ts-results-es
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A TypeScript implementation of Rust's Result and Option objects.
178 lines • 7.98 kB
JavaScript
;
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
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 = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
return g.next = verb(0), g["throw"] = verb(1), g["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 (g && (g = 0, op[0] && (_ = 0)), _) try {
if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
if (y = 0, t) op = [op[0] & 2, 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 };
}
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.AsyncOption = void 0;
var asyncresult_js_1 = require("./asyncresult.js");
var option_js_1 = require("./option.js");
/**
* An async-aware `Option` counterpart.
*
* Can be combined with asynchronous code without having to ``await`` anything right until
* the moment when you're ready to extract the final ``Option`` out of it.
*
* Can also be combined with synchronous code for convenience.
*/
var AsyncOption = /** @class */ (function () {
/**
* Constructs an `AsyncOption` from an `Option` or a `Promise` of an `Option`.
*
* @example
* ```typescript
* const option = new AsyncOption(Promise.resolve(Some('username')))
* ```
*/
function AsyncOption(start) {
this.promise = Promise.resolve(start);
}
/**
* Calls `mapper` if the option is `Some`, otherwise keeps the `None` value intact.
* This function can be used for control flow based on `Option` values.
*
* @example
* ```typescript
* let hasValue = Some(1).toAsyncOption()
* let noValue = None.toAsyncOption()
*
* await hasValue.andThen(async (value) => Some(value * 2)).promise // Some(2)
* await hasValue.andThen(async (value) => None).promise // None
* await noValue.andThen(async (value) => Ok(value * 2)).promise // None
* ```
*/
AsyncOption.prototype.andThen = function (mapper) {
var _this = this;
return this.thenInternal(function (option) { return __awaiter(_this, void 0, void 0, function () {
var mapped;
return __generator(this, function (_a) {
if (option.isNone()) {
return [2 /*return*/, option];
}
mapped = mapper(option.value);
return [2 /*return*/, mapped instanceof AsyncOption ? mapped.promise : mapped];
});
}); });
};
/**
* Maps an `AsyncOption<T>` to `AsyncOption<U>` by applying a function to a contained
* `Some` value, leaving a `None` value untouched.
*
* This function can be used to compose the results of two functions.
*
* @example
* ```typescript
* let hasValue = Ok(1).toAsyncOption()
* let noValue = None.toAsyncOption()
*
* await hasValue.map(async (value) => value * 2).promise // Some(2)
* await noValue.map(async (value) => value * 2).promise // None
* ```
*/
AsyncOption.prototype.map = function (mapper) {
var _this = this;
return this.thenInternal(function (option) { return __awaiter(_this, void 0, void 0, function () {
var _a;
return __generator(this, function (_b) {
switch (_b.label) {
case 0:
if (option.isNone()) {
return [2 /*return*/, option];
}
_a = option_js_1.Some;
return [4 /*yield*/, mapper(option.value)];
case 1: return [2 /*return*/, _a.apply(void 0, [_b.sent()])];
}
});
}); });
};
/**
* Returns the value from `other` if this `AsyncOption` contains `None`, otherwise returns self.
*
* If `other` is a result of a function call consider using `orElse` instead, it will
* only evaluate the function when needed.
*
* @example
* ```
* const noValue = new AsyncOption(None)
* const hasValue = new AsyncOption(Some(1))
*
* await noValue.or(Some(123)).promise // Some(123)
* await hasValue.or(Some(123)).promise // Some(1)
* ```
*/
AsyncOption.prototype.or = function (other) {
return this.orElse(function () { return other; });
};
/**
* Returns the value obtained by calling `other` if this `AsyncOption` contains `None`, otherwise
* returns self.
*
* @example
* ```
* const noValue = new AsyncOption(None)
* const hasValue = new AsyncOption(Some(1))
*
* await noValue.orElse(() => Some(123)).promise // Some(123)
* await hasValue.orElse(() => Some(123)).promise // Some(1)
* ```
*/
AsyncOption.prototype.orElse = function (other) {
var _this = this;
return this.thenInternal(function (option) { return __awaiter(_this, void 0, void 0, function () {
var otherValue;
return __generator(this, function (_a) {
if (option.isSome()) {
return [2 /*return*/, option];
}
otherValue = other();
return [2 /*return*/, otherValue instanceof AsyncOption ? otherValue.promise : otherValue];
});
}); });
};
/**
* Converts an `AsyncOption<T>` to an `AsyncResult<T, E>` so that `None` is converted to
* `Err(error)` and `Some` is converted to `Ok`.
*/
AsyncOption.prototype.toResult = function (error) {
return new asyncresult_js_1.AsyncResult(this.promise.then(function (option) { return option.toResult(error); }));
};
AsyncOption.prototype.thenInternal = function (mapper) {
return new AsyncOption(this.promise.then(mapper));
};
return AsyncOption;
}());
exports.AsyncOption = AsyncOption;
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