View Javadoc
1   /*
2    * Copyright (c) 1997, 2013, 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  
26  package java.text;
27  
28  import java.io.InvalidObjectException;
29  import java.io.Serializable;
30  import java.util.HashMap;
31  import java.util.Map;
32  import java.util.Set;
33  
34  /**
35   * An {@code AttributedCharacterIterator} allows iteration through both text and
36   * related attribute information.
37   *
38   * <p>
39   * An attribute is a key/value pair, identified by the key.  No two
40   * attributes on a given character can have the same key.
41   *
42   * <p>The values for an attribute are immutable, or must not be mutated
43   * by clients or storage.  They are always passed by reference, and not
44   * cloned.
45   *
46   * <p>A <em>run with respect to an attribute</em> is a maximum text range for
47   * which:
48   * <ul>
49   * <li>the attribute is undefined or {@code null} for the entire range, or
50   * <li>the attribute value is defined and has the same non-{@code null} value for the
51   *     entire range.
52   * </ul>
53   *
54   * <p>A <em>run with respect to a set of attributes</em> is a maximum text range for
55   * which this condition is met for each member attribute.
56   *
57   * <p>When getting a run with no explicit attributes specified (i.e.,
58   * calling {@link #getRunStart()} and {@link #getRunLimit()}), any
59   * contiguous text segments having the same attributes (the same set
60   * of attribute/value pairs) are treated as separate runs if the
61   * attributes have been given to those text segments separately.
62   *
63   * <p>The returned indexes are limited to the range of the iterator.
64   *
65   * <p>The returned attribute information is limited to runs that contain
66   * the current character.
67   *
68   * <p>
69   * Attribute keys are instances of {@link AttributedCharacterIterator.Attribute} and its
70   * subclasses, such as {@link java.awt.font.TextAttribute}.
71   *
72   * @see AttributedCharacterIterator.Attribute
73   * @see java.awt.font.TextAttribute
74   * @see AttributedString
75   * @see Annotation
76   * @since 1.2
77   */
78  
79  public interface AttributedCharacterIterator extends CharacterIterator {
80  
81      /**
82       * Defines attribute keys that are used to identify text attributes. These
83       * keys are used in {@code AttributedCharacterIterator} and {@code AttributedString}.
84       * @see AttributedCharacterIterator
85       * @see AttributedString
86       * @since 1.2
87       */
88  
89      public static class Attribute implements Serializable {
90  
91          /**
92           * The name of this {@code Attribute}. The name is used primarily by {@code readResolve}
93           * to look up the corresponding predefined instance when deserializing
94           * an instance.
95           * @serial
96           */
97          private String name;
98  
99          // table of all instances in this class, used by readResolve
100         private static final Map<String, Attribute> instanceMap = new HashMap<>(7);
101 
102         /**
103          * Constructs an {@code Attribute} with the given name.
104          *
105          * @param name the name of {@code Attribute}
106          */
107         protected Attribute(String name) {
108             this.name = name;
109             if (this.getClass() == Attribute.class) {
110                 instanceMap.put(name, this);
111             }
112         }
113 
114         /**
115          * Compares two objects for equality. This version only returns true
116          * for {@code x.equals(y)} if {@code x} and {@code y} refer
117          * to the same object, and guarantees this for all subclasses.
118          */
119         public final boolean equals(Object obj) {
120             return super.equals(obj);
121         }
122 
123         /**
124          * Returns a hash code value for the object. This version is identical to
125          * the one in {@code Object}, but is also final.
126          */
127         public final int hashCode() {
128             return super.hashCode();
129         }
130 
131         /**
132          * Returns a string representation of the object. This version returns the
133          * concatenation of class name, {@code "("}, a name identifying the attribute
134          * and {@code ")"}.
135          */
136         public String toString() {
137             return getClass().getName() + "(" + name + ")";
138         }
139 
140         /**
141          * Returns the name of the attribute.
142          *
143          * @return the name of {@code Attribute}
144          */
145         protected String getName() {
146             return name;
147         }
148 
149         /**
150          * Resolves instances being deserialized to the predefined constants.
