[dart2js] Separate Iterables for Map.{keys,values,entries}

The default `MapBase.entries` and `MapBase.values` maps over the keys and does lookups. It is faster to scan the data like `get keys`.

This is essentially the dart2js version of 23a98d808c0

Change-Id: I03894efda459d9a4f7f07c4c79524ba5e4d925cb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/399027
Reviewed-by: Mayank Patke <[email protected]>
Commit-Queue: Stephen Adams <[email protected]>

Author: rakudrama

pkg/compiler/test/inference/data/map_tracer_keys.dart

@@ -29,7 +29,7 @@ test1() {
   theMap
       /*update: Dictionary([exact=JsLinkedHashMap], key: [exact=JSString], value: [null|exact=JSNumNotInt], map: {a: [exact=JSNumNotInt], b: [exact=JSNumNotInt], c: [exact=JSNumNotInt], d: [null|exact=JSNumNotInt]})*/
       ['d'] = 5.5;
-  /*iterator: [exact=LinkedHashMapKeyIterable]*/
+  /*iterator: [exact=LinkedHashMapKeysIterable]*/
   /*current: [exact=LinkedHashMapKeyIterator]*/
   /*moveNext: [exact=LinkedHashMapKeyIterator]*/
   for (var key in theMap.
@@ -60,7 +60,7 @@ test2() {
   theMap
       /*update: Map([exact=JsLinkedHashMap], key: [exact=JSString], value: [null|exact=JSNumNotInt])*/
       [aList2] = 5.5;
-  /*iterator: [exact=LinkedHashMapKeyIterable]*/
+  /*iterator: [exact=LinkedHashMapKeysIterable]*/
   /*current: [exact=LinkedHashMapKeyIterator]*/
   /*moveNext: [exact=LinkedHashMapKeyIterator]*/
   for (var key in theMap.
@@ -91,7 +91,7 @@ test3() {
   theMap
       /*update: Dictionary([exact=JsLinkedHashMap], key: [exact=JSString], value: Union(null, [exact=JSExtendableArray], [exact=JSNumNotInt]), map: {a: [exact=JSNumNotInt], b: [exact=JSNumNotInt], c: [exact=JSNumNotInt], d: Container([null|exact=JSExtendableArray], element: [exact=JSUInt31], length: 1)})*/
       ['d'] = aList3;
-  /*iterator: [exact=LinkedHashMapKeyIterable]*/
+  /*iterator: [exact=LinkedHashMapKeysIterable]*/
   /*current: [exact=LinkedHashMapKeyIterator]*/
   /*moveNext: [exact=LinkedHashMapKeyIterator]*/
   for (var key in theMap.
@@ -119,7 +119,7 @@ consume4(
 /*member: test4:[null]*/
 test4() {
   var theMap = {'a': 2.2, 'b': 3.3, 'c': 4.4, 'd': 5.5};
-  /*iterator: [exact=LinkedHashMapKeyIterable]*/
+  /*iterator: [exact=LinkedHashMapKeysIterable]*/
   /*current: [exact=LinkedHashMapKeyIterator]*/
   /*moveNext: [exact=LinkedHashMapKeyIterator]*/
   for (var key in theMap.
@@ -147,7 +147,7 @@ consume5(
 /*member: test5:[null]*/
 test5() {
   var theMap = {'a': 2.2, 'b': 3.3, 'c': 4.4, aList5: 5.5};
-  /*iterator: [exact=LinkedHashMapKeyIterable]*/
+  /*iterator: [exact=LinkedHashMapKeysIterable]*/
   /*current: [exact=LinkedHashMapKeyIterator]*/
   /*moveNext: [exact=LinkedHashMapKeyIterator]*/
   for (var key in theMap.
@@ -174,7 +174,7 @@ consume6(
 /*member: test6:[null]*/
 test6() {
   var theMap = {'a': 2.2, 'b': 3.3, 'c': 4.4, 'd': aList6};
-  /*iterator: [exact=LinkedHashMapKeyIterable]*/
+  /*iterator: [exact=LinkedHashMapKeysIterable]*/
   /*current: [exact=LinkedHashMapKeyIterator]*/
   /*moveNext: [exact=LinkedHashMapKeyIterator]*/
   for (var key in theMap.

sdk/lib/_internal/js_runtime/lib/linked_hash_map.dart

@@ -44,13 +44,11 @@ class JsLinkedHashMap<K, V> extends MapBase<K, V>
   bool get isEmpty => _length == 0;
   bool get isNotEmpty => !isEmpty;
 
-  Iterable<K> get keys {
-    return LinkedHashMapKeyIterable<K>(this);
-  }
+  Iterable<K> get keys => LinkedHashMapKeysIterable<K>(this);
 
