54 lines
973 B
JavaScript
54 lines
973 B
JavaScript
|
'use strict';
|
||
|
|
|
||
|
|
var Writable = require('readable-stream/writable');
|
||
|
|
|
||
|
|
function listenerCount(stream, evt) {
|
||
|
|
return stream.listeners(evt).length;
|
||
|
|
}
|
||
|
|
|
||
|
|
function hasListeners(stream) {
|
||
|
|
return !!(listenerCount(stream, 'readable') || listenerCount(stream, 'data'));
|
||
|
|
}
|
||
|
|
|
||
|
|
function sink(stream) {
|
||
|
|
var sinkAdded = false;
|
||
|
|
var sinkStream = new Writable({
|
||
|
|
objectMode: true,
|
||
|
|
write: function(file, enc, cb) {
|
||
|
|
cb();
|
||
|
|
},
|
||
|
|
});
|
||
|
|
|
||
|
|
function addSink() {
|
||
|
|
if (sinkAdded) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (hasListeners(stream)) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
sinkAdded = true;
|
||
|
|
stream.pipe(sinkStream);
|
||
|
|
}
|
||
|
|
|
||
|
|
function removeSink(evt) {
|
||
|
|
if (evt !== 'readable' && evt !== 'data') {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (hasListeners(stream)) {
|
||
|
|
sinkAdded = false;
|
||
|
|
stream.unpipe(sinkStream);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
stream.on('newListener', removeSink);
|
||
|
|
stream.on('removeListener', removeSink);
|
||
|
|
stream.on('removeListener', addSink);
|
||
|
|
|
||
|
|
return addSink;
|
||
|
|
}
|
||
|
|
|
||
|
|
module.exports = sink;
|