@stdlib/array-base-resolve-getter
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0.2.1 • Public • Published
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resolveGetter

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Return an accessor function for retrieving an element from an array-like object.

Installation

npm install @stdlib/array-base-resolve-getter

Usage

var resolveGetter = require( '@stdlib/array-base-resolve-getter' );

resolveGetter( x )

Returns an accessor function for retrieving an element from an array-like object.

var x = [ 1, 2, 3, 4 ];

var get = resolveGetter( x );
var v = get( x, 2 );
// returns 3

The returned accessor function accepts the following arguments:

  • arr: input array.
  • idx: element index.

Notes

  • If provided an array-like object having an unsupported data type, the function returns a default accessor function for accessing elements from any array-like object; otherwise, the function returns an accessor function which should only be provided an array instance having the same data type (e.g., if provided a Float64Array, the returned accessor function should only be provided instances of Float64Array).
  • Accessor functions do not verify that provided input arrays are array instances having a specific data type, as doing so would introduce performance overhead. If array instances corresponding to other data types are provided to an accessor function, JavaScript runtimes will consider the function polymorphic, potentially triggering de-optimization. In order to ensure maximum performance, always ensure that an accessor function is monomorphic.
  • Accessor functions do not perform bounds checking.
  • Accessor functions do not verify that provided input arrays implement the get/set protocol.
  • An indexed array-like object is a data structure in which one retrieves elements via integer indices using bracket [] notation (e.g., Float64Array, Int32Array, Array, etc). This is in contrast to an accessor array-like object in which one retrieves elements using get and set methods (e.g., Complex64Array and Complex128Array).

Examples

var filled = require( '@stdlib/array-filled' );
var resolveGetter = require( '@stdlib/array-base-resolve-getter' );

var arr = filled( 1.0, 10, 'float64' );
var v = resolveGetter( arr )( arr, 2 );
// returns 1.0

arr = filled( 2.0, 10, 'float32' );
v = resolveGetter( arr )( arr, 2 );
// returns 2.0

arr = filled( 3, 10, 'int32' );
v = resolveGetter( arr )( arr, 2 );
// returns 3

arr = filled( 4, 10, 'int16' );
v = resolveGetter( arr )( arr, 2 );
// returns 4

arr = filled( 5, 10, 'int8' );
v = resolveGetter( arr )( arr, 2 );
// returns 5

arr = filled( 6, 10, 'uint32' );
v = resolveGetter( arr )( arr, 2 );
// returns 6

arr = filled( 7, 10, 'uint16' );
v = resolveGetter( arr )( arr, 2 );
// returns 7

arr = filled( 8, 10, 'uint8' );
v = resolveGetter( arr )( arr, 2 );
// returns 8

arr = filled( 9, 10, 'uint8c' );
v = resolveGetter( arr )( arr, 2 );
// returns 9

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.

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npm i @stdlib/array-base-resolve-getter

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