'use strict'
var through2 = require('through2');
module.exports = modify;
function modify(){
 return through2.obj(function(file, encoding, cb){
 //如果文件为空，不做任何操作，转入下一个操作，即下一个pipe
 if(file.isNull()){
 console.log('isNull');
 this.push(file);
 return cb();
 }
 //插件不支持对stream直接操作，抛出异常
 if(file.isStream()){
 console.log('isStream');
 this.emit('error');
 return cb();
 }
 //内容转换，处理好后，再转成Buffer形式
 var content = versionFun(file.contents.toString());
 file.contents = new Buffer(content);
 //下面这两句基本是标配，可参考through2的API
 this.push(file);
 cb();
 });
}
function versionFun(data){
 return data.replace(/{{something}}/, ' Monkey 2 Dorie ');
}

'use strict'
var through = require('through-gulp');
module.exports = modify;
function modify(){
 var stream = through(function(file, encoding, callback){
 //如果文件为空，不做任何操作，转入下一个操作，即下一个pipe
 if(file.isNull()){
 console.log('file is null!');
 this.push(file);
 return callback(); 
 }
 //插件不支持对stream直接操作，抛出异常
 if(file.isStream()){
 console.log('file is stream!');
 this.emit('error');
 return callback(); 
 }
 //内容转换，处理好后，再转成Buffer形式
 var content = versionFun(file.contents.toString('utf-8'));
 file.contents = new Buffer(content, 'utf-8');
 this.push(file);
 callback();
 }, function(callback){
 console.log('处理完毕!');
 callback();
 });
 return stream;
}
function versionFun(data){
 return data.replace(/{{something}}/, ' Monkey 2 Dorie ');
}