Use native iterators instead of Lumino iterators

docs/source/index.rst

@@ -13,6 +13,7 @@ Lumino
    changelog
    api
    examples
+   migration
 
 Indices and tables
 ==================

examples/example-dockpanel-amd/src/index.js

@@ -53,15 +53,18 @@ define(['@lumino/commands', '@lumino/widgets'], function (
     return root;
   }
 
-  function ContentWidget(name) {
-    Widget.call(this, { node: ContentWidget.prototype.createNode() });
-    this.setFlag(Widget.Flag.DisallowLayout);
-    this.addClass('content');
-    this.addClass(name.toLowerCase());
-    this.title.label = name;
-    this.title.closable = true;
-    this.title.caption = 'Long description for: ' + name;
+  class ContentWidget extends Widget {
+    constructor(name) {
+      super({ node: ContentWidget.prototype.createNode() });
+      this.setFlag(Widget.Flag.DisallowLayout);
+      this.addClass('content');
+      this.addClass(name.toLowerCase());
+      this.title.label = name;
+      this.title.closable = true;
+      this.title.caption = 'Long description for: ' + name;
+    }
   }
+
   ContentWidget.prototype = Object.create(Widget.prototype);
 
   ContentWidget.prototype.createNode = function () {

examples/example-dockpanel/tsconfig.json

@@ -8,9 +8,9 @@
     "sourceMap": true,
     "module": "commonjs",
     "moduleResolution": "node",
-    "target": "ES5",
+    "target": "ES6",
     "outDir": "./build",
-    "lib": ["ES5", "ES2015.Promise", "ES2015.Iterable", "DOM"],
+    "lib": ["ES6", "DOM"],
     "types": []
   },
   "include": ["src/*"]

packages/algorithm/src/chain.ts

@@ -7,90 +7,31 @@
 |
 | The full license is in the file LICENSE, distributed with this software.
 |----------------------------------------------------------------------------*/
-import { IIterator, iter, IterableOrArrayLike } from './iter';
 
 /**
  * Chain together several iterables.
  *
- * @param objects - The iterable or array-like objects of interest.
+ * @param objects - The iterable objects of interest.
  *
  * @returns An iterator which yields the values of the iterables
  *   in the order in which they are supplied.
  *
  * #### Example
  * ```typescript
- * import { chain, toArray } from '@lumino/algorithm';
+ * import { chain } from '@lumino/algorithm';
  *
  * let data1 = [1, 2, 3];
  * let data2 = [4, 5, 6];
  *
  * let stream = chain(data1, data2);
  *
- * toArray(stream);  // [1, 2, 3, 4, 5, 6]
+ * Array.from(stream);  // [1, 2, 3, 4, 5, 6]
  * ```
  */
-export function chain<T>(...objects: IterableOrArrayLike<T>[]): IIterator<T> {
-  return new ChainIterator<T>(iter(objects.map(iter)));
-}
-
-/**
- * An iterator which chains together several iterators.
- */
-export class ChainIterator<T> implements IIterator<T> {
-  /**
-   * Construct a new chain iterator.
-   *
-   * @param source - The iterator of iterators of interest.
-   */
-  constructor(source: IIterator<IIterator<T>>) {
-    this._source = source;
-    this._active = undefined;
-  }
-
-  /**
-   * Get an iterator over the object's values.
-   *
-   * @returns An iterator which yields the object's values.
-   */
-  iter(): IIterator<T> {
-    return this;
-  }
-
-  /**
-   * Create an independent clone of the iterator.
-   *
-   * @returns A new independent clone of the iterator.
-   */
-  clone(): IIterator<T> {
-    let result = new ChainIterator<T>(this._source.clone());
-    result._active = this._active && this._active.clone();
-    result._cloned = true;
-    this._cloned = true;
-    return result;
-  }
-
-  /**
-   * Get the next value from the iterator.
-   *
-   * @returns The next value from the iterator, or `undefined`.
-   */
-  next(): T | undefined {
-    if (this._active === undefined) {
-      let active = this._source.next();
-      if (active === undefined) {
-        return undefined;
-      }
-      this._active = this._cloned ? active.clone() : active;
-    }
-    let value = this._active.next();
-    if (value !== undefined) {
-      return value;
+export function* chain<T>(...objects: Iterable<T>[]): IterableIterator<T> {
+  for (const object of objects) {
+    for (const value of object) {
+      yield value;
     }
-    this._active = undefined;
-    return this.next();
   }
-
-  private _source: IIterator<IIterator<T>>;
-  private _active: IIterator<T> | undefined;
-  private _cloned = false;
 }

