feat: add findIndex method to array/uint64

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

@@ -309,6 +309,56 @@ The returned [iterator][mdn-iterator-protocol] protocol-compliant object has the
 -   **next**: function which returns an [iterator][mdn-iterator-protocol] protocol-compliant object containing the next iterated value (if one exists) assigned to a `value` property and a `done` property having a `boolean` value indicating whether the [iterator][mdn-iterator-protocol] is finished.
 -   **return**: function which closes an [iterator][mdn-iterator-protocol] and returns a single (optional) argument in an [iterator][mdn-iterator-protocol] protocol-compliant object.
 
+<a name="method-find-index"></a>
+
+#### Uint64Array.prototype.findIndex( predicate\[, thisArg] )
+
+Returns the index of the first element in an array for which a predicate function returns a truthy value.
+
+```javascript
+var isEven = require( '@stdlib/assert/is-even' ).isPrimitive;
+var Number = require( '@stdlib/number/ctor' );
+
+function predicate( v ) {
+    return ( isEven( Number( v ) ) );
+}
+
+var arr = new Uint64Array( [ 1, 3, 4, 6 ] );
+
+var idx = arr.findIndex( predicate );
+// returns 2
+```
+
+The `predicate` function is provided three arguments:
+
+-   **value**: current array element.
+-   **index**: current array element index.
+-   **arr**: the array on which this method was called.
+
+To set the function execution context, provide a `thisArg`.
+
+```javascript
+var isEven = require( '@stdlib/assert/is-even' ).isPrimitive;
+var Number = require( '@stdlib/number/ctor' );
+
+function predicate( v, i ) {
+    this.count += 1;
+    return ( i >= 0 && isEven( Number( v ) ) );
+}
+
+var arr = new Uint64Array( [ 1, 3, 5, 7 ] );
+
+var context = {
+    'count': 0
+};
+
+var idx = arr.findIndex( predicate, context );
+// returns -1
+
+var count = context.count;
+// returns 4
+```
+
 <a name="method-get"></a>
 
 #### Uint64Array.prototype.get( i )

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

@@ -0,0 +1,91 @@
+/**
+* @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 isEqual = require( '@stdlib/number/uint64/base/assert/is-equal' );
+var Uint64 = require( '@stdlib/number/uint64/ctor' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var Uint64Array = require( './../lib' );
+
+
+// MAIN //
+
+bench( format( '%s:findIndex', pkg ), function benchmark( b ) {
+	var arr;
+	var out;
+	var v;
+	var i;
+
+	arr = new Uint64Array( 10 );
+
+	v = new Uint64( 1 );
+
+	// Benchmark worst case scenario (i.e., the predicate never passes, so the method must visit every element)...
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		out = arr.findIndex( predicate );
+		if ( out !== -1 ) {
+			b.fail( 'should return -1' );
+		}
+	}
+	b.toc();
+	if ( out !== -1 ) {
+		b.fail( 'should return -1' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+
+	function predicate( u ) {
+		return isEqual( u, v );
+	}
+});
+
+bench( format( '%s::this_context:findIndex', pkg ), function benchmark( b ) {
+	var arr;
+	var out;
+	var v;
+	var i;
+
+	arr = new Uint64Array( 10 );
+
+	v = new Uint64( 1 );
+
+	// Benchmark worst case scenario (i.e., the predicate never passes, so the method must visit every element)...
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		out = arr.findIndex( predicate, {} );
+		if ( out !== -1 ) {
+			b.fail( 'should return -1' );
+		}
+	}
+	b.toc();
+	if ( out !== -1 ) {
+		b.fail( 'should return -1' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+
+	function predicate( u ) {
+		return isEqual( u, v );
+	}
+});

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

@@ -0,0 +1,113 @@
+/**
+* @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 isEqual = require( '@stdlib/number/uint64/base/assert/is-equal' );
+var Uint64 = require( '@stdlib/number/uint64/ctor' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var Uint64Array = require( './../lib' );
+
+
+// VARIABLES //
+
+var SEARCH_VALUE = new Uint64( 1 );
+
+
+// FUNCTIONS //
+
+/**
+* Predicate function.
+*
+* @private
+* @param {Uint64} value - array element
+* @returns {boolean} boolean indicating whether a value passes a test
+*/
+function predicate( value ) {
+	return isEqual( value, SEARCH_VALUE );
+}
+
+/**
+* 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 predicate never passes, so the method must visit every element)...
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			out = arr.findIndex( predicate );
+			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:findIndex:len=%d', pkg, len ), f );
+	}
+}
+
+main();

