content: /* ========================================================================
   * JCommon : a free general purpose class library for the Java(tm) platform
   * ========================================================================
   *
   * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jcommon/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library 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. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
   * in the United States and other countries.]
   *
   * ------------------------------
   * HierarchicalConfiguration.java
   * ------------------------------
   * (C) Copyright 2004, by Object Refinery Limited.
   *
   * Original Author:  Thomas Morgner;
   * Contributor(s):   David Gilbert (for Object Refinery Limited);
   *
   * $Id: HierarchicalConfiguration.java,v 1.8 2008/09/10 09:17:28 mungady Exp $
   *
   * Changes
   * -------
   * 07-Jun-2004 : Added JCommon header (DG);
   * 29-Jul-2004 : Replaced 'enum' variable name (reserved word in JDK 1.5) (DG);
   *
   */
  
  package org.jfree.base.config;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.Iterator;
  import java.util.Properties;
  import java.util.TreeSet;
  
  import org.jfree.util.Configuration;
  import org.jfree.util.PublicCloneable;
  
  /**
   * A hierarchical configuration. Such a configuration can have one or more
   * parent configurations providing usefull default values.
   *
   * @author Thomas Morgner
   */
  public class HierarchicalConfiguration
      implements ModifiableConfiguration, PublicCloneable
  {
  
    /**
     * The instance configuration properties.
     */
    private Properties configuration;
  
    /**
     * The parent configuration (null if this is the root configuration).
     */
    private transient Configuration parentConfiguration;
  
    /**
     * Creates a new configuration.
     */
    public HierarchicalConfiguration()
    {
      this.configuration = new Properties();
    }
  
    /**
     * Creates a new configuration.
     *
     * @param parentConfiguration the parent configuration.
     */
    public HierarchicalConfiguration(final Configuration parentConfiguration)
    {
      this();
      this.parentConfiguration = parentConfiguration;
    }
  
    /**
     * Returns the configuration property with the specified key.
     *
     * @param key the property key.
     * @return the property value.
     */
    public String getConfigProperty(final String key)
    {
      return getConfigProperty(key, null);
    }
  
    /**
     * Returns the configuration property with the specified key (or the
     * specified default value if there is no such property).
     * <p/>
     * If the property is not defined in this configuration, the code will
     * lookup the property in the parent configuration.
     *
     * @param key          the property key.
     * @param defaultValue the default value.
     * @return the property value.
     */
    public String getConfigProperty(final String key, final String defaultValue)
    {
      String value = this.configuration.getProperty(key);
      if (value == null)
      {
        if (isRootConfig())
        {
          value = defaultValue;
        }
        else
        {
          value = this.parentConfiguration.getConfigProperty(key, defaultValue);
        }
      }
      return value;
    }
  
    /**
     * Sets a configuration property.
     *
     * @param key   the property key.
     * @param value the property value.
     */
    public void setConfigProperty(final String key, final String value)
    {
      if (key == null)
      {
        throw new NullPointerException();
      }
  
      if (value == null)
      {
        this.configuration.remove(key);
      }
      else
      {
        this.configuration.setProperty(key, value);
      }
    }
  
    /**
     * Returns true if this object has no parent.
     *
     * @return true, if this report is the root configuration, false otherwise.
     */
    private boolean isRootConfig()
    {
      return this.parentConfiguration == null;
    }
  
    /**
     * Checks, whether the given key is localy defined in this instance or
     * whether the key's value is inherited.
     *
     * @param key the key that should be checked.
     * @return true, if the key is defined locally, false otherwise.
     */
    public boolean isLocallyDefined(final String key)
    {
      return this.configuration.containsKey(key);
    }
  
    /**
     * Returns the collection of properties for the configuration.
     *
     * @return the properties.
     */
    protected Properties getConfiguration()
    {
      return this.configuration;
    }
  
    /**
     * The new configuartion will be inserted into the list of report
     * configuration, so that this configuration has the given report
     * configuration instance as parent.
     *
     * @param config the new report configuration.
     */
    public void insertConfiguration(final HierarchicalConfiguration config)
    {
      config.setParentConfig(getParentConfig());
      setParentConfig(config);
    }
  