packages/algorithm/src/empty.ts

@@ -7,7 +7,6 @@
 |
 | The full license is in the file LICENSE, distributed with this software.
 |----------------------------------------------------------------------------*/
-import { IIterator } from './iter';
 
 /**
  * Create an empty iterator.
@@ -16,45 +15,14 @@ import { IIterator } from './iter';
  *
  * #### Example
  * ```typescript
- * import { empty, toArray } from '@lumino/algorithm';
+ * import { empty } from '@lumino/algorithm';
  *
  * let stream = empty<number>();
  *
- * toArray(stream);  // []
+ * Array.from(stream);  // []
  * ```
  */
-export function empty<T>(): IIterator<T> {
-  return new EmptyIterator<T>();
-}
-
-/**
- * An iterator which is always empty.
- */
-export class EmptyIterator<T> implements IIterator<T> {
-  /**
-   * Get an iterator over the object's values.
-   *
-   * @returns An iterator which yields the object's values.
-   */
-  iter(): IIterator<T> {
-    return this;
-  }
-
-  /**
-   * Create an independent clone of the iterator.
-   *
-   * @returns A new independent clone of the iterator.
-   */
-  clone(): IIterator<T> {
-    return new EmptyIterator<T>();
-  }
-
-  /**
-   * Get the next value from the iterator.
-   *
-   * @returns The next value from the iterator, or `undefined`.
-   */
-  next(): T | undefined {
-    return undefined;
-  }
+// eslint-disable-next-line require-yield, @typescript-eslint/no-unused-vars
+export function* empty<T>(): IterableIterator<T> {
+  return;
 }

packages/algorithm/src/enumerate.ts

@@ -7,82 +7,32 @@
 |
 | The full license is in the file LICENSE, distributed with this software.
 |----------------------------------------------------------------------------*/
-import { IIterator, iter, IterableOrArrayLike } from './iter';
 
 /**
  * Enumerate an iterable object.
  *
- * @param object - The iterable or array-like object of interest.
+ * @param object - The iterable object of interest.
  *
  * @param start - The starting enum value. The default is `0`.
  *
  * @returns An iterator which yields the enumerated values.
  *
  * #### Example
  * ```typescript
- * import { enumerate, toArray } from '@lumino/algorithm';
+ * import { enumerate } from '@lumino/algorithm';
  *
  * let data = ['foo', 'bar', 'baz'];
  *
  * let stream = enumerate(data, 1);
  *
- * toArray(stream);  // [[1, 'foo'], [2, 'bar'], [3, 'baz']]
+ * Array.from(stream);  // [[1, 'foo'], [2, 'bar'], [3, 'baz']]
  * ```
  */
-export function enumerate<T>(
-  object: IterableOrArrayLike<T>,
+export function* enumerate<T>(
+  object: Iterable<T>,
   start = 0
-): IIterator<[number, T]> {
-  return new EnumerateIterator<T>(iter(object), start);
-}
-
-/**
- * An iterator which enumerates the source values.
- */
-export class EnumerateIterator<T> implements IIterator<[number, T]> {
-  /**
-   * Construct a new enumerate iterator.
-   *
-   * @param source - The iterator of values of interest.
-   *
-   * @param start - The starting enum value.
-   */
-  constructor(source: IIterator<T>, start: number) {
-    this._source = source;
-    this._index = start;
-  }
-
-  /**
-   * Get an iterator over the object's values.
-   *
-   * @returns An iterator which yields the object's values.
-   */
-  iter(): IIterator<[number, T]> {
-    return this;
+): IterableIterator<[number, T]> {
+  for (const value of object) {
+    yield [start++, value];
   }
-
-  /**
-   * Create an independent clone of the iterator.
-   *
-   * @returns A new independent clone of the iterator.
-   */
-  clone(): IIterator<[number, T]> {
-    return new EnumerateIterator<T>(this._source.clone(), this._index);
-  }
-
-  /**
-   * Get the next value from the iterator.
-   *
-   * @returns The next value from the iterator, or `undefined`.
-   */
-  next(): [number, T] | undefined {
-    let value = this._source.next();
-    if (value === undefined) {
-      return undefined;
-    }
-    return [this._index++, value];
-  }
-
-  private _source: IIterator<T>;
-  private _index: number;
 }

