1 | 'use strict'
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2 |
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3 |
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4 |
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5 |
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6 |
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7 |
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8 |
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9 | var Stream = require('stream')
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10 | var PassThrough = Stream.PassThrough
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11 | var slice = Array.prototype.slice
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12 |
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13 | module.exports = function merge2 () {
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14 | var streamsQueue = []
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15 | var merging = false
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16 | var args = slice.call(arguments)
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17 | var options = args[args.length - 1]
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18 |
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19 | if (options && !Array.isArray(options) && options.pipe == null) args.pop()
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20 | else options = {}
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21 |
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22 | var doEnd = options.end !== false
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23 | if (options.objectMode == null) options.objectMode = true
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24 | if (options.highWaterMark == null) options.highWaterMark = 64 * 1024
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25 | var mergedStream = PassThrough(options)
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26 |
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27 | function addStream () {
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28 | for (var i = 0, len = arguments.length; i < len; i++) {
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29 | streamsQueue.push(pauseStreams(arguments[i], options))
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30 | }
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31 | mergeStream()
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32 | return this
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33 | }
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34 |
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35 | function mergeStream () {
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36 | if (merging) return
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37 | merging = true
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38 |
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39 | var streams = streamsQueue.shift()
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40 | if (!streams) return endStream()
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41 | if (!Array.isArray(streams)) streams = [streams]
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42 |
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43 | var pipesCount = streams.length + 1
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44 |
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45 | function next () {
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46 | if (--pipesCount > 0) return
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47 | merging = false
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48 | mergeStream()
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49 | }
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50 |
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51 | function pipe (stream) {
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52 | function onend () {
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53 | stream.removeListener('merge2UnpipeEnd', onend)
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54 | stream.removeListener('end', onend)
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55 | next()
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56 | }
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57 |
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58 | if (stream._readableState.endEmitted) return next()
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59 |
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60 | stream.on('merge2UnpipeEnd', onend)
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61 | stream.on('end', onend)
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62 | stream.pipe(mergedStream, {end: false})
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63 |
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64 | stream.resume()
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65 | }
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66 |
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67 | for (var i = 0; i < streams.length; i++) pipe(streams[i])
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68 |
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69 | next()
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70 | }
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71 |
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72 | function endStream () {
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73 | merging = false
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74 |
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75 | mergedStream.emit('queueDrain')
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76 | return doEnd && mergedStream.end()
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77 | }
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78 |
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79 | mergedStream.setMaxListeners(0)
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80 | mergedStream.add = addStream
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81 | mergedStream.on('unpipe', function (stream) {
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82 | stream.emit('merge2UnpipeEnd')
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83 | })
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84 |
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85 | if (args.length) addStream.apply(null, args)
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86 | return mergedStream
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87 | }
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88 |
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89 |
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90 | function pauseStreams (streams, options) {
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91 | if (!Array.isArray(streams)) {
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92 |
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93 | if (!streams._readableState && streams.pipe) streams = streams.pipe(PassThrough(options))
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94 | if (!streams._readableState || !streams.pause || !streams.pipe) {
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95 | throw new Error('Only readable stream can be merged.')
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96 | }
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97 | streams.pause()
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98 | } else {
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99 | for (var i = 0, len = streams.length; i < len; i++) streams[i] = pauseStreams(streams[i])
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100 | }
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101 | return streams
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102 | }
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