83 lines
1.8 KiB
JavaScript
83 lines
1.8 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var isnan = require( '@stdlib/math/base/assert/is-nan' );
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var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
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// MAIN //
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/**
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* Returns an accumulator function which incrementally computes a maximum value.
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*
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* @returns {Function} accumulator function
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*
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* @example
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* var accumulator = incrmax();
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*
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* var max = accumulator();
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* // returns null
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*
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* max = accumulator( 3.14 );
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* // returns 3.14
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*
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* max = accumulator( -5.0 );
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* // returns 3.14
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*
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* max = accumulator( 10.1 );
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* // returns 10.1
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*
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* max = accumulator();
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* // returns 10.1
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*/
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function incrmax() {
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var max;
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return accumulator;
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/**
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* If provided a value, the accumulator function returns an updated maximum value. If not provided a value, the accumulator function returns the current max.
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*
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* @private
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* @param {number} [x] - new value
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* @returns {(number|null)} max value or null
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*/
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function accumulator( x ) {
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if ( arguments.length === 0 ) {
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return ( max === void 0 ) ? null : max;
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}
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if (
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max === void 0 ||
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x > max ||
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isnan( x ) ||
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( x === max && isPositiveZero( x ) )
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) {
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max = x;
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}
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return max;
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}
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}
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// EXPORTS //
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module.exports = incrmax;
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