Implement type argument access and reification of runtime types.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

 // Copyright (c) 2014, 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.
 
 library code_generator;
 
 import 'glue.dart';
 
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../js/js.dart' as js;
@@ skipping 310 matching lines @@
         visitExpression(node.left),
         visitExpression(node.right));
   }
 
   @override
   js.Expression visitNot(tree_ir.Not node) {
     return new js.Prefix("!", visitExpression(node.operand));
   }
 
   @override
-  js.Expression visitReifyTypeVar(tree_ir.ReifyTypeVar node) {
-    return giveup(node);
-    // TODO: implement visitReifyTypeVar
-  }
-
-  @override
   js.Expression visitThis(tree_ir.This node) {
     return new js.This();
   }
 
   @override
   js.Expression visitTypeOperator(tree_ir.TypeOperator node) {
     return giveup(node);
     // TODO: implement visitTypeOperator
   }
 
@@ skipping 156 matching lines @@
   void visitSetField(tree_ir.SetField node) {
     js.PropertyAccess field =
         new js.PropertyAccess.field(
             visitExpression(node.object),
             glue.instanceFieldPropertyName(node.field));
     js.Assignment asn = new js.Assignment(field, visitExpression(node.value));
     accumulator.add(new js.ExpressionStatement(asn));
     visitStatement(node.next);
   }
 
+  js.Expression buildStaticHelperInvocation(FunctionElement helper,
+                                            List<js.Expression> arguments) {
+    registry.registerStaticUse(helper);
+    return buildStaticInvoke(new Selector.fromElement(helper), helper,
+        arguments);
+  }
+
+  @override
+  js.Expression visitReifyRuntimeType(tree_ir.ReifyRuntimeType node) {
+    FunctionElement createType = glue.getCreateRuntimeType();
+    FunctionElement typeToString = glue.getRuntimeTypeToString();
+    return buildStaticHelperInvocation(createType,
+        [buildStaticHelperInvocation(typeToString,
+            [visitExpression(node.value)])]);
+  }
+
+  @override
+  js.Expression visitReadTypeVariable(tree_ir.ReadTypeVariable node) {
+    if (node.context != node.variable.element.enclosingClass) {
+      giveup(node, 'substitution not implemented');

[asgerf, 2015/03/02 13:52:36]

I am confused. This should never happen because the context is always set to the
variable's enclosing class, and other the hand, some kind of substitution does
seem to be implemented below.

[karlklose, 2015/03/05 09:54:58]

Acknowledged.

+    }
+    js.Expression index = js.number(glue.getTypeVariableIndex(node.variable));
+    if (glue.needsSubstitutionForTypeVariableAccess(node.context)) {
+      js.Expression substitution = glue.getSubstitutionName(node.context);
+      return buildStaticHelperInvocation(
+          glue.getTypeArgumentWithSubstitution(),
+          [visitExpression(node.target), substitution, index]);
+    } else {
+      return buildStaticHelperInvocation(
+          glue.getTypeArgumentByIndex(),
+          [visitExpression(node.target), index]);
+    }
+  }
+
+
   // Dart-specific IR nodes
 
   @override
+  visitReifyTypeVar(tree_ir.ReifyTypeVar node) {
+    return errorUnsupportedNode(node);
+  }
+
+  @override
   visitFunctionExpression(tree_ir.FunctionExpression node) {
     return errorUnsupportedNode(node);
   }
 
   @override
   visitFunctionDeclaration(tree_ir.FunctionDeclaration node) {
     return errorUnsupportedNode(node);
   }
 
   @override
   visitFieldInitializer(tree_ir.FieldInitializer node) {
     return errorUnsupportedNode(node);
   }
 
   @override
   visitSuperInitializer(tree_ir.SuperInitializer node) {
     return errorUnsupportedNode(node);
   }
 
-  dynamic errorUnsupportedNode(tree_ir.DartSpecificNode node) {
+  errorUnsupportedNode(tree_ir.DartSpecificNode node) {
     throw "Unsupported node in JS backend: $node";
   }
 }