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

@@ -275,6 +275,41 @@
     true
 
 
+{{alias}}.prototype.findIndex( predicate[, thisArg] )
+    Returns the index of the first element in an array for which a predicate
+    function returns a truthy value.
+
+    A predicate function is provided the following arguments:
+
+    - value: current array element.
+    - index: current array element index.
+    - arr: the array on which the method was called.
+
+    If a predicate function never returns a truthy value, the method returns
+    `-1`.
+
+    Parameters
+    ----------
+    predicate: Function
+        Predicate function which tests array elements.
+
+    thisArg: any (optional)
+        Execution context.
+
+    Returns
+    -------
+    out: integer
+        Array index or `-1`.
+
+    Examples
+    --------
+    > function predicate( v ) { return ( {{alias:@stdlib/assert/is-even}}.isPrimitive( {{alias:@stdlib/number/ctor}}( v ) ) ); };
+    > var arr = new {{alias}}( [ 1, 3, 4, 6 ] )
+    <Uint64Array>[ 1n, 3n, 4n, 6n ]
+    > var idx = arr.findIndex( predicate )
+    2
+
+
 {{alias}}.prototype.get( i )
     Returns an array element located at integer position (index) `i`.
 

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.
 	*/
@@ -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.
@@ -454,6 +454,28 @@
 	*/
 	entries(): TypedIterator<[number, Uint64]>;
 
+	/**
+	* Returns the index of the first element in an array for which a predicate function returns a truthy value.
+	*
+	* @param predicate - test function
+	* @param thisArg - execution context
+	* @returns index or -1
+	*
+	* @example
+	* var isEven = require( '@stdlib/assert/is-even' ).isPrimitive;
+	* var Number = require( '@stdlib/number/ctor' );
+	*
+	* function predicate( v ) {
+	*     return ( isEven( Number( v ) ) );
+	* }
+	*
+	* var arr = new Uint64Array( [ 1, 3, 4, 6 ] );
+	*
+	* var idx = arr.findIndex( predicate );
+	* // returns 2
+	*/
+	findIndex<U = unknown>( predicate: Predicate<U>, thisArg?: ThisParameterType<Predicate<U>> ): number;
+
 	/**
 	* Returns an array element.
 	*

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

@@ -702,6 +702,51 @@
 	}
 });
 
+/**
+* Returns the index of the first element in an array for which a predicate function returns a truthy value.
+*
+* @name findIndex
+* @memberof Uint64Array.prototype
+* @type {Function}
+* @param {Function} predicate - test function
+* @param {*} [thisArg] - predicate function execution context
+* @throws {TypeError} `this` must be a 64-bit unsigned integer array
+* @throws {TypeError} first argument must be a function
+* @returns {integer} index or -1
+*
+* @example
+* var isEven = require( '@stdlib/assert/is-even' ).isPrimitive;
+* var Number = require( '@stdlib/number/ctor' );
+*
+* function predicate( v ) {
+*     return ( isEven( Number( v ) ) );
+* }
+*
+* var arr = new Uint64Array( [ 1, 3, 4, 6 ] );
+*
+* var idx = arr.findIndex( predicate );
+* // returns 2
+*/
+setReadOnly( Uint64Array.prototype, 'findIndex', function findIndex( predicate, thisArg ) {
+	var buf;
+	var i;
+	var u;
+	if ( !isUint64Array( this ) ) {
+		throw new TypeError( 'invalid invocation. `this` is not a 64-bit unsigned integer array.' );
+	}
+	if ( !isFunction( predicate ) ) {
+		throw new TypeError( format( 'invalid argument. First argument must be a function. Value: `%s`.', predicate ) );
+	}
+	buf = this._buffer;
+	for ( i = 0; i < this._length; i++ ) {
+		u = getUint64( buf, i );
+		if ( predicate.call( thisArg, u, i, this ) ) {
+			return i;
+		}
+	}
+	return -1;
+});
+
 /**
 * Returns an array element.
 *
@@ -839,7 +884,7 @@
 		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 ) );
 		}