runtime-branding/dist/index.js

Runtime Branding API for TypeScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const brand = Symbol();
// TODO: do we need a global branding map?
/**
 * Creates a new brand, identified by the provided branding object.
 *
 * @param brandObject An object that represents the brand. The shape of this object should be unique, and symbols may be used as unique keys.
 * @param callback An optional callback with variable arguments which is invoked during object branding
 */
function createBranding(brandObject, callback) {
    const brandedObjects = new WeakSet();
    function has(obj) {
        return brandedObjects.has(obj);
    }
    function assert(obj) {
        if (!brandedObjects.has(obj)) {
            throw new Error("Object not branded.");
        }
    }
    function branding(obj) {
        if (has(obj)) {
            throw new Error("Object already branded.");
        }
        brandedObjects.add(obj);
        if (callback) {
            try {
                callback(obj, brandObject);
            }
            catch (e) {
                brandedObjects.delete(obj);
                throw e;
            }
        }
        return obj;
    }
    function refine(newBrand, newCallback) {
        const b = Object.assign({}, newBrand, brandObject);
        const refinedBranding = createBranding(b, newCallback);
        return merge(refinedBranding);
    }
    function merge(branding1) {
        return mixin(branding, branding1);
    }
    function generic() {
        return branding;
    }
    branding.has = has; // TODO: maybe all these should be built separately, then Object.assigned to branding()
    branding.assert = assert;
    branding.refine = refine;
    branding.merge = merge;
    branding.generic = generic;
    branding[brand] = brandObject;
    return branding;
}
exports.createBranding = createBranding;
/**
 * Mixes two different brandings in a single one.
 *
 * @param fn1 The first branding function
 * @param fn2 The second branding function
 */
function mixin(fn1, fn2) {
    function has(obj) {
        return fn1.has(obj) && fn2.has(obj);
    }
    function assert(obj) {
        fn1.assert(obj);
        fn2.assert(obj);
    }
    function branding(obj) {
        fn1(obj);
        fn2(obj);
        return obj;
    }
    function refine(newBrand, callback) {
        const b = Object.assign({}, newBrand, fn1[brand], fn2[brand]);
        return createBranding(b, callback);
    }
    function merge(branding1) {
        return mixin(branding, branding1);
    }
    function generic() {
        return branding;
    }
    const newBrand = Object.assign({}, fn1[brand], fn2[brand]);
    branding.has = has;
    branding.assert = assert;
    branding.refine = refine;
    branding.merge = merge;
    branding.generic = generic;
    branding[brand] = newBrand;
    return branding;
}
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