/*
 * Copyright (c) 1998-2010 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *
 *   Free Software Foundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */
package com.caucho.quercus.env;

import java.io.IOException;
import java.io.PrintWriter;

/**
 * Represents a PHP default value.
 */
@SuppressWarnings("serial")
public class DefaultValue extends NullValue {

   public static final DefaultValue DEFAULT = new DefaultValue();

   private DefaultValue() {
   }

   /**
    * Returns the null value singleton.
    */
   public static DefaultValue create() {
      return DEFAULT;
   }

   /**
    * Returns true for a DefaultValue
    */
   @Override
   public boolean isDefault() {
      return true;
   }

   /**
    * Converts to a boolean.
    */
   @Override
   public boolean toBoolean() {
      return false;
   }

   /**
    * Converts to a long.
    */
   @Override
   public long toLong() {
      return 0;
   }

   /**
    * Converts to a double.
    */
   @Override
   public double toDouble() {
      return 0;
   }

   /**
    * Converts to an object.
    */
   public Object toObject() {
      return "";
   }

   /**
    * Converts to a callable
    */
   @Override
   public Callable toCallable(Env env) {
      return null;
   }

   /**
    * Prints the value.
    * @param env
    */
   @Override
   public void print(Env env) {
   }

   /**
    * Converts to a string.
    * @param env
    */
   @Override
   public String toString() {
      return "";
   }

   /**
    * Generates code to recreate the expression.
    *
    * @param out the writer to the Java source code.
    */
   @Override
   public void generate(PrintWriter out)
           throws IOException {
      out.print("DefaultValue.DEFAULT");
   }

   /**
    * Generates code to recreate the expression.
    *
    * @param out the writer to the Java source code.
    */
   public void generateLong(PrintWriter out)
           throws IOException {
      out.print("0");
   }

   /**
    * Generates code to recreate the expression.
    *
    * @param out the writer to the Java source code.
    */
   public void generateString(PrintWriter out)
           throws IOException {
      out.print("\"\"");
   }

   //
   // Java Serialization
   //
   private Object readResolve() {
      return DEFAULT;
   }
}
