parser-combinator/build/lib/data/option.js

Parser combinators

"use strict";

Object.defineProperty(exports, "__esModule", {
    value: true
});

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

/*
 * Parsec
 * https://github.com/d-plaindoux/parsec
 *
 * Copyright (c) 2016 Didier Plaindoux
 * Licensed under the LGPL2 license.
 */

/**
 * Private class Option, accessible from someOrNone() or none()
 */
var Option = function () {
    function Option(value) {
        _classCallCheck(this, Option);

        this.value = value;
    }

    _createClass(Option, [{
        key: "isPresent",
        value: function isPresent() {
            return this.value !== null && this.value !== undefined;
        }
    }, {
        key: "map",
        value: function map(bindCall) {
            if (this.isPresent()) {
                return someOrNone(bindCall(this.value));
            } else {
                return this;
            }
        }
    }, {
        key: "flatmap",
        value: function flatmap(bindCall) {
            if (this.isPresent()) {
                return bindCall(this.value);
            } else {
                return this;
            }
        }
    }, {
        key: "filter",
        value: function filter(f) {
            if (this.isPresent() && f(this.value)) {
                return this;
            }

            // equivalent of return none() without cyclic creation
            // eslint : no-use-before-define
            return new Option();
        }
    }, {
        key: "get",
        value: function get() {
            return this.value;
        }
    }, {
        key: "orElse",
        value: function orElse(value) {
            if (this.isPresent()) {
                return this.value;
            } else {
                return value;
            }
        }
    }, {
        key: "orLazyElse",
        value: function orLazyElse(value) {
            if (this.isPresent()) {
                return this.value;
            } else {
                return value();
            }
        }
    }]);

    return Option;
}();

function someOrNone(value) {
    return new Option(value);
}

function none() {
    return new Option();
}

exports.default = {
    some: someOrNone,
    none: none
};
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