J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | package javax.swing.text; |
| 26 | |
| 27 | import java.text.CharacterIterator; |
| 28 | |
| 29 | /** |
| 30 | * A segment of a character array representing a fragment |
| 31 | * of text. It should be treated as immutable even though |
| 32 | * the array is directly accessible. This gives fast access |
| 33 | * to fragments of text without the overhead of copying |
| 34 | * around characters. This is effectively an unprotected |
| 35 | * String. |
| 36 | * <p> |
| 37 | * The Segment implements the java.text.CharacterIterator |
| 38 | * interface to support use with the i18n support without |
| 39 | * copying text into a string. |
| 40 | * |
| 41 | * @author Timothy Prinzing |
| 42 | */ |
| 43 | public class Segment implements Cloneable, CharacterIterator, CharSequence { |
| 44 | |
| 45 | /** |
| 46 | * This is the array containing the text of |
| 47 | * interest. This array should never be modified; |
| 48 | * it is available only for efficiency. |
| 49 | */ |
| 50 | public char[] array; |
| 51 | |
| 52 | /** |
| 53 | * This is the offset into the array that |
| 54 | * the desired text begins. |
| 55 | */ |
| 56 | public int offset; |
| 57 | |
| 58 | /** |
| 59 | * This is the number of array elements that |
| 60 | * make up the text of interest. |
| 61 | */ |
| 62 | public int count; |
| 63 | |
| 64 | private boolean partialReturn; |
| 65 | |
| 66 | /** |
| 67 | * Creates a new segment. |
| 68 | */ |
| 69 | public Segment() { |
| 70 | this(null, 0, 0); |
| 71 | } |
| 72 | |
| 73 | /** |
| 74 | * Creates a new segment referring to an existing array. |
| 75 | * |
| 76 | * @param array the array to refer to |
| 77 | * @param offset the offset into the array |
| 78 | * @param count the number of characters |
| 79 | */ |
| 80 | public Segment(char[] array, int offset, int count) { |
| 81 | this.array = array; |
| 82 | this.offset = offset; |
| 83 | this.count = count; |
| 84 | partialReturn = false; |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Flag to indicate that partial returns are valid. If the flag is true, |
| 89 | * an implementation of the interface method Document.getText(position,length,Segment) |
| 90 | * should return as much text as possible without making a copy. The default |
| 91 | * state of the flag is false which will cause Document.getText(position,length,Segment) |
| 92 | * to provide the same return behavior it always had, which may or may not |
| 93 | * make a copy of the text depending upon the request. |
| 94 | * |
| 95 | * @param p whether or not partial returns are valid. |
| 96 | * @since 1.4 |
| 97 | */ |
| 98 | public void setPartialReturn(boolean p) { |
| 99 | partialReturn = p; |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * Flag to indicate that partial returns are valid. |
| 104 | * |
| 105 | * @return whether or not partial returns are valid. |
| 106 | * @since 1.4 |
| 107 | */ |
| 108 | public boolean isPartialReturn() { |
| 109 | return partialReturn; |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Converts a segment into a String. |
| 114 | * |
| 115 | * @return the string |
| 116 | */ |
| 117 | public String toString() { |
| 118 | if (array != null) { |
| 119 | return new String(array, offset, count); |
| 120 | } |
| 121 | return new String(); |
| 122 | } |
| 123 | |
| 124 | // --- CharacterIterator methods ------------------------------------- |
| 125 | |
| 126 | /** |
| 127 | * Sets the position to getBeginIndex() and returns the character at that |
| 128 | * position. |
| 129 | * @return the first character in the text, or DONE if the text is empty |
| 130 | * @see #getBeginIndex |
| 131 | * @since 1.3 |
| 132 | */ |
| 133 | public char first() { |
| 134 | pos = offset; |
| 135 | if (count != 0) { |
| 136 | return array[pos]; |
| 137 | } |
| 138 | return DONE; |
| 139 | } |
| 140 | |
| 141 | /** |
| 142 | * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty) |
| 143 | * and returns the character at that position. |
| 144 | * @return the last character in the text, or DONE if the text is empty |
| 145 | * @see #getEndIndex |
| 146 | * @since 1.3 |
| 147 | */ |
| 148 | public char last() { |
| 149 | pos = offset + count; |
| 150 | if (count != 0) { |
| 151 | pos -= 1; |
| 152 | return array[pos]; |
| 153 | } |
| 154 | return DONE; |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Gets the character at the current position (as returned by getIndex()). |
| 159 | * @return the character at the current position or DONE if the current |
| 160 | * position is off the end of the text. |
| 161 | * @see #getIndex |
| 162 | * @since 1.3 |
| 163 | */ |