    /**
     * Set the parent configuration. The parent configuration is queried, if the
     * requested configuration values was not found in this report
     * configuration.
     *
     * @param config the parent configuration.
     */
    protected void setParentConfig(final Configuration config)
    {
      if (this.parentConfiguration == this)
      {
        throw new IllegalArgumentException("Cannot add myself as parent configuration.");
      }
      this.parentConfiguration = config;
    }
  
    /**
     * Returns the parent configuration. The parent configuration is queried, if
     * the requested configuration values was not found in this report
     * configuration.
     *
     * @return the parent configuration.
     */
    protected Configuration getParentConfig()
    {
      return this.parentConfiguration;
    }
  
    /**
     * Returns all defined configuration properties for the report. The
     * enumeration contains all keys of the changed properties, properties set
     * from files or the system properties are not included.
     *
     * @return all defined configuration properties for the report.
     */
    public Enumeration getConfigProperties()
    {
      return this.configuration.keys();
    }
  
    /**
     * Searches all property keys that start with a given prefix.
     *
     * @param prefix the prefix that all selected property keys should share
     * @return the properties as iterator.
     */
    public Iterator findPropertyKeys(final String prefix)
    {
      final TreeSet keys = new TreeSet();
      collectPropertyKeys(prefix, this, keys);
      return Collections.unmodifiableSet(keys).iterator();
    }
  
    /**
     * Collects property keys from this and all parent report configurations,
     * which start with the given prefix.
     *
     * @param prefix    the prefix, that selects the property keys.
     * @param config    the currently processed report configuration.
     * @param collector the target list, that should receive all valid keys.
     */
    private void collectPropertyKeys(final String prefix,
                                     final Configuration config,
                                     final TreeSet collector)
    {
      final Enumeration enum1 = config.getConfigProperties();
      while (enum1.hasMoreElements())
      {
        final String key = (String) enum1.nextElement();
        if (key.startsWith(prefix))
        {
          if (collector.contains(key) == false)
          {
            collector.add(key);
          }
        }
      }
  
      if (config instanceof HierarchicalConfiguration)
      {
        final HierarchicalConfiguration hconfig = (HierarchicalConfiguration) config;
        if (hconfig.parentConfiguration != null)
        {
          collectPropertyKeys(prefix, hconfig.parentConfiguration, collector);
        }
      }
    }
  
    /**
     * Checks, whether the parent configuration can be serialized. Usually the
     * global configuration is not serialized and should return false here.
     *
     * @return true, if the parent config can be serialized, false otherwise.
     */
    protected boolean isParentSaved()
    {
      return true;
    }
  
    /**
     * A callback method to reconnect this configuration with the global
     * configuration after deserialization.
     */
    protected void configurationLoaded()
    {
    }
  
    /**
     * Helper method for serialization.
     *
     * @param out the output stream where to write the object.
     * @throws java.io.IOException if errors occur while writing the stream.
     */
    private void writeObject(final ObjectOutputStream out)
        throws IOException
    {
      out.defaultWriteObject();
      if (isParentSaved() == false)
      {
        out.writeBoolean(false);
      }
      else
      {
        out.writeBoolean(true);
        out.writeObject(this.parentConfiguration);
      }
    }
  
    /**
     * Helper method for serialization.
     *
     * @param in the input stream from where to read the serialized object.
     * @throws IOException            when reading the stream fails.
     * @throws ClassNotFoundException if a class definition for a serialized
     *                                object could not be found.
     */
    private void readObject(final ObjectInputStream in)
        throws IOException, ClassNotFoundException
    {
      in.defaultReadObject();
      final boolean readParent = in.readBoolean();
      if (readParent)
      {
          this.parentConfiguration = (ModifiableConfiguration) in.readObject();
      }
      else
      {
          this.parentConfiguration = null;
      }
      configurationLoaded();
    }
  
    /**
     * Returns a clone of this instance.
     *
     * @return A clone.
     *
     * @throws CloneNotSupportedException if there is a problem cloning.
     */
    public Object clone() throws CloneNotSupportedException
    {
      HierarchicalConfiguration config = (HierarchicalConfiguration) super.clone();
      config.configuration = (Properties) this.configuration.clone();
      return config;
    }
  }
  