npm package: @stdlib/strided-base-mskunary-addon-dispatch
Description: Dispatch to a native add-on applying a unary function to an input strided array according to a mask strided array.
Author: The Stdlib Authors
Latest version: 0.3.1

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# dispatch

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Dispatch to a native add-on applying a unary function to an input strided array according to a mask strided array.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/strided-base-mskunary-addon-dispatch
```

</section>

<section class="usage">

## Usage

```javascript
var dispatch = require( '@stdlib/strided-base-mskunary-addon-dispatch' );
```

#### dispatch( addon, fallback )

Returns a function which dispatches to a native add-on applying a unary function to an input strided array according to a mask strided array.

<!-- eslint-disable max-len -->

```javascript
function addon( N, dtypeX, x, strideX, dtypeMask, mask, strideMask, dtypeY, y, strideY ) {
    // Call into native add-on...
}

function fallback( N, dtypeX, x, strideX, dtypeMask, mask, strideMask, dtypeY, y, strideY ) {
    // Fallback JavaScript implementation...
}

// Create a dispatch function:
var f = dispatch( addon, fallback );

// ...

// Invoke the dispatch function with strided array arguments:
f( 2, 'generic', [ 1, 2 ], 1, 'generic', [ 0, 0 ], 1, 'generic', [ 0, 0 ], 1 );
```

The returned function has the following signature:

```text
f( N, dtypeX, x, strideX, dtypeMask, mask, strideMask, dtypeY, y, strideY )
```

where

-   **N**: number of indexed elements.
-   **dtypeX**: `x` data type.
-   **x**: input array.
-   **strideX**: `x` stride length.
-   **dtypeMask**: `mask` data type.
-   **mask**: mask array.
-   **strideMask**: `mask` stride length.
-   **dtypeY**: `y` data type.
-   **y**: output array.
-   **strideY**: `y` stride length.

The `addon` function should have the following signature:

```text
f( N, dtypeX, x, strideX, dtypeMask, mask, strideMask, dtypeY, y, strideY )
```

where

-   **N**: number of indexed elements.
-   **dtypeX**: `x` data type (enumeration constant).
-   **x**: input array.
-   **strideX**: `x` stride length.
-   **dtypeMask**: `mask` data type (enumeration constant).
-   **mask**: mask array.
-   **strideMask**: `mask` stride length.
-   **dtypeY**: `y` data type (enumeration constant).
-   **y**: output array.
-   **strideY**: `y` stride length.

The `fallback` function should have the following signature:

```text
f( N, dtypeX, x, strideX, dtypeMask, mask, strideMask, dtypeY, y, strideY )
```

where

-   **N**: number of indexed elements.
-   **dtypeX**: `x` data type.
-   **x**: input array.
-   **strideX**: `x` stride length.
-   **dtypeMask**: `mask` data type.
-   **mask**: mask array.
-   **strideMask**: `mask` stride length.
-   **dtypeY**: `y` data type.
-   **y**: output array.
-   **strideY**: `y` stride length.

#### dispatch.ndarray( addon, fallback )

Returns a function which dispatches to a native add-on applying a unary function to an input strided array according to a mask strided array using alternative indexing semantics.

<!-- eslint-disable max-len, max-params -->

```javascript
function addon( N, dtypeX, x, strideX, dtypeMask, mask, strideMask, dtypeY, y, strideY ) {
    // Call into native add-on...
}

function fallback( N, dtypeX, x, strideX, offsetX, dtypeMask, mask, strideMask, offsetMask, dtypeY, y, strideY, offsetY ) {
    // Fallback JavaScript implementation...
}

// Create a dispatch function:
var f = dispatch.ndarray( addon, fallback );

// ...

