standard-data-structures/src/immutable/option.js

A collection of standard data-structures for node and browser

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
/* tslint:disable no-use-before-declare prefer-function-over-method */
const noSuchValueException_1 = require("../internals/noSuchValueException");
const either_1 = require("./either");
/**
 * Used to represent an optional value
 */
class Option {
    /**
     * Returns `true` if the instance is [[Some]]
     */
    get isSome() {
        return !this.isNone;
    }
    /**
     * Creates an [[Option]] from an [[Either]]
     */
    static fromEither(either) {
        return either.fold(Option.none(), () => Option.none(), Option.some);
    }
    /**
     * Checks if the Option type is of [[None]] type
     */
    static isNone(A) {
        return A.isNone;
    }
    /**
     * Checks if the Option type is of [[Some]] type
     */
    static isSome(A) {
        return A.isSome;
    }
    /**
     * Creates a [[None]] object
     */
    static none() {
        return new None();
    }
    /**
     * Creates a [[Some]] object
     */
    static some(A) {
        return new Some(A);
    }
    /**
     * Transforms the value inside the [[Option]] type.
     */
    map(ab) {
        return this.chain(a => Option.some(ab(a)));
    }
}
exports.Option = Option;
/**
 * Is an [[Option]] type that represents existence of a value.
 */
class Some extends Option {
    constructor(value) {
        super();
        this.value = value;
    }
    /**
     * Refer [[Option.chain]]
     */
    chain(ab) {
        return ab(this.value);
    }
    /**
     * Refer [[Option.fold]]
     */
    fold(S, some) {
        return some(this.value, S);
    }
    /**
     * Refer [[Option.getOrElse]]
     */
    getOrElse(a) {
        return this.value;
    }
    /**
     * Refer [[Option.isNone]]
     */
    get isNone() {
        return false;
    }
    /**
     * Refer [[Option.asEither]]
     */
    get asEither() {
        return either_1.Either.right(this.value);
    }
}
exports.Some = Some;
/**
 * Is an [[Option]] type that represents absence of any value.
 */
class None extends Option {
    /**
     * Refer [[Option.chain]]
     */
    chain(ab) {
        return this;
    }
    /**
     * Refer [[Option.fold]]
     */
    fold(S, some) {
        return S;
    }
    /**
     * Refer [[Option.getOrElse]]
     */
    getOrElse(A) {
        return A;
    }
    /**
     * Refer [[Option.isNone]]
     */
    get isNone() {
        return true;
    }
    /**
     * Refer [[Option.asEither]]
     */
    get asEither() {
        return either_1.Either.left(new noSuchValueException_1.NoSuchValueException());
    }
}
exports.None = None;