HashAttributeSet.java

/* HashAttributeSet.java -- 
   Copyright (C) 2003, 2004, 2005, 2006  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
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General Public License for more details.

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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.print.attribute;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Iterator;

/**
 * <code>HashAttributeSet</code> provides an implementation of
 * {@link javax.print.attribute.AttributeSet}.
 */
public class HashAttributeSet implements AttributeSet, Serializable
{
  private static final long serialVersionUID = 5311560590283707917L;
  
  private Class myInterface;
  private transient HashMap attributeMap = new HashMap();

  /**
   * Creates an empty <code>HashAttributeSet</code> object.
   */
  public HashAttributeSet()
  {
    this(Attribute.class);
  }

  /**
   * Creates a <code>HashAttributeSet</code> object with the given
   * attribute in it.
   *
   * @param attribute the attribute to put into the set
   *
   * @exception NullPointerException if attribute is null
   */
  public HashAttributeSet(Attribute attribute)
  {
    this(attribute, Attribute.class);
  }

  /**
   * Creates a <code>HashAttributeSet</code> object with the given
   * attributes in it.
   *
   * @param attributes the array of attributes to put into the set. If
   * <code>null</code> an empty set is created.
   *
   * @exception NullPointerException if one of the attributes of the given
   * array is null.
   */
  public HashAttributeSet(Attribute[] attributes)
  {
    this(attributes, Attribute.class);
  }

  /**
   * Creates a <code>HashAttributeSet</code> object with attributes
   * of the given attributes set in it.
   *
   * @param attributes the attributes set to put into the set. If 
   * <code>null</code> an empty set is created.
   */
  public HashAttributeSet(AttributeSet attributes)
  {
    this(attributes, Attribute.class);
  }

  /**
   * Creates an empty <code>HashAttributeSet</code> object.
   *
   * @param interfaceName the interface that all members must implement
   *
   * @exception NullPointerException if interfaceName is null
   */
  protected HashAttributeSet(Class<?> interfaceName)
  {
    if (interfaceName == null)
      throw new NullPointerException("interfaceName may not be null");
    
    myInterface = interfaceName;
  }
  
  /**
   * Creates a <code>HashAttributeSet</code> object with the given
   * attribute in it.
   * 
   * @param attribute the attribute to put into the set.
   * @param interfaceName the interface that all members must implement.
   *
   * @exception ClassCastException if attribute is not an interface of
   * interfaceName
   * @exception NullPointerException if attribute or interfaceName is null
   */
  protected HashAttributeSet(Attribute attribute, Class<?> interfaceName)
  {
    this(interfaceName);
    
    if (attribute == null)
      throw new NullPointerException();
    
    addInternal(attribute, interfaceName);
  }

  /**
   * Creates a <code>HashAttributeSet</code> object with the given
   * attributes in it.
   *
   * @param attributes the array of attributes to put into the set. If
   * <code>null</code> an empty set is created.
   * @param interfaceName the interface that all members must implement.
   *
   * @exception ClassCastException if any element of attributes is not an
   * interface of interfaceName
   * @exception NullPointerException if attributes or interfaceName is null
   */
  protected HashAttributeSet(Attribute[] attributes, Class<?> interfaceName)
  {
    this(interfaceName);
    
    if (attributes != null)
      {
        for (int index = 0; index < attributes.length; index++)
          addInternal(attributes[index], interfaceName);
      }
  }

  /**
   * Creates a <code>HashAttributeSet</code> object with attributes
   * of the given attributes set in it.
   *
   * @param attributes the attributes set to put into the set. If 
   * <code>null</code> an empty set is created.
   * @param interfaceName the interface that all members must implement.
   *
   * @exception ClassCastException if any element of attributes is not an
   * interface of interfaceName
   */
  protected HashAttributeSet(AttributeSet attributes, Class<?> interfaceName)
  {
    this(interfaceName);
    
    if (attributes != null)
      addAllInternal(attributes, interfaceName);
  }

  /**
   * Adds the specified attribute value to this attribute set 
   * if it is not already present.
   * 
   * This operation removes any existing attribute of the same category 
   * before adding the given attribute to the set. 
   * 
   * @param attribute the attribute to add.
   * @return <code>true</code> if the set is changed, false otherwise.
   * @throws NullPointerException if the attribute is <code>null</code>.
   * @throws UnmodifiableSetException if the set does not support modification.
   */
  public boolean add(Attribute attribute)
  {
    return addInternal(attribute, myInterface);
  }

  private boolean addInternal(Attribute attribute, Class interfaceName)
  {
    if (attribute == null)
      throw new NullPointerException("attribute may not be null");

    AttributeSetUtilities.verifyAttributeCategory(interfaceName,
                                                  myInterface);

    Object old = attributeMap.put
      (attribute.getCategory(), AttributeSetUtilities.verifyAttributeValue
                                  (attribute, interfaceName));
    return !attribute.equals(old);
  }

