Make json-maps implement Map<String, dynamic>.

Fixes #26407.
http://dartbug.com/26407

R=lrn@google.com

Review-Url: https://codereview.chromium.org/1980663002 .

CHANGELOG.md

@@ -14,6 +14,9 @@
   * Added 'RawSynchronousSocket', a basic synchronous socket implementation.
 * `dart:convert`
   * Removed deprecated `ChunkedConverter` class.
+  * JSON maps are now typed as `Map<String, dynamic>` instead of
+    `Map<dynamic, dynamic>`. A JSON-map is not a `HashMap` or `LinkedHashMap`
+    anymore (but just a `Map`).
 
 ### Dart VM
 

runtime/lib/convert_patch.dart

@@ -142,7 +142,7 @@ class _BuildJsonListener extends _JsonListener {
 
   void beginObject() {
     pushContainer();
-    currentContainer = {};
+    currentContainer = <String, dynamic>{};
   }
 
   void propertyName() {

sdk/lib/_internal/js_runtime/lib/convert_patch.dart

@@ -123,7 +123,7 @@ _convertJsonToDartLazy(object) {
   return object;
 }
 
-class _JsonMap implements LinkedHashMap {
+class _JsonMap implements Map<String, dynamic> {
   // The original JavaScript object remains unchanged until
   // the map is eventually upgraded, in which case we null it
   // out to reclaim the memory used by it.
@@ -156,7 +156,7 @@ class _JsonMap implements LinkedHashMap {
   bool get isEmpty => length == 0;
   bool get isNotEmpty => length > 0;
 
-  Iterable get keys {
+  Iterable<String> get keys {
     if (_isUpgraded) return _upgradedMap.keys;
     return new _JsonMapKeyIterable(this);
   }
@@ -280,12 +280,12 @@ class _JsonMap implements LinkedHashMap {
     return JS('JSExtendableArray', '#', keys);
   }
 
-  Map _upgrade() {
+  Map<String, dynamic> _upgrade() {
     if (_isUpgraded) return _upgradedMap;
 
     // Copy all the (key, value) pairs to a freshly allocated
     // linked hash map thus preserving the ordering.
-    Map result = {};
+    Map result = <String, dynamic>{};
     List<String> keys = _computeKeys();
     for (int i = 0; i < keys.length; i++) {
       String key = keys[i];
@@ -331,7 +331,7 @@ class _JsonMap implements LinkedHashMap {
   static _newJavaScriptObject() => JS('=Object', 'Object.create(null)');
 }
 
-class _JsonMapKeyIterable extends ListIterable {
+class _JsonMapKeyIterable extends ListIterable<String> {
   final _JsonMap _parent;
 
   _JsonMapKeyIterable(this._parent);
@@ -347,7 +347,7 @@ class _JsonMapKeyIterable extends ListIterable {
   /// Although [ListIterable] defines its own iterator, we return the iterator
   /// of the underlying list [_keys] in order to propagate
   /// [ConcurrentModificationError]s.
-  Iterator get iterator {
+  Iterator<String> get iterator {
     return _parent._isUpgraded
         ? _parent.keys.iterator
         : _parent._computeKeys().iterator;

tests/corelib/json_map_test.dart

@@ -53,7 +53,6 @@ void test(bool revive) {
   testToString();
   testConcurrentModifications();
   testType();
-  testNonStringKeys();
   testClear();
 
   testListEntry();
@@ -300,23 +299,8 @@ void testConcurrentModifications() {
 
 void testType() {
   Expect.isTrue(jsonify({}) is Map);
-  Expect.isTrue(jsonify({}) is HashMap);
-  Expect.isTrue(jsonify({}) is LinkedHashMap);
-
   Expect.isTrue(jsonify({}) is Map<String, dynamic>);
-  Expect.isTrue(jsonify({}) is HashMap<String, dynamic>);
-  Expect.isTrue(jsonify({}) is LinkedHashMap<String, dynamic>);
-
-  Expect.isTrue(jsonify({}) is Map<int, dynamic>);
-  Expect.isTrue(jsonify({}) is HashMap<int, dynamic>);
-  Expect.isTrue(jsonify({}) is LinkedHashMap<int, dynamic>);
-}
-
-void testNonStringKeys() {
-  Map map = jsonify({});
-  map[1] = 2;
-  Expect.equals(1, map.length);
-  Expect.equals(2, map[1]);
+  Expect.isFalse(jsonify({}) is Map<int, dynamic>);
 }
 
 void testClear() {

tests/corelib/map_test.dart

@@ -21,8 +21,6 @@ void main() {
   test(new MapView(new SplayTreeMap()));
   test(new MapBaseMap());
   test(new MapMixinMap());
-  test(newJsonMap());
-  test(newJsonMapCustomReviver());
   testLinkedHashMap();
   testMapLiteral();
   testNullValue();
@@ -53,8 +51,6 @@ void main() {
   testNumericKeys(new LinkedHashMap<num, String>.identity());
   testNumericKeys(new MapBaseMap<num, String>());
   testNumericKeys(new MapMixinMap<num, String>());
-  testNumericKeys(newJsonMap());
-  testNumericKeys(newJsonMapCustomReviver());
 
   testNaNKeys(new Map());
   testNaNKeys(new Map<num, String>());
@@ -64,8 +60,6 @@ void main() {
   testNaNKeys(new LinkedHashMap<num, String>());
   testNaNKeys(new MapBaseMap<num, String>());
   testNaNKeys(new MapMixinMap<num, String>());
-  testNaNKeys(newJsonMap());
-  testNaNKeys(newJsonMapCustomReviver());
   // Identity maps fail the NaN-keys tests because the test assumes that
   // NaN is not equal to NaN.
 
@@ -96,8 +90,6 @@ void main() {
 
   testIterationOrder(new LinkedHashMap());
   testIterationOrder(new LinkedHashMap.identity());
-  testIterationOrder(newJsonMap());
-  testIterationOrder(newJsonMapCustomReviver());
 
   testOtherKeys(new SplayTreeMap<int, int>());
   testOtherKeys(
@@ -121,8 +113,6 @@ void main() {
       isValidKey: (v) => v is int));
   testOtherKeys(new MapBaseMap<int, int>());
   testOtherKeys(new MapMixinMap<int, int>());
-  testOtherKeys(newJsonMap());
-  testOtherKeys(newJsonMapCustomReviver());
 
   testUnmodifiableMap(const {1: 37});
   testUnmodifiableMap(new UnmodifiableMapView({1: 37}));