001 /* CharBuffer.java -- 002 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package java.nio; 040 041 import java.io.IOException; 042 043 /** 044 * @since 1.4 045 */ 046 public abstract class CharBuffer extends Buffer 047 implements Comparable<CharBuffer>, CharSequence, Readable, Appendable 048 { 049 int array_offset; 050 char[] backing_buffer; 051 052 CharBuffer (int capacity, int limit, int position, int mark) 053 { 054 super (capacity, limit, position, mark); 055 array_offset = 0; 056 } 057 058 /** 059 * Allocates a new <code>CharBuffer</code> object with a given capacity. 060 */ 061 public static CharBuffer allocate (int capacity) 062 { 063 return new CharBufferImpl (capacity); 064 } 065 066 /** 067 * Wraps a <code>char</code> array into a <code>CharBuffer</code> 068 * object. 069 * 070 * @param array the array to wrap 071 * @param offset the offset of the region in the array to wrap 072 * @param length the length of the region in the array to wrap 073 * 074 * @return a new <code>CharBuffer</code> object 075 * 076 * @exception IndexOutOfBoundsException If the preconditions on the offset 077 * and length parameters do not hold 078 */ 079 public static final CharBuffer wrap(char[] array, int offset, int length) 080 { 081 return new CharBufferImpl(array, 0, array.length, offset + length, offset, -1, false); 082 } 083 084 /** 085 * Wraps a character sequence into a <code>CharBuffer</code> object. 086 * 087 * @param seq the sequence to wrap 088 * 089 * @return a new <code>CharBuffer</code> object 090 */ 091 public static final CharBuffer wrap(CharSequence seq) 092 { 093 return wrap(seq, 0, seq.length()); 094 } 095 096 /** 097 * Wraps a character sequence into a <code>CharBuffer</code> object. 098 * 099 * @param seq the sequence to wrap 100 * @param start the index of the first character to wrap 101 * @param end the index of the first character not to wrap 102 * 103 * @return a new <code>CharBuffer</code> object 104 * 105 * @exception IndexOutOfBoundsException If the preconditions on the offset 106 * and length parameters do not hold 107 */ 108 public static final CharBuffer wrap(CharSequence seq, int start, int end) 109 { 110 return new CharSequenceBuffer(seq, start, end); 111 } 112 113 /** 114 * Wraps a <code>char</code> array into a <code>CharBuffer</code> 115 * object. 116 * 117 * @param array the array to wrap 118 * 119 * @return a new <code>CharBuffer</code> object 120 */ 121 public static final CharBuffer wrap(char[] array) 122 { 123 return wrap(array, 0, array.length); 124 } 125 126 /** 127 * This method transfers <code>char</code>s from this buffer into the given 128 * destination array. Before the transfer, it checks if there are fewer than 129 * length <code>char</code>s remaining in this buffer. 130 * 131 * @param dst The destination array 132 * @param offset The offset within the array of the first <code>char</code> 133 * to be written; must be non-negative and no larger than dst.length. 134 * @param length The maximum number of bytes to be written to the given array; 135 * must be non-negative and no larger than dst.length - offset. 136 * 137 * @exception BufferUnderflowException If there are fewer than length 138 * <code>char</code>s remaining in this buffer. 139 * @exception IndexOutOfBoundsException If the preconditions on the offset 140 * and length parameters do not hold. 141 */ 142 public CharBuffer get (char[] dst, int offset, int length) 143 { 144 checkArraySize(dst.length, offset, length); 145 checkForUnderflow(length); 146 147 for (int i = offset; i < offset + length; i++) 148 { 149 dst [i] = get (); 150 } 151 152 return this; 153 } 154 155 /** @since 1.5 */ 156 public int read(CharBuffer buffer) throws IOException 157 { 158 // We want to call put(), so we don't manipulate the CharBuffer 159 // directly. 160 int rem = Math.min(buffer.remaining(), remaining()); 161 char[] buf = new char[rem]; 162 get(buf); 163 buffer.put(buf); 164 return rem; 165 } 166 167 /** 168 * This method transfers <code>char</code>s from this buffer into the given 169 * destination array. 170 * 171 * @param dst The byte array to write into. 172 * 173 * @exception BufferUnderflowException If there are fewer than dst.length 174 * <code>char</code>s remaining in this buffer. 175 */ 176 public CharBuffer get (char[] dst) 177 { 178 return get (dst, 0, dst.length); 179 } 180 181 /** 182 * Writes the content of the the <code>CharBUFFER</code> src 183 * into the buffer. Before the transfer, it checks if there is fewer than 184 * <code>src.remaining()</code> space remaining in this buffer. 