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feat: add findLast method to array/fixed-endian-factory #3312

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50 changes: 49 additions & 1 deletion lib/node_modules/@stdlib/array/fixed-endian-factory/README.md
Original file line number Diff line number Diff line change
@@ -450,6 +450,54 @@ var count = context.count;
// returns 4
```

<a name="method-find-last"></a>

#### TypedArray.prototype.findLast( predicate\[, thisArg] )

Returns the last element in an array for which a predicate function returns a truthy value.

```javascript
var Float64ArrayFE = fixedEndianFactory( 'float64' );

function predicate( element ) {
return element < 0.0;
}

var arr = new Float64ArrayFE( 'little-endian', [ -1.0, 2.0, -4.0, 3.0 ] );

var res = arr.findLast( predicate );
// returns -4.0
```

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 Float64ArrayFE = fixedEndianFactory( 'float64' );

function predicate( v ) {
this.count += 1;
return ( v < 0.0 );
}

var arr = new Float64ArrayFE( 'little-endian', [ -1.0, 2.0, 3.0 ] );

var context = {
'count': 0
};

var z = arr.findLast( predicate, context );
// returns -1.0

var count = context.count;
// returns 3
```

<a name="method-for-each"></a>

#### TypedArrayFE.prototype.forEach( callbackFn\[, thisArg] )
@@ -923,7 +971,7 @@ var out = arr.with( 0, 0.0 );
var v = out.get( 0 );
// returns 0.0
```

</section>

<!-- /.usage -->
Original file line number Diff line number Diff line change
@@ -0,0 +1,60 @@
/**
* @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 isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
var pkg = require( './../package.json' ).name;
var factory = require( './../lib' );


// VARIABLES //

var Float64ArrayFE = factory( 'float64' );


// MAIN //

bench( pkg+':findLast', function benchmark( b ) {
var out;
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++ ) {
out = arr.findLast( predicate );
if ( typeof out !== 'number' ) {
b.fail( 'should return a number' );
}
}
b.toc();
if ( !isNumber( out ) ) {
b.fail( 'should return a number' );
}
b.pass( 'benchmark finished' );
b.end();

function predicate( v ) {
return v > 0.0;
}
});
Original file line number Diff line number Diff line change
@@ -0,0 +1,113 @@
/**
* @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 isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
var pkg = require( './../package.json' ).name;
var factory = require( './../lib' );


// VARIABLES //

var Float64ArrayFE = factory( 'float64' );


// FUNCTIONS //

/**
* Predicate function.
*
* @private
* @param {number} value - array element
* @param {NonNegativeInteger} idx - array element index
* @param {TypedArray} arr - array instance
* @returns {boolean} boolean indicating whether a value passes a test
*/
function predicate( value ) {
return value < 0.0;
}

/**
* 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 out;
var i;

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
out = arr.findLast( predicate );
if ( typeof out !== 'number' ) {
b.fail( 'should return a number' );
}
}
b.toc();
if ( !isNumber( out ) ) {
b.fail( 'should return a number' );
}
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+':findLast:len='+len, f );
}
}

main();
33 changes: 33 additions & 0 deletions lib/node_modules/@stdlib/array/fixed-endian-factory/lib/main.js
Original file line number Diff line number Diff line change
@@ -617,6 +617,39 @@ function factory( dtype ) { // eslint-disable-line max-lines-per-function, stdli
return new this.constructor( flag2byteOrder( this._isLE ), out );
});

/**
* Returns the last element in an array for which a predicate function returns a truthy value.
*
* @private
* @name findLast
* @memberof TypedArray.prototype
* @type {Function}
* @param {Function} predicate - test function
* @param {*} [thisArg] - predicate function execution context
* @throws {TypeError} `this` must be a typed array
* @throws {TypeError} first argument must be a function
* @returns {(*|void)} array element or undefined
*/
setReadOnly( TypedArray.prototype, 'findLast', function findLast( predicate, thisArg ) {
var buf;
var v;
var i;

if ( !isTypedArray( this ) ) {
throw new TypeError( format( 'invalid invocation. `this` is not %s %s.', CHAR2ARTICLE[ dtype[0] ], CTOR_NAME ) );
}
if ( !isFunction( predicate ) ) {
throw new TypeError( format( 'invalid argument. First argument must be a function. Value: `%s`.', predicate ) );
}
buf = this._buffer;
for ( i = this._length-1; i >= 0; i-- ) {
v = buf[ GETTER ]( i * BYTES_PER_ELEMENT, this._isLE );
if ( predicate.call( thisArg, v, i, this ) ) {
return v;
}
}
});

/**
* Invokes a function once for each array element.
*
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