| /* CharArrayReader.java -- Read an array of characters as a stream |
| Copyright (C) 1998, 2001, 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.io; |
| |
| /** |
| * This class permits an array of chars to be read as an input stream. |
| * |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| * @author Warren Levy (warrenl@cygnus.com) |
| */ |
| public class CharArrayReader extends Reader |
| { |
| /** |
| * The array that contains the data supplied during read operations |
| */ |
| protected char[] buf; |
| |
| /** |
| * The array index of the next char to be read from the buffer |
| * <code>buf</code> |
| */ |
| protected int pos; |
| |
| /** |
| * The currently marked position in the stream. This defaults to 0, so a |
| * reset operation on the stream resets it to read from array index 0 in |
| * the buffer - even if the stream was initially created with an offset |
| * greater than 0 |
| */ |
| protected int markedPos; |
| |
| /** |
| * This indicates the maximum number of chars that can be read from this |
| * stream. It is the array index of the position after the last valid |
| * char in the buffer <code>buf</code> |
| */ |
| protected int count; |
| |
| /** |
| * Create a new CharArrayReader that will read chars from the passed |
| * in char array. This stream will read from the beginning to the end |
| * of the array. It is identical to calling an overloaded constructor |
| * as <code>CharArrayReader(buf, 0, buf.length)</code>. |
| * <p> |
| * Note that this array is not copied. If its contents are changed |
| * while this stream is being read, those changes will be reflected in the |
| * chars supplied to the reader. Please use caution in changing the |
| * contents of the buffer while this stream is open. |
| * |
| * @param buffer The char array buffer this stream will read from. |
| */ |
| public CharArrayReader(char[] buffer) |
| { |
| this(buffer, 0, buffer.length); |
| } |
| |
| /** |
| * Create a new CharArrayReader that will read chars from the passed |
| * in char array. This stream will read from position |
| * <code>offset</code> in the array for a length of |
| * <code>length</code> chars past <code>offset</code>. If the |
| * stream is reset to a position before <code>offset</code> then |
| * more than <code>length</code> chars can be read from the stream. |
| * The <code>length</code> value should be viewed as the array index |
| * one greater than the last position in the buffer to read. |
| * <p> |
| * Note that this array is not copied. If its contents are changed |
| * while this stream is being read, those changes will be reflected in the |
| * chars supplied to the reader. Please use caution in changing the |
| * contents of the buffer while this stream is open. |
| * |
| * @param buffer The char array buffer this stream will read from. |
| * @param offset The index into the buffer to start reading chars from |
| * @param length The number of chars to read from the buffer |
| */ |
| public CharArrayReader(char[] buffer, int offset, int length) |
| { |
| super(); |
| if (offset < 0 || length < 0 || offset > buffer.length) |
| throw new IllegalArgumentException(); |
| |
| buf = buffer; |
| |
| count = offset + length; |
| if (count > buf.length) |
| count = buf.length; |
| |
| pos = offset; |
| markedPos = pos; |
| } |
| |
| /** |
| * This method closes the stream. |
| */ |
| public void close() |
| { |
| synchronized (lock) |
| { |
| buf = null; |
| } |
| } |
| |
| /** |
| * This method sets the mark position in this stream to the current |
| * position. Note that the <code>readlimit</code> parameter in this |
| * method does nothing as this stream is always capable of |
| * remembering all the chars int it. |
| * <p> |
| * Note that in this class the mark position is set by default to |
| * position 0 in the stream. This is in constrast to some other |
| * stream types where there is no default mark position. |
| * |
| * @param readAheadLimit The number of chars this stream must |
| * remember. This parameter is ignored. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void mark(int readAheadLimit) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| // readAheadLimit is ignored per Java Class Lib. book, p. 318. |
| markedPos = pos; |
| } |
| } |
| |
| /** |
| * This method overrides the <code>markSupported</code> method in |
| * <code>Reader</code> in order to return <code>true</code> - |
| * indicating that this stream class supports mark/reset |
| * functionality. |
| * |
| * @return <code>true</code> to indicate that this class supports |
| * mark/reset. |
| */ |
| public boolean markSupported() |
| { |
| return true; |
| } |
| |
| /** |
| * This method reads one char from the stream. The <code>pos</code> |
| * counter is advanced to the next char to be read. The char read |
| * is returned as an int in the range of 0-65535. If the stream |
| * position is already at the end of the buffer, no char is read and |
| * a -1 is returned in order to indicate the end of the stream. |
| * |
| * @return The char read, or -1 if end of stream |
| */ |
| public int read() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| if (pos < 0) |
| throw new ArrayIndexOutOfBoundsException(pos); |
| |
| if (pos < count) |
| return ((int) buf[pos++]) & 0xFFFF; |
| return -1; |
| } |
| } |
| |
| /** |
| * This method reads chars from the stream and stores them into a |
| * caller supplied buffer. It starts storing the data at index |
| * <code>offset</code> into the buffer and attempts to read |
| * <code>len</code> chars. This method can return before reading |
| * the number of chars requested if the end of the stream is |
| * encountered first. The actual number of chars read is returned. |
| * If no chars can be read because the stream is already at the end |
| * of stream position, a -1 is returned. |
| * <p> |
| * This method does not block. |
| * |
| * @param b The array into which the chars read should be stored. |
| * @param off The offset into the array to start storing chars |
| * @param len The requested number of chars to read |
| * |
| * @return The actual number of chars read, or -1 if end of stream. |
| */ |
| public int read(char[] b, int off, int len) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| /* Don't need to check pos value, arraycopy will check it. */ |
| if (off < 0 || len < 0 || off + len > b.length) |
| throw new IndexOutOfBoundsException(); |
| |
| if (pos >= count) |
| return -1; |
| |
| int numChars = Math.min(count - pos, len); |
| System.arraycopy(buf, pos, b, off, numChars); |
| pos += numChars; |
| return numChars; |
| } |
| } |
| |
| /** |
| * Return true if more characters are available to be read. |
| * |
| * @return <code>true</code> to indicate that this stream is ready |
| * to be read. |
| * |
| * @specnote The JDK 1.3 API docs are wrong here. This method will |
| * return false if there are no more characters available. |
| */ |
| public boolean ready() throws IOException |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| return (pos < count); |
| } |
| |
| /** |
| * This method sets the read position in the stream to the mark |
| * point by setting the <code>pos</code> variable equal to the |
| * <code>mark</code> variable. Since a mark can be set anywhere in |
| * the array, the mark/reset methods int this class can be used to |
| * provide random search capabilities for this type of stream. |
| */ |
| public void reset() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| pos = markedPos; |
| } |
| } |
| |
| /** |
| * This method attempts to skip the requested number of chars in the |
| * input stream. It does this by advancing the <code>pos</code> value by the |
| * specified number of chars. It this would exceed the length of the |
| * buffer, then only enough chars are skipped to position the stream at |
| * the end of the buffer. The actual number of chars skipped is returned. |
| * |
| * @param n The requested number of chars to skip |
| * |
| * @return The actual number of chars skipped. |
| */ |
| public long skip(long n) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| // Even though the var numChars is a long, in reality it can never |
| // be larger than an int since the result of subtracting 2 positive |
| // ints will always fit in an int. Since we have to return a long |
| // anyway, numChars might as well just be a long. |
| long numChars = Math.min((long) (count - pos), n < 0 ? 0L : n); |
| pos += numChars; |
| return numChars; |
| } |
| } |
| } |