| 164 | public char current() { |
| 165 | if (count != 0 && pos < offset + count) { |
| 166 | return array[pos]; |
| 167 | } |
| 168 | return DONE; |
| 169 | } |
| 170 | |
| 171 | /** |
| 172 | * Increments the iterator's index by one and returns the character |
| 173 | * at the new index. If the resulting index is greater or equal |
| 174 | * to getEndIndex(), the current index is reset to getEndIndex() and |
| 175 | * a value of DONE is returned. |
| 176 | * @return the character at the new position or DONE if the new |
| 177 | * position is off the end of the text range. |
| 178 | * @since 1.3 |
| 179 | */ |
| 180 | public char next() { |
| 181 | pos += 1; |
| 182 | int end = offset + count; |
| 183 | if (pos >= end) { |
| 184 | pos = end; |
| 185 | return DONE; |
| 186 | } |
| 187 | return current(); |
| 188 | } |
| 189 | |
| 190 | /** |
| 191 | * Decrements the iterator's index by one and returns the character |
| 192 | * at the new index. If the current index is getBeginIndex(), the index |
| 193 | * remains at getBeginIndex() and a value of DONE is returned. |
| 194 | * @return the character at the new position or DONE if the current |
| 195 | * position is equal to getBeginIndex(). |
| 196 | * @since 1.3 |
| 197 | */ |
| 198 | public char previous() { |
| 199 | if (pos == offset) { |
| 200 | return DONE; |
| 201 | } |
| 202 | pos -= 1; |
| 203 | return current(); |
| 204 | } |
| 205 | |
| 206 | /** |
| 207 | * Sets the position to the specified position in the text and returns that |
| 208 | * character. |
| 209 | * @param position the position within the text. Valid values range from |
| 210 | * getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown |
| 211 | * if an invalid value is supplied. |
| 212 | * @return the character at the specified position or DONE if the specified position is equal to getEndIndex() |
| 213 | * @since 1.3 |
| 214 | */ |
| 215 | public char setIndex(int position) { |
| 216 | int end = offset + count; |
| 217 | if ((position < offset) || (position > end)) { |
| 218 | throw new IllegalArgumentException("bad position: " + position); |
| 219 | } |
| 220 | pos = position; |
| 221 | if ((pos != end) && (count != 0)) { |
| 222 | return array[pos]; |
| 223 | } |
| 224 | return DONE; |
| 225 | } |
| 226 | |
| 227 | /** |
| 228 | * Returns the start index of the text. |
| 229 | * @return the index at which the text begins. |
| 230 | * @since 1.3 |
| 231 | */ |
| 232 | public int getBeginIndex() { |
| 233 | return offset; |
| 234 | } |
| 235 | |
| 236 | /** |
| 237 | * Returns the end index of the text. This index is the index of the first |
| 238 | * character following the end of the text. |
| 239 | * @return the index after the last character in the text |
| 240 | * @since 1.3 |
| 241 | */ |
| 242 | public int getEndIndex() { |
| 243 | return offset + count; |
| 244 | } |
| 245 | |
| 246 | /** |
| 247 | * Returns the current index. |
| 248 | * @return the current index. |
| 249 | * @since 1.3 |
| 250 | */ |
| 251 | public int getIndex() { |
| 252 | return pos; |
| 253 | } |
| 254 | |
| 255 | // --- CharSequence methods ------------------------------------- |
| 256 | |
| 257 | /** |
| 258 | * {@inheritDoc} |
| 259 | * @since 1.6 |
| 260 | */ |
| 261 | public char charAt(int index) { |
| 262 | if (index < 0 |
| 263 | || index >= count) { |
| 264 | throw new StringIndexOutOfBoundsException(index); |
| 265 | } |
| 266 | return array[offset + index]; |
| 267 | } |
| 268 | |
| 269 | /** |
| 270 | * {@inheritDoc} |
| 271 | * @since 1.6 |
| 272 | */ |
| 273 | public int length() { |
| 274 | return count; |
| 275 | } |
| 276 | |
| 277 | /** |
| 278 | * {@inheritDoc} |
| 279 | * @since 1.6 |
| 280 | */ |
| 281 | public CharSequence subSequence(int start, int end) { |
| 282 | if (start < 0) { |
| 283 | throw new StringIndexOutOfBoundsException(start); |
| 284 | } |
| 285 | if (end > count) { |
| 286 | throw new StringIndexOutOfBoundsException(end); |
| 287 | } |
| 288 | if (start > end) { |
| 289 | throw new StringIndexOutOfBoundsException(end - start); |
| 290 | } |
| 291 | Segment segment = new Segment(); |
| 292 | segment.array = this.array; |
| 293 | segment.offset = this.offset + start; |
| 294 | segment.count = end - start; |
| 295 | return segment; |
| 296 | } |
| 297 | |
| 298 | /** |
| 299 | * Creates a shallow copy. |
| 300 | * |
| 301 | * @return the copy |
| 302 | */ |
| 303 | public Object clone() { |
| 304 | Object o; |
| 305 | try { |
| 306 | o = super.clone(); |
| 307 | } catch (CloneNotSupportedException cnse) { |
| 308 | o = null; |
| 309 | } |
| 310 | return o; |
| 311 | } |
| 312 | |
| 313 | private int pos; |
| 314 | |
| 315 | |
| 316 | } |