packages/algorithm/src/filter.ts

@@ -7,89 +7,35 @@
 |
 | The full license is in the file LICENSE, distributed with this software.
 |----------------------------------------------------------------------------*/
-import { IIterator, iter, IterableOrArrayLike } from './iter';
 
 /**
  * Filter an iterable for values which pass a test.
  *
- * @param object - The iterable or array-like object of interest.
+ * @param object - The iterable object of interest.
  *
  * @param fn - The predicate function to invoke for each value.
  *
  * @returns An iterator which yields the values which pass the test.
  *
  * #### Example
  * ```typescript
- * import { filter, toArray } from '@lumino/algorithm';
+ * import { filter } from '@lumino/algorithm';
  *
  * let data = [1, 2, 3, 4, 5, 6];
  *
  * let stream = filter(data, value => value % 2 === 0);
  *
- * toArray(stream);  // [2, 4, 6]
+ * Array.from(stream);  // [2, 4, 6]
  * ```
  */
-export function filter<T>(
-  object: IterableOrArrayLike<T>,
+export function* filter<T>(
+  object: Iterable<T>,
   fn: (value: T, index: number) => boolean
-): IIterator<T> {
-  return new FilterIterator<T>(iter(object), fn);
-}
-
-/**
- * An iterator which yields values which pass a test.
- */
-export class FilterIterator<T> implements IIterator<T> {
-  /**
-   * Construct a new filter iterator.
-   *
-   * @param source - The iterator of values of interest.
-   *
-   * @param fn - The predicate function to invoke for each value.
-   */
-  constructor(source: IIterator<T>, fn: (value: T, index: number) => boolean) {
-    this._source = source;
-    this._fn = fn;
-  }
-
-  /**
-   * Get an iterator over the object's values.
-   *
-   * @returns An iterator which yields the object's values.
-   */
-  iter(): IIterator<T> {
-    return this;
-  }
-
-  /**
-   * Create an independent clone of the iterator.
-   *
-   * @returns A new independent clone of the iterator.
-   */
-  clone(): IIterator<T> {
-    let result = new FilterIterator<T>(this._source.clone(), this._fn);
-    result._index = this._index;
-    return result;
-  }
-
-  /**
-   * Get the next value from the iterator.
-   *
-   * @returns The next value from the iterator, or `undefined`.
-   */
-  next(): T | undefined {
-    let fn = this._fn;
-    let it = this._source;
-    let value: T | undefined;
-    while ((value = it.next()) !== undefined) {
-      if (fn(value, this._index++)) {
-        return value;
-      }
+): IterableIterator<T> {
+  let index = 0;
+  for (const value of object) {
+    if (fn(value, index++)) {
+      yield value;
     }
-    return undefined;
   }
-
-  private _index = 0;
-  private _source: IIterator<T>;
-  private _fn: (value: T, index: number) => boolean;
 }