-  Iterable<V> get values {
-    return MappedIterable<K, V>(keys, (each) => this[each] as V);
-  }
+  Iterable<V> get values => LinkedHashMapValuesIterable<V>(this);
+
+  Iterable<MapEntry<K, V>> get entries => LinkedHashMapEntriesIterable(this);
 
   bool containsKey(Object? key) {
     if (_isStringKey(key)) {
@@ -339,13 +337,13 @@ class LinkedHashMapCell {
   LinkedHashMapCell(this.hashMapCellKey, this.hashMapCellValue);
 }
 
-class LinkedHashMapKeyIterable<E> extends EfficientLengthIterable<E>
+class LinkedHashMapKeysIterable<E> extends EfficientLengthIterable<E>
     implements HideEfficientLengthIterable<E> {
   final JsLinkedHashMap _map;
-  LinkedHashMapKeyIterable(this._map);
+  LinkedHashMapKeysIterable(this._map);
 
   int get length => _map._length;
-  bool get isEmpty => _map._length == 0;
+  bool get isEmpty => _map.isEmpty;
 
   Iterator<E> get iterator {
     return LinkedHashMapKeyIterator<E>(_map, _map._modifications);
@@ -374,9 +372,8 @@ class LinkedHashMapKeyIterator<E> implements Iterator<E> {
   LinkedHashMapCell? _cell;
   E? _current;
 
-  LinkedHashMapKeyIterator(this._map, this._modifications) {
-    _cell = _map._first;
-  }
+  LinkedHashMapKeyIterator(this._map, this._modifications)
+      : _cell = _map._first;
 
   @pragma('dart2js:as:trust')
   E get current => _current as E;
@@ -397,6 +394,102 @@ class LinkedHashMapKeyIterator<E> implements Iterator<E> {
   }
 }
 
+class LinkedHashMapValuesIterable<E> extends EfficientLengthIterable<E>
+    implements HideEfficientLengthIterable<E> {
+  final JsLinkedHashMap _map;
+  LinkedHashMapValuesIterable(this._map);
+
+  int get length => _map._length;
+  bool get isEmpty => _map.isEmpty;
+
+  Iterator<E> get iterator {
+    return LinkedHashMapValueIterator<E>(_map, _map._modifications);
+  }
+
+  void forEach(void f(E element)) {
+    LinkedHashMapCell? cell = _map._first;
+    int modifications = _map._modifications;
+    while (cell != null) {
+      f(JS('', '#', cell.hashMapCellValue));
+      if (modifications != _map._modifications) {
+        throw ConcurrentModificationError(_map);
+      }
+      cell = cell._next;
+    }
+  }
+}
+
+class LinkedHashMapValueIterator<E> implements Iterator<E> {
+  final JsLinkedHashMap _map;
+  final int _modifications;
+  LinkedHashMapCell? _cell;
+  E? _current;
+
+  LinkedHashMapValueIterator(this._map, this._modifications)
+      : _cell = _map._first;
+
+  @pragma('dart2js:as:trust')
+  E get current => _current as E;
+
+  bool moveNext() {
+    if (_modifications != _map._modifications) {
+      throw ConcurrentModificationError(_map);
+    }
+    var cell = _cell;
+    if (cell == null) {
+      _current = null;
+      return false;
+    } else {
+      _current = JS('', '#', cell.hashMapCellValue);
+      _cell = cell._next;
+      return true;
+    }
+  }
+}
+
+class LinkedHashMapEntriesIterable<K, V>
+    extends EfficientLengthIterable<MapEntry<K, V>>
+    implements HideEfficientLengthIterable<MapEntry<K, V>> {
+  final JsLinkedHashMap _map;
+  LinkedHashMapEntriesIterable(this._map);
+
+  int get length => _map._length;
+  bool get isEmpty => _map.isEmpty;
+
+  Iterator<MapEntry<K, V>> get iterator {
+    return LinkedHashMapEntryIterator<K, V>(_map, _map._modifications);
+  }
+}
+
+class LinkedHashMapEntryIterator<K, V> implements Iterator<MapEntry<K, V>> {
+  final JsLinkedHashMap _map;
+  final int _modifications;
+  LinkedHashMapCell? _cell;
+  MapEntry<K, V>? _current;
+
+  LinkedHashMapEntryIterator(this._map, this._modifications)
+      : _cell = _map._first;
+
+  MapEntry<K, V> get current => _current!;
+
+  bool moveNext() {
+    if (_modifications != _map._modifications) {
+      throw ConcurrentModificationError(_map);
+    }
+    var cell = _cell;
+    if (cell == null) {
+      _current = null;
+      return false;
+    } else {
+      final K key = JS('', '#', cell.hashMapCellKey);
+      final V value = JS('', '#', cell.hashMapCellValue);
+      _current = MapEntry(key, value);
+      _cell = cell._next;
+      return true;
+    }
+  }
+}
+
 base class JsIdentityLinkedHashMap<K, V> extends JsLinkedHashMap<K, V> {
   JsIdentityLinkedHashMap();