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feat: add findLastIndex method to array/fixed-endian-factory #3295

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48 changes: 48 additions & 0 deletions lib/node_modules/@stdlib/array/fixed-endian-factory/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -511,6 +511,54 @@ var count = context.count;
// returns 3
```

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

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

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

```javascript
function predicate( v ) {
return v % 2 !== 0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

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

var out = arr.findLastIndex( 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
function predicate( v ) {
this.count += 1;
return v % 2 !== 0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

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

var context = {
'count': 0
};

var out = arr.findLastIndex( predicate, context );
// returns 2

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

<a name="method-get"></a>

#### TypedArrayFE.prototype.get( i )
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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 isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
var pkg = require( './../package.json' ).name;
var factory = require( './../lib' );


// VARIABLES //

var Float64ArrayFE = factory( 'float64' );


// MAIN //

bench( pkg+':findLastIndex', function benchmark( b ) {
var arr;
var out;
var i;

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

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
out = arr.findLastIndex( predicate );
if ( typeof out !== 'number' ) {
b.fail( 'should return a number' );
}
}
b.toc();
if ( !isInteger( out ) ) {
b.fail( 'should return an integer' );
}
b.pass( 'benchmark finished' );
b.end();

function predicate( v ) {
return v < 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 isInteger = require( '@stdlib/assert/is-integer' ).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;
}

/**
* 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.findLastIndex( predicate );
if ( typeof out !== 'number' ) {
b.fail( 'should return a number' );
}
}
b.toc();
if ( !isInteger( out ) ) {
b.fail( 'should return an integer' );
}
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+':findLastIndex:len='+len, f );
}
}

main();
31 changes: 31 additions & 0 deletions lib/node_modules/@stdlib/array/fixed-endian-factory/lib/main.js
Original file line number Diff line number Diff line change
Expand Up @@ -644,6 +644,37 @@ function factory( dtype ) { // eslint-disable-line max-lines-per-function, stdli
}
});

/**
* Returns the index of the last element in an array for which a predicate function returns a truthy value.
*
* @private
* @name findLastIndex
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Suggested change
* @name findLastIndex
* @private
* @name findLastIndex

* @memberof TypedArray.prototype
* @type {Function}
* @param {Function} predicate - predicate function
* @param {*} [thisArg] - predicate function execution context
* @throws {TypeError} `this` must be a typed array
* @throws {TypeError} first argument must be a function
* @returns {integer} index or -1
*/
setReadOnly( TypedArray.prototype, 'findLastIndex', function findLastIndex( predicate, thisArg ) {
var buf;
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-- ) {
if ( predicate.call( thisArg, buf[ GETTER ]( i * BYTES_PER_ELEMENT, this._isLE ), i, this ) ) {
return i;
}
}
return -1;
});

/**
* Returns an array element.
*
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