main.js (1819B)
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 isnan = require( '@stdlib/math/base/assert/is-nan' ); 24 var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' ); 25 26 27 // MAIN // 28 29 /** 30 * Returns an accumulator function which incrementally computes a maximum value. 31 * 32 * @returns {Function} accumulator function 33 * 34 * @example 35 * var accumulator = incrmax(); 36 * 37 * var max = accumulator(); 38 * // returns null 39 * 40 * max = accumulator( 3.14 ); 41 * // returns 3.14 42 * 43 * max = accumulator( -5.0 ); 44 * // returns 3.14 45 * 46 * max = accumulator( 10.1 ); 47 * // returns 10.1 48 * 49 * max = accumulator(); 50 * // returns 10.1 51 */ 52 function incrmax() { 53 var max; 54 return accumulator; 55 56 /** 57 * If provided a value, the accumulator function returns an updated maximum value. If not provided a value, the accumulator function returns the current max. 58 * 59 * @private 60 * @param {number} [x] - new value 61 * @returns {(number|null)} max value or null 62 */ 63 function accumulator( x ) { 64 if ( arguments.length === 0 ) { 65 return ( max === void 0 ) ? null : max; 66 } 67 if ( 68 max === void 0 || 69 x > max || 70 isnan( x ) || 71 ( x === max && isPositiveZero( x ) ) 72 ) { 73 max = x; 74 } 75 return max; 76 } 77 } 78 79 80 // EXPORTS // 81 82 module.exports = incrmax;