Fasta builders.

pkg/fasta/lib/src/builder/type_builder.dart

Index: pkg/fasta/lib/src/builder/type_builder.dart
diff --git a/pkg/fasta/lib/src/builder/type_builder.dart b/pkg/fasta/lib/src/builder/type_builder.dart
new file mode 100644
index 0000000000000000000000000000000000000000..850bb43a780a25df4a6d7c410b167088638d6095
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+++ b/pkg/fasta/lib/src/builder/type_builder.dart
@@ -0,0 +1,25 @@
+// Copyright (c) 2016, 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 fasta.type_builder;
+
+import 'builder.dart' show
+    Builder,
+    TypeVariableBuilder;
+
+import 'scope.dart' show
+    Scope;
+
+// TODO(ahe): Make const class.
+abstract class TypeBuilder extends Builder {
+  void resolveIn(Scope scope);
+
+  String get debugName;
+
+  StringBuffer printOn(StringBuffer buffer);
+
+  String toString() => "$debugName(${printOn(new StringBuffer())})";
+
+  TypeBuilder subst(Map<TypeVariableBuilder, TypeBuilder> substitution) => this;
+}