Support user generated custom native JS classes.

pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart

Index: pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart b/pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart
index b10abf2aca6eac24e5d1e881138d6ab3ce8a2e49..ac34f0c34148dcb34a3ab9c78d2594ef488860a0 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart
@@ -14,7 +14,8 @@ import '../../js/js.dart' as js;
 import '../../js_backend/js_backend.dart' show
     Namer,
     JavaScriptBackend,
-    JavaScriptConstantCompiler;
+    JavaScriptConstantCompiler,
+    StringBackedName;
 
 import '../js_emitter.dart' show
     ClassStubGenerator,
@@ -28,6 +29,7 @@ import '../js_emitter.dart' show
 import '../../elements/elements.dart' show
     FieldElement,
     MethodElement,
+    Name,
     ParameterElement;
 
 import '../../universe/universe.dart' show Universe, ReceiverMaskSet;
@@ -201,6 +203,7 @@ class ProgramBuilder {
   }
 
   MainFragment _buildMainFragment(LibrariesMap librariesMap) {
+    _buildJsInteropStubs(librariesMap);
     // Construct the main output from the libraries and the registered holders.
     MainFragment result = new MainFragment(
         librariesMap.outputUnit,
@@ -319,6 +322,99 @@ class ProgramBuilder {
     return libraries;
   }
 
+  void _buildJsInteropStubs(LibrariesMap librariesMap) {
+    if (_classes.containsKey(_compiler.objectClass)) {
+      var toStringInvocation = namer.invocationName(new Selector.call(
+          new Name("toString", _compiler.objectClass.library),
+          CallStructure.NO_ARGS));
+      // TODO(jacobr): register toString as used so that it is always accessible
+      // from JavaScript.
+      _classes[_compiler.objectClass].callStubs.add(_buildStubMethod(
+          new StringBackedName("toString"),
+          js.js('function() { return this.#(this) }', toStringInvocation)));
+    }
+
+    // We add all members from classes marked with isJsInterop to the base
+    // Interceptor class with implementations that directly call the
+    // corresponding JavaScript member. We do not attempt to bind this when
+    // tearing off JavaScript methods as we cannot distinguish between calling
+    // a regular getter that returns a JavaScript function and tearing off
+    // a method in the case where there exist multiple JavaScript classes
+    // that conflict on whether the member is a getter or a method.
+    var interceptorClass = _classes[backend.jsInterceptorClass];
+    var stubNames = new Set<String>();
+    librariesMap.forEach((LibraryElement library, List<Element> elements) {
+      for (Element e in elements) {
+        if (e is ClassElement && e.isJsInterop) {
+          e.declaration.forEachMember((_, Element member) {
+            if (!member.isInstanceMember) return;
+            if (member.isGetter || member.isField || member.isFunction) {
+              var selectors =
+                  _compiler.codegenWorld.getterInvocationsByName(member.name);
+              if (selectors != null && !selectors.isEmpty) {
+                for (var selector in selectors.keys) {
+                  var stubName = namer.invocationName(selector);
+                  if (stubNames.add(stubName.key)) {
+                    interceptorClass.callStubs.add(_buildStubMethod(
+                        stubName,
+                        js.js(
+                            'function(obj) { return obj.# }', [member.name]),
+                        element: member));
+                  }
+                }
+              }
+            }
+
+            if (member.isSetter || (member.isField && !member.isConst)) {
+              var selectors =
+                  _compiler.codegenWorld.setterInvocationsByName(member.name);
+              if (selectors != null && !selectors.isEmpty) {
+                var stubName = namer.setterForElement(member);
+                if (stubNames.add(stubName.key)) {
+                  interceptorClass.callStubs.add(_buildStubMethod(
+                      stubName,
+                      js.js('function(obj, v) { return obj.# = v }',
+                          [member.name]),
+                      element: member));
+                }
+              }
+            }
+
+            if (member.isFunction) {
+              var selectors =
+                  _compiler.codegenWorld.invocationsByName(member.name);
+              FunctionElement fn = member;
+              // Named arguments are not yet supported. In the future we
+              // may want to map named arguments to an object literal containing
+              // all named arguments.
+              if (selectors != null && !selectors.isEmpty) {
+                for (var selector in selectors.keys) {
+                  // Check whether the arity matches this member.
+                  var argumentCount = selector.argumentCount;
+                  if (argumentCount > fn.parameters.length) break;
+                  if (argumentCount < fn.parameters.length &&
+                      !fn.parameters[argumentCount].isOptional) break;
+                  var stubName = namer.invocationName(selector);
+                  if (!stubNames.add(stubName.key)) break;
+                  var parameters = <js.Parameter>[];
+                  for (var i = 0; i < argumentCount; i++) {
+                    parameters.add(
+                        new js.Parameter(new String.fromCharCode(97 + i)));
+                  }
+                  interceptorClass.callStubs.add(_buildStubMethod(
+                      stubName,
+                      js.js('function(obj, #) { return obj.#(#) }',
+                          [parameters, member.name, parameters]),
+                          element: member));
+                }
+              }
+            }
+          });
+        }
+      }
+    });
+  }
+
   // Note that a library-element may have multiple [Library]s, if it is split
   // into multiple output units.
   Library _buildLibrary(LibraryElement library, List<Element> elements) {
@@ -366,14 +462,20 @@ class ProgramBuilder {
 
