Better typings for IteratorResult (#60565)

alexdima · alexdima · commit 3e5bdc4571fc · 2018-10-11T15:50:08.000+02:00
diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
@@ -21,6 +21,7 @@
 		"./vs/base/common/diff/diff.ts",
 		"./vs/base/common/diff/diffChange.ts",
 		"./vs/base/common/errors.ts",
+		// "./vs/base/common/event.ts",
 		"./vs/base/common/functional.ts",
 		"./vs/base/common/idGenerator.ts",
 		"./vs/base/common/iterator.ts",
@@ -49,6 +50,7 @@
 		"./vs/base/common/urilpc.ts",
 		"./vs/base/common/uuid.ts",
 		"./vs/base/common/winjs.base.d.ts",
+		"./vs/base/common/worker/simpleWorker.ts",
 		"./vs/base/node/paths.ts",
 		"./vs/base/node/ports.ts",
 		"./vs/base/parts/contextmenu/common/contextmenu.ts",
diff --git a/src/vs/base/common/iterator.ts b/src/vs/base/common/iterator.ts
@@ -3,10 +3,16 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-export interface IteratorResult<T> {
-	readonly done: boolean;
-	readonly value: T | undefined;
+export interface IteratorDefinedResult<T> {
+	readonly done: false;
+	readonly value: T;
 }
+export interface IteratorUndefinedResult {
+	readonly done: true;
+	readonly value: undefined;
+}
+export const FIN: IteratorUndefinedResult = { done: true, value: undefined };
+export type IteratorResult<T> = IteratorDefinedResult<T> | IteratorUndefinedResult;
 
 export interface Iterator<T> {
 	next(): IteratorResult<T>;
@@ -15,7 +21,7 @@ export interface Iterator<T> {
 export module Iterator {
 	const _empty: Iterator<any> = {
 		next() {
-			return { done: true, value: undefined };
+			return FIN;
 		}
 	};
 
@@ -27,7 +33,7 @@ export module Iterator {
 		return {
 			next(): IteratorResult<T> {
 				if (index >= length) {
-					return { done: true, value: undefined };
+					return FIN;
 				}
 
 				return { done: false, value: array[index++] };
@@ -48,8 +54,12 @@ export module Iterator {
 	export function map<T, R>(iterator: Iterator<T>, fn: (t: T) => R): Iterator<R> {
 		return {
 			next() {
-				const { done, value } = iterator.next();
-				return { done, value: done ? undefined : fn(value!) };
+				const element = iterator.next();
+				if (element.done) {
+					return FIN;
+				} else {
+					return { done: false, value: fn(element.value) };
+				}
 			}
 		};
 	}
@@ -58,14 +68,12 @@ export module Iterator {
 		return {
 			next() {
 				while (true) {
-					const { done, value } = iterator.next();
-
-					if (done) {
-						return { done, value: undefined };
+					const element = iterator.next();
+					if (element.done) {
+						return FIN;
 					}
-
-					if (fn(value!)) {
-						return { done, value };
+					if (fn(element.value)) {
+						return { done: false, value: element.value };
 					}
 				}
 			}
@@ -74,7 +82,7 @@ export module Iterator {
 
 	export function forEach<T>(iterator: Iterator<T>, fn: (t: T) => void): void {
 		for (let next = iterator.next(); !next.done; next = iterator.next()) {
-			fn(next.value!);
+			fn(next.value);
 		}
 	}
 
diff --git a/src/vs/base/common/linkedList.ts b/src/vs/base/common/linkedList.ts
@@ -3,7 +3,7 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { Iterator } from 'vs/base/common/iterator';
+import { Iterator, IteratorResult, FIN } from 'vs/base/common/iterator';
 
 class Node<E> {
 	element: E;
@@ -94,26 +94,20 @@ export class LinkedList<E> {
 	}
 
