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1: /* CharArrayWriter.java -- Write chars to a buffer 2: Copyright (C) 1998, 1999, 2001, 2002, 2005 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package java.io; 40: 41: /** 42: * This class allows data to be written to a char array buffer and 43: * and then retrieved by an application. The internal char array 44: * buffer is dynamically resized to hold all the data written. Please 45: * be aware that writing large amounts to data to this stream will 46: * cause large amounts of memory to be allocated. 47: * <p> 48: * The size of the internal buffer defaults to 32 and it is resized 49: * in increments of 1024 chars. This behavior can be over-ridden by using the 50: * following two properties: 51: * <p> 52: * <ul> 53: * <li><xmp>gnu.java.io.CharArrayWriter.initialBufferSize</xmp></li> 54: * <li><xmp>gnu.java.io.CharArrayWriter.bufferIncrementSize</xmp></li> 55: * </ul> 56: * <p> 57: * There is a constructor that specified the initial buffer size and 58: * that is the preferred way to set that value because it it portable 59: * across all Java class library implementations. 60: * <p> 61: * 62: * @author Aaron M. Renn (arenn@urbanophile.com) 63: * @author Tom Tromey (tromey@cygnus.com) 64: */ 65: public class CharArrayWriter extends Writer 66: { 67: /** 68: * The default initial buffer size 69: */ 70: private static final int DEFAULT_INITIAL_BUFFER_SIZE = 32; 71: 72: /** 73: * This method initializes a new <code>CharArrayWriter</code> with 74: * the default buffer size of 32 chars. If a different initial 75: * buffer size is desired, see the constructor 76: * <code>CharArrayWriter(int size)</code>. 77: */ 78: public CharArrayWriter () 79: { 80: this (DEFAULT_INITIAL_BUFFER_SIZE); 81: } 82: 83: /** 84: * This method initializes a new <code>CharArrayWriter</code> with 85: * a specified initial buffer size. 86: * 87: * @param size The initial buffer size in chars 88: */ 89: public CharArrayWriter (int size) 90: { 91: super (); 92: buf = new char[size]; 93: } 94: 95: /** 96: * Closes the stream. This method is guaranteed not to free the contents 97: * of the internal buffer, which can still be retrieved. 98: */ 99: public void close () 100: { 101: } 102: 103: /** 104: * This method flushes all buffered chars to the stream. 105: */ 106: public void flush () 107: { 108: } 109: 110: /** 111: * This method discards all of the chars that have been written to the 112: * internal buffer so far by setting the <code>count</code> variable to 113: * 0. The internal buffer remains at its currently allocated size. 114: */ 115: public void reset () 116: { 117: synchronized (lock) 118: { 119: count = 0; 120: } 121: } 122: 123: /** 124: * This method returns the number of chars that have been written to 125: * the buffer so far. This is the same as the value of the protected 126: * <code>count</code> variable. If the <code>reset</code> method is 127: * called, then this value is reset as well. Note that this method does 128: * not return the length of the internal buffer, but only the number 129: * of chars that have been written to it. 130: * 131: * @return The number of chars in the internal buffer 132: * 133: * @see #reset() 134: */ 135: public int size () 136: { 137: return count; 138: } 139: 140: /** 141: * This method returns a char array containing the chars that have been 142: * written to this stream so far. This array is a copy of the valid 143: * chars in the internal buffer and its length is equal to the number of 144: * valid chars, not necessarily to the the length of the current 145: * internal buffer. Note that since this method allocates a new array, 146: * it should be used with caution when the internal buffer is very large. 147: */ 148: public char[] toCharArray () 149: { 150: synchronized (lock) 151: { 152: char[] nc = new char[count]; 153: System.arraycopy(buf, 0, nc, 0, count); 154: return nc; 155: } 156: } 157: 158: /** 159: * Returns the chars in the internal array as a <code>String</code>. The 160: * chars in the buffer are converted to characters using the system default 161: * encoding. There is an overloaded <code>toString()</code> method that 162: * allows an application specified character encoding to be used. 163: * 164: * @return A <code>String</code> containing the data written to this 165: * stream so far 166: */ 167: public String toString () 168: { 169: synchronized (lock) 170: { 171: return new String (buf, 0, count); 172: } 173: } 174: 175: /** 176: * This method writes the writes the specified char into the internal 177: * buffer. 