replace Iterator.prototype.sliding with an extra parameter of Iterator.prototype.windows

tc39/proposal-iterator-chunking#24

Author: zloirock

CHANGELOG.md

@@ -1,7 +1,9 @@
 ## Changelog
 ##### Unreleased
-- [`Map` upsert proposal](https://github.com/tc39/proposal-upsert):
+- [`Map` upsert stage 3 proposal](https://github.com/tc39/proposal-upsert):
   - Fixed [a FF `WeakMap.prototype.getOrInsertComputed` bug with callback calling before validation a key](https://bugzilla.mozilla.org/show_bug.cgi?id=1988369)
+- [`Iterator` chunking stage 2 proposal](https://github.com/tc39/proposal-iterator-chunking):
+  - `Iterator.prototype.sliding` method replaced with an extra parameter of `Iterator.prototype.windows` method, [tc39/proposal-iterator-chunking/#24](https://github.com/tc39/proposal-iterator-chunking/pull/24)
 - Compat data improvements:
   - [`Map.prototype.{ getOrInsert, getOrInsertComputed }` and `WeakMap.prototype.getOrInsert`](https://github.com/tc39/proposal-upsert) marked as shipped from FF144
   - Added [Deno 2.5](https://github.com/denoland/deno/releases/tag/v2.5.0) compat data mapping

README.md

@@ -3068,31 +3068,31 @@ core-js(-pure)/full/symbol/custom-matcher
 ```
 
 ##### [`Iterator` chunking](https://github.com/tc39/proposal-iterator-chunking)[⬆](#index)
-Modules [`esnext.iterator.chunks`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.iterator.chunks.js), [`esnext.iterator.sliding`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.iterator.sliding.js)
+Modules [`esnext.iterator.chunks`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.iterator.chunks.js)
 and [`esnext.iterator.windows`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.iterator.windows.js)
 ```ts
 class Iterator {
   chunks(chunkSize: number): Iterator<any>;
-  sliding(windowSize: number): Iterator<any>;
-  windows(windowSize: number): Iterator<any>;
+  windows(windowSize: number, undersized?: 'only full' | 'allow partial' | undefined): Iterator<any>;
 }
 ```
 [*CommonJS entry points:*](#commonjs-api)
 ```
-core-js/proposals/iterator-chunking
+core-js/proposals/iterator-chunking-v2
 core-js(-pure)/full/iterator/chunks
-core-js(-pure)/full/iterator/sliding
 core-js(-pure)/full/iterator/windows
 ```
 [*Examples*](https://tinyurl.com/24xnkcnn)
 ```js
 const digits = () => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9].values();
 
-let chunksOf2 = Array.from(digits().chunks(2));  // [ [0, 1], [2, 3], [4, 5], [6, 7], [8, 9] ]
+let chunks = Array.from(digits().chunks(2));  // [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9]]
 
-let slidingOf2 = Array.from(digits().sliding(2));  // [ [0, 1], [1, 2], [2, 3], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [8, 9] ]
+let windows = Array.from(digits().windows(2));  // [[0, 1], [1, 2], [2, 3], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [8, 9]]
 
