add JsArray and JsObject.asJsMap()

sdk/lib/js/dart2js/js_dart2js.dart

Index: sdk/lib/js/dart2js/js_dart2js.dart
diff --git a/sdk/lib/js/dart2js/js_dart2js.dart b/sdk/lib/js/dart2js/js_dart2js.dart
index 7f806b73f3744794eeca4b725e61093b6cf12008..25d46e66ae74951b1e244429118d0f275b5e26dd 100644
--- a/sdk/lib/js/dart2js/js_dart2js.dart
+++ b/sdk/lib/js/dart2js/js_dart2js.dart
@@ -4,6 +4,7 @@
 
 library dart.js;
 
+import 'dart:collection' show ListMixin, Maps;
 import 'dart:_foreign_helper' show JS;
 import 'dart:_js_helper' show convertDartClosureToJS;
 
@@ -101,7 +102,7 @@ return ret;
 })()''', constr, constr, args));
   }
 
-  factory JsObject._json(data) => new JsObject._fromJs(_convertDataTree(data));
+  factory JsObject._json(data) => _convertToDart(_convertDataTree(data));
 
   static _convertDataTree(data) {
     if (data is Map) {
@@ -154,6 +155,8 @@ return ret;
       _convertToDart(JS('=Object', '#[#].apply(#, #)', _convertToJS(this), name,
           _convertToJS(this),
           args == null ? null : args.map(_convertToJS).toList()));
+
+  Map<String, dynamic> asJsMap() => new _JsObjectAsMap(this);
 }
 
 class JsFunction extends JsObject implements Serializable<JsFunction> {
@@ -164,6 +167,90 @@ class JsFunction extends JsObject implements Serializable<JsFunction> {
           args == null ? null : args.map(_convertToJS).toList()));
 }
 
+/// A [JsObject] subtype for JavaScript arrays.
+class JsArray extends JsObject with ListMixin {
+  JsArray._fromJs(jsObject) : super._fromJs(jsObject);
+
+  // Iterable
+  /*@override*/ int get length => super['length'];
+
+  // Collection
+  /*@override*/ void add(value) { callMethod('push', [value]); }
+
+  // List
+  /*@override*/ operator [](index) {
+    if (index is int && (index < 0 || index >= this.length)) {

[vsm, 2013/08/20 15:44:13]

Should JsArray throw on non-int indices?

[alexandre.ardhuin, 2013/08/20 20:58:55]

In Js an array is an object. So it's possible to set a property even if it's not
a Number. I have kept this semantic.

I hesitate to get rid of this Range check because Js don't have it.

+      throw new RangeError.value(index);
+    }
+    return super[index];
+  }
+  /*@override*/ void operator []=(index, value) {
+    if (index is int && (index < 0 || index >= this.length)) {
+      throw new RangeError.value(index);
+    }
+    super[index] = value;
+  }
+  /*@override*/ void set length(int length) { super['length'] = length; }
+  /*@override*/ void sort([int compare(a, b)]) {
+    final sortedList = toList()..sort(compare);
+    setRange(0, sortedList.length, sortedList);
+  }
+  /*@override*/ void insert(int index, element) {
+    callMethod('splice', [index, 0, element]);
+  }
+  /*@override*/ removeAt(int index) {
+    if (index < 0 || index >= this.length) throw new RangeError.value(index);
+    return callMethod('splice', [index, 1])[0];
+  }
+  /*@override*/ removeLast() => callMethod('pop');
+  /*@override*/ void setRange(int start, int length, List from,
+                              [int startFrom = 0]) {
+    final args = [start, length];
+    for(int i = startFrom; i < startFrom + length; i++) {
+      args.add(from[i]);
+    }
+    callMethod('splice', args);
+  }
+  /*@override*/ void removeRange(int start, int end) {
+    callMethod('splice', [start, end - start]);
+  }
+}
+
+class _JsObjectAsMap implements Map<String, dynamic> {
+  JsObject _jsObject;

[vsm, 2013/08/20 15:44:13]

It seems odd that Array extends JsObject while Map wraps it.  What's the reason
for the difference?

[alexandre.ardhuin, 2013/08/20 20:58:55]

Ideally I would have made JsObject implementing Map<String, dynamic>. This is
not possible if JsArray (that implements List) extends JsObject because Map and
List have some incompatible functions (for instance list.forEach(void f(E
element)) vs. map.forEach(void f(K key, V value)))

Moreover in Js there is not really maps.

So I had decided to reflect the Js types by making JsArray extends JsObject (in
Js Array "extends" Object) and provide a way (with .asDartMap()) to handle
JsObject as a Map.

+
+  _JsObjectAsMap(this._jsObject);
+
+  /*@override*/ operator [](String key) => _jsObject[key];
+  /*@override*/ void operator []=(String key, value) {
+    _jsObject[key] = value;
+  }
+  /*@override*/ remove(String key) {
+    final value = this[key];
+    _jsObject.deleteProperty(key);
+    return value;
+  }
+  /*@override*/ Iterable<String> get keys =>
+      context['Object'].callMethod('keys', [_jsObject]);
+
+  // use Maps to implement functions
+  /*@override*/ bool containsValue(value) => Maps.containsValue(this, value);
+  /*@override*/ bool containsKey(String key) => Maps.containsKey(this, key);
+  /*@override*/ putIfAbsent(String key, ifAbsent()) =>
+      Maps.putIfAbsent(this, key, ifAbsent);
+  /*@override*/ void addAll(Map<String, dynamic> other) {
+    if (other != null) {
+      other.forEach((k,v) => this[k] = v);
+    }
+  }
+  /*@override*/ void clear() => Maps.clear(this);
+  /*@override*/ void forEach(void f(String key, value)) => Maps.forEach(this, f);
+  /*@override*/ Iterable get values => Maps.getValues(this);
+  /*@override*/ int get length => Maps.length(this);
+  /*@override*/ bool get isEmpty => Maps.isEmpty(this);
+  /*@override*/ bool get isNotEmpty => Maps.isNotEmpty(this);
+}
+
 abstract class Serializable<T> {
   T toJs();
 }
@@ -179,6 +266,10 @@ dynamic _convertToJS(dynamic o) {
     return _convertToJS(o.toJs());
   } else if (o is Function) {
     return _convertToJS(new Callback(o));
+  } else if (o is Map) {
+    return _convertToJS(jsify(o));
+  } else if (o is Iterable) {
+    return _convertToJS(jsify(o));
   } else {
     return JS('=Object', 'new DartProxy(#)', o);
   }
@@ -193,6 +284,8 @@ dynamic _convertToDart(dynamic o) {
     return o;
   } else if (JS('bool', '# instanceof Function', o)) {
     return new JsFunction._fromJs(JS('=Object', '#', o));
+  } else if (JS('bool', '# instanceof Array', o)) {
+    return new JsArray._fromJs(JS('=Object', '#', o));

[vsm, 2013/08/20 15:44:13]

After talking to sra, I think the right to put here (and 2 lines above) instead
of "=Object" is "var".  Though you may want to sanity check code size.

[alexandre.ardhuin, 2013/08/20 20:58:55]

Done

   } else if (JS('bool', '# instanceof DartProxy', o)) {
     return JS('var', '#.o', o);
   } else {