178: * 179: * @param oneChar The char to be read passed as an int 180: */ 181: public void write (int oneChar) 182: { 183: synchronized (lock) 184: { 185: resize (1); 186: buf[count++] = (char) oneChar; 187: } 188: } 189: 190: /** 191: * This method writes <code>len</code> chars from the passed in array 192: * <code>buf</code> starting at index <code>offset</code> into that buffer 193: * 194: * @param buffer The char array to write data from 195: * @param offset The index into the buffer to start writing data from 196: * @param len The number of chars to write 197: */ 198: public void write (char[] buffer, int offset, int len) 199: { 200: synchronized (lock) 201: { 202: if (len >= 0) 203: resize (len); 204: System.arraycopy(buffer, offset, buf, count, len); 205: count += len; 206: } 207: } 208: 209: /** 210: * This method writes <code>len</code> chars from the passed in 211: * <code>String</code> <code>buf</code> starting at index 212: * <code>offset</code> into the internal buffer. 213: * 214: * @param str The <code>String</code> to write data from 215: * @param offset The index into the string to start writing data from 216: * @param len The number of chars to write 217: */ 218: public void write (String str, int offset, int len) 219: { 220: synchronized (lock) 221: { 222: if (len >= 0) 223: resize (len); 224: str.getChars(offset, offset + len, buf, count); 225: count += len; 226: } 227: } 228: 229: /** 230: * This method writes all the chars that have been written to this stream 231: * from the internal buffer to the specified <code>Writer</code>. 232: * 233: * @param out The <code>Writer</code> to write to 234: * 235: * @exception IOException If an error occurs 236: */ 237: public void writeTo (Writer out) throws IOException 238: { 239: synchronized (lock) 240: { 241: out.write(buf, 0, count); 242: } 243: } 244: 245: /** 246: * Appends the Unicode character, <code>c</code>, to the output stream 247: * underlying this writer. This is equivalent to <code>write(c)</code>. 248: * 249: * @param c the character to append. 250: * @return a reference to this object. 251: * @since 1.5 252: */ 253: public CharArrayWriter append(char c) 254: { 255: write(c); 256: return this; 257: } 258: 259: /** 260: * Appends the specified sequence of Unicode characters to the 261: * output stream underlying this writer. This is equivalent to 262: * appending the results of calling <code>toString()</code> on the 263: * character sequence. As a result, the entire sequence may not be 264: * appended, as it depends on the implementation of 265: * <code>toString()</code> provided by the 266: * <code>CharSequence</code>. For example, if the character 267: * sequence is wrapped around an input buffer, the results will 268: * depend on the current position and length of that buffer. 269: * 270: * @param cs the character sequence to append. If seq is null, 271: * then the string "null" (the string representation of null) 272: * is appended. 273: * @return a reference to this object. 274: * @since 1.5 275: */ 276: public CharArrayWriter append(CharSequence cs) 277: { 278: try 279: { 280: write(cs == null ? "null" : cs.toString()); 281: } 282: catch (IOException _) 283: { 284: // Can't happen. 285: } 286: return this; 287: } 288: 289: /** 290: * Appends the specified subsequence of Unicode characters to the 291: * output stream underlying this writer, starting and ending at the 292: * specified positions within the sequence. The behaviour of this 293: * method matches the behaviour of writing the result of 294: * <code>append(seq.subSequence(start,end))</code> when the sequence 295: * is not null. 296: * 297: * @param cs the character sequence to append. If seq is null, 298: * then the string "null" (the string representation of null) 299: * is appended. 300: * @param start the index of the first Unicode character to use from 301: * the sequence. 302: * @param end the index of the last Unicode character to use from the 303: * sequence. 304: * @return a reference to this object. 305: * @throws IndexOutOfBoundsException if either of the indices are negative, 306: * the start index occurs after the end index, or the end index is 307: * beyond the end of the sequence. 308: * @since 1.5 309: */ 310: public CharArrayWriter append(CharSequence cs, int start, int end) 311: { 312: try 313: { 314: write(cs == null ? "null" : cs.subSequence(start, end).toString()); 315: } 316: catch (IOException _) 317: { 318: // Can't happen. 319: } 320: return this; 321: } 322: 323: /** 324: * This private method makes the buffer bigger when we run out of room 325: * by allocating a larger buffer and copying the valid chars from the 326: * old array into it. This is obviously slow and should be avoided by 327: * application programmers by setting their initial buffer size big 328: * enough to hold everything if possible. 329: */ 330: private void resize (int len) 331: { 332: if (count + len >= buf.length) 333: { 334: int newlen = buf.length * 2; 335: if (count + len > newlen) 336: newlen = count + len; 337: char[] newbuf = new char[newlen]; 338: System.arraycopy(buf, 0, newbuf, 0, count); 339: buf = newbuf; 340: } 341: } 342: 343: /** 344: * The internal buffer where the data written is stored 345: */ 346: protected char[] buf; 347: 348: /** 349: * The number of chars that have been written to the buffer 350: */ 351: protected int count; 352: }