Partial fix for call methods #542

lib/src/compiler/code_generator.dart

Index: lib/src/compiler/code_generator.dart
diff --git a/lib/src/compiler/code_generator.dart b/lib/src/compiler/code_generator.dart
index d0bdf2043190b9a91a642c7f84ea0751b1be688b..2c5a906696277ea986bef981bb02007e828914a1 100644
--- a/lib/src/compiler/code_generator.dart
+++ b/lib/src/compiler/code_generator.dart
@@ -701,6 +701,7 @@ class CodeGenerator extends GeneralizingAstVisitor
     var fields = <FieldDeclaration>[];
     var staticFields = <FieldDeclaration>[];
     var methods = <MethodDeclaration>[];
+    bool isCallable = false;
     for (var member in node.members) {
       if (member is ConstructorDeclaration) {
         ctors.add(member);
@@ -708,6 +709,11 @@ class CodeGenerator extends GeneralizingAstVisitor
         (member.isStatic ? staticFields : fields).add(member);
       } else if (member is MethodDeclaration) {
         methods.add(member);
+        if (member.name.name == 'call' &&
+            !member.isGetter &&
+            !member.isSetter) {

[vsm, 2016/06/15 15:23:25]

Per spec / VM, 'call' could be a getter or field.  Are you thinking about this
as:
(a) TODO
(b) something we should explicitly not support
?

[Jennifer Messerly, 2016/06/15 16:50:32]

Oh crazy... it felt like some of the tests seem to expect the opposite, which I
why I added this check (it makes at least one pass). Unclear what's going on
there. Yeah I'll leave it as a TODO because A) seems like something no one has
or will ever use, and B) it would require yet another special case in codegen
for these guys =(

+          isCallable = true;
+        }
       }
     }
 
@@ -738,7 +744,7 @@ class CodeGenerator extends GeneralizingAstVisitor
     _emitSuperHelperSymbols(_superHelperSymbols, body);
 
     // Emit the class, e.g. `core.Object = class Object { ... }`
-    _defineClass(classElem, className, classExpr, body);
+    _defineClass(classElem, className, classExpr, isCallable, body);
 
     // Emit things that come after the ES6 `class ... { ... }`.
     var jsPeerName = _getJSPeerName(classElem);
@@ -746,7 +752,7 @@ class CodeGenerator extends GeneralizingAstVisitor
 
     _emitClassTypeTests(classElem, className, body);
 
-    _defineNamedConstructors(ctors, body, className);
+    _defineNamedConstructors(ctors, body, className, isCallable);
     _emitVirtualFieldSymbols(virtualFieldSymbols, body);
     _emitClassSignature(methods, classElem, ctors, extensions, className, body);
     _defineExtensionMembers(extensions, className, body);
@@ -764,6 +770,23 @@ class CodeGenerator extends GeneralizingAstVisitor
     return _statement(body);
   }
 
+  /// Emits code to support a class with a "call" method and an unnamed
+  /// constructor.
+  ///
+  /// This ensures instances created by the unnamed constructor are functions.
+  /// Named constructors are handled elsewhere, see [_defineNamedConstructors].
+  JS.Expression _emitCallableClass(JS.ClassExpression classExpr) {
+    var newClassExpr = js.call(r'''function (...args) {
+          let call = this.call.bind(this);
+          call.__proto__ = this.__proto__;
+          call.new.apply(call, args);
+          return call;
+        }''');
+    // Name the constructor function the same as the class.
+    return js.call('dart.callableClass(#, #)',
+        [new JS.NamedFunction(classExpr.name, newClassExpr), classExpr]);
+  }
+
   void _emitClassTypeTests(ClassElement classElem, JS.Expression className,
       List<JS.Statement> body) {
     if (classElem == objectClass) {
@@ -979,11 +1002,19 @@ class CodeGenerator extends GeneralizingAstVisitor
   }
 
   void _defineClass(ClassElement classElem, JS.Expression className,
-      JS.ClassExpression classExpr, List<JS.Statement> body) {
+      JS.ClassExpression classExpr, bool isCallable, List<JS.Statement> body) {
+    bool isCallableUnnamed = isCallable && classElem.unnamedConstructor != null;
+
     if (classElem.typeParameters.isNotEmpty) {
-      body.add(new JS.ClassDeclaration(classExpr));
+      if (isCallableUnnamed) {
+        body.add(js.statement(
+            'const # = #;', [classExpr.name, _emitCallableClass(classExpr)]));
+      } else {
+        body.add(new JS.ClassDeclaration(classExpr));
+      }
     } else {
-      body.add(js.statement('# = #;', [className, classExpr]));
+      var expr = isCallableUnnamed ? _emitCallableClass(classExpr) : classExpr;
+      body.add(js.statement('# = #;', [className, expr]));
     }
   }
 
@@ -1401,11 +1432,15 @@ class CodeGenerator extends GeneralizingAstVisitor
   }
 
   void _defineNamedConstructors(List<ConstructorDeclaration> ctors,
-      List<JS.Statement> body, JS.Expression className) {
+      List<JS.Statement> body, JS.Expression className, bool isCallable) {
+    var runtimeHelper = isCallable
+        ? 'defineNamedConstructorCallable'
+        : 'defineNamedConstructor';
+
     for (ConstructorDeclaration member in ctors) {
       if (member.name != null && member.factoryKeyword == null) {
-        body.add(js.statement('dart.defineNamedConstructor(#, #);',
-            [className, _constructorName(member.element)]));
+        body.add(js.statement('dart.#(#, #);',
+            [runtimeHelper, className, _constructorName(member.element)]));
       }
     }
   }