427 lines
10 KiB
Markdown
427 lines
10 KiB
Markdown
|
<!--
|
||
|
|
|
||
|
|
@license Apache-2.0
|
||
|
|
|
||
|
|
Copyright (c) 2018 The Stdlib Authors.
|
||
|
|
|
||
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
you may not use this file except in compliance with the License.
|
||
|
|
You may obtain a copy of the License at
|
||
|
|
|
||
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
|
||
|
|
Unless required by applicable law or agreed to in writing, software
|
||
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
See the License for the specific language governing permissions and
|
||
|
|
limitations under the License.
|
||
|
|
|
||
|
|
-->
|
||
|
|
|
||
|
|
# inmapAsync
|
||
|
|
|
||
|
|
> Invoke a function for each element in a collection and update the collection in-place.
|
||
|
|
|
||
|
|
<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
|
||
|
|
|
||
|
|
<section class="intro">
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.intro -->
|
||
|
|
|
||
|
|
<!-- Package usage documentation. -->
|
||
|
|
|
||
|
|
<section class="usage">
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
var inmapAsync = require( '@stdlib/utils/async/inmap' );
|
||
|
|
```
|
||
|
|
|
||
|
|
#### inmapAsync( collection, \[options,] fcn, done )
|
||
|
|
|
||
|
|
Invokes a function for each element in a `collection` and updates the `collection` in-place.
|
||
|
|
|
||
|
|
<!-- eslint-disable no-use-before-define -->
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, index, next ) {
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
console.log( value );
|
||
|
|
next( null, value*index );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( collection === arr );
|
||
|
|
console.log( collection );
|
||
|
|
}
|
||
|
|
|
||
|
|
var arr = [ 3000, 2500, 1000 ];
|
||
|
|
|
||
|
|
inmapAsync( arr, fcn, done );
|
||
|
|
/*
|
||
|
|
1000
|
||
|
|
2500
|
||
|
|
3000
|
||
|
|
true
|
||
|
|
[ 0, 2500, 2000 ]
|
||
|
|
*/
|
||
|
|
```
|
||
|
|
|
||
|
|
The `next` callback accepts two arguments: `error` and `result`. The second argument to the `next` callback is used to update the `collection` element for the corresponding collection `index`, thus mutating the input `collection`.
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, index, next ) {
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
next( null, 'beep: '+index );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( collection );
|
||
|
|
// => [ 'beep: 0', 'beep: 1', 'beep: 2' ]
|
||
|
|
}
|
||
|
|
|
||
|
|
var arr = [ 3000, 2500, 1000 ];
|
||
|
|
|
||
|
|
inmapAsync( arr, fcn, done );
|
||
|
|
```
|
||
|
|
|
||
|
|
If the `next` callback is called with an `error` argument, the input `collection` may be **partially** mutated.
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, index, next ) {
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
if ( index === 1 ) {
|
||
|
|
return next( new Error( 'boop' ) );
|
||
|
|
}
|
||
|
|
next( null, 'beep: '+index );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
// Ignore error...
|
||
|
|
}
|
||
|
|
console.log( collection );
|
||
|
|
// => [ 'beep: 0', 2000, 3000 ]
|
||
|
|
}
|
||
|
|
|
||
|
|
var arr = [ 1000, 2000, 3000 ];
|
||
|
|
|
||
|
|
inmapAsync( arr, fcn, done );
|
||
|
|
```
|
||
|
|
|
||
|
|
The function accepts the following `options`:
|
||
|
|
|
||
|
|
- `limit`: the maximum number of pending invocations at any one time. Default: `infinity`.
|
||
|
|
- `series`: `boolean` indicating whether to sequentially invoke `fcn` for each `collection` element. If `true`, the function sets `options.limit=1`. Default: `false`.
|
||
|
|
- `thisArg`: the execution context for `fcn`.
|
||
|
|
|
||
|
|
By default, all elements are processed concurrently, which means that the function does **not** guarantee completion order. To process each `collection` element sequentially, set the `series` option to `true`.
