// Generator start -------  thunk 用法

const Thunk = function(fn) {
  return function (...args) {
    return function (callback) {
      return fn.call(this, ...args, callback);
    }
  };
};
const run_thunk = function (fn) {
  var gen = fn();

  function next(data) {
    var result = gen.next(data);
    if (result.done) return;
    result.value(next);
  }
  next();
}

 var readFile = Thunk(fs.readFile);
 function* g() {
   var f1 = yield readFile(‘fileA‘);
   var f2 = yield readFile(‘fileB‘);
   // ...
   var fn = yield readFile(‘fileN‘);
 }
 run_thunk(g);

---------- promise用法
function run_promise(gen){
  var g = gen();

  function next(data){
    var result = g.next(data);
    if (result.done) return result.value;
    result.value.then(function(data){
      next(data);
    });
  }
  next();
}

 var fs = require(‘fs‘);

 var readFile = function (fileName){
   return new Promise(function (resolve, reject){
     fs.readFile(fileName, function(error, data){
       if (error) return reject(error);
       resolve(data);
     });
   });
 };

 var gen = function* (){
   var f1 = yield readFile(‘/etc/fstab‘);
   var f2 = yield readFile(‘/etc/shells‘);
   console.log(f1.toString());
   console.log(f2.toString());
 };

 run_promise(gen);


// -----------co 用法

var gen = function* () {
  var f1 = yield readFile(‘/etc/fstab‘);
  var f2 = yield readFile(‘/etc/shells‘);
  console.log(f1.toString());
  console.log(f2.toString());
};

// var co = require(‘co‘);
// co(gen);
// co(gen).then(function (){
//   console.log(‘Generator 函数执行完成‘);
// });

//------------co end

// Generator end -------

ES6.0 Generator 三种用法