103 lines
2.2 KiB
JavaScript
103 lines
2.2 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 objectKeys = require( '@stdlib/utils/keys' );
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var hasOwnProp = require( '@stdlib/assert/has-own-property' );
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var PROMOTION_RULES = require( './promotion_rules.json' );
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// FUNCTIONS //
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/**
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* Generates a full table of promotion rules.
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*
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* @private
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* @returns {Object} table
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*/
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function generateFullTable() {
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var dtypes;
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var ntypes;
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var out;
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var tmp;
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var dt1;
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var dt2;
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var o;
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var j;
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var i;
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out = {};
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dtypes = objectKeys( PROMOTION_RULES );
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ntypes = dtypes.length;
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for ( i = 0; i < ntypes; i++ ) {
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dt1 = dtypes[ i ];
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o = PROMOTION_RULES[ dt1 ];
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tmp = {};
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for ( j = 0; j < ntypes; j++ ) {
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dt2 = dtypes[ j ];
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tmp[ dt2 ] = o[ dt2 ];
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}
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out[ dt1 ] = tmp;
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}
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return out;
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}
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// MAIN //
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/**
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* Returns the array data type with the smallest size and closest "kind" to which array data types can be safely cast.
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*
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* @param {string} [dtype1] - array data type
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* @param {string} [dtype2] - array data type
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* @returns {(Object|integer|string|null)} promotion rule(s) or null
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*
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* @example
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* var table = promotionRules();
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* // returns {...}
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*
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* @example
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* var dt = promotionRules( 'float32', 'uint32' );
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* // returns 'float64'
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*
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* @example
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* var dt = promotionRules( 'float32', 'foo' );
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* // returns null
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*/
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function promotionRules( dtype1, dtype2 ) {
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var o;
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if ( arguments.length === 0 ) {
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return generateFullTable();
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}
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if ( hasOwnProp( PROMOTION_RULES, dtype1 ) ) {
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o = PROMOTION_RULES[ dtype1 ];
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if ( hasOwnProp( o, dtype2 ) ) {
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return o[ dtype2 ];
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}
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}
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return null;
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}
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// EXPORTS //
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module.exports = promotionRules;
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