Proxy coify

coify.js

'use strict';

const co  = require('co');

const toString = Object.prototype.toString;
const genTag   = '[object GeneratorFunction]';

const handler = {
  get( target, key, receiver ) {
    const fn = target[ key ];
    const str = toString.call( fn );
    if ( str === genTag ) {
      return co.wrap( fn );
    }
    return Reflect.get( target, key, receiver );
  }
};

module.exports = function coify( obj ) {
  const proxy = new Proxy( obj, handler );
  if ( typeof obj === 'function' ) {
    proxy.prototype = new Proxy( obj.prototype, handler );
  }
  return proxy;
};