pipeline:用于链接数据处理的双向管道（类似于流）

加工管道 用法 let pipeline = new Pipeline ( ) ; let firstLayer = { request : function ( input ) { // cannot handle the request if ( input . value !== 'foo' ) { input . next ( ) ; } input . resolve ( 'foo' ) ; } , response : function ( value ) { return 'the ' + value ; } } ; let secondLayer = { request : function ( input ) { // handle the request input . resolve ( 'response' ) ; }