tiny-types/lib/predicates/isEqualTo.js

A tiny library that brings Tiny Types to JavaScript and TypeScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.isEqualTo = isEqualTo;
const TinyType_1 = require("../TinyType");
const Predicate_1 = require("./Predicate");
/**
 * @desc Ensures that the `value` is equal to `expectedValue`.
 * This {@link Predicate} is typically used in combination with other {@link Predicate}s.
 *
 * @example <caption>Comparing Tiny Types</caption>
 * import { ensure, isEqualTo, TinyType, TinyTypeOf } from 'tiny-types';
 *
 * class AccountId         extends TinyTypeOf<number>() {}
 * class Command           extends TinyTypeOf<AccountId>() {}
 * class UpgradeAccount    extends Command {}
 *
 * class AccountsService {
 *     constructor(public readonly loggedInUser: AccountId) {}
 *     handle(command: Command) {
 *         ensure('AccountId', command.value, isEqualTo(this.loggedInUser));
 *     }
 *  }
 *
 * @example <caption>Comparing primitives</caption>
 * import { ensure, isEqualTo, TinyType } from 'tiny-types';
 *
 * class Admin extends TinyType {
 *     constructor(public readonly id: number) {
 *         ensure('Admin::id', id, isEqualTo(1));
 *     }
 * }
 *
 * @param {string | number | symbol | TinyType | object} expectedValue
 * @returns {Predicate<any>}
 */
function isEqualTo(expectedValue) {
    return Predicate_1.Predicate.to(`be equal to ${String(expectedValue)}`, (value) => (hasEquals(value) && hasEquals(expectedValue))
        ? value.equals(expectedValue)
        : value === expectedValue);
}
function hasEquals(value) {
    return !!value && (value instanceof TinyType_1.TinyType || value.equals);
}
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