// Invoke the dispatch function with strided array arguments:
f( 2, 'generic', [ 1, 2 ], 1, 0, 'generic', [ 0, 0 ], 1, 0, 'generic', [ 0, 0 ], 1, 0 );
```

The returned function has the following signature:

```text
f( N, dtypeX, x, strideX, offsetX, dtypeMask, mask, strideMask, offsetMask, dtypeY, y, strideY, offsetY )
```

where

-   **N**: number of indexed elements.
-   **dtypeX**: `x` data type.
-   **x**: input array.
-   **strideX**: `x` stride length.
-   **offsetX**: starting `x` index.
-   **dtypeMask**: `mask` data type.
-   **mask**: mask array.
-   **strideMask**: `mask` stride length.
-   **offsetmask**: starting `mask` index.
-   **dtypeY**: `y` data type.
-   **y**: output array.
-   **strideY**: `y` stride length.
-   **offsetY**: starting `y` index.

The `addon` function should have the following signature:

```text
f( N, dtypeX, x, strideX, dtypeMask, mask, strideMask, dtypeY, y, strideY )
```

where

-   **N**: number of indexed elements.
-   **dtypeX**: `x` data type (enumeration constant).
-   **x**: input array.
-   **strideX**: `x` stride length.
-   **dtypeMask**: `mask` data type (enumeration constant).
-   **mask**: mask array.
-   **strideMask**: `mask` stride length.
-   **dtypeY**: `y` data type (enumeration constant).
-   **y**: output array.
-   **strideY**: `y` stride length.

The `fallback` function should have the following signature:

```text
f( N, dtypeX, x, strideX, offsetX, dtypeMask, mask, strideMask, offsetMask, dtypeY, y, strideY, offsetY )
```

where

-   **N**: number of indexed elements.
-   **dtypeX**: `x` data type.
-   **x**: input array.
-   **strideX**: `x` stride length.
-   **offsetX**: starting `x` index.
-   **dtypeMask**: `mask` data type.
-   **mask**: mask array.
-   **strideMask**: `mask` stride length.
-   **offsetmask**: starting `mask` index.
-   **dtypeY**: `y` data type.
-   **y**: output array.
-   **strideY**: `y` stride length.
-   **offsetY**: starting `y` index.

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   To determine whether to dispatch to the `addon` function, the returned dispatch function checks whether the provided arrays are typed arrays. If the provided arrays are typed arrays, the dispatch function invokes the `addon` function; otherwise, the dispatch function invokes the `fallback` function.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint-disable max-len, max-params -->

<!-- eslint no-undef: "error" -->

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var Uint8Array = require( '@stdlib/array-uint8' );
var dispatch = require( '@stdlib/strided-base-mskunary-addon-dispatch' );

function addon( N, dx, x, sx, dm, m, sm, dy, y, sy ) {
    console.log( x );
    // => <Float64Array>[ 3, 4 ]

    console.log( y );
    // => <Float64Array>[ 7, 8 ]
}

function fallback( N, dx, x, sx, ox, dm, m, sm, om, dy, y, sy, oy ) {
    console.log( x );
    // => [ 1, 2, 3, 4 ]

    console.log( y );
    // => [ 5, 6, 7, 8 ]
}

// Create a dispatch function:
var f = dispatch.ndarray( addon, fallback );

// Create strided arrays:
var x = new Float64Array( [ 1, 2, 3, 4 ] );
var y = new Float64Array( [ 5, 6, 7, 8 ] );
var m = new Uint8Array( x.length );

// Dispatch to the add-on function:
f( 2, 'float64', x, 1, 2, 'uint8', m, 1, 2, 'float64', y, 1, 2 );

// Define new strided arrays:
x = [ 1, 2, 3, 4 ];
y = [ 5, 6, 7, 8 ];
m = [ 0, 0, 0, 0 ];

// Dispatch to the fallback function:
f( 2, 'generic', x, 1, 2, 'generic', m, 1, 2, 'generic', y, 1, 2 );
```

</section>

<!-- /.examples -->

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<section class="references">

</section>

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<section class="related">

</section>

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* * *

## Notice

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For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

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---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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