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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
import map from './map';
import wrapAsync from './internal/wrapAsync';
import awaitify from './internal/awaitify'
/**
* Sorts a list by the results of running each `coll` value through an async
* `iteratee`.
*
* @name sortBy
* @static
* @memberOf module:Collections
* @method
* @category Collection
* @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over.
* @param {AsyncFunction} iteratee - An async function to apply to each item in
* `coll`.
* The iteratee should complete with a value to use as the sort criteria as
* its `result`.
* Invoked with (item, callback).
* @param {Function} callback - A callback which is called after all the
* `iteratee` functions have finished, or an error occurs. Results is the items
* from the original `coll` sorted by the values returned by the `iteratee`
* calls. Invoked with (err, results).
* @returns {Promise} a promise, if no callback passed
* @example
*
* // bigfile.txt is a file that is 251100 bytes in size
* // mediumfile.txt is a file that is 11000 bytes in size
* // smallfile.txt is a file that is 121 bytes in size
*
* // asynchronous function that returns the file size in bytes
* function getFileSizeInBytes(file, callback) {
* fs.stat(file, function(err, stat) {
* if (err) {
* return callback(err);
* }
* callback(null, stat.size);
* });
* }
*
* // Using callbacks
* async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], getFileSizeInBytes,
* function(err, results) {
* if (err) {
* console.log(err);
* } else {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }
* }
* );
*
* // By modifying the callback parameter the
* // sorting order can be influenced:
*
* // ascending order
* async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], function(file, callback) {
* getFileSizeInBytes(file, function(getFileSizeErr, fileSize) {
* if (getFileSizeErr) return callback(getFileSizeErr);
* callback(null, fileSize);
* });
* }, function(err, results) {
* if (err) {
* console.log(err);
* } else {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }
* }
* );
*
* // descending order
* async.sortBy(['bigfile.txt','mediumfile.txt','smallfile.txt'], function(file, callback) {
* getFileSizeInBytes(file, function(getFileSizeErr, fileSize) {
* if (getFileSizeErr) {
* return callback(getFileSizeErr);
* }
* callback(null, fileSize * -1);
* });
* }, function(err, results) {
* if (err) {
* console.log(err);
* } else {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'bigfile.txt', 'mediumfile.txt', 'smallfile.txt']
* }
* }
* );
*
* // Error handling
* async.sortBy(['mediumfile.txt','smallfile.txt','missingfile.txt'], getFileSizeInBytes,
* function(err, results) {
* if (err) {
* console.log(err);
* // [ Error: ENOENT: no such file or directory ]
* } else {
* console.log(results);
* }
* }
* );
*
* // Using Promises
* async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], getFileSizeInBytes)
* .then( results => {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }).catch( err => {
* console.log(err);
* });
*
* // Error handling
* async.sortBy(['mediumfile.txt','smallfile.txt','missingfile.txt'], getFileSizeInBytes)
* .then( results => {
* console.log(results);
* }).catch( err => {
* console.log(err);
* // [ Error: ENOENT: no such file or directory ]
* });
*
* // Using async/await
* (async () => {
* try {
* let results = await async.sortBy(['bigfile.txt','mediumfile.txt','smallfile.txt'], getFileSizeInBytes);
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }
* catch (err) {
* console.log(err);
* }
* })();
*
* // Error handling
* async () => {
* try {
* let results = await async.sortBy(['missingfile.txt','mediumfile.txt','smallfile.txt'], getFileSizeInBytes);
* console.log(results);
* }
* catch (err) {
* console.log(err);
* // [ Error: ENOENT: no such file or directory ]
* }
* }
*
*/
function sortBy (coll, iteratee, callback) {
var _iteratee = wrapAsync(iteratee);
return map(coll, (x, iterCb) => {
_iteratee(x, (err, criteria) => {
if (err) return iterCb(err);
iterCb(err, {value: x, criteria});
});
}, (err, results) => {
if (err) return callback(err);
callback(null, results.sort(comparator).map(v => v.value));
});
function comparator(left, right) {
var a = left.criteria, b = right.criteria;
return a < b ? -1 : a > b ? 1 : 0;
}
}
export default awaitify(sortBy, 3)
|