  /**
   * Adds all of the elements in the specified set to this attribute set.
   * 
   * @param attributes the set of attributes to add.
   * @return <code>true</code> if the set is changed, false otherwise.
   * @throws UnmodifiableSetException if the set does not support modification.
   * 
   * @see #add(Attribute)
   */
  public boolean addAll(AttributeSet attributes)
  {
    return addAllInternal(attributes, myInterface);
  }

  private boolean addAllInternal(AttributeSet attributes, Class interfaceName)
  {
    boolean modified = false;
    Attribute[] array = attributes.toArray();

    for (int index = 0; index < array.length; index++)
      if (addInternal(array[index], interfaceName))
        modified = true;

    return modified;
  }

  /**
   * Removes all attributes from this attribute set.
   * 
   * @throws UnmodifiableSetException if the set does not support modification.
   */
  public void clear()
  {
    attributeMap.clear();
  }

  /**
   * Checks if this attributes set contains an attribute with the given 
   * category.
   * 
   * @param category the category to test for.
   * @return <code>true</code> if an attribute of the category is contained
   * in the set, <code>false</code> otherwise.
   */
  public boolean containsKey(Class<?> category)
  {
    return attributeMap.containsKey(category);
  }

  /**
   * Checks if this attribute set contains the given attribute.
   * 
   * @param attribute the attribute to test for.
   * @return <code>true</code> if the attribute is contained in the set,
   * <code>false</code> otherwise.
   */
  public boolean containsValue(Attribute attribute)
  {
    return attributeMap.containsValue(attribute);
  }

  /**
   * Tests this set for equality with the given object. <code>true</code> is
   * returned, if the given object is also of type <code>AttributeSet</code>
   * and the contained attributes are the same as in this set.
   * 
   * @param obj the Object to test.
   * @return <code>true</code> if equal, false otherwise.
   */
  public boolean equals(Object obj)
  {
    if (! (obj instanceof HashAttributeSet))
      return false;

    return attributeMap.equals(((HashAttributeSet) obj).attributeMap);
  }

  /**
   * Returns the attribute object contained in this set for the given attribute
   * category. 
   * 
   * @param category the category of the attribute. A <code>Class</code> 
   * instance of a class implementing the <code>Attribute</code> interface. 
   * @return The attribute for this category or <code>null</code> if no 
   * attribute is contained for the given category. 
   * @throws NullPointerException if category is null.
   * @throws ClassCastException if category is not implementing 
   * <code>Attribute</code>.
   */
  public Attribute get(Class<?> category)
  {
    if (category == null)
      throw new NullPointerException("category may not be null");
    
    return (Attribute) attributeMap.get(category);
  }
  
  /**
   * Returns the hashcode value. The hashcode value is the sum of all hashcodes
   * of the attributes contained in this set.
   * 
   * @return The hashcode for this attribute set.
   */
  public int hashCode()
  {
    int hashcode = 0;
    Iterator it = attributeMap.values().iterator();
    while (it.hasNext())
      hashcode = hashcode + it.next().hashCode();
          
    return hashcode;
  }

  /**
   * Checks if the attribute set is empty.
   *
   * @return <code>true</code> if the attribute set is empty, false otherwise.
   */
  public boolean isEmpty()
  {
    return attributeMap.isEmpty();
  }

  /**
   * Removes the given attribute from the set. If the given attribute is <code>null</code>
   * nothing is done and <code>false</code> is returned.
   * 
   * @param attribute the attribute to remove.  
   * @return <code>true</code> if removed, false in all other cases. 
   * @throws UnmodifiableSetException if the set does not support modification.
   */
  public boolean remove(Attribute attribute)
  {
    if (attribute == null)
      return false;

    return attributeMap.remove(attribute.getCategory()) != null;
  }

  /**
   * Removes the attribute entry of the given category from the set. If the given
   * category is <code>null</code> nothing is done and <code>false</code> is returned.
   * 
   * @param category the category of the entry to be removed.
   * @return <code>true</code> if an attribute is removed, false in all other cases. 
   * @throws UnmodifiableSetException if the set does not support modification.
   */
  public boolean remove(Class<?> category)
  {
    if (category == null)
      return false;

    return attributeMap.remove(category) != null;
  }

  /**
   * Returns the number of elements in this attribute set.
   *
   * @return The number of elements.
   */
  public int size()
  {
    return attributeMap.size();
  }

  /**
   * Returns the content of the attribute set as an array
   *
   * @return An array of attributes.
   */
  public Attribute[] toArray()
  {
    int index = 0;
    Iterator it = attributeMap.values().iterator();
    Attribute[] array = new Attribute[size()];

    while (it.hasNext())
      {
        array[index] = (Attribute) it.next();
        index++;
      }
    
    return array;
  }
  
  // Implemented as specified in serialized form
  private void readObject(ObjectInputStream s)
    throws ClassNotFoundException, IOException
  {
    myInterface = (Class) s.readObject();
    int size = s.readInt();
    attributeMap = new HashMap(size);
    for (int i=0; i < size; i++)
      add((Attribute) s.readObject());
  }
         
  private void writeObject(ObjectOutputStream s) throws IOException
  {
    s.writeObject(myInterface);
    s.writeInt(size());
    Iterator it = attributeMap.values().iterator();
    while (it.hasNext())
      s.writeObject(it.next());    
  }
}