feat: add keys method to array/fixed-endian-factory

lib/node_modules/@stdlib/array/fixed-endian-factory/README.md

@@ -905,6 +905,29 @@ var str = arr.join( ' - ' );
 // returns '1 - 2 - 3'
 ```
 
+
+<a name="method-keys"></a>
+
+#### TypedArrayFE.prototype.keys()
+
+Returns an iterator for iterating over each index key in a typed array.
+
+```javascript
+var Float64ArrayFE = fixedEndianFactory( 'float64' );
+
+var arr = new Float64ArrayFE( 'little-endian', 2 );
+var iter = arr.keys();
+
+var v = iter.next().value;
+// returns 0
+
+v = iter.next().value;
+// returns 1
+
+var bool = iter.next().done;
+// returns true
+```
+
 <a name="method-with"></a>
 
 #### TypedArrayFE.prototype.with( index, value )

lib/node_modules/@stdlib/array/fixed-endian-factory/benchmark/benchmark.keys.js

@@ -0,0 +1,56 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 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 isIterator = require( '@stdlib/assert/is-iterator-like' );
+var pkg = require( './../package.json' ).name;
+var factory = require( './../lib' );
+
+
+// VARIABLES //
+
+var Float64ArrayFE = factory( 'float64' );
+
+
+// MAIN //
+
+bench( pkg+':keys', function benchmark( b ) {
+	var iter;
+	var arr;
+	var i;
+
+	arr = new Float64ArrayFE( 'little-endian', [ 1.0, 2.0, 2.0, 1.0 ] );
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		iter = arr.keys();
+		if ( typeof iter !== 'object' ) {
+			b.fail( 'should return an object' );
+		}
+	}
+	b.toc();
+	if ( !isIterator( iter ) ) {
+		b.fail( 'should return an iterator' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/array/fixed-endian-factory/benchmark/benchmark.keys.length.js

@@ -0,0 +1,97 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 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 zeroTo = require( '@stdlib/array/zero-to' );
+var isIterator = require( '@stdlib/assert/is-iterator-like' );
+var pkg = require( './../package.json' ).name;
+var factory = require( './../lib' );
+
+
+// VARIABLES //
+
+var Float64ArrayFE = factory( 'float64' );
+
+/**
+* Creates a benchmark function.
+*
+* @private
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( len ) {
+	var arr = new Float64ArrayFE( 'little-endian', zeroTo( len ) );
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var iter;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			iter = arr.keys();
+			if ( typeof iter !== 'object' ) {
+				b.fail( 'should return an object' );
+			}
+		}
+		b.toc();
+		if ( !isIterator( iter ) ) {
+			b.fail( 'should return an iterator' );
+		}
+		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( pkg+':keys:len='+len, f );
+	}
+}
+
+main();

lib/node_modules/@stdlib/array/fixed-endian-factory/lib/main.js

@@ -1111,6 +1111,92 @@ function factory( dtype ) { // eslint-disable-line max-lines-per-function, stdli
 		return out;
 	});
 
+	/**
+	* Returns an iterator for iterating over each index key in a typed array.
+	*
+	* @private
+	* @name keys
+	* @memberof TypedArray.prototype
+	* @type {Function}
+	* @throws {TypeError} `this` must be a typed array instance
+	* @returns {Iterator} Iterator
+	*/
+	setReadOnly( TypedArray.prototype, 'keys', function keys() {
+		var self;
+		var iter;
+		var len;
+		var FLG;
+		var i;
+		if ( !isTypedArray( this ) ) {
+			throw new TypeError( format( 'invalid invocation. `this` is not %s %s.', CHAR2ARTICLE[ dtype[0] ], CTOR_NAME ) );
+		}
+
+		self = this;
+		len = this._length;
+
+		// Initialize an iteration index:
+		i = -1;
+
+		// Create an iterator protocol-compliant object:
+		iter = {};
+		setReadOnly( iter, 'next', next );
+		setReadOnly( iter, 'return', end );
+
+		if ( ITERATOR_SYMBOL ) {
+			setReadOnly( iter, ITERATOR_SYMBOL, factory );
+		}
+		return iter;
+
+		/**
+		* Returns an iterator protocol-compliant object containing the next iterated value.
+		*
+		* @private
+		* @returns {Object} iterator protocol-compliant object
+		*/
+		function next() {
+			i += 1;
+			if ( FLG || i >= len ) {
+				return {
+					'done': true
+				};
+			}
+			return {
+				'value': i,
+				'done': false
+			};
+		}
+
+		/**
+		* Finishes an iterator.
+		*
+		* @private
+		* @param {*} [value] - value to return
+		* @returns {Object} iterator protocol-compliant object
+		*/
+		function end( value ) {
+			FLG = true;
+			if ( arguments.length ) {
+				return {
+					'value': value,
+					'done': true
+				};
+			}
+			return {
+				'done': true
+			};
+		}
+
+		/**
+		* Returns a new iterator.
+		*
+		* @private
+		* @returns {Iterator} iterator
+		*/
+		function factory() {
+			return self.keys();
+		}
+	});
+
 	return TypedArray;
 
 	/**