145 lines
3.2 KiB
JavaScript
145 lines
3.2 KiB
JavaScript
'use strict';
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/*
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* merge2
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* https://github.com/teambition/merge2
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*
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* Copyright (c) 2014-2020 Teambition
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* Licensed under the MIT license.
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*/
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const Stream = require('stream');
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const PassThrough = Stream.PassThrough;
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const slice = Array.prototype.slice;
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module.exports = merge2;
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function merge2() {
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const streamsQueue = [];
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const args = slice.call(arguments);
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let merging = false;
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let options = args[args.length - 1];
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if (options && !Array.isArray(options) && options.pipe == null) {
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args.pop();
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} else {
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options = {};
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}
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const doEnd = options.end !== false;
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const doPipeError = options.pipeError === true;
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if (options.objectMode == null) {
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options.objectMode = true;
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}
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if (options.highWaterMark == null) {
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options.highWaterMark = 64 * 1024;
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}
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const mergedStream = PassThrough(options);
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function addStream() {
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for (let i = 0, len = arguments.length; i < len; i++) {
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streamsQueue.push(pauseStreams(arguments[i], options));
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}
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mergeStream();
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return this;
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}
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function mergeStream() {
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if (merging) {
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return;
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}
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merging = true;
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let streams = streamsQueue.shift();
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if (!streams) {
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process.nextTick(endStream);
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return;
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}
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if (!Array.isArray(streams)) {
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streams = [streams];
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}
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let pipesCount = streams.length + 1;
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function next() {
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if (--pipesCount > 0) {
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return;
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}
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merging = false;
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mergeStream();
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}
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function pipe(stream) {
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function onend() {
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stream.removeListener('merge2UnpipeEnd', onend);
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stream.removeListener('end', onend);
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if (doPipeError) {
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stream.removeListener('error', onerror);
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}
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next();
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}
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function onerror(err) {
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mergedStream.emit('error', err);
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}
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// skip ended stream
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if (stream._readableState.endEmitted) {
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return next();
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}
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stream.on('merge2UnpipeEnd', onend);
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stream.on('end', onend);
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if (doPipeError) {
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stream.on('error', onerror);
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}
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stream.pipe(mergedStream, { end: false });
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// compatible for old stream
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stream.resume();
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}
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for (let i = 0; i < streams.length; i++) {
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pipe(streams[i]);
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}
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next();
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}
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function endStream() {
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merging = false;
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// emit 'queueDrain' when all streams merged.
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mergedStream.emit('queueDrain');
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if (doEnd) {
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mergedStream.end();
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}
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}
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mergedStream.setMaxListeners(0);
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mergedStream.add = addStream;
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mergedStream.on('unpipe', function (stream) {
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stream.emit('merge2UnpipeEnd');
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});
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if (args.length) {
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addStream.apply(null, args);
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}
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return mergedStream;
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}
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// check and pause streams for pipe.
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function pauseStreams(streams, options) {
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if (!Array.isArray(streams)) {
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// Backwards-compat with old-style streams
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if (!streams._readableState && streams.pipe) {
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streams = streams.pipe(PassThrough(options));
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}
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if (!streams._readableState || !streams.pause || !streams.pipe) {
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throw new Error('Only readable stream can be merged.');
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}
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streams.pause();
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} else {
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for (let i = 0, len = streams.length; i < len; i++) {
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streams[i] = pauseStreams(streams[i], options);
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}
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}
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return streams;
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}
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