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3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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).
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17   * You should have received a copy of the GNU General Public License version
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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 <i>run</i> 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 &gt;= 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 }