feat: add lastIndexOf method to array/uint64

lib/node_modules/@stdlib/array/uint64/README.md

@@ -342,6 +342,39 @@ var z = arr.get( 100 );
 // returns undefined
 ```
 
+<a name="method-last-index-of"></a>
+
+#### Uint64Array.prototype.lastIndexOf( searchElement\[, fromIndex] )
+
+Returns the last index at which a given element can be found.
+
+```javascript
+var Uint64 = require( '@stdlib/number/uint64/ctor' );
+
+var arr = new Uint64Array( [ 1, 2, 3, 4, 3 ] );
+
+var idx = arr.lastIndexOf( new Uint64( 3 ) );
+// returns 4
+
+idx = arr.lastIndexOf( 3, 3 );
+// returns 2
+
+idx = arr.lastIndexOf( 2, -3 );
+// returns 1
+```
+
+If `searchElement` is not present in the array, the method returns `-1`.
+
+```javascript
+var arr = new Uint64Array( [ 1, 2 ] );
+
+var idx = arr.lastIndexOf( 3 );
+// returns -1
+
+idx = arr.lastIndexOf( 2, 0 );
+// returns -1
+```
+
 <a name="method-set"></a>
 
 #### Uint64Array.prototype.set( value\[, i] )

lib/node_modules/@stdlib/array/uint64/benchmark/benchmark.last_index_of.js

@@ -0,0 +1,52 @@
+/**
+* @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 bench = require( '@stdlib/bench' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var Uint64Array = require( './../lib' );
+
+
+// MAIN //
+
+bench( format( '%s:lastIndexOf', pkg ), function benchmark( b ) {
+	var out;
+	var arr;
+	var i;
+
+	arr = new Uint64Array( 10 );
+
+	// Benchmark worst case scenario (i.e., the search element is never present, so the method must scan the entire array)...
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		out = arr.lastIndexOf( i+1 );
+		if ( out !== -1 ) {
+			b.fail( 'should return -1' );
+		}
+	}
+	b.toc();
+	if ( out !== -1 ) {
+		b.fail( 'should return -1' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/array/uint64/benchmark/benchmark.last_index_of.length.js

@@ -0,0 +1,95 @@
+/**
+* @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 bench = require( '@stdlib/bench' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var Uint64Array = require( './../lib' );
+
+
+// FUNCTIONS //
+
+/**
+* Creates a benchmark function.
+*
+* @private
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( len ) {
+	var arr = new Uint64Array( len );
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var out;
+		var i;
+
+		// Benchmark worst case scenario (i.e., the search element is never present, so the method must scan the entire array)...
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			out = arr.lastIndexOf( i+1 );
+			if ( out !== -1 ) {
+				b.fail( 'should return -1' );
+			}
+		}
+		b.toc();
+		if ( out !== -1 ) {
+			b.fail( 'should return -1' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+*/
+function main() {
+	var len;
+	var min;
+	var max;
+	var f;
+	var i;
+
+	min = 1; // 10^min
+	max = 6; // 10^max
+
+	for ( i = min; i <= max; i++ ) {
+		len = pow( 10, i );
+		f = createBenchmark( len );
+		bench( format( '%s:lastIndexOf:len=%d', pkg, len ), f );
+	}
+}
+
+main();

lib/node_modules/@stdlib/array/uint64/docs/repl.txt

@@ -299,6 +299,36 @@
     <Uint64>[ 2n ]
 
 
+{{alias}}.prototype.lastIndexOf( searchElement[, fromIndex] )
+    Returns the last index at which a given element can be found.
+
+    If method does not find a search element, the method returns `-1`.
+
+    Parameters
+    ----------
+    searchElement: Uint64|number|bigint
+        Search element.
+
+    fromIndex: integer (optional)
+        Array index at which to start the search backward. If provided a
+        negative value, the method resolves the start index relative to the
+        last array element. Default: -1.
+
+    Returns
+    -------
+    out: integer
+        Array index or `-1`.
+
+    Examples
+    --------
+    > var arr = new {{alias}}( [ 1, 2, 3, 2 ] )
+    <Uint64Array>[ 1n, 2n, 3n, 2n ]
+    > var idx = arr.lastIndexOf( new {{alias:@stdlib/number/uint64/ctor}}( 2 ) )
+    3
+    > idx = arr.lastIndexOf( 2, 2 )
+    1
+
+
 {{alias}}.prototype.set( v[, i] )
     Sets one or more array elements.
 

lib/node_modules/@stdlib/array/uint64/docs/types/index.d.ts

@@ -28,7 +28,7 @@
 import ArrayBuffer = require( '@stdlib/array/buffer' );
 
 // Define a union type representing both iterable and non-iterable iterators:
 type Iterator = Iter | IterableIterator;
 
 // Define a type representing a value from which a 64-bit unsigned integer can be derived:
 type Uint = Uint64 | bigint | number;
@@ -36,7 +36,7 @@
 /**
 * Locale-specific configuration options.
 */
 interface LocaleOptions<T = unknown> {
 	/**
 	* Configuration property.
 	*/
@@ -118,7 +118,7 @@
 * @param arr - array on which the method was called
 * @returns boolean indicating whether an element in an array passes a test
 */
 type Predicate<U> = NullaryPredicate<U> | UnaryPredicate<U> | BinaryPredicate<U> | TernaryPredicate<U>;
 
 /**
 * Callback invoked for each element in an array.
@@ -162,7 +162,7 @@
 * @param arr - array on which the method was called
 * @returns undefined
 */
 type Callback<U> = NullaryCallback<U> | UnaryCallback<U> | BinaryCallback<U> | TernaryCallback<U>;
 
 /**
 * Callback invoked for each element in an array.