185 * 186 * @param src The source data. 187 * 188 * @exception BufferOverflowException If there is insufficient space in this 189 * buffer for the remaining <code>char</code>s in the source buffer. 190 * @exception IllegalArgumentException If the source buffer is this buffer. 191 * @exception ReadOnlyBufferException If this buffer is read-only. 192 */ 193 public CharBuffer put (CharBuffer src) 194 { 195 if (src == this) 196 throw new IllegalArgumentException (); 197 198 checkForOverflow(src.remaining()); 199 200 if (src.remaining () > 0) 201 { 202 char[] toPut = new char [src.remaining ()]; 203 src.get (toPut); 204 put (toPut); 205 } 206 207 return this; 208 } 209 210 /** 211 * Writes the content of the the <code>char array</code> src 212 * into the buffer. Before the transfer, it checks if there is fewer than 213 * length space remaining in this buffer. 214 * 215 * @param src The array to copy into the buffer. 216 * @param offset The offset within the array of the first byte to be read; 217 * must be non-negative and no larger than src.length. 218 * @param length The number of bytes to be read from the given array; 219 * must be non-negative and no larger than src.length - offset. 220 * 221 * @exception BufferOverflowException If there is insufficient space in this 222 * buffer for the remaining <code>char</code>s in the source array. 223 * @exception IndexOutOfBoundsException If the preconditions on the offset 224 * and length parameters do not hold 225 * @exception ReadOnlyBufferException If this buffer is read-only. 226 */ 227 public CharBuffer put (char[] src, int offset, int length) 228 { 229 checkArraySize(src.length, offset, length); 230 checkForOverflow(length); 231 232 for (int i = offset; i < offset + length; i++) 233 put (src [i]); 234 235 return this; 236 } 237 238 /** 239 * Writes the content of the the <code>char array</code> src 240 * into the buffer. 241 * 242 * @param src The array to copy into the buffer. 243 * 244 * @exception BufferOverflowException If there is insufficient space in this 245 * buffer for the remaining <code>char</code>s in the source array. 246 * @exception ReadOnlyBufferException If this buffer is read-only. 247 */ 248 public final CharBuffer put (char[] src) 249 { 250 return put (src, 0, src.length); 251 } 252 253 /** 254 * Tells whether ot not this buffer is backed by an accessible 255 * <code>char</code> array. 256 */ 257 public final boolean hasArray () 258 { 259 return (backing_buffer != null 260 && !isReadOnly ()); 261 } 262 263 /** 264 * Returns the <code>char</code> array that backs this buffer. 265 * 266 * @exception ReadOnlyBufferException If this buffer is read-only. 267 * @exception UnsupportedOperationException If this buffer is not backed 268 * by an accessible array. 269 */ 270 public final char[] array () 271 { 272 if (backing_buffer == null) 273 throw new UnsupportedOperationException (); 274 275 checkIfReadOnly(); 276 277 return backing_buffer; 278 } 279 280 /** 281 * Returns the offset within this buffer's backing array of the first element. 282 * 283 * @exception ReadOnlyBufferException If this buffer is read-only. 284 * @exception UnsupportedOperationException If this buffer is not backed 285 * by an accessible array. 286 */ 287 public final int arrayOffset () 288 { 289 if (backing_buffer == null) 290 throw new UnsupportedOperationException (); 291 292 checkIfReadOnly(); 293 294 return array_offset; 295 } 296 297 /** 298 * Calculates a hash code for this buffer. 299 * 300 * This is done with int arithmetic, 301 * where ** represents exponentiation, by this formula:<br> 302 * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... + 303 * (s[limit()-1]+30)*31**(limit()-1)</code>. 304 * Where s is the buffer data. Note that the hashcode is dependent 305 * on buffer content, and therefore is not useful if the buffer 306 * content may change. 307 */ 308 public int hashCode () 309 { 310 int hashCode = get(position()) + 31; 311 int multiplier = 1; 312 for (int i = position() + 1; i < limit(); ++i) 313 { 314 multiplier *= 31; 315 hashCode += (get(i) + 30)*multiplier; 316 } 317 return hashCode; 318 } 319 320 /** 321 * Checks if this buffer is equal to obj. 322 */ 323 public boolean equals (Object obj) 324 { 325 if (obj instanceof CharBuffer) 326 { 327 return compareTo ((CharBuffer) obj) == 0; 328 } 329 330 return false; 331 } 332 333 /** 334 * Compares two <code>CharBuffer</code> objects. 335 * 336 * @exception ClassCastException If obj is not an object derived from 337 * <code>CharBuffer</code>. 