Fasta parser listener infrastructure.

pkg/fasta/lib/src/source/unhandled_listener.dart

Index: pkg/fasta/lib/src/source/unhandled_listener.dart
diff --git a/pkg/fasta/lib/src/source/unhandled_listener.dart b/pkg/fasta/lib/src/source/unhandled_listener.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ec4430511d21872b7251f0967849f9211d4c5e74
--- /dev/null
+++ b/pkg/fasta/lib/src/source/unhandled_listener.dart
@@ -0,0 +1,73 @@
+// 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.unhandled_listener;
+
+import 'package:dart_scanner/src/token.dart' show
+    Token;
+
+import 'stack_listener.dart' show
+    NullValue,
+    StackListener;
+
+export 'stack_listener.dart' show
+    NullValue;
+
+// TODO(ahe): Get rid of this.
+enum Unhandled {
+  ConditionalUri,
+  ConditionalUris,
+  DottedName,
+  Hide,
+  Initializers,
+  Interpolation,
+  Metadata,
+  Show,
+  TypeVariables,
+}
+
+// TODO(ahe): Get rid of this class when all listeners are complete.
+abstract class UnhandledListener extends StackListener {
+  void endMetadataStar(int count, bool forParameter) {
+    debugEvent("MetadataStar");
+    push(popList(count) ?? NullValue.Metadata);
+  }
+
+  void endConditionalUri(Token ifKeyword, Token equalitySign) {
+    debugEvent("ConditionalUri");
+    pop(); // URI.
+    popIfNotNull(equalitySign);  // String.
+    pop(); // DottedName.
+    push(Unhandled.ConditionalUri);
+  }
+
+  void endConditionalUris(int count) {
+    debugEvent("ConditionalUris");
+    popList(count);
+    push(Unhandled.ConditionalUris);
+  }
+
+  void endHide(Token hideKeyword) {
+    debugEvent("Hide");
+    pop();
+    push(Unhandled.Hide);
+  }
+
+  void endShow(Token showKeyword) {
+    debugEvent("Show");
+    pop();
+    push(Unhandled.Show);
+  }
+
+  void endCombinators(int count) {
+    debugEvent("Combinators");
+    push(popList(count) ?? NullValue.Combinators);
+  }
+
+  void endDottedName(int count, Token firstIdentifier) {
+    debugEvent("DottedName");
+    popList(count);
+    push(Unhandled.DottedName);
+  }
+}