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    1   /*
    2    * Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   package javax.swing.text;
   26   
   27   import java.util.Enumeration;
   28   
   29   /**
   30    * A collection of unique attributes.  This is a read-only,
   31    * immutable interface.  An attribute is basically a key and
   32    * a value assigned to the key.  The collection may represent
   33    * something like a style run, a logical style, etc.  These
   34    * are generally used to describe features that will contribute
   35    * to some graphical representation such as a font.  The
   36    * set of possible keys is unbounded and can be anything.
   37    * Typically View implementations will respond to attribute
   38    * definitions and render something to represent the attributes.
   39    * <p>
   40    * Attributes can potentially resolve in a hierarchy.  If a
   41    * key doesn't resolve locally, and a resolving parent
   42    * exists, the key will be resolved through the parent.
   43    *
   44    * @author  Timothy Prinzing
   45    * @see MutableAttributeSet
   46    */
   47   public interface AttributeSet {
   48   
   49       /**
   50        * This interface is the type signature that is expected
   51        * to be present on any attribute key that contributes to
   52        * the determination of what font to use to render some
   53        * text.  This is not considered to be a closed set, the
   54        * definition can change across version of the platform and can
   55        * be amended by additional user added entries that
   56        * correspond to logical settings that are specific to
   57        * some type of content.
   58        */
   59       public interface FontAttribute {
   60       }
   61   
   62       /**
   63        * This interface is the type signature that is expected
   64        * to be present on any attribute key that contributes to
   65        * presentation of color.
   66        */
   67       public interface ColorAttribute {
   68       }
   69   
   70       /**
   71        * This interface is the type signature that is expected
   72        * to be present on any attribute key that contributes to
   73        * character level presentation.  This would be any attribute
   74        * that applies to a so-called <term>run</term> of
   75        * style.
   76        */
   77       public interface CharacterAttribute {
   78       }
   79   
   80       /**
   81        * This interface is the type signature that is expected
   82        * to be present on any attribute key that contributes to
   83        * the paragraph level presentation.
   84        */
   85       public interface ParagraphAttribute {
   86       }
   87   
   88       /**
   89        * Returns the number of attributes that are defined locally in this set.
   90        * Attributes that are defined in the parent set are not included.
   91        *
   92        * @return the number of attributes >= 0
   93        */
   94       public int getAttributeCount();
   95   
   96       /**
   97        * Checks whether the named attribute has a value specified in
   98        * the set without resolving through another attribute
   99        * set.
  100        *
  101        * @param attrName the attribute name
  102        * @return true if the attribute has a value specified
  103        */
  104       public boolean isDefined(Object attrName);
  105   
  106       /**
  107        * Determines if the two attribute sets are equivalent.
  108        *
  109        * @param attr an attribute set
  110        * @return true if the sets are equivalent
  111        */
  112       public boolean isEqual(AttributeSet attr);
  113   
  114       /**
  115        * Returns an attribute set that is guaranteed not
  116        * to change over time.
  117        *
  118        * @return a copy of the attribute set
  119        */
  120       public AttributeSet copyAttributes();
  121   
  122       /**
  123        * Fetches the value of the given attribute. If the value is not found
  124        * locally, the search is continued upward through the resolving
  125        * parent (if one exists) until the value is either
  126        * found or there are no more parents.  If the value is not found,
  127        * null is returned.
  128        *
  129        * @param key the non-null key of the attribute binding
  130        * @return the value of the attribute, or {@code null} if not found
  131        */
  132       public Object getAttribute(Object key);
  133   
  134       /**
  135        * Returns an enumeration over the names of the attributes that are
  136        * defined locally in the set. Names of attributes defined in the
  137        * resolving parent, if any, are not included. The values of the
  138        * <code>Enumeration</code> may be anything and are not constrained to
  139        * a particular <code>Object</code> type.
  140        * <p>
  141        * This method never returns {@code null}. For a set with no attributes, it
  142        * returns an empty {@code Enumeration}.
  143        *
  144        * @return the names
  145        */
  146       public Enumeration<?> getAttributeNames();
  147   
  148       /**
  149        * Returns {@code true} if this set defines an attribute with the same
  150        * name and an equal value. If such an attribute is not found locally,
  151        * it is searched through in the resolving parent hierarchy.
  152        *
  153        * @param name the non-null attribute name
  154        * @param value the value
  155        * @return {@code true} if the set defines the attribute with an
  156        *     equal value, either locally or through its resolving parent
  157        * @throws NullPointerException if either {@code name} or
  158        *      {@code value} is {@code null}
  159        */
  160       public boolean containsAttribute(Object name, Object value);
  161   
  162       /**
  163        * Returns {@code true} if this set defines all the attributes from the
  164        * given set with equal values. If an attribute is not found locally,
  165        * it is searched through in the resolving parent hierarchy.
  166        *
  167        * @param attributes the set of attributes to check against
  168        * @return {@code true} if this set defines all the attributes with equal
  169        *              values, either locally or through its resolving parent
  170        * @throws NullPointerException if {@code attributes} is {@code null}
  171        */
  172       public boolean containsAttributes(AttributeSet attributes);
  173   
  174       /**
  175        * Gets the resolving parent.
  176        *
  177        * @return the parent
  178        */
  179       public AttributeSet getResolveParent();
  180   
  181       /**
  182        * Attribute name used to name the collection of
  183        * attributes.
  184        */
  185       public static final Object NameAttribute = StyleConstants.NameAttribute;
  186   
  187       /**
  188        * Attribute name used to identify the resolving parent
  189        * set of attributes, if one is defined.
  190        */
  191       public static final Object ResolveAttribute = StyleConstants.ResolveAttribute;
  192   
  193   }

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