338 */ 339 public int compareTo (CharBuffer other) 340 { 341 int num = Math.min(remaining(), other.remaining()); 342 int pos_this = position(); 343 int pos_other = other.position(); 344 345 for (int count = 0; count < num; count++) 346 { 347 char a = get(pos_this++); 348 char b = other.get(pos_other++); 349 350 if (a == b) 351 continue; 352 353 if (a < b) 354 return -1; 355 356 return 1; 357 } 358 359 return remaining() - other.remaining(); 360 } 361 362 /** 363 * Returns the byte order of this buffer. 364 */ 365 public abstract ByteOrder order (); 366 367 /** 368 * Reads the <code>char</code> at this buffer's current position, 369 * and then increments the position. 370 * 371 * @exception BufferUnderflowException If there are no remaining 372 * <code>char</code>s in this buffer. 373 */ 374 public abstract char get (); 375 376 /** 377 * Writes the <code>char</code> at this buffer's current position, 378 * and then increments the position. 379 * 380 * @exception BufferOverflowException If there no remaining 381 * <code>char</code>s in this buffer. 382 * @exception ReadOnlyBufferException If this buffer is read-only. 383 */ 384 public abstract CharBuffer put (char b); 385 386 /** 387 * Absolute get method. 388 * 389 * @exception IndexOutOfBoundsException If index is negative or not smaller 390 * than the buffer's limit. 391 */ 392 public abstract char get (int index); 393 394 /** 395 * Absolute put method. 396 * 397 * @exception IndexOutOfBoundsException If index is negative or not smaller 398 * than the buffer's limit. 399 * @exception ReadOnlyBufferException If this buffer is read-only. 400 */ 401 public abstract CharBuffer put (int index, char b); 402 403 /** 404 * Compacts this buffer. 405 * 406 * @exception ReadOnlyBufferException If this buffer is read-only. 407 */ 408 public abstract CharBuffer compact (); 409 410 /** 411 * Tells wether or not this buffer is direct. 412 */ 413 public abstract boolean isDirect (); 414 415 /** 416 * Creates a new <code>CharBuffer</code> whose content is a shared 417 * subsequence of this buffer's content. 418 */ 419 public abstract CharBuffer slice (); 420 421 /** 422 * Creates a new <code>CharBuffer</code> that shares this buffer's 423 * content. 424 */ 425 public abstract CharBuffer duplicate (); 426 427 /** 428 * Creates a new read-only <code>CharBuffer</code> that shares this 429 * buffer's content. 430 */ 431 public abstract CharBuffer asReadOnlyBuffer (); 432 433 /** 434 * Returns the remaining content of the buffer as a string. 435 */ 436 public String toString () 437 { 438 if (hasArray ()) 439 return new String (array (), position (), length ()); 440 441 char[] buf = new char [length ()]; 442 int pos = position (); 443 get (buf, 0, buf.length); 444 position (pos); 445 return new String (buf); 446 } 447 448 /** 449 * Returns the length of the remaining chars in this buffer. 450 */ 451 public final int length () 452 { 453 return remaining (); 454 } 455 456 /** 457 * Creates a new character buffer that represents the specified subsequence 458 * of this buffer, relative to the current position. 459 * 460 * @exception IndexOutOfBoundsException If the preconditions on start and 461 * end do not hold. 462 */ 463 public abstract CharSequence subSequence (int start, int length); 464 465 /** 466 * Relative put method. 467 * 468 * @exception BufferOverflowException If there is insufficient space in this 469 * buffer. 470 * @exception IndexOutOfBoundsException If the preconditions on the start 471 * and end parameters do not hold. 472 * @exception ReadOnlyBufferException If this buffer is read-only. 473 */ 474 public CharBuffer put (String str, int start, int length) 475 { 476 return put (str.toCharArray (), start, length); 477 } 478 479 /** 480 * Relative put method. 481 * 482 * @exception BufferOverflowException If there is insufficient space in this 483 * buffer. 484 * @exception ReadOnlyBufferException If this buffer is read-only. 485 */ 486 public final CharBuffer put (String str) 487 { 488 return put (str.toCharArray (), 0, str.length ()); 489 } 490 491 /** 492 * Returns the character at <code>position() + index</code>. 493 * 494 * @exception IndexOutOfBoundsException If index is negative not smaller than 495 * <code>remaining()</code>. 496 */ 497 public final char charAt (int index) 498 { 499 if (index < 0 500 || index >= remaining ()) 501 throw new IndexOutOfBoundsException (); 502 503 return get (position () + index); 504 } 505 506 /** @since 1.5 */ 507 public CharBuffer append(char c) 508 { 509 put(c); 510 return this; 511 } 512 513 /** @since 1.5 */ 514 public CharBuffer append(CharSequence cs) 515 { 516 put(cs == null ? "null" : cs.toString()); 517 return this; 518 } 519 520 /** @since 1.5 */ 521 public CharBuffer append(CharSequence cs, int start, int end) 522 { 523 put(cs == null ? "null" : cs.subSequence(start, end).toString()); 524 return this; 525 } 526 }