forked from gulpjs/ordered-read-streams
-
Notifications
You must be signed in to change notification settings - Fork 0
/
index.js
141 lines (111 loc) · 2.7 KB
/
index.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
var Readable = require('streamx').Readable;
function isReadable(stream) {
if (typeof stream.pipe !== 'function') {
return false;
}
if (!stream.readable) {
return false;
}
if (typeof stream.read !== 'function') {
return false;
}
return true;
}
function assertReadableStream(stream) {
if (!isReadable(stream)) {
throw new Error('All input streams must be readable');
}
}
function OrderedStreams(streams, options) {
streams = streams || [];
if (!Array.isArray(streams)) {
streams = [streams];
}
streams = Array.prototype.concat.apply([], streams);
streams.forEach(assertReadableStream);
options = Object.assign({}, options, {
read: read,
predestroy: predestroy,
});
var readable = new Readable(options);
var streamIdx = 0;
var activeStream = streams[streamIdx];
var destroyedIdx = -1;
var destroyedByError = false;
var readableClosed = false;
streams.forEach(setup);
function setup(stream, idx) {
stream.on('data', onData);
stream.once('error', onError);
stream.once('end', onEnd);
stream.once('close', onClose);
stream.pause();
function cleanup() {
stream.off('data', onData);
stream.off('error', onError);
stream.off('end', onEnd);
stream.off('close', onClose);
}
function onError(err) {
destroyedByError = true;
cleanup();
readable.destroy(err);
}
function onEnd() {
streamIdx++;
activeStream = streams[streamIdx];
cleanup();
if (activeStream) {
activeStream.resume();
} else {
readable.push(null);
}
}
function onClose() {
destroyedIdx = idx;
readableClosed = true;
cleanup();
readable.destroy();
}
}
function predestroy() {
streams.forEach(destroyStream);
}
function destroyStream(stream, idx) {
if (destroyedIdx === idx) {
return;
}
if (destroyedByError) {
return stream.destroy();
}
if (readableClosed) {
return stream.destroy();
}
stream.destroy(new Error('Wrapper destroyed'));
}
function onData(chunk) {
var drained = readable.push(chunk);
// If the stream is not drained, we pause the activeStream
// The activeStream will be resumed on the next call to `read`
if (!drained) {
activeStream.pause();
}
}
function read(cb) {
if (activeStream) {
activeStream.resume();
} else {
readable.push(null);
}
cb();
}
function addSource(stream) {
assertReadableStream(stream);
var idx = streams.push(stream);
setup(stream, idx);
activeStream = streams[streamIdx];
}
readable.addSource = addSource;
return readable;
}
module.exports = OrderedStreams;