|
||
|
|
|
||
|
|
<!-- eslint-disable no-use-before-define -->
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, index, next ) {
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
console.log( value );
|
||
|
|
next( null, value*index );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( collection === arr );
|
||
|
|
console.log( collection );
|
||
|
|
}
|
||
|
|
|
||
|
|
var arr = [ 3000, 2500, 1000 ];
|
||
|
|
|
||
|
|
var opts = {
|
||
|
|
'series': true
|
||
|
|
};
|
||
|
|
|
||
|
|
inmapAsync( arr, opts, fcn, done );
|
||
|
|
/* =>
|
||
|
|
3000
|
||
|
|
2500
|
||
|
|
1000
|
||
|
|
true
|
||
|
|
[ 0, 2500, 2000 ]
|
||
|
|
*/
|
||
|
|
```
|
||
|
|
|
||
|
|
To limit the maximum number of pending function invocations, set the `limit` option.
|
||
|
|
|
||
|
|
<!-- eslint-disable no-use-before-define -->
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, index, next ) {
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
console.log( value );
|
||
|
|
next( null, value*index );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( collection === arr );
|
||
|
|
console.log( collection );
|
||
|
|
}
|
||
|
|
|
||
|
|
var arr = [ 3000, 2500, 1000 ];
|
||
|
|
|
||
|
|
var opts = {
|
||
|
|
'limit': 2
|
||
|
|
};
|
||
|
|
|
||
|
|
inmapAsync( arr, opts, fcn, done );
|
||
|
|
/* =>
|
||
|
|
2500
|
||
|
|
3000
|
||
|
|
1000
|
||
|
|
true,
|
||
|
|
[ 0, 2500, 2000 ]
|
||
|
|
*/
|
||
|
|
```
|
||
|
|
|
||
|
|
To set the execution context of `fcn`, set the `thisArg` option.
|
||
|
|
|
||
|
|
<!-- eslint-disable no-use-before-define -->
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, index, next ) {
|
||
|
|
this.count += 1;
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
next( null, value*index );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
var arr = [ 3000, 2500, 1000 ];
|
||
|
|
|
||
|
|
var context = {
|
||
|
|
'count': 0
|
||
|
|
};
|
||
|
|
|
||
|
|
var opts = {
|
||
|
|
'thisArg': context
|
||
|
|
};
|
||
|
|
|
||
|
|
inmapAsync( arr, opts, fcn, done );
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( collection === arr );
|
||
|
|
// => true
|
||
|
|
|
||
|
|
console.log( collection );
|
||
|
|
// => [ 0, 2500, 2000 ]
|
||
|
|
|
||
|
|
console.log( context.count );
|
||
|
|
// => 3
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
When invoked, `fcn` is provided a maximum of four arguments:
|
||
|
|
|
||
|
|
- `value`: collection value.
|
||
|
|
- `index`: collection index.
|
||
|
|
- `collection`: the input `collection`.
|
||
|
|
- `next`: a callback which should be called once `fcn` has finished processing a collection `value`.
|
||
|
|
|
||
|
|
The actual number of provided arguments depends on function `length`. If `fcn` accepts two arguments, `fcn` is provided `value` and `next`. If `fcn` accepts three arguments, `fcn` is provided `value`, `index`, and `next`. For every other `fcn` signature, `fcn` is provided all four arguments.
|
||
|
|
|
||
|
|
<!-- eslint-disable no-use-before-define -->
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, i, collection, next ) {
|
||
|
|
console.log( 'collection: %s. %d: %d', collection.join( ',' ), i, value );
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
console.log( value );
|
||
|
|
next( null, value*i );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( collection === arr );
|
||
|
|
// => true
|
||
|
|
|
||
|
|
console.log( collection );
|
||
|
|
// => [ 0, 2500, 2000 ]
|
||
|
|
}
|
||
|
|
|
||
|
|
var arr = [ 3000, 2500, 1000 ];
|
||
|
|
|
||
|
|
inmapAsync( arr, fcn, done );
|
||
|
|
/* =>
|
||
|
|
collection: 3000,2500,1000. 0: 3000
|
||
|
|
collection: 3000,2500,1000. 1: 2500
|
||
|
|
collection: 3000,2500,1000. 2: 1000
|
||
|
|
1000
|
||
|
|
2500
|
||
|
|
3000
|
||
|
|
*/
|
||
|
|
```
|
||
|
|
|
||
|
|
#### inmapAsync.factory( \[options,] fcn )
|
||
|
|
|
||
|
|
Returns a `function` which invokes a function once for each element in a `collection`.
