/* AttributeSet.java -- 
   Copyright (C) 2002, 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

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it under the terms of the GNU General Public License as published by
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package javax.swing.text;

import java.util.Enumeration;

/**
 * A set of attributes. An attribute has a key and a value. They typically
 * describe features of a piece of text that make up its graphical
 * representation.
 *
 * An <code>AttributeSet</code> may have a resolving parent,
 * that is another <code>AttributeSet</code> that is searched for attribute
 * keys that are not stored locally in this <code>AttributeSet</code>.
 *
 * @author original author unknown
 * @author Roman Kennke (roman@kennke.org)
 */
public interface AttributeSet
{ 
  /**
   * Used as keys to identify character-run attributes.
   */
  static interface CharacterAttribute
  {
    // This interface is a marker interface and has no methods.
  }

  /**
   * Used as keys to identify color attributes.
   */
  static interface ColorAttribute
  {
    // This interface is a marker interface and has no methods.
  }

  /**
   * Used as keys to identify font attributes.
   */
  static interface FontAttribute
  {
    // This interface is a marker interface and has no methods.
  }

  /**
   * Used as keys to identify paragraph level attributes.
   */
  static interface ParagraphAttribute
  {
    // This interface is a marker interface and has no methods.
  }

  /**
   * Key of the attribute that is used to describe the name of an
   * <code>AttributeSet</code>.
   */
  Object NameAttribute = StyleConstants.NameAttribute;

  /**
   * Key of the attribute that is used to identify the resolving parent of
   * an <code>AttributeSet</code>.
   */
  Object ResolveAttribute = StyleConstants.ResolveAttribute;

  /**
   * Returns <code>true</code> if this <code>AttributeSet</code> contains
   * an attribute with the specified <code>name</code> and <code>value</code>,
   * <code>false</code> otherwise.
   *
   * @param name the name of the requested attribute
   * @param value the value of the requested attribute
   *
   * @return <code>true</code> if this <code>AttributeSet</code> contains
   *         an attribute with the specified <code>name</code> and
   *         <code>value</code>, <code>false</code> otherwise
   */
  boolean containsAttribute(Object name, Object value);

  /**
   * Returns <code>true</code> of this <code>AttributeSet</code> contains all
   * of the specified <code>attributes</code>.
   *
   * @param attributes the requested attributes
   *
   * @return <code>true</code> of this <code>AttributeSet</code> contains all
   *         of the specified <code>attributes</code>
   */
  boolean containsAttributes(AttributeSet attributes);

  /**
   * Creates and returns a copy of this <code>AttributeSet</code>.
   *
   * @return a copy of this <code>AttributeSet</code>
   */
  AttributeSet copyAttributes();

  /**
   * Returns the attribute with the specified <code>key</code> or
   * <code>null</code> if no such attribute is defined in this
   * <code>AttributeSet</code> and its resolving parents.
   *
   * @param key the key of the attribute that is looked up
   *
   * @return the attribute with the specified <code>key</code> or
   *         <code>null</code> if no such attribute is defined in this
   *         <code>AttributeSet</code> and its resolving parents
   */
  Object getAttribute(Object key);

  /**
   * Returns the number of attributes that are stored locally in this
   * <code>AttributeSet</code>.
   *
   * @return the number of attributes that are stored locally in this
   * <code>AttributeSet</code>
   */
  int getAttributeCount();

  /**
   * Returns the names of the attributes that are stored in this
   * <code>AttributeSet</code>.
   *
   * @return the names of the attributes that are stored in this
   *         <code>AttributeSet</code>
   */
  Enumeration<?> getAttributeNames();

  /**
   * Returns the resolving parent of this <code>AttributeSet</code>.
   * If a key is not stored locally, then a {@link #getAttribute(Object)}
   * request is resolved up in the resolving parent of this
   * <code>AttributeSet</code>.
   *
   * @return the resolving parent of this <code>AttributeSet</code>
   */
  AttributeSet getResolveParent();

  /**
   * Returns <code>true</code> if an attribute with the specified name is
   * defined locally in this <code>AttributeSet</code>, without resolving
   * through the resolving parents.
   *
   * @return <code>true</code> if an attribute with the specified name is
   *          defined locally in this <code>AttributeSet</code>
   */
  boolean isDefined(Object attrName);

  /**
   * Returns <code>true</code> if all of the attributes in <code>attr</code>
   * are equal to the attributes in this <code>AttributeSet</code>,
   * <code>false</code> otherwise.
   *
   * @param attr the attributes to be compared to <code>this</code>
   *
   * @return <code>true</code> if all of the attributes in <code>attr</code>
   *         are equal to the attributes in this <code>AttributeSet</code>,
   *         <code>false</code> otherwise
   */
  boolean isEqual(AttributeSet attr);     
}