/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
'use strict';
Object.defineProperty(exports, "__esModule", { value: true });
const events_1 = require("./events");
const Is = require("./is");
var CancellationToken;
(function (CancellationToken) {
    CancellationToken.None = Object.freeze({
        isCancellationRequested: false,
        onCancellationRequested: events_1.Event.None
    });
    CancellationToken.Cancelled = Object.freeze({
        isCancellationRequested: true,
        onCancellationRequested: events_1.Event.None
    });
    function is(value) {
        let candidate = value;
        return candidate && (candidate === CancellationToken.None
            || candidate === CancellationToken.Cancelled
            || (Is.boolean(candidate.isCancellationRequested) && !!candidate.onCancellationRequested));
    }
    CancellationToken.is = is;
})(CancellationToken = exports.CancellationToken || (exports.CancellationToken = {}));
const shortcutEvent = Object.freeze(function (callback, context) {
    let handle = setTimeout(callback.bind(context), 0);
    return { dispose() { clearTimeout(handle); } };
});
class MutableToken {
    constructor() {
        this._isCancelled = false;
    }
    cancel() {
        if (!this._isCancelled) {
            this._isCancelled = true;
            if (this._emitter) {
                this._emitter.fire(undefined);
                this._emitter = undefined;
            }
        }
    }
    get isCancellationRequested() {
        return this._isCancelled;
    }
    get onCancellationRequested() {
        if (this._isCancelled) {
            return shortcutEvent;
        }
        if (!this._emitter) {
            this._emitter = new events_1.Emitter();
        }
        return this._emitter.event;
    }
}
class CancellationTokenSource {
    get token() {
        if (!this._token) {
            // be lazy and create the token only when
            // actually needed
            this._token = new MutableToken();
        }
        return this._token;
    }
    cancel() {
        if (!this._token) {
            // save an object by returning the default
            // cancelled token when cancellation happens
            // before someone asks for the token
            this._token = CancellationToken.Cancelled;
        }
        else {
            this._token.cancel();
        }
    }
    dispose() {
        this.cancel();
    }
}
exports.CancellationTokenSource = CancellationTokenSource;
