GeneratorFunctionBuilder - Builds new generator function with code.

example.js

var builder = new GeneratorFunctionBuilder('param1', 'param2');
var Func = builder
  .append('var ab = %d', 1234)
  .append('yield param1 + param2');
  .build();

/**
 * It is same with...
 * function* Func(param1, param2) {
 *   var ab = 1234;
 *   yield param1 + param2;
 * }
 */

GeneratorFunctionBuilder.js

'use strict';

var util = require('util');
var GeneratorFunction = (function*(){}).constructor;

module.exports = GeneratorFunctionBuilder;

/**
 * Builds new generator function with code.
 */
function GeneratorFunctionBuilder() {
    this.src = '';
    this.arguments = [];
    for (var i in arguments) this.arguments.push(arguments[i]);
}

GeneratorFunctionBuilder.prototype.append = function() {
    this.src += util.format.apply(null, arguments) + ';\n';
    return this;
}

GeneratorFunctionBuilder.prototype.build = function() {
    this.arguments.push(this.src);
    return GeneratorFunction.apply(null, this.arguments);
}