promise-channel/index.js

Like Go Channels but using JavaScript Promises.

"use strict";
var __extends = (this && this.__extends) || (function () {
    var extendStatics = Object.setPrototypeOf ||
        ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
        function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
var __generator = (this && this.__generator) || function (thisArg, body) {
    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
    function verb(n) { return function (v) { return step([n, v]); }; }
    function step(op) {
        if (f) throw new TypeError("Generator is already executing.");
        while (_) try {
            if (f = 1, y && (t = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t;
            if (y = 0, t) op = [0, t.value];
            switch (op[0]) {
                case 0: case 1: t = op; break;
                case 4: _.label++; return { value: op[1], done: false };
                case 5: _.label++; y = op[1]; op = [0]; continue;
                case 7: op = _.ops.pop(); _.trys.pop(); continue;
                default:
                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
                    if (t[2]) _.ops.pop();
                    _.trys.pop(); continue;
            }
            op = body.call(thisArg, _);
        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
    }
};
var __await = (this && this.__await) || function (v) { return this instanceof __await ? (this.v = v, this) : new __await(v); }
var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
    if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
    var g = generator.apply(thisArg, _arguments || []), i, q = [];
    return i = {}, verb("next"), verb("throw"), verb("return"), i[Symbol.asyncIterator] = function () { return this; }, i;
    function verb(n) { if (g[n]) i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; }
    function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
    function step(r) { r.value instanceof __await ? Promise.resolve(r.value.v).then(fulfill, reject) : settle(q[0][2], r);  }
    function fulfill(value) { resume("next", value); }
    function reject(value) { resume("throw", value); }
    function settle(f, v) { if (f(v), q.shift(), q.length) resume(q[0][0], q[0][1]); }
};
var __values = (this && this.__values) || function (o) {
    var m = typeof Symbol === "function" && o[Symbol.iterator], i = 0;
    if (m) return m.call(o);
    return {
        next: function () {
            if (o && i >= o.length) o = void 0;
            return { value: o && o[i++], done: !o };
        }
    };
};
Object.defineProperty(exports, "__esModule", { value: true });
var Deferred = require("promise-defer");
var Channel = /** @class */ (function () {
    function Channel() {
        this._open = true;
        this._onClose = new Deferred();
        this._readQueue = [];
        this._writeQueue = [];
    }
    Object.defineProperty(Channel.prototype, "open", {
        get: function () {
            return this._open;
        },
        enumerable: true,
        configurable: true
    });
    Object.defineProperty(Channel.prototype, "onClose", {
        get: function () {
            return this._onClose;
        },
        enumerable: true,
        configurable: true
    });
    Channel.prototype.close = function (reason) {
        this._open = false;
        this._onClose.resolve(reason);
        var e = new CloseError(reason);
        try {
            for (var _a = __values(this._readQueue), _b = _a.next(); !_b.done; _b = _a.next()) {
                var pending = _b.value;
                pending.reject(e);
            }
        }
        catch (e_1_1) { e_1 = { error: e_1_1 }; }
        finally {
            try {
                if (_b && !_b.done && (_c = _a.return)) _c.call(_a);
            }
            finally { if (e_1) throw e_1.error; }
        }
        try {
            for (var _d = __values(this._writeQueue), _e = _d.next(); !_e.done; _e = _d.next()) {
                var pending = _e.value;
                pending.reject(e);
            }
        }
        catch (e_2_1) { e_2 = { error: e_2_1 }; }
        finally {
            try {
                if (_e && !_e.done && (_f = _d.return)) _f.call(_d);
            }
            finally { if (e_2) throw e_2.error; }
        }
        return this._onClose.promise;
        var e_1, _c, e_2, _f;
    };
    Channel.prototype.read = function () {
        if (!this._open)
            return Promise.reject(new CloseError("Read while closed"));
        if (this._writeQueue.length) {
            var write = this._writeQueue.shift();
            var value = write.value;
            write.resolve();
            return Promise.resolve(value);
        }
        var read = new PendingRead();
        this._readQueue.push(read);
        return read.promise;
    };
    Channel.prototype.write = function (value) {
        if (!this.open)
            return Promise.reject(new CloseError("Write while closed"));
        if (this._readQueue.length) {
            var read = this._readQueue.shift();
            read.resolve(value);
            return Promise.resolve();
        }
        var write = new PendingWrite(value);
        this._writeQueue.push(write);
        return write.promise;
    };
    Channel.prototype[Symbol.asyncIterator] = function () {
        return __asyncGenerator(this, arguments, function _a() {
            var channel, result, e_3;
            return __generator(this, function (_a) {
                switch (_a.label) {
                    case 0:
                        channel = this;
                        _a.label = 1;
                    case 1:
                        _a.trys.push([1, 6, , 7]);
                        _a.label = 2;
                    case 2:
                        if (!channel.open) return [3 /*break*/, 5];
                        return [4 /*yield*/, __await(channel.read())];
                    case 3:
                        result = _a.sent();
                        return [4 /*yield*/, result];
                    case 4:
                        _a.sent();
                        return [3 /*break*/, 2];
                    case 5: return [3 /*break*/, 7];
                    case 6:
                        e_3 = _a.sent();
                        if (e_3 instanceof CloseError) {
                            return [2 /*return*/, e_3.reason];
                        }
                        else {
                            throw e_3;
                        }
                        return [3 /*break*/, 7];
                    case 7: return [2 /*return*/];
                }
            });
        });
    };
    return Channel;
}());
var CloseError = /** @class */ (function (_super) {
    __extends(CloseError, _super);
    function CloseError(reason) {
        var _this = _super.call(this, "Channel closed") || this;
        _this.closed = true;
        _this.reason = reason;
        return _this;
    }
    return CloseError;
}(Error));
var PendingWrite = /** @class */ (function () {
    function PendingWrite(value) {
        this.value = value;
        this.deferred = new Deferred();
    }
    Object.defineProperty(PendingWrite.prototype, "promise", {
        get: function () {
            return this.deferred.promise;
        },
        enumerable: true,
        configurable: true
    });
    PendingWrite.prototype.resolve = function () {
        this.deferred.resolve();
    };
    PendingWrite.prototype.reject = function (e) {
        this.deferred.reject(e);
    };
    return PendingWrite;
}());
var PendingRead = /** @class */ (function () {
    function PendingRead() {
        this.deferred = new Deferred();
    }
    Object.defineProperty(PendingRead.prototype, "promise", {
        get: function () {
            return this.deferred.promise;
        },
        enumerable: true,
        configurable: true
    });
    PendingRead.prototype.resolve = function (value) {
        this.deferred.resolve(value);
    };
    PendingRead.prototype.reject = function (e) {
        this.deferred.reject(e);
    };
    return PendingRead;
}());
exports.default = Channel;