1 files changed, 65 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/ASTNode.java b/src/main/java/com/google/devtools/build/lib/syntax/ASTNode.java
new file mode 100644
index 0000000000..81ca5847b3
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/syntax/ASTNode.java
@@ -0,0 +1,65 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.syntax;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.devtools.build.lib.events.Location;
+
+import java.io.Serializable;
+
+/**
+ * Root class for nodes in the Abstract Syntax Tree of the Build language.
+ */
+public abstract class ASTNode implements Serializable {
+
+  private Location location;
+
+  protected ASTNode() {}
+
+  @VisibleForTesting  // productionVisibility = Visibility.PACKAGE_PRIVATE
+  public void setLocation(Location location) {
+    this.location = location;
+  }
+
+  public Location getLocation() {
+    return location;
+  }
+
+  /**
+   * Print the syntax node in a form useful for debugging.  The output is not
+   * precisely specified, and should not be used by pretty-printing routines.
+   */
+  @Override
+  public abstract String toString();
+
+  @Override
+  public int hashCode() {
+    throw new UnsupportedOperationException(); // avoid nondeterminism
+  }
+
+  @Override
+  public boolean equals(Object that) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Implements the double dispatch by calling into the node specific
+   * <code>visit</code> method of the {@link SyntaxTreeVisitor}
+   *
+   * @param visitor the {@link SyntaxTreeVisitor} instance to dispatch to.
+   */
+  public abstract void accept(SyntaxTreeVisitor visitor);
+
+}