source: trip-planner-front/node_modules/asynckit/lib/streamify.js

Last change on this file was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago

initial commit

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Line 
1var async = require('./async.js');
2
3// API
4module.exports = {
5 iterator: wrapIterator,
6 callback: wrapCallback
7};
8
9/**
10 * Wraps iterators with long signature
11 *
12 * @this ReadableAsyncKit#
13 * @param {function} iterator - function to wrap
14 * @returns {function} - wrapped function
15 */
16function wrapIterator(iterator)
17{
18 var stream = this;
19
20 return function(item, key, cb)
21 {
22 var aborter
23 , wrappedCb = async(wrapIteratorCallback.call(stream, cb, key))
24 ;
25
26 stream.jobs[key] = wrappedCb;
27
28 // it's either shortcut (item, cb)
29 if (iterator.length == 2)
30 {
31 aborter = iterator(item, wrappedCb);
32 }
33 // or long format (item, key, cb)
34 else
35 {
36 aborter = iterator(item, key, wrappedCb);
37 }
38
39 return aborter;
40 };
41}
42
43/**
44 * Wraps provided callback function
45 * allowing to execute snitch function before
46 * real callback
47 *
48 * @this ReadableAsyncKit#
49 * @param {function} callback - function to wrap
50 * @returns {function} - wrapped function
51 */
52function wrapCallback(callback)
53{
54 var stream = this;
55
56 var wrapped = function(error, result)
57 {
58 return finisher.call(stream, error, result, callback);
59 };
60
61 return wrapped;
62}
63
64/**
65 * Wraps provided iterator callback function
66 * makes sure snitch only called once,
67 * but passes secondary calls to the original callback
68 *
69 * @this ReadableAsyncKit#
70 * @param {function} callback - callback to wrap
71 * @param {number|string} key - iteration key
72 * @returns {function} wrapped callback
73 */
74function wrapIteratorCallback(callback, key)
75{
76 var stream = this;
77
78 return function(error, output)
79 {
80 // don't repeat yourself
81 if (!(key in stream.jobs))
82 {
83 callback(error, output);
84 return;
85 }
86
87 // clean up jobs
88 delete stream.jobs[key];
89
90 return streamer.call(stream, error, {key: key, value: output}, callback);
91 };
92}
93
94/**
95 * Stream wrapper for iterator callback
96 *
97 * @this ReadableAsyncKit#
98 * @param {mixed} error - error response
99 * @param {mixed} output - iterator output
100 * @param {function} callback - callback that expects iterator results
101 */
102function streamer(error, output, callback)
103{
104 if (error && !this.error)
105 {
106 this.error = error;
107 this.pause();
108 this.emit('error', error);
109 // send back value only, as expected
110 callback(error, output && output.value);
111 return;
112 }
113
114 // stream stuff
115 this.push(output);
116
117 // back to original track
118 // send back value only, as expected
119 callback(error, output && output.value);
120}
121
122/**
123 * Stream wrapper for finishing callback
124 *
125 * @this ReadableAsyncKit#
126 * @param {mixed} error - error response
127 * @param {mixed} output - iterator output
128 * @param {function} callback - callback that expects final results
129 */
130function finisher(error, output, callback)
131{
132 // signal end of the stream
133 // only for successfully finished streams
134 if (!error)
135 {
136 this.push(null);
137 }
138
139 // back to original track
140 callback(error, output);
141}
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