immutable-js/src/Native.js

Immutable types in JavaScript

/**
 *  Copyright (c) 2015, Jan Biasi.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 */

import clone from './util/clone';

export var IS_NATIVE_FLAG = '@@__IS_NATIVE__@@';
export function isNative(maybeNative) {
    return !!(maybeNative && maybeNative[IS_NATIVE_FLAG]);
}

var NATIVE_COLLECTION_TYPEDEF = '[native Collection]'
export class NativeCollection {
    constructor() {
        var args = Array.prototype.slice.call(arguments);
        if(args.length > 1) {
            let array = new NativeArray();
            array.__initialSize = args.length;
            args.forEach(v => array.push(v));
            return array;
        } else if(args.length === 1) {
            var single = args[0];
            if(Array.isArray(single)) {
                let array = new NativeArray();
                single.forEach(v => array.push(v));
                array.__initialSize = single.length || 0;
                return array;
            } else if(typeof single === 'object') {
                let object = new NativeObject();
                object.__initialSize = Object.keys(single).length;
                return object.extend(single);
            }
        } else {
            return new NativeObject();
        }
    }

    toString() {
        return NATIVE_COLLECTION_TYPEDEF;
    }
}

var NATIVE_ARRAY_TYPEDEF = '[native Array]';
export class NativeArray extends Array {
    constructor() {
        super(0);
    }

    toString() {
        return NATIVE_ARRAY_TYPEDEF;
    }

    toNative() {
        return this;
    }

    isNativeArray(maybeNativeArray) {
        return maybeNativeArray && maybeNativeArray.toString &&
            maybeNativeArray.toString() === NATIVE_ARRAY_TYPEDEF;
    }

    __clone() {
        return this.slice();
    }
}

var NATIVE_OBJECT_TYPEDEF = '[native Object]';
export class NativeObject extends Object {
    constructor() {
        super(null);
    }

    __clone() {
        return clone(this);
    }

    extend(source) {
        var object = Object.assign(new NativeObject(), source);
        return object;
    }

    toString() {
        return NATIVE_OBJECT_TYPEDEF;
    }

    isNativeObject(maybeNativeObject) {
        return maybeNativeObject && maybeNativeObject.toString &&
            maybeNativeObject.toString() === NATIVE_OBJECT_TYPEDEF;
    }
}

NativeCollection.prototype[IS_NATIVE_FLAG] = true;
NativeObject.prototype[IS_NATIVE_FLAG] = true;
NativeArray.prototype[IS_NATIVE_FLAG] = true;