-let windowsOf2 = Array.from(digits().windows(2));  // [ [0, 1], [1, 2], [2, 3], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [8, 9] ]
+let windowsPartial = Array.from([0, 1].values().windows(3, 'allow partial'));  // [[0, 1]]
+
+let windowsFull = Array.from([0, 1].values().windows(3));  // []
 ```
 
 #### Stage 1 proposals[⬆](#index)

packages/core-js/internals/iterator-window.js

@@ -16,12 +16,12 @@ var IteratorProxy = createIteratorProxy(function () {
   var next = this.next;
   var buffer = this.buffer;
   var windowSize = this.windowSize;
-  var sliding = this.sliding;
+  var allowPartial = this.allowPartial;
   var result, done;
   while (true) {
     result = anObject(call(next, iterator));
     done = this.done = !!result.done;
-    if (sliding && done && buffer.length && buffer.length < windowSize) return createIterResultObject(buffer, false);
+    if (allowPartial && done && buffer.length && buffer.length < windowSize) return createIterResultObject(buffer, false);
     if (done) return createIterResultObject(undefined, true);
 
     if (buffer.length === windowSize) this.buffer = buffer = slice(buffer, 1);
@@ -30,16 +30,16 @@ var IteratorProxy = createIteratorProxy(function () {
   }
 }, false, true);
 
-// `Iterator.prototype.sliding` and `Iterator.prototype.windows` methods
+// `Iterator.prototype.windows` and obsolete `Iterator.prototype.sliding` methods
 // https://github.com/tc39/proposal-iterator-chunking
-module.exports = function (O, windowSize, sliding) {
+module.exports = function (O, windowSize, allowPartial) {
   anObject(O);
   if (typeof windowSize != 'number' || !windowSize || windowSize >>> 0 !== windowSize) {
-    return iteratorClose(O, 'throw', new $RangeError('windowSize must be integer in [1, 2^32-1]'));
+    return iteratorClose(O, 'throw', new $RangeError('`windowSize` must be integer in [1, 2^32-1]'));
   }
   return new IteratorProxy(getIteratorDirect(O), {
     windowSize: windowSize,
     buffer: [],
-    sliding: sliding
+    allowPartial: allowPartial
   });
 };

packages/core-js/modules/esnext.iterator.windows.js

@@ -2,10 +2,17 @@
 var $ = require('../internals/export');
 var iteratorWindow = require('../internals/iterator-window');
 
+var $TypeError = TypeError;
+var ALLOW_PARTIAL = 'allow partial';
+
 // `Iterator.prototype.windows` method
 // https://github.com/tc39/proposal-iterator-chunking
 $({ target: 'Iterator', proto: true, real: true, forced: true }, {
-  windows: function windows(windowSize) {
-    return iteratorWindow(this, windowSize, false);
+  windows: function windows(windowSize /* , undersized */) {
+    var undersized = arguments.length < 2 ? undefined : arguments[1];
+    if (undersized !== undefined && undersized !== 'only full' && undersized !== ALLOW_PARTIAL) {
+      throw new $TypeError('Incorrect `undersized` argument');
+    }
+    return iteratorWindow(this, windowSize, undersized === ALLOW_PARTIAL);
   }
 });

packages/core-js/proposals/iterator-chunking-v2.js

@@ -0,0 +1,4 @@
+'use strict';
+// https://github.com/tc39/proposal-iterator-chunking
+require('../modules/esnext.iterator.chunks');
+require('../modules/esnext.iterator.windows');

tests/compat-data/tests-coverage.mjs

@@ -29,6 +29,7 @@ const ignore = new Set([
   'esnext.function.un-this',
   'esnext.iterator.as-indexed-pairs',
   'esnext.iterator.indexed',
+  'esnext.iterator.sliding',
   'esnext.map.emplace',
   'esnext.map.update-or-insert',
   'esnext.map.upsert',

tests/compat/tests.js

@@ -1903,9 +1903,6 @@ GLOBAL.tests = {
   'esnext.iterator.range': function () {
     return Iterator.range;
   },
-  'esnext.iterator.sliding': function () {
-    return Iterator.prototype.sliding;
-  },
   'esnext.iterator.to-async': function () {
     return Iterator.prototype.toAsync;
   },

tests/entries/unit.mjs

@@ -955,6 +955,7 @@ for (PATH of ['core-js-pure', 'core-js']) {
   load('proposals/iterator-range');
   load('proposals/iterator-sequencing');
   load('proposals/iterator-chunking');
+  load('proposals/iterator-chunking-v2');
   load('proposals/joint-iteration');
   load('proposals/json-parse-with-source');
   load('proposals/keys-composition');

tests/unit-global/esnext.iterator.windows.js

@@ -17,6 +17,9 @@ QUnit.test('Iterator#windows', assert => {
   assert.arrayEqual(from(windows.call(createIterator([1, 2]), 3)), [], 'basic functionality #3');
   assert.arrayEqual(from(windows.call(createIterator([]), 2)), [], 'basic functionality on empty iterable');
 
+  assert.arrayEqual(from(windows.call(createIterator([1, 2]), 3, 'only full')), [], 'undersized #1');
+  assert.arrayEqual(from(windows.call(createIterator([1, 2]), 3, 'allow partial')), [[1, 2]], 'undersized #2');
+
   const it = createIterator([1, 2, 3]);
   const result = windows.call(it, 3);
   assert.isIterable(result, 'returns iterable');
@@ -45,4 +48,7 @@ QUnit.test('Iterator#windows', assert => {
   const itObservable = createIterator([1, 2, 3], observableReturn);
   assert.throws(() => windows.call(itObservable, 0x100000000), RangeError, 'throws on argument more then 2^32 - 1');
   assert.true(itObservable.called, 'iterator closed on argument validation error');
+
+  assert.throws(() => windows.call(createIterator([1]), 2, null), TypeError, 'incorrect `undersized` argument #1');
+  assert.throws(() => windows.call(createIterator([1]), 2, 'allowpartial'), TypeError, 'incorrect `undersized` argument #2');
 });

tests/unit-pure/esnext.iterator.windows.js

@@ -16,6 +16,9 @@ QUnit.test('Iterator#windows', assert => {
   assert.arrayEqual(from(windows.call(createIterator([1, 2]), 3)), [], 'basic functionality #3');
   assert.arrayEqual(from(windows.call(createIterator([]), 2)), [], 'basic functionality on empty iterable');
 
+  assert.arrayEqual(from(windows.call(createIterator([1, 2]), 3, 'only full')), [], 'undersized #1');
+  assert.arrayEqual(from(windows.call(createIterator([1, 2]), 3, 'allow partial')), [[1, 2]], 'undersized #2');
+
   const it = createIterator([1, 2, 3]);
   const result = windows.call(it, 3);
   assert.isIterable(result, 'returns iterable');
@@ -44,4 +47,7 @@ QUnit.test('Iterator#windows', assert => {
   const itObservable = createIterator([1, 2, 3], observableReturn);
   assert.throws(() => windows.call(itObservable, 0x100000000), RangeError, 'throws on argument more then 2^32 - 1');
   assert.true(itObservable.called, 'iterator closed on argument validation error');
+
+  assert.throws(() => windows.call(createIterator([1]), 2, null), TypeError, 'incorrect `undersized` argument #1');
+  assert.throws(() => windows.call(createIterator([1]), 2, 'allowpartial'), TypeError, 'incorrect `undersized` argument #2');
 });