151          *
152          * @return the resolved {@code Attribute} object
153          * @throws InvalidObjectException if the object to resolve is not
154          *                                an instance of {@code Attribute}
155          */
156         protected Object readResolve() throws InvalidObjectException {
157             if (this.getClass() != Attribute.class) {
158                 throw new InvalidObjectException("subclass didn't correctly implement readResolve");
159             }
160 
161             Attribute instance = instanceMap.get(getName());
162             if (instance != null) {
163                 return instance;
164             } else {
165                 throw new InvalidObjectException("unknown attribute name");
166             }
167         }
168 
169         /**
170          * Attribute key for the language of some text.
171          * <p> Values are instances of {@link java.util.Locale Locale}.
172          * @see java.util.Locale
173          */
174         public static final Attribute LANGUAGE = new Attribute("language");
175 
176         /**
177          * Attribute key for the reading of some text. In languages where the written form
178          * and the pronunciation of a word are only loosely related (such as Japanese),
179          * it is often necessary to store the reading (pronunciation) along with the
180          * written form.
181          * <p>Values are instances of {@link Annotation} holding instances of {@link String}.
182          *
183          * @see Annotation
184          * @see java.lang.String
185          */
186         public static final Attribute READING = new Attribute("reading");
187 
188         /**
189          * Attribute key for input method segments. Input methods often break
190          * up text into segments, which usually correspond to words.
191          * <p>Values are instances of {@link Annotation} holding a {@code null} reference.
192          * @see Annotation
193          */
194         public static final Attribute INPUT_METHOD_SEGMENT = new Attribute("input_method_segment");
195 
196         // make sure the serial version doesn't change between compiler versions
197         private static final long serialVersionUID = -9142742483513960612L;
198 
199     };
200 
201     /**
202      * Returns the index of the first character of the run
203      * with respect to all attributes containing the current character.
204      *
205      * <p>Any contiguous text segments having the same attributes (the
206      * same set of attribute/value pairs) are treated as separate runs
207      * if the attributes have been given to those text segments separately.
208      *
209      * @return the index of the first character of the run
210      */
211     public int getRunStart();
212 
213     /**
214      * Returns the index of the first character of the run
215      * with respect to the given {@code attribute} containing the current character.
216      *
217      * @param attribute the desired attribute.
218      * @return the index of the first character of the run
219      */
220     public int getRunStart(Attribute attribute);
221 
222     /**
223      * Returns the index of the first character of the run
224      * with respect to the given {@code attributes} containing the current character.
225      *
226      * @param attributes a set of the desired attributes.
227      * @return the index of the first character of the run
228      */
229     public int getRunStart(Set<? extends Attribute> attributes);
230 
231     /**
232      * Returns the index of the first character following the run
233      * with respect to all attributes containing the current character.
234      *
235      * <p>Any contiguous text segments having the same attributes (the
236      * same set of attribute/value pairs) are treated as separate runs
237      * if the attributes have been given to those text segments separately.
238      *
239      * @return the index of the first character following the run
240      */
241     public int getRunLimit();
242 
243     /**
244      * Returns the index of the first character following the run
245      * with respect to the given {@code attribute} containing the current character.
246      *
247      * @param attribute the desired attribute
248      * @return the index of the first character following the run
249      */
250     public int getRunLimit(Attribute attribute);
251 
252     /**
253      * Returns the index of the first character following the run
254      * with respect to the given {@code attributes} containing the current character.
255      *
256      * @param attributes a set of the desired attributes
257      * @return the index of the first character following the run
258      */
259     public int getRunLimit(Set<? extends Attribute> attributes);
260 
261     /**
262      * Returns a map with the attributes defined on the current
263      * character.
264      *
265      * @return a map with the attributes defined on the current character
266      */
267     public Map<Attribute,Object> getAttributes();
268 
269     /**
270      * Returns the value of the named {@code attribute} for the current character.
271      * Returns {@code null} if the {@code attribute} is not defined.
272      *
273      * @param attribute the desired attribute
274      * @return the value of the named {@code attribute} or {@code null}
275      */
276     public Object getAttribute(Attribute attribute);
277 
278     /**
279      * Returns the keys of all attributes defined on the
280      * iterator's text range. The set is empty if no
281      * attributes are defined.
282      *
283      * @return the keys of all attributes
284      */
285     public Set<Attribute> getAllAttributeKeys();
286 };