 	iterator(): Iterator<E> {
-		let element: { done: boolean; value: E | undefined };
+		let element: { done: false; value: E; };
 		let node = this._first;
 		return {
-			next(): { done: boolean; value: E | undefined } {
+			next(): IteratorResult<E> {
 				if (!node) {
-					if (!element) {
-						element = { done: true, value: undefined };
-					} else {
-						element.done = true;
-						element.value = undefined;
-					}
+					return FIN;
+				}
+
+				if (!element) {
+					element = { done: false, value: node.element };
 				} else {
-					if (!element) {
-						element = { done: false, value: node.element };
-					} else {
-						element.done = false;
-						element.value = node.element;
-					}
-					node = node.next;
+					element.value = node.element;
 				}
+				node = node.next;
 				return element;
 			}
 		};
diff --git a/src/vs/base/common/map.ts b/src/vs/base/common/map.ts
@@ -5,7 +5,7 @@
 
 import { URI } from 'vs/base/common/uri';
 import { CharCode } from 'vs/base/common/charCode';
-import { Iterator } from './iterator';
+import { Iterator, IteratorResult, FIN } from './iterator';
 
 export function values<V = any>(set: Set<V>): V[];
 export function values<K = any, V = any>(map: Map<K, V>): V[];
@@ -332,24 +332,23 @@ export class TernarySearchTree<E> {
 	}
 
 	private _nodeIterator(node: TernarySearchTreeNode<E>): Iterator<E> {
-		let res = {
-			done: false,
-			value: undefined
-		};
+		let res: { done: false; value: E; };
 		let idx: number;
 		let data: E[];
-		let next = () => {
+		let next = (): IteratorResult<E> => {
 			if (!data) {
 				// lazy till first invocation
 				data = [];
 				idx = 0;
 				this._forEach(node, value => data.push(value));
 			}
 			if (idx >= data.length) {
-				res.done = true;
-				res.value = undefined;
+				return FIN;
+			}
+
+			if (!res) {
+				res = { done: false, value: data[idx++] };
 			} else {
-				res.done = false;
 				res.value = data[idx++];
 			}
 			return res;
diff --git a/src/vs/base/common/worker/simpleWorker.ts b/src/vs/base/common/worker/simpleWorker.ts
@@ -84,24 +84,18 @@ class SimpleWorkerProtocol {
 
 	public sendMessage(method: string, args: any[]): Promise<any> {
 		let req = String(++this._lastSentReq);
-		let reply: IMessageReply = {
-			resolve: null,
-			reject: null
-		};
-		let result = new Promise<any>((resolve, reject) => {
-			reply.resolve = resolve;
-			reply.reject = reject;
-		});
-		this._pendingReplies[req] = reply;
-
-		this._send({
-			vsWorker: this._workerId,
-			req: req,
-			method: method,
-			args: args
+		return new Promise<any>((resolve, reject) => {
+			this._pendingReplies[req] = {
+				resolve: resolve,
+				reject: reject
+			};
+			this._send({
+				vsWorker: this._workerId,
+				req: req,
+				method: method,
+				args: args
+			});
 		});
-
-		return result;
 	}
 
 	public handleMessage(serializedMessage: string): void {
@@ -110,6 +104,7 @@ class SimpleWorkerProtocol {
 			message = JSON.parse(serializedMessage);
 		} catch (e) {
 			// nothing
+			return;
 		}
 		if (!message || !message.vsWorker) {
 			return;
@@ -191,8 +186,7 @@ export class SimpleWorkerClient<T> extends Disposable {
 	constructor(workerFactory: IWorkerFactory, moduleId: string) {
 		super();
 
-		let lazyProxyResolve: (v: T) => void = null;
-		let lazyProxyReject: (err: any) => void = null;
+		let lazyProxyReject: ((err: any) => void) | null = null;
 
 		this._worker = this._register(workerFactory.create(
 			'vs/base/common/worker/simpleWorker',
@@ -202,7 +196,9 @@ export class SimpleWorkerClient<T> extends Disposable {
 			(err: any) => {
 				// in Firefox, web workers fail lazily :(
 				// we will reject the proxy
-				lazyProxyReject(err);
+				if (lazyProxyReject) {
+					lazyProxyReject(err);
+				}
 			}
 		));
 
