Add fasta-based summary generation code.

pkg/analyzer/lib/src/summary/fasta/stack_listener.dart

Index: pkg/analyzer/lib/src/summary/fasta/stack_listener.dart
diff --git a/pkg/analyzer/lib/src/summary/fasta/stack_listener.dart b/pkg/analyzer/lib/src/summary/fasta/stack_listener.dart
new file mode 100644
index 0000000000000000000000000000000000000000..f7e0bbd13472ed57f6758141490c1c2e27c1a8f2
--- /dev/null
+++ b/pkg/analyzer/lib/src/summary/fasta/stack_listener.dart
@@ -0,0 +1,139 @@
+// 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 fe.stack_listener;
+
+import 'dart:collection' show
+    Queue;
+
+import 'package:front_end/src/fasta/parser/identifier_context.dart';
+import 'package:front_end/src/fasta/parser/listener.dart';
+import 'package:front_end/src/fasta/scanner/token.dart';
+
+enum NullValue {
+  Arguments,
+  Combinators,
+  FormalParameters,
+  FunctionBody,
+  IdentifierList,
+  Initializers,
+  Metadata,
+  Modifiers,
+  Type,
+  TypeArguments,
+  TypeList,
+  TypeVariable,
+  TypeVariables,
+}
+
+abstract class StackListener extends Listener {
+  final Queue<Object> stack = new Queue<Object>();
+
+  Uri get uri;
+
+  void push(Object node) {
+    if (node == null) throw "null not allowed.";
+    stack.addLast(node);
+  }
+
+  Object peek() {
+    Object node = stack.last;
+    return node is NullValue ? null : node;
+  }
+
+  Object pop({NullValue expect: null}) {
+    Object node = stack.removeLast();
+    if (expect != null && expect != node) {
+      throw "unexpected value: $expect vs $node";
+    }
+    return node is NullValue ? null : node;
+  }
+
+  Object popIfNotNull(Object value) {
+    return value == null ? null : pop();
+  }
+
+  List popList(int n) {
+    if (n == 0) return null;
+    List list = new List(n);
+    for (int i = n - 1; i >= 0; i--) {
+      list[i] = pop();
+    }
+    return list;
+  }
+
+  void debugEvent(String name) {
+    // print("  ${stack.join('\n  ')}");
+    // print(name);
+  }
+
+  void logEvent(String name) {
+    print("  ${stack.join('\n  ')}");
+    throw "Unhandled event: $name in $runtimeType $uri.";
+  }
+
+  void handleIdentifier(Token token, IdentifierContext context) {
+    debugEvent("handleIdentifier");
+    push(token.value);
+  }
+
+  void checkEmpty() {
+    if (stack.isNotEmpty) {
+      throw "Stack not empty $uri:\n"
+          "  ${stack.join('\n  ')}";
+    }
+  }
+
+  void endTopLevelDeclaration(Token token) {
+    debugEvent("TopLevelDeclaration");
+    checkEmpty();
+  }
+
+  void endCompilationUnit(int count, Token token) {
+    debugEvent("CompilationUnit");
+    checkEmpty();
+  }
+
+  void handleNoTypeArguments(Token token) {
+    debugEvent("NoTypeArguments");
+    push(NullValue.TypeArguments);
+  }
+
+  void handleNoTypeVariables(Token token) {
+    debugEvent("NoTypeVariables");
+    push(NullValue.TypeVariables);
+  }
+
+  void handleNoType(Token token) {
+    debugEvent("NoType");
+    push(NullValue.Type);
+  }
+
+  void handleNoFormalParameters(Token token) {
+    debugEvent("NoFormalParameters");
+    push(NullValue.FormalParameters);
+  }
+
+  void handleNoArguments(Token token) {
+    debugEvent("NoArguments");
+    var typeArguments = pop();
+    assert(typeArguments == null);
+    push(NullValue.Arguments);
+  }
+
+  void handleNoFunctionBody(Token token) {
+    debugEvent("NoFunctionBody");
+    push(NullValue.FunctionBody);
+  }
+
+  void handleNoInitializers() {
+    debugEvent("NoInitializers");
+    push(NullValue.Initializers);
+  }
+
+  void handleParenthesizedExpression(BeginGroupToken token) {
+    debugEvent("ParenthesizedExpression");
+  }
+}
+