1 /*
2 * Copyright (c) 1996, 2000, 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 /*
27 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
28 * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved
29 *
30 * The original version of this source code and documentation
31 * is copyrighted and owned by Taligent, Inc., a wholly-owned
32 * subsidiary of IBM. These materials are provided under terms
33 * of a License Agreement between Taligent and Sun. This technology
34 * is protected by multiple US and International patents.
35 *
36 * This notice and attribution to Taligent may not be removed.
37 * Taligent is a registered trademark of Taligent, Inc.
38 *
39 */
40
41 package java.text;
42
43
44 /**
45 * This interface defines a protocol for bidirectional iteration over text.
46 * The iterator iterates over a bounded sequence of characters. Characters
47 * are indexed with values beginning with the value returned by getBeginIndex() and
48 * continuing through the value returned by getEndIndex()-1.
49 * <p>
50 * Iterators maintain a current character index, whose valid range is from
51 * getBeginIndex() to getEndIndex(); the value getEndIndex() is included to allow
52 * handling of zero-length text ranges and for historical reasons.
53 * The current index can be retrieved by calling getIndex() and set directly
54 * by calling setIndex(), first(), and last().
55 * <p>
56 * The methods previous() and next() are used for iteration. They return DONE if
57 * they would move outside the range from getBeginIndex() to getEndIndex() -1,
58 * signaling that the iterator has reached the end of the sequence. DONE is
59 * also returned by other methods to indicate that the current index is
60 * outside this range.
61 *
62 * <P>Examples:<P>
63 *
64 * Traverse the text from start to finish
65 * <pre>
66 * public void traverseForward(CharacterIterator iter) {
67 * for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
68 * processChar(c);
69 * }
70 * }
71 * </pre>
72 *
73 * Traverse the text backwards, from end to start
74 * <pre>
75 * public void traverseBackward(CharacterIterator iter) {
76 * for(char c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) {
77 * processChar(c);
78 * }
79 * }
80 * </pre>
81 *
82 * Traverse both forward and backward from a given position in the text.
83 * Calls to notBoundary() in this example represents some
84 * additional stopping criteria.
85 * <pre>
86 * public void traverseOut(CharacterIterator iter, int pos) {
87 * for (char c = iter.setIndex(pos);
88 * c != CharacterIterator.DONE && notBoundary(c);
89 * c = iter.next()) {
90 * }
91 * int end = iter.getIndex();
92 * for (char c = iter.setIndex(pos);
93 * c != CharacterIterator.DONE && notBoundary(c);
94 * c = iter.previous()) {
95 * }
96 * int start = iter.getIndex();
97 * processSection(start, end);
98 * }
99 * </pre>
100 *
101 * @see StringCharacterIterator
102 * @see AttributedCharacterIterator
103 */
104
105 public interface CharacterIterator extends Cloneable
106 {
107
108 /**
109 * Constant that is returned when the iterator has reached either the end
110 * or the beginning of the text. The value is '\\uFFFF', the "not a
111 * character" value which should not occur in any valid Unicode string.
112 */
113 public static final char DONE = '\uFFFF';
114
115 /**
116 * Sets the position to getBeginIndex() and returns the character at that
117 * position.
118 * @return the first character in the text, or DONE if the text is empty
119 * @see #getBeginIndex()
120 */
121 public char first();
122
123 /**
124 * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
125 * and returns the character at that position.
126 * @return the last character in the text, or DONE if the text is empty
127 * @see #getEndIndex()
128 */
129 public char last();
130
131 /**
132 * Gets the character at the current position (as returned by getIndex()).
133 * @return the character at the current position or DONE if the current
134 * position is off the end of the text.
135 * @see #getIndex()
136 */
137 public char current();
138
139 /**
140 * Increments the iterator's index by one and returns the character
141 * at the new index. If the resulting index is greater or equal
142 * to getEndIndex(), the current index is reset to getEndIndex() and
143 * a value of DONE is returned.
144 * @return the character at the new position or DONE if the new
145 * position is off the end of the text range.
146 */
147 public char next();
148
149 /**
150 * Decrements the iterator's index by one and returns the character
151 * at the new index. If the current index is getBeginIndex(), the index
152 * remains at getBeginIndex() and a value of DONE is returned.
153 * @return the character at the new position or DONE if the current
154 * position is equal to getBeginIndex().
155 */
156 public char previous();
157
158 /**
159 * Sets the position to the specified position in the text and returns that
160 * character.
161 * @param position the position within the text. Valid values range from
162 * getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown
163 * if an invalid value is supplied.
164 * @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
165 */
166 public char setIndex(int position);
167
168 /**
169 * Returns the start index of the text.
170 * @return the index at which the text begins.
171 */
172 public int getBeginIndex();
173
174 /**
175 * Returns the end index of the text. This index is the index of the first
176 * character following the end of the text.
177 * @return the index after the last character in the text
178 */
179 public int getEndIndex();
180
181 /**
182 * Returns the current index.
183 * @return the current index.
184 */
185 public int getIndex();
186
187 /**
188 * Create a copy of this iterator
189 * @return A copy of this
190 */
191 public Object clone();
192
193 }