62 lines
1.2 KiB
JavaScript
62 lines
1.2 KiB
JavaScript
'use strict';
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var Writable = require('flush-write-stream');
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function listenerCount(stream, evt) {
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return stream.listeners(evt).length;
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}
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function hasListeners(stream) {
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return !!(listenerCount(stream, 'readable') || listenerCount(stream, 'data'));
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}
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function sinker(file, enc, callback) {
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callback();
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}
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function sink(stream) {
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var sinkAdded = false;
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var sinkOptions = {
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objectMode: stream._readableState.objectMode,
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};
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var sinkStream = new Writable(sinkOptions, sinker);
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function addSink() {
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if (sinkAdded) {
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return;
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}
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if (hasListeners(stream)) {
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return;
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}
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sinkAdded = true;
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stream.pipe(sinkStream);
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}
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function removeSink(evt) {
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if (evt !== 'readable' && evt !== 'data') {
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return;
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}
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if (hasListeners(stream)) {
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sinkAdded = false;
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stream.unpipe(sinkStream);
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}
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}
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stream.on('newListener', removeSink);
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stream.on('removeListener', removeSink);
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stream.on('removeListener', addSink);
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// Sink the stream to start flowing
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// Do this on nextTick, it will flow at slowest speed of piped streams
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process.nextTick(addSink);
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return stream;
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}
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module.exports = sink;
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