main.js (1660B)
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 // MAIN // 22 23 /** 24 * Returns array iteration order. 25 * 26 * ## Notes 27 * 28 * - Return value key: 29 * 30 * - `0`: unordered (i.e., strides of mixed sign; e.g., `[ 9, -3, 1 ]`) 31 * - `1`: ordered left-to-right (i.e., all nonnegative strides) 32 * - `-1`: ordered right-to-left (i.e., all negative strides) 33 * 34 * @param {IntegerArray} strides - stride array 35 * @returns {integer} iteration order 36 * 37 * @example 38 * var o = iterationOrder( [ 2, 1 ] ); 39 * // returns 1 40 * 41 * o = iterationOrder( [ -2, 1 ] ); 42 * // returns 0 43 * 44 * o = iterationOrder( [ -2, -1 ] ); 45 * // returns -1 46 */ 47 function iterationOrder( strides ) { 48 var cnt; 49 var i; 50 51 cnt = 0; 52 for ( i = 0; i < strides.length; i++ ) { 53 if ( strides[ i ] < 0 ) { 54 cnt += 1; 55 } 56 } 57 if ( cnt === 0 ) { 58 // All nonnegative strides: 59 return 1|0; // asm-type annotation 60 } 61 if ( cnt === strides.length ) { 62 // All negative strides: 63 return -1|0; // asm-type annotation 64 } 65 // Strides of mixed signs: 66 return 0|0; // asm-type annotation 67 } 68 69 70 // EXPORTS // 71 72 module.exports = iterationOrder;