@@ -206,7 +206,7 @@
 * @param arr - array on which the method was called
 * @returns transformed value
 */
 type MapFcn<U> = NullaryMapFcn<U> | UnaryMapFcn<U> | BinaryMapFcn<U> | TernaryMapFcn<U>;
 
 /**
 * Reducer function invoked for each element in an array.
@@ -260,7 +260,7 @@
 * @param arr - array on which the method was called
 * @returns accumulated result
 */
 type Reducer<U> = NullaryReducer<U> | UnaryReducer<U> | BinaryReducer<U> | TernaryReducer<U> | QuaternaryReducer<U>;
 
 /**
 * Comparator function.
@@ -269,7 +269,7 @@
 * @param b - second value for comparison
 * @returns number indicating comparison result
 */
 type CompareFcn = ( a: Uint64, b: Uint64 ) => number;
 
 /**
 * Class for creating a 64-bit unsigned integer array.
@@ -482,6 +482,32 @@
 	*/
 	get( i: number ): Uint64 | void;
 
+	/**
+	* Returns the last index at which a given element can be found.
+	*
+	* @param searchElement - element to find
+	* @param fromIndex - index at which to start searching backward (inclusive)
+	* @returns index or -1
+	*
+	* @example
+	* var Uint64 = require( '@stdlib/number/uint64/ctor' );
+	*
+	* var arr = new Uint64Array( [ 1, 2, 3, 4, 3 ] );
+	*
+	* var idx = arr.lastIndexOf( new Uint64( 3 ) );
+	* // returns 4
+	*
+	* idx = arr.lastIndexOf( 3, 3 );
+	* // returns 2
+	*
+	* idx = arr.lastIndexOf( 5, 3 );
+	* // returns -1
+	*
+	* idx = arr.lastIndexOf( 2n, -3 );
+	* // returns 1
+	*/
+	lastIndexOf( searchElement: Uint, fromIndex?: number ): number;
+
 	/**
 	* Sets an array element.
 	*

lib/node_modules/@stdlib/array/uint64/lib/main.js

@@ -749,6 +749,75 @@
 	return getUint64( this._buffer, idx );
 });
 
+/**
+* Returns the last index at which a given element can be found.
+*
+* @name lastIndexOf
+* @memberof Uint64Array.prototype
+* @type {Function}
+* @param {(Uint64|bigint|number)} searchElement - element to find
+* @param {integer} [fromIndex] - index at which to start searching backward (inclusive)
+* @throws {TypeError} `this` must be a 64-bit unsigned integer array
+* @throws {TypeError} first argument must be either a 64-bit unsigned integer or a value which can be converted to a 64-bit unsigned integer
+* @throws {TypeError} second argument must be an integer
+* @returns {integer} index or -1
+*
+* @example
+* var Uint64 = require( '@stdlib/number/uint64/ctor' );
+*
+* var arr = new Uint64Array( [ 1, 2, 3, 4, 3 ] );
+*
+* var idx = arr.lastIndexOf( new Uint64( 3 ) );
+* // returns 4
+*
+* idx = arr.lastIndexOf( 3, 3 );
+* // returns 2
+*
+* idx = arr.lastIndexOf( 5, 3 );
+* // returns -1
+*
+* idx = arr.lastIndexOf( 2n, -3 );
+* // returns 1
+*/
+setReadOnly( Uint64Array.prototype, 'lastIndexOf', function lastIndexOf( searchElement, fromIndex ) {
+	var words;
+	var buf;
+	var idx;
+	var i;
+	if ( !isUint64Array( this ) ) {
+		throw new TypeError( 'invalid invocation. `this` is not a 64-bit unsigned integer array.' );
+	}
+	if ( !isUint64( searchElement ) ) {
+		try {
+			searchElement = new Uint64( searchElement );
+		} catch ( err ) { // eslint-disable-line no-unused-vars
+			throw new TypeError( format( 'invalid argument. First argument must be either a 64-bit unsigned integer or a value which can be converted to a 64-bit unsigned integer. Value: `%s`.', searchElement ) );
+		}
+	}
+	if ( arguments.length > 1 ) {
+		if ( !isIntegerPrimitive( fromIndex ) ) {
+			throw new TypeError( format( 'invalid argument. Second argument must be an integer. Value: `%s`.', fromIndex ) );
+		}
+		if ( fromIndex >= this._length ) {
+			fromIndex = this._length - 1;
+		} else if ( fromIndex < 0 ) {
+			fromIndex += this._length;
+		}
+	} else {
+		fromIndex = this._length - 1;
+	}
+	words = [ 0, 0 ];
+	toWords( searchElement, words, 1, 0 );
+	buf = this._buffer;
+	for ( i = fromIndex; i >= 0; i-- ) {
+		idx = 2 * i;
+		if ( words[ 0 ] === buf[ idx+indices.HIGH ] && words[ 1 ] === buf[ idx+indices.LOW ] ) { // eslint-disable-line max-len
+			return i;
+		}
+	}
+	return -1;
+});
+
 /**
 * Number of array elements.
 *
@@ -848,7 +917,7 @@
 		buf[ idx+indices.LOW ] = words[ 1 ];
 		return;
 	}
 	if ( isNonNegativeInteger( value ) || ( isBigInt( value ) && isNonNegativeInteger( Number( value ) ) ) ) {
 		if ( idx >= this._length ) {
 			throw new RangeError( format( 'invalid argument. Index argument is out-of-bounds. Value: `%u`.', idx ) );
 		}