All files / gmskrev/lib ndarray.js

47.7% Statements 52/109
100% Branches 1/1
0% Functions 0/1
47.7% Lines 52/109

Press n or j to go to the next uncovered block, b, p or k for the previous block.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 1101x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x                                                                                                                   1x 1x 1x 1x 1x  
/**
* @license Apache-2.0
*
* Copyright (c) 2026 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 arraylike2object = require( '@stdlib/array/base/arraylike2object' );
var accessors = require( './accessors.js' );
 
 
// MAIN //
 
/**
* Reverses a strided array in-place according to a mask and using alternative indexing semantics.
*
* @param {PositiveInteger} N - number of indexed elements
* @param {Collection} x - input array
* @param {integer} strideX - stride length for `x`
* @param {NonNegativeInteger} offsetX - starting index for `x`
* @param {NumericArray} mask - mask array
* @param {integer} strideMask - stride length for `mask`
* @param {NonNegativeInteger} offsetMask - starting index for `mask`
* @returns {Collection} input array
*
* @example
* var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ];
* var mask = [ 0, 0, 0, 1, 0, 0, 0, 0 ];
*
* gmskrev( x.length, x, 1, 0, mask, 1, 0 );
* // x => [ -3.0, -1.0, 0.0, -5.0, 4.0, 3.0, 1.0, -2.0 ]
*/
function gmskrev( N, x, strideX, offsetX, mask, strideMask, offsetMask ) {
	var right;
	var left;
	var tmp;
	var ox;
	var om;
	var ix;
	var jx;
	var im;
	var jm;

	if ( N <= 0 ) {
		return x;
	}
	ox = arraylike2object( x );
	om = arraylike2object( mask );
	if ( ox.accessorProtocol || om.accessorProtocol ) {
		accessors( N, ox, strideX, offsetX, om, strideMask, offsetMask );
		return x;
	}
	left = 0;
	right = N - 1;
	ix = offsetX;
	jx = offsetX + ( right * strideX );
	im = offsetMask;
	jm = offsetMask + ( right * strideMask );
	while ( left < right ) {
		// Scan to find the next unmasked elements...
		while ( left < right && mask[ im ] !== 0 ) {
			left += 1;
			ix += strideX;
			im += strideMask;
		}
		while ( right > left && mask[ jm ] !== 0 ) {
			right -= 1;
			jx -= strideX;
			jm -= strideMask;
		}
		// Check whether there are any more elements left to reverse...
		if ( left >= right ) {
			break;
		}
		// Swap unmasked elements...
		tmp = x[ ix ];
		x[ ix ] = x[ jx ];
		x[ jx ] = tmp;

		// Adjust indices to point to the next reversal candidates...
		left += 1;
		ix += strideX;
		im += strideMask;
		right -= 1;
		jx -= strideX;
		jm -= strideMask;
	}
	return x;
}
 
 
// EXPORTS //
 
module.exports = gmskrev;