Merge from vscode 817eb6b0c720a4ecbc13c020afbbebfed667aa09 (#7356)

src/vs/base/common/iterator.ts

@@ -18,6 +18,22 @@ export interface Iterator<T> {
 	next(): IteratorResult<T>;
 }
 
+interface NativeIteratorYieldResult<TYield> {
+	done?: false;
+	value: TYield;
+}
+
+interface NativeIteratorReturnResult<TReturn> {
+	done: true;
+	value: TReturn;
+}
+
+type NativeIteratorResult<T, TReturn = any> = NativeIteratorYieldResult<T> | NativeIteratorReturnResult<TReturn>;
+
+export interface NativeIterator<T> {
+	next(): NativeIteratorResult<T>;
+}
+
 export module Iterator {
 	const _empty: Iterator<any> = {
 		next() {
@@ -56,6 +72,20 @@ export module Iterator {
 		};
 	}
 
+	export function fromNativeIterator<T>(it: NativeIterator<T>): Iterator<T> {
+		return {
+			next(): IteratorResult<T> {
+				const result = it.next();
+
+				if (result.done) {
+					return FIN;
+				}
+
+				return { done: false, value: result.value };
+			}
+		};
+	}
+
 	export function from<T>(elements: Iterator<T> | T[] | undefined): Iterator<T> {
 		if (!elements) {
 			return Iterator.empty();
@@ -160,12 +190,12 @@ export interface INextIterator<T> {
 
 export class ArrayIterator<T> implements INextIterator<T> {
 
-	private items: T[];
+	private readonly items: readonly T[];
 	protected start: number;
 	protected end: number;
 	protected index: number;
 
-	constructor(items: T[], start: number = 0, end: number = items.length, index = start - 1) {
+	constructor(items: readonly T[], start: number = 0, end: number = items.length, index = start - 1) {
 		this.items = items;
 		this.start = start;
 		this.end = end;
@@ -193,7 +223,7 @@ export class ArrayIterator<T> implements INextIterator<T> {
 
 export class ArrayNavigator<T> extends ArrayIterator<T> implements INavigator<T> {
 
-	constructor(items: T[], start: number = 0, end: number = items.length, index = start - 1) {
+	constructor(items: readonly T[], start: number = 0, end: number = items.length, index = start - 1) {
 		super(items, start, end, index);
 	}