All files / utils/async/every-by-right/lib limit.js

100% Statements 134/134
100% Branches 25/25
100% Functions 3/3
100% Lines 134/134

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 1353x 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 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 2x 2x 2x 38x 22x 38x 14x 14x 36x 36x 36x 36x 36x 38x 86x 86x 82x 82x 86x 38x 38x 38x 38x 38x 38x 38x 96x 96x 96x 12x 96x 66x 84x 18x 18x 96x 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 96x 12x 12x 12x 96x 8x 8x 8x 8x 76x 76x 76x 76x 96x 6x 6x 6x 6x 96x 14x 14x 96x 22x 22x 22x 96x 38x 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 logger = require( 'debug' );
 
 
// VARIABLES //
 
var debug = logger( 'every-by-right-async:limit' );
 
 
// MAIN //
 
/**
* Invokes a predicate function once for each element in a collection, limiting the number of concurrently pending functions, and iterating from right to left.
*
* @private
* @param {Collection} collection - input collection
* @param {Options} opts - function options
* @param {*} [opts.thisArg] - execution context
* @param {PositiveInteger} [opts.limit] - maximum number of pending function invocations
* @param {Function} predicate - predicate function
* @param {Callback} done - function to invoke upon completion or upon encountering an error
* @returns {void}
*/
function limit( collection, opts, predicate, done ) {
	var count;
	var flg;
	var lim;
	var len;
	var idx;
	var i;
 
	len = collection.length;
	debug( 'Collection length: %d', len );
 
	if ( len === 0 ) {
		debug( 'Finished processing a collection.' );
		return done( null, true );
	}
	if ( len < opts.limit ) {
		lim = len;
	} else {
		lim = opts.limit;
	}
	debug( 'Concurrency limit: %d', lim );
	debug( 'Number of arguments: %d', predicate.length );
 
	count = 0;
	idx = len;
	for ( i = 0; i < lim; i++ ) {
		// This guard is necessary to protect against synchronous functions which exhaust all collection elements...
		if ( idx > 0 ) {
			next(); // eslint-disable-line node/callback-return
		}
	}
 
	/**
	* Callback to invoke a provided function for the next element in a collection.
	*
	* @private
	*/
	function next() {
		idx -= 1;
		debug( 'Collection element %d: %s.', idx, JSON.stringify( collection[ idx ] ) );
		if ( predicate.length === 2 ) {
			predicate.call( opts.thisArg, collection[ idx ], clbk );
		} else if ( predicate.length === 3 ) {
			predicate.call( opts.thisArg, collection[ idx ], idx, clbk );
		} else {
			predicate.call( opts.thisArg, collection[ idx ], idx, collection, clbk ); // eslint-disable-line max-len
		}
	}
 
	/**
	* Callback invoked once a provided function finishes processing a collection element.
	*
	* @private
	* @param {*} [error] - error
	* @param {*} [result] - test result
	* @returns {void}
	*/
	function clbk( error, result ) {
		if ( flg ) {
			// Prevent further processing of collection elements:
			return;
		}
		if ( error ) {
			flg = true;
			debug( 'Encountered an error: %s', error.message );
			return done( error );
		}
		count += 1;
		debug( 'Processed %d of %d collection elements.', count, len );
 
		debug( 'Test result: %s', !!result );
		if ( !result && !flg ) {
			flg = true;
			debug( 'Finished processing a collection.' );
			return done( null, false );
		}
		if ( idx > 0 ) {
			return next();
		}
		if ( count === len ) {
			debug( 'Finished processing a collection.' );
			return done( null, true );
		}
	}
}
 
 
// EXPORTS //
 
module.exports = limit;