declarative-js/src/optional/Optional.js

_declarative-js_ is modern JavaScript library, that helps to: - tackle array transformation with built in JavaScript array api (e.g. `array.filter(toBe.unique())`), - provide a type-level solution for representing optional values instead of null referen

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var ToArray_1 = require("../internal/ToArray");
exports.Optional = OptionalImpl;
function OptionalImpl(value) {
    this.value = value;
}
OptionalImpl.prototype = {
    orElse: function (value) {
        return this.isPresent() ? this.value : value;
    },
    isPresent: function () {
        return this.value != undefined;
    },
    isAbsent: function () {
        return this.value == undefined;
    },
    orElseGet: function (supplier) {
        return this.isPresent() ? this.value : supplier();
    },
    orElseThrow: function (errorMessage) {
        if (!this.isPresent()) {
            throw new Error(errorMessage);
        }
        return this.value;
    },
    ifPresent: function (consumer) {
        if (this.isPresent()) {
            consumer();
        }
    },
    ifAbsent: function (consumer) {
        if (this.isAbsent()) {
            consumer();
        }
    },
    get: function () {
        if (this.value == undefined) {
            throw new Error('Value is not defined');
        }
        return this.value;
    },
    map: function (mapper) {
        return this.isPresent() ? new exports.Optional(mapper(this.value)) : new exports.Optional();
    },
    filter: function (predicate) {
        if (this.isPresent()) {
            return predicate(this.value) ? this : new exports.Optional();
        }
        return new exports.Optional();
    },
    toArray: function () {
        return ToArray_1.toArray(this.value);
    }
};
exports.optional = function (value) {
    return new exports.Optional(value);
};