time-to-botec

Benchmark sampling in different programming languages
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reduce_right.js (2568B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2018 The Stdlib Authors.
      5 *
      6 * Licensed under the Apache License, Version 2.0 (the "License");
      7 * you may not use this file except in compliance with the License.
      8 * You may obtain a copy of the License at
      9 *
     10 *    http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing, software
     13 * distributed under the License is distributed on an "AS IS" BASIS,
     14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15 * See the License for the specific language governing permissions and
     16 * limitations under the License.
     17 */
     18 
     19 'use strict';
     20 
     21 // MODULES //
     22 
     23 var isCollection = require( '@stdlib/assert/is-collection' );
     24 var isFunction = require( '@stdlib/assert/is-function' );
     25 
     26 
     27 // MAIN //
     28 
     29 /**
     30 * Applies a function against an accumulator and each element in a collection and returns the accumulated result, iterating from right to left.
     31 *
     32 * ## Notes
     33 *
     34 * -   For dynamic array resizing, the only behavior made intentionally consistent with `reduce` (iterating from left to right) is when elements are pushed onto the beginning (end) of an array. In other words, for `reduce()`, `[].push()` behavior is consistent with `reduceRight()` `[].unshift()` behavior.
     35 *
     36 *
     37 * @param {Collection} collection - input collection
     38 * @param {*} initial - initial value
     39 * @param {Function} reducer - reduction function
     40 * @param {*} [thisArg] - reduction function execution context
     41 * @throws {TypeError} first argument must be a collection
     42 * @throws {TypeError} third argument must be a function
     43 * @returns {*} accumulated result
     44 *
     45 * @example
     46 * function sum( acc, value, index ) {
     47 *     console.log( '%s: %d', index, value );
     48 *     return acc + value;
     49 * }
     50 *
     51 * var arr = [ 1, 2, 3, 4 ];
     52 *
     53 * var s = reduceRight( arr, 0, sum );
     54 * // returns 10
     55 */
     56 function reduceRight( collection, initial, reducer, thisArg ) {
     57 	var len;
     58 	var acc;
     59 	var i;
     60 	if ( !isCollection( collection ) ) {
     61 		throw new TypeError( 'invalid argument. First argument must be a collection. Value: `'+collection+'`.' );
     62 	}
     63 	if ( !isFunction( reducer ) ) {
     64 		throw new TypeError( 'invalid argument. Third argument must be a function. Value:`'+reducer+'`.' );
     65 	}
     66 	len = collection.length;
     67 	acc = initial;
     68 	for ( i = len-1; i >= 0; i-- ) {
     69 		acc = reducer.call( thisArg, acc, collection[ i ], i, collection );
     70 
     71 		// Account for dynamically resizing a collection...
     72 		if ( len !== collection.length ) {
     73 			i += ( collection.length - len );
     74 			len = collection.length;
     75 		}
     76 	}
     77 	return acc;
     78 }
     79 
     80 
     81 // EXPORTS //
     82 
     83 module.exports = reduceRight;