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
function fcn( value, index, next ) {
|
||
|
|
setTimeout( onTimeout, value );
|
||
|
|
function onTimeout() {
|
||
|
|
console.log( value );
|
||
|
|
next( null, value*index );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function done( error, collection ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( collection );
|
||
|
|
}
|
||
|
|
|
||
|
|
var f = inmapAsync.factory( fcn );
|
||
|
|
|
||
|
|
var arr1 = [ 3000, 2500, 1000 ];
|
||
|
|
|
||
|
|
f( arr1, done );
|
||
|
|
/* =>
|
||
|
|
1000
|
||
|
|
2500
|
||
|
|
3000
|
||
|
|
[ 0, 2500, 2000 ]
|
||
|
|
*/
|
||
|
|
|
||
|
|
var arr2 = [ 300, 250, 100 ];
|
||
|
|
|
||
|
|
f( arr2, done );
|
||
|
|
/* =>
|
||
|
|
100
|
||
|
|
250
|
||
|
|
300
|
||
|
|
[ 0, 250, 200 ]
|
||
|
|
*/
|
||
|
|
```
|
||
|
|
|
||
|
|
The function accepts the same `options` as `inmapAsync()`.
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.usage -->
|
||
|
|
|
||
|
|
<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
|
||
|
|
|
||
|
|
<section class="notes">
|
||
|
|
|
||
|
|
## Notes
|
||
|
|
|
||
|
|
- A `collection` may be either an [`Array`][mdn-array], [`Typed Array`][mdn-typed-array], or an array-like [`Object`][mdn-object] (excluding `strings` and `functions`).
|
||
|
|
- If a provided function calls the `next` callback with a truthy `error` argument, the function suspends execution and immediately calls the `done` callback for subsequent `error` handling.
|
||
|
|
- The function invokes the `done` callback with the input `collection` provided as the second argument.
|
||
|
|
- The function modifies `collection` elements in-place.
|
||
|
|
- The function does **not** support dynamic `collection` resizing.
|
||
|
|
- The function does **not** skip `undefined` elements.
|
||
|
|
- **Neither** `inmapAsync` nor the function returned by the `factory` method **guarantee** asynchronous execution. To guarantee asynchrony, wrap the `done` callback in a function which either executes at the end of the current stack (e.g., `nextTick`) or during a subsequent turn of the event loop (e.g., `setImmediate`, `setTimeout`).
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.notes -->
|
||
|
|
|
||
|
|
<!-- Package usage examples. -->
|
||
|
|
|
||
|
|
<section class="examples">
|
||
|
|
|
||
|
|
## Examples
|
||
|
|
|
||
|
|
<!-- eslint no-undef: "error" -->
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
var resolve = require( 'path' ).resolve;
|
||
|
|
var readFile = require( '@stdlib/fs/read-file' );
|
||
|
|
var inmapAsync = require( '@stdlib/utils/async/inmap' );
|
||
|
|
|
||
|
|
var files = [
|
||
|
|
resolve( __dirname, 'package.json' ),
|
||
|
|
resolve( __dirname, 'README.md' )
|
||
|
|
];
|
||
|
|
|
||
|
|
function done( error, results ) {
|
||
|
|
if ( error ) {
|
||
|
|
throw error;
|
||
|
|
}
|
||
|
|
console.log( results );
|
||
|
|
}
|
||
|
|
|
||
|
|
function read( file, next ) {
|
||
|
|
var opts = {
|
||
|
|
'encoding': 'utf8'
|
||
|
|
};
|
||
|
|
readFile( file, opts, onFile );
|
||
|
|
|
||
|
|
function onFile( error, data ) {
|
||
|
|
if ( error ) {
|
||
|
|
error = new Error( 'unable to read file: '+file );
|
||
|
|
return next( error );
|
||
|
|
}
|
||
|
|
next( null, data );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
inmapAsync( files, read, done );
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.examples -->
|
||
|
|
|
||
|
|
<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
|
||
|
|
|
||
|
|
<section class="references">
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.references -->
|
||
|
|
|
||
|
|
<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
|
||
|
|
|
||
|
|
<section class="links">
|
||
|
|
|
||
|
|
[mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
|
||
|
|
|
||
|
|
[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
|
||
|
|
|
||
|
|
[mdn-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.links -->
|