83 lines
1.8 KiB
JavaScript
83 lines
1.8 KiB
JavaScript
/**
|
|
* @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 isnan = require( '@stdlib/math/base/assert/is-nan' );
|
|
var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Returns an accumulator function which incrementally computes a maximum value.
|
|
*
|
|
* @returns {Function} accumulator function
|
|
*
|
|
* @example
|
|
* var accumulator = incrmax();
|
|
*
|
|
* var max = accumulator();
|
|
* // returns null
|
|
*
|
|
* max = accumulator( 3.14 );
|
|
* // returns 3.14
|
|
*
|
|
* max = accumulator( -5.0 );
|
|
* // returns 3.14
|
|
*
|
|
* max = accumulator( 10.1 );
|
|
* // returns 10.1
|
|
*
|
|
* max = accumulator();
|
|
* // returns 10.1
|
|
*/
|
|
function incrmax() {
|
|
var max;
|
|
return accumulator;
|
|
|
|
/**
|
|
* If provided a value, the accumulator function returns an updated maximum value. If not provided a value, the accumulator function returns the current max.
|
|
*
|
|
* @private
|
|
* @param {number} [x] - new value
|
|
* @returns {(number|null)} max value or null
|
|
*/
|
|
function accumulator( x ) {
|
|
if ( arguments.length === 0 ) {
|
|
return ( max === void 0 ) ? null : max;
|
|
}
|
|
if (
|
|
max === void 0 ||
|
|
x > max ||
|
|
isnan( x ) ||
|
|
( x === max && isPositiveZero( x ) )
|
|
) {
|
|
max = x;
|
|
}
|
|
return max;
|
|
}
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = incrmax;
|