001 /*
002 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025 package javax.swing.text;
026
027 import java.text.CharacterIterator;
028
029 /**
030 * A segment of a character array representing a fragment
031 * of text. It should be treated as immutable even though
032 * the array is directly accessible. This gives fast access
033 * to fragments of text without the overhead of copying
034 * around characters. This is effectively an unprotected
035 * String.
036 * <p>
037 * The Segment implements the java.text.CharacterIterator
038 * interface to support use with the i18n support without
039 * copying text into a string.
040 *
041 * @author Timothy Prinzing
042 * @version 1.31 05/05/07
043 */
044 public class Segment implements Cloneable, CharacterIterator,
045 CharSequence {
046
047 /**
048 * This is the array containing the text of
049 * interest. This array should never be modified;
050 * it is available only for efficiency.
051 */
052 public char[] array;
053
054 /**
055 * This is the offset into the array that
056 * the desired text begins.
057 */
058 public int offset;
059
060 /**
061 * This is the number of array elements that
062 * make up the text of interest.
063 */
064 public int count;
065
066 private boolean partialReturn;
067
068 /**
069 * Creates a new segment.
070 */
071 public Segment() {
072 this (null, 0, 0);
073 }
074
075 /**
076 * Creates a new segment referring to an existing array.
077 *
078 * @param array the array to refer to
079 * @param offset the offset into the array
080 * @param count the number of characters
081 */
082 public Segment(char[] array, int offset, int count) {
083 this .array = array;
084 this .offset = offset;
085 this .count = count;
086 partialReturn = false;
087 }
088
089 /**
090 * Flag to indicate that partial returns are valid. If the flag is true,
091 * an implementation of the interface method Document.getText(position,length,Segment)
092 * should return as much text as possible without making a copy. The default
093 * state of the flag is false which will cause Document.getText(position,length,Segment)
094 * to provide the same return behavior it always had, which may or may not
095 * make a copy of the text depending upon the request.
096 *
097 * @param p whether or not partial returns are valid.
098 * @since 1.4
099 */
100 public void setPartialReturn(boolean p) {
101 partialReturn = p;
102 }
103
104 /**
105 * Flag to indicate that partial returns are valid.
106 *
107 * @return whether or not partial returns are valid.
108 * @since 1.4
109 */
110 public boolean isPartialReturn() {
111 return partialReturn;
112 }
113
114 /**
115 * Converts a segment into a String.
116 *
117 * @return the string
118 */
119 public String toString() {
120 if (array != null) {
121 return new String(array, offset, count);
122 }
123 return new String();
124 }
125
126 // --- CharacterIterator methods -------------------------------------
127
128 /**
129 * Sets the position to getBeginIndex() and returns the character at that
130 * position.
131 * @return the first character in the text, or DONE if the text is empty
132 * @see #getBeginIndex
133 * @since 1.3
134 */
135 public char first() {
136 pos = offset;
137 if (count != 0) {
138 return array[pos];
139 }
140 return DONE;
141 }
142
143 /**
144 * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
145 * and returns the character at that position.
146 * @return the last character in the text, or DONE if the text is empty
147 * @see #getEndIndex
148 * @since 1.3
149 */
150 public char last() {
151 pos = offset + count;
152 if (count != 0) {
153 pos -= 1;
154 return array[pos];
155 }
156 return DONE;
157 }
158
159 /**
160 * Gets the character at the current position (as returned by getIndex()).
161 * @return the character at the current position or DONE if the current
162 * position is off the end of the text.
163 * @see #getIndex
164 * @since 1.3
165 */
166 public char current() {
167 if (count != 0 && pos < offset + count) {
168 return array[pos];
169 }
170 return DONE;
171 }
172
173 /**
174 * Increments the iterator's index by one and returns the character
175 * at the new index. If the resulting index is greater or equal
176 * to getEndIndex(), the current index is reset to getEndIndex() and
177 * a value of DONE is returned.
178 * @return the character at the new position or DONE if the new
179 * position is off the end of the text range.
180 * @since 1.3
181 */
182 public char next() {
183 pos += 1;
184 int end = offset + count;
185 if (pos >= end) {
186 pos = end;
187 return DONE;
188 }
189 return current();
190 }
191
192 /**
193 * Decrements the iterator's index by one and returns the character
194 * at the new index. If the current index is getBeginIndex(), the index
195 * remains at getBeginIndex() and a value of DONE is returned.
196 * @return the character at the new position or DONE if the current
197 * position is equal to getBeginIndex().
198 * @since 1.3
199 */
200 public char previous() {
201 if (pos == offset) {
202 return DONE;
203 }
204 pos -= 1;
205 return current();
206 }
207
208 /**
209 * Sets the position to the specified position in the text and returns that
210 * character.
211 * @param position the position within the text. Valid values range from
212 * getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown
213 * if an invalid value is supplied.
214 * @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
215 * @since 1.3
216 */
217 public char setIndex(int position) {
218 int end = offset + count;
219 if ((position < offset) || (position > end)) {
220 throw new IllegalArgumentException("bad position: "
221 + position);
222 }
223 pos = position;
224 if ((pos != end) && (count != 0)) {
225 return array[pos];
226 }
227 return DONE;
228 }
229
230 /**
231 * Returns the start index of the text.
232 * @return the index at which the text begins.
233 * @since 1.3
234 */
235 public int getBeginIndex() {
236 return offset;
237 }
238
239 /**
240 * Returns the end index of the text. This index is the index of the first
241 * character following the end of the text.
242 * @return the index after the last character in the text
243 * @since 1.3
244 */
245 public int getEndIndex() {
246 return offset + count;
247 }
248
249 /**
250 * Returns the current index.
251 * @return the current index.
252 * @since 1.3
253 */
254 public int getIndex() {
255 return pos;
256 }
257
258 // --- CharSequence methods -------------------------------------
259
260 /**
261 * {@inheritDoc}
262 * @since 1.6
263 */
264 public char charAt(int index) {
265 if (index < 0 || index >= count) {
266 throw new StringIndexOutOfBoundsException(index);
267 }
268 return array[offset + index];
269 }
270
271 /**
272 * {@inheritDoc}
273 * @since 1.6
274 */
275 public int length() {
276 return count;
277 }
278
279 /**
280 * {@inheritDoc}
281 * @since 1.6
282 */
283 public CharSequence subSequence(int start, int end) {
284 if (start < 0) {
285 throw new StringIndexOutOfBoundsException(start);
286 }
287 if (end > count) {
288 throw new StringIndexOutOfBoundsException(end);
289 }
290 if (start > end) {
291 throw new StringIndexOutOfBoundsException(end - start);
292 }
293 Segment segment = new Segment();
294 segment.array = this .array;
295 segment.offset = this .offset + start;
296 segment.count = end - start;
297 return segment;
298 }
299
300 /**
301 * Creates a shallow copy.
302 *
303 * @return the copy
304 */
305 public Object clone() {
306 Object o;
307 try {
308 o = super .clone();
309 } catch (CloneNotSupportedException cnse) {
310 o = null;
311 }
312 return o;
313 }
314
315 private int pos;
316
317 }
|