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    @stdlib/utils-memoize
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    0.0.8 • Public • Published

    memoize

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    Memoize a function.

    Installation

    npm install @stdlib/utils-memoize

    Usage

    var memoize = require( '@stdlib/utils-memoize' );

    memoize( fcn[, hashFunction] )

    Memoizes a function.

    var randu = require( '@stdlib/random-base-randu' );
    
    function rand( n ) {
        return n * randu();
    }
    
    var memoized = memoize( rand );
    
    var v1 = memoized( 5 );
    var v2 = memoized( 5 );
    
    var bool = ( v1 === v2 );
    // returns true

    By default, the implementation serializes provided arguments as a string and stores results using the string as an identifier. To use a custom hash function, provide a hash function argument.

    function add( obj ) {
        return obj.x + obj.y + obj.z;
    }
    
    obj = {
        'x': 3,
        'y': 4,
        'z': 5
    };
    
    // Default behavior...
    
    var memoized = memoize( add );
    
    var v1 = memoized( obj );
    // returns 12
    
    var str = obj.toString();
    // returns '[object Object]'
    
    var v2 = memoized.cache[ str ];
    // returns 12
    
    obj.x = 1000;
    
    var v3 = memoized( obj );
    // returns 12
    
    // Custom hash function...
    
    function hashFunction( args ) {
        return JSON.stringify( args );
    }
    
    memoized = memoize( add, hashFunction );
    
    v1 = memoized( obj );
    // returns 1009
    
    str = hashFunction( [ obj ] );
    // returns '[{"x":1000,"y":4,"z":5}]'
    
    v2 = memoized.cache[ str ];
    // returns 1009
    
    obj.x = 6;
    
    v3 = memoized( obj );
    // returns 15

    memoized.cache

    Results cache. Note that, while the property is read-only, cache contents may be modified independently of the memoized function.

    function beep( x ) {
        throw new Error( 'boop' );
    }
    
    var memoized = memoize( beep );
    
    var cache = memoized.cache;
    // returns {}
    
    // Modify the cache:
    cache[ 'bop' ] = 'bip';
    
    var str = memoized( 'bop' );
    // returns 'bip'

    Notes

    • The implementation does not set the length of the returned function. Accordingly, the returned function length is always 0.
    • The evaluation context is always null.

    Examples

    var randu = require( '@stdlib/random-base-randu' );
    var floor = require( '@stdlib/math-base-special-floor' );
    var memoize = require( '@stdlib/utils-memoize' );
    
    var fcn;
    var n;
    var v;
    var i;
    
    function rand( n ) {
        return n * randu();
    }
    
    fcn = memoize( rand );
    
    for ( i = 0; i < 100; i++ ) {
        n = floor( randu() * 5 );
        v = fcn( n );
        console.log( 'rand(%d) = %d', n, v );
    }

    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 © 2016-2022. The Stdlib Authors.

    Install

    npm i @stdlib/utils-memoize

    Homepage

    stdlib.io

    DownloadsWeekly Downloads

    173

    Version

    0.0.8

    License

    Apache-2.0

    Unpacked Size

    41.4 kB

    Total Files

    9

    Last publish

    Collaborators

    • stdlib-bot
    • kgryte
    • planeshifter
    • rreusser