Partial fix for call methods #542

lib/src/compiler/code_generator.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:collection' show HashMap, HashSet;
 import 'dart:math' show min, max;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart' show Token, TokenType;
@@ skipping 683 matching lines @@
     if (findAnnotation(classElem, isPublicJSAnnotation) != null) return null;
 
     // If this is a JavaScript type, emit it now and then exit.
     var jsTypeDef = _emitJsType(classElem);
     if (jsTypeDef != null) return jsTypeDef;
 
     var ctors = <ConstructorDeclaration>[];
     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);
       } else if (member is FieldDeclaration) {
         (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;
+        }
       }
     }
 
     JS.Expression className;
     if (classElem.typeParameters.isNotEmpty) {
       // Generic classes will be defined inside a function that closes over the
       // type parameter. So we can use their local variable name directly.
       className = new JS.Identifier(classElem.name);
     } else {
       className = _emitTopLevelName(classElem);
@@ skipping 10 matching lines @@
     var classExpr = _emitClassExpression(classElem,
         _emitClassMethods(node, ctors, fields, superclasses, virtualFields),
         fields: allFields);
 
     var body = <JS.Statement>[];
     var extensions = _extensionsToImplement(classElem);
     _initExtensionSymbols(classElem, methods, fields, body);
     _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);
     _setBaseClass(classElem, className, jsPeerName, body);
 
     _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);
     _emitClassMetadata(node.metadata, className, body);
 
     JS.Statement classDef = _statement(body);
     var typeFormals = classElem.typeParameters;
     if (typeFormals.isNotEmpty) {
       classDef = _defineClassTypeArguments(classElem, typeFormals, classDef);
     }
 
     body = <JS.Statement>[classDef];
     _emitStaticFields(staticFields, staticFieldOverrides, classElem, body);
     _registerExtensionType(classElem, jsPeerName, body);
     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) {
       // We rely on ES6 static inheritance.  All types that are represented by
       // class constructor functions will see these definitions, with [this]
       // being bound to the class constructor.
 
       // The 'instanceof' checks don't work for primitive types (which have fast
       // definitions below) and don't work for native types. In those cases we
       // fall through to the general purpose checking code.
@@ skipping 195 matching lines @@
             virtualFieldSymbols.add(js.statement(
                 'const # = Symbol(#.name + "." + #.toString());',
                 [virtualField, className, fieldName]));
           }
         }
       }
     }
   }
 
   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]));
     }
   }
 
   void _emitVirtualFieldSymbols(
       List<JS.Statement> virtualFields, List<JS.Statement> body) {
     body.addAll(virtualFields);
   }
 
   List<JS.Identifier> _emitTypeFormals(List<TypeParameterElement> typeFormals) {
     return typeFormals
@@ skipping 397 matching lines @@
           'dart.setExtensionBaseClass(#, #);', [className, newBaseClass]));
     } else if (_hasDeferredSupertype.contains(classElem)) {
       var newBaseClass = _emitType(classElem.type.superclass,
           nameType: false, subClass: classElem, className: className);
       body.add(
           js.statement('dart.setBaseClass(#, #);', [className, newBaseClass]));
     }
   }
 
   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)]));
       }
     }
   }
 
   /// Emits static fields for a class, and initialize them eagerly if possible,
   /// otherwise define them as lazy properties.
   void _emitStaticFields(
       List<FieldDeclaration> staticFields,
       Set<FieldElement> staticFieldOverrides,
       ClassElement classElem,
@@ skipping 3714 matching lines @@
 }
 
 bool isLibraryPrefix(Expression node) =>
     node is SimpleIdentifier && node.staticElement is PrefixElement;
 
 LibraryElement _getLibrary(AnalysisContext c, String uri) =>
     c.computeLibraryElement(c.sourceFactory.forUri(uri));
 
 bool _isDartRuntime(LibraryElement l) =>
     l.isInSdk && l.source.uri.toString() == 'dart:_runtime';