId: lookupEntityByIdIn
  };

  return w;
};