   Class _buildClass(ClassElement element) {
     bool onlyForRti = collector.classesOnlyNeededForRti.contains(element);
+    bool onlyJsInterop = element.isJsInterop;
+    if (onlyJsInterop) {
+      // TODO(jacobr): check whether the class has any active static fields
+      // if it does not we can suppress it completelly. 
+      onlyForRti = true; // XXX is this right?
+    }
 
     List<Method> methods = [];
     List<StubMethod> callStubs = <StubMethod>[];
 
     ClassStubGenerator classStubGenerator =
-        new ClassStubGenerator(_compiler, namer, backend);
+    new ClassStubGenerator(_compiler, namer, backend);
     RuntimeTypeGenerator runtimeTypeGenerator =
-        new RuntimeTypeGenerator(_compiler, _task, namer);
+    new RuntimeTypeGenerator(_compiler, _task, namer);
 
     void visitMember(ClassElement enclosing, Element member) {
       assert(invariant(element, member.isDeclaration));
@@ -390,7 +492,7 @@ class ProgramBuilder {
         if (selectors != null && !selectors.isEmpty) {
 
           Map<js.Name, js.Expression> callStubsForMember =
-              classStubGenerator.generateCallStubsForGetter(member, selectors);
+          classStubGenerator.generateCallStubsForGetter(member, selectors);
           callStubsForMember.forEach((js.Name name, js.Expression code) {
             callStubs.add(_buildStubMethod(name, code, element: member));
           });
@@ -399,13 +501,13 @@ class ProgramBuilder {
     }
 
     List<StubMethod> typeVariableReaderStubs =
-        runtimeTypeGenerator.generateTypeVariableReaderStubs(element);
+    runtimeTypeGenerator.generateTypeVariableReaderStubs(element);
 
     List<StubMethod> noSuchMethodStubs = <StubMethod>[];
 
     if (backend.enabledNoSuchMethod && element == _compiler.objectClass) {
       Map<js.Name, Selector> selectors =
-          classStubGenerator.computeSelectorsForNsmHandlers();
+      classStubGenerator.computeSelectorsForNsmHandlers();
       selectors.forEach((js.Name name, Selector selector) {
         // If the program contains `const Symbol` names we have to retain them.
         String selectorName = selector.name;
@@ -414,8 +516,8 @@ class ProgramBuilder {
           _symbolsMap[name] = selectorName;
         }
         noSuchMethodStubs
-            .add(classStubGenerator.generateStubForNoSuchMethod(name,
-                                                                selector));
+        .add(classStubGenerator.generateStubForNoSuchMethod(name,
+        selector));
       });
     }
 
@@ -436,39 +538,47 @@ class ProgramBuilder {
     }
 
     List<Field> instanceFields =
-        onlyForRti ? const <Field>[] : _buildFields(element, false);
+    onlyForRti ? const <Field>[] : _buildFields(element, false);
     List<Field> staticFieldsForReflection =
-        onlyForRti ? const <Field>[] : _buildFields(element, true);
+    onlyForRti ? const <Field>[] : _buildFields(element, true);
 
     TypeTestProperties typeTests =
-        runtimeTypeGenerator.generateIsTests(
-            element,
-            storeFunctionTypeInMetadata: _storeFunctionTypesInMetadata);
+    runtimeTypeGenerator.generateIsTests(
+        element,
+        storeFunctionTypeInMetadata: _storeFunctionTypesInMetadata);
 
     List<StubMethod> checkedSetters = <StubMethod>[];
-    for (Field field in instanceFields) {
-      if (field.needsCheckedSetter) {
-        assert(!field.needsUncheckedSetter);
-        Element element = field.element;
-        js.Expression code = backend.generatedCode[element];
-        assert(code != null);
-        js.Name name = namer.deriveSetterName(field.accessorName);
-        checkedSetters.add(_buildStubMethod(name, code, element: element));
+    List<StubMethod> isChecks = <StubMethod>[];
+    if (!onlyJsInterop) {
+      for (Field field in instanceFields) {
+        if (field.needsCheckedSetter) {
+          assert(!field.needsUncheckedSetter);
+          Element element = field.element;
+          js.Expression code = backend.generatedCode[element];
+          assert(code != null);
+          js.Name name = namer.deriveSetterName(field.accessorName);
+          checkedSetters.add(_buildStubMethod(name, code, element: element));
+        }
       }
-    }
 
-    List<StubMethod> isChecks = <StubMethod>[];
-    typeTests.properties.forEach((js.Name name, js.Node code) {
-      isChecks.add(_buildStubMethod(name, code));
-    });
+      typeTests.properties.forEach((js.Name name, js.Node code) {
+        isChecks.add(_buildStubMethod(name, code));
+      });
+    }
+    if (element.isJsInterop) {
+      // TODO(jacobr): make sure we aren't adding the same is checks multiple times..
+      typeTests.properties.forEach((js.Name name, js.Node code) {
+        _classes[backend.jsInterceptorClass].isChecks.add(_buildStubMethod(name, code));
+      });
+    }
 
     js.Name name = namer.className(element);
     String holderName = namer.globalObjectFor(element);
     // TODO(floitsch): we shouldn't update the registry in the middle of
     // building a class.
     Holder holder = _registry.registerHolder(holderName);
-    bool isInstantiated =
-        _compiler.codegenWorld.directlyInstantiatedClasses.contains(element);
+    bool isInstantiated = onlyJsInterop ? false :
+    _compiler.codegenWorld.directlyInstantiatedClasses.contains(element);
 
     Class result;
     if (element.isMixinApplication && !onlyForRti) {