All files / utils/async/for-each-right/lib factory.js

100% Statements 156/156
100% Branches 20/20
100% Functions 3/3
100% Lines 156/156

Press n or j to go to the next uncovered block, b, p or k for the previous block.

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 1573x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 145x 145x 145x 145x 145x 145x 145x 84x 84x 42x 42x 42x 145x 61x 61x 145x 36x 36x 145x 4x 145x 57x 57x 67x 67x 67x 67x 67x 67x 67x 67x 67x 67x 67x 67x 67x 101x 33x 33x 101x 36x 36x 32x 32x 32x 32x 32x 32x 32x 32x 32x 32x 32x 8x 8x 24x 32x 101x 145x 3x 3x 3x 3x 3x  
/**
* @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.
*/
 
'use strict';
 
// MODULES //
 
var isFunction = require( '@stdlib/assert/is-function' );
var isCollection = require( '@stdlib/assert/is-collection' );
var format = require( '@stdlib/string/format' );
var PINF = require( '@stdlib/constants/float64/pinf' );
var validate = require( './validate.js' );
var limit = require( './limit.js' );
 
 
// MAIN //
 
/**
* Returns a function to invoke a function once for each element in a collection, iterating from right to left.
*
* ## Notes
*
* -   If a provided function calls the provided callback with a truthy error argument, the function suspends execution and immediately calls the `done` callback for subsequent error handling.
* -   This function does **not** guarantee that execution is asynchronous. To do so, 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`).
*
* @param {Options} [options] - function options
* @param {*} [options.thisArg] - execution context
* @param {PositiveInteger} [options.limit] - maximum number of pending invocations at any one time
* @param {boolean} [options.series=false] - boolean indicating whether to wait for a previous invocation to complete before invoking a provided function for the next element in a collection
* @param {Function} fcn - function to invoke for each element in a collection
* @throws {TypeError} options argument must be an object
* @throws {TypeError} must provide valid options
* @throws {TypeError} last argument must be a function
* @returns {Function} function which invokes the provided function once for each element in a collection
*
* @example
* var readFile = require( '@stdlib/fs/read-file' );
*
* function read( file, next ) {
*     var opts = {
*         'encoding': 'utf8'
*     };
*     readFile( file, opts, onFile );
*
*     function onFile( error ) {
*         if ( error ) {
*             return next( error );
*         }
*         console.log( 'Successfully read file: %s', file );
*         next();
*     }
* }
*
* var opts = {
*     'series': true
* };
*
* // Create a `forEachRightAsync` function which invokes `read` for each collection element sequentially:
* var forEachRightAsync = factory( opts, read );
*
* // Create a collection over which to iterate:
* var files = [
*     './beep.js',
*     './path/to/file.js'
* ];
*
* // Define a callback which handles errors:
* function done( error ) {
*     if ( error ) {
*         throw error;
*     }
*     console.log( 'Successfully read all files.' );
* }
*
* // Run `read` for each element in `files`:
* forEachRightAsync( files, done );
*/
function factory( options, fcn ) {
	var opts;
	var err;
	var f;
 
	opts = {};
	if ( arguments.length > 1 ) {
		err = validate( opts, options );
		if ( err ) {
			throw err;
		}
		f = fcn;
	} else {
		f = options;
	}
	if ( !isFunction( f ) ) {
		throw new TypeError( format( 'invalid argument. Last argument must be a function. Value: `%s`.', f ) );
	}
	if ( opts.series ) {
		opts.limit = 1;
	} else if ( !opts.limit ) {
		opts.limit = PINF;
	}
	return forEachRightAsync;
 
	/**
	* Invokes a function for each element in a collection, iterating from right to left.
	*
	* @private
	* @param {Collection} collection - input collection
	* @param {Callback} done - function to invoke upon completion
	* @throws {TypeError} first argument must be a collection
	* @throws {TypeError} last argument must be a function
	* @returns {void}
	*/
	function forEachRightAsync( collection, done ) {
		if ( !isCollection( collection ) ) {
			throw new TypeError( format( 'invalid argument. First argument must be a collection. Value: `%s`.', collection ) );
		}
		if ( !isFunction( done ) ) {
			throw new TypeError( format( 'invalid argument. Last argument must be a function. Value: `%s`.', done ) );
		}
		return limit( collection, opts, f, clbk );
 
		/**
		* Callback invoked upon completion.
		*
		* @private
		* @param {*} [error] - error
		* @returns {void}
		*/
		function clbk( error ) {
			if ( error ) {
				return done( error );
			}
			done();
		}
	}
}
 
 
// EXPORTS //
 
module.exports = factory;