2.1/user/src/com/google/gwt/rpc/client/ast/NullValueCommand.java

/*
 * Copyright 2009 Google Inc.
 * 
 * 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.gwt.rpc.client.ast;

import com.google.gwt.rpc.client.ast.RpcCommandVisitor.Context;

/**
 * Represents a null or undefined value on the client.
 */
public class NullValueCommand extends ScalarValueCommand {
  /**
   * The singleton instance of NullValueCommand.
   */
  public static final NullValueCommand INSTANCE = new NullValueCommand();

  private NullValueCommand() {
  }

  @Override
  public Object getValue() {
    return null;
  }

  @Override
  public void traverse(RpcCommandVisitor visitor, Context ctx) {
    visitor.visit(this, ctx);
    visitor.endVisit(this, ctx);
  }
}