All files / copy-within/lib normalize_indices.js

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/**
* @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 isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
var unary = require( '@stdlib/ndarray/base/unary' );
var baseEmpty = require( '@stdlib/ndarray/base/empty' );
var getDType = require( '@stdlib/ndarray/base/dtype' );
var getShape = require( '@stdlib/ndarray/base/shape' );
var getOrder = require( '@stdlib/ndarray/base/order' );
 
 
// FUNCTIONS //
 
/**
* Normalizes a relative index.
*
* @private
* @param {integer} idx - relative index
* @param {NonNegativeInteger} len - number of indexed elements
* @returns {NonNegativeInteger} normalized index
*/
function normalize( idx, len ) {
	if ( idx < 0 ) {
		idx += len;
		if ( idx < 0 ) {
			return 0;
		}
		return idx;
	}
	if ( idx > len ) {
		return len;
	}
	return idx;
}
 
 
// MAIN //
 
/**
* Normalizes an index argument.
*
* ## Notes
*
* -   When a `target`, `start`, and/or `end` index is negative, the respective index is determined relative to the last indexed element, with out-of-bounds indices clamped to index bounds.
* -   If provided an ndarray, the function normalizes each element and returns a new ndarray having the same shape and data type as the provided ndarray.
*
* @private
* @param {(ndarray|integer)} idx - index argument
* @param {NonNegativeInteger} len - number of indexed elements
* @returns {(ndarray|NonNegativeInteger)} normalized index argument
*/
function normalizeIndices( idx, len ) {
	var out;

	if ( isInteger( idx ) ) {
		return normalize( idx, len );
	}
	out = baseEmpty( getDType( idx ), getShape( idx, false ), getOrder( idx ) );
	unary( [ idx, out ], clbk );
	return out;

	/**
	* Normalizes a relative index.
	*
	* @private
	* @param {integer} v - relative index
	* @returns {NonNegativeInteger} normalized index
	*/
	function clbk( v ) {
		return normalize( v, len );
	}
}
 
 
// EXPORTS //
 
module.exports = normalizeIndices;