@@ -227,26 +223,25 @@ export class SimpleWorkerClient<T> extends Disposable {
 			loaderConfiguration = (<any>self).requirejs.s.contexts._.config;
 		}
 
-		this._lazyProxy = new Promise<T>((resolve, reject) => {
-			lazyProxyResolve = resolve;
-			lazyProxyReject = reject;
-		});
-
 		// Send initialize message
 		this._onModuleLoaded = this._protocol.sendMessage(INITIALIZE, [
 			this._worker.getId(),
 			moduleId,
 			loaderConfiguration
 		]);
-		this._onModuleLoaded.then((availableMethods: string[]) => {
-			let proxy = <T>{};
-			for (let i = 0; i < availableMethods.length; i++) {
-				(proxy as any)[availableMethods[i]] = createProxyMethod(availableMethods[i], proxyMethodRequest);
-			}
-			lazyProxyResolve(proxy);
-		}, (e) => {
-			lazyProxyReject(e);
-			this._onError('Worker failed to load ' + moduleId, e);
+
+		this._lazyProxy = new Promise<T>((resolve, reject) => {
+			lazyProxyReject = reject;
+			this._onModuleLoaded.then((availableMethods: string[]) => {
+				let proxy = <T>{};
+				for (let i = 0; i < availableMethods.length; i++) {
+					(proxy as any)[availableMethods[i]] = createProxyMethod(availableMethods[i], proxyMethodRequest);
+				}
+				resolve(proxy);
+			}, (e) => {
+				reject(e);
+				this._onError('Worker failed to load ' + moduleId, e);
+			});
 		});
 
 		// Create proxy to loaded code
@@ -290,10 +285,10 @@ export interface IRequestHandler {
  */
 export class SimpleWorkerServer {
 
-	private _requestHandler: IRequestHandler;
+	private _requestHandler: IRequestHandler | null;
 	private _protocol: SimpleWorkerProtocol;
 
-	constructor(postSerializedMessage: (msg: string) => void, requestHandler: IRequestHandler) {
+	constructor(postSerializedMessage: (msg: string) => void, requestHandler: IRequestHandler | null) {
 		this._requestHandler = requestHandler;
 		this._protocol = new SimpleWorkerProtocol({
 			sendMessage: (msg: string): void => {
@@ -353,29 +348,27 @@ export class SimpleWorkerServer {
 			(<any>self).require.config(loaderConfig);
 		}
 
-		let resolve: (value?: string[]) => void;
-		let reject: (error?: any) => void;
-		let r = new Promise<string[]>((_resolve, _reject) => {
-			resolve = _resolve;
-			reject = _reject;
-		});
-
-		// Use the global require to be sure to get the global config
-		(<any>self).require([moduleId], (...result: any[]) => {
-			let handlerModule = result[0];
-			this._requestHandler = handlerModule.create();
+		return new Promise<string[]>((resolve, reject) => {
+			// Use the global require to be sure to get the global config
+			(<any>self).require([moduleId], (...result: any[]) => {
+				let handlerModule = result[0];
+				this._requestHandler = handlerModule.create();
 
-			let methods: string[] = [];
-			for (let prop in this._requestHandler) {
-				if (typeof this._requestHandler[prop] === 'function') {
-					methods.push(prop);
+				if (!this._requestHandler) {
+					reject(new Error(`No RequestHandler!`));
+					return;
 				}
-			}
 
-			resolve(methods);
-		}, reject);
+				let methods: string[] = [];
+				for (let prop in this._requestHandler) {
+					if (typeof this._requestHandler[prop] === 'function') {
+						methods.push(prop);
+					}
+				}
 
-		return r;
+				resolve(methods);
+			}, reject);
+		});
 	}
 }
 
diff --git a/src/vs/editor/common/services/editorSimpleWorker.ts b/src/vs/editor/common/services/editorSimpleWorker.ts
