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Diffstat (limited to 'libjava/classpath/java/io/PushbackInputStream.java')
| -rw-r--r-- | libjava/classpath/java/io/PushbackInputStream.java | 335 |
1 files changed, 0 insertions, 335 deletions
diff --git a/libjava/classpath/java/io/PushbackInputStream.java b/libjava/classpath/java/io/PushbackInputStream.java deleted file mode 100644 index 6273787..0000000 --- a/libjava/classpath/java/io/PushbackInputStream.java +++ /dev/null @@ -1,335 +0,0 @@ -/* PushbackInputStream.java -- An input stream that can unread bytes - Copyright (C) 1998, 1999, 2001, 2002, 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 subclass of <code>FilterInputStream</code> provides the ability to - * unread data from a stream. It maintains an internal buffer of unread - * data that is supplied to the next read operation. This is conceptually - * similar to mark/reset functionality, except that in this case the - * position to reset the stream to does not need to be known in advance. - * <p> - * The default pushback buffer size one byte, but this can be overridden - * by the creator of the stream. - * <p> - * - * @author Aaron M. Renn (arenn@urbanophile.com) - * @author Warren Levy (warrenl@cygnus.com) - */ -public class PushbackInputStream extends FilterInputStream -{ - /** - * This is the default buffer size - */ - private static final int DEFAULT_BUFFER_SIZE = 1; - - /** - * This is the buffer that is used to store the pushed back data - */ - protected byte[] buf; - - /** - * This is the position in the buffer from which the next byte will be - * read. Bytes are stored in reverse order in the buffer, starting from - * <code>buf[buf.length - 1]</code> to <code>buf[0]</code>. Thus when - * <code>pos</code> is 0 the buffer is full and <code>buf.length</code> when - * it is empty - */ - protected int pos; - - /** - * This method initializes a <code>PushbackInputStream</code> to - * read from the specified subordinate <code>InputStream</code> - * with a default pushback buffer size of 1. - * - * @param in The subordinate stream to read from - */ - public PushbackInputStream(InputStream in) - { - this(in, DEFAULT_BUFFER_SIZE); - } - - /** - * This method initializes a <code>PushbackInputStream</code> to - * read from the specified subordinate <code>InputStream</code> with - * the specified buffer size - * - * @param in The subordinate <code>InputStream</code> to read from - * @param size The pushback buffer size to use - */ - public PushbackInputStream(InputStream in, int size) - { - super(in); - if (size < 0) - throw new IllegalArgumentException(); - buf = new byte[size]; - pos = buf.length; - } - - /** - * This method returns the number of bytes that can be read from this - * stream before a read can block. A return of 0 indicates that blocking - * might (or might not) occur on the very next read attempt. - * <p> - * This method will return the number of bytes available from the - * pushback buffer plus the number of bytes available from the - * underlying stream. - * - * @return The number of bytes that can be read before blocking could occur - * - * @exception IOException If an error occurs - */ - public int available() throws IOException - { - try - { - return (buf.length - pos) + super.available(); - } - catch (NullPointerException npe) - { - throw new IOException ("Stream closed"); - } - } - - /** - * This method closes the stream and releases any associated resources. - * - * @exception IOException If an error occurs. - */ - public synchronized void close() throws IOException - { - buf = null; - super.close(); - } - - /** - * This method returns <code>false</code> to indicate that it does - * not support mark/reset functionality. - * - * @return This method returns <code>false</code> to indicate that - * this class does not support mark/reset functionality - */ - public boolean markSupported() - { - return false; - } - - /** - * This method always throws an IOException in this class because - * mark/reset functionality is not supported. - * - * @exception IOException Always thrown for this class - */ - public void reset() throws IOException - { - throw new IOException("Mark not supported in this class"); - } - - /** - * This method reads an unsigned byte from the input stream and returns it - * as an int in the range of 0-255. This method also will return -1 if - * the end of the stream has been reached. The byte returned will be read - * from the pushback buffer, unless the buffer is empty, in which case - * the byte will be read from the underlying stream. - * <p> - * This method will block until the byte can be read. - * - * @return The byte read or -1 if end of stream - * - * @exception IOException If an error occurs - */ - public synchronized int read() throws IOException - { - if (pos < buf.length) - return ((int) buf[pos++]) & 0xFF; - - return super.read(); - } - - /** - * This method read bytes from a 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> bytes. This method can return before reading the - * number of bytes requested. The actual number of bytes read is - * returned as an int. A -1 is returned to indicate the end of the - * stream. - * <p> - * This method will block until some data can be read. - * <p> - * This method first reads bytes from the pushback buffer in order to - * satisfy the read request. If the pushback buffer cannot provide all - * of the bytes requested, the remaining bytes are read from the - * underlying stream. - * - * @param b The array into which the bytes read should be stored - * @param off The offset into the array to start storing bytes - * @param len The requested number of bytes to read - * - * @return The actual number of bytes read, or -1 if end of stream. - * - * @exception IOException If an error occurs. - */ - public synchronized int read(byte[] b, int off, int len) throws IOException - { - int numBytes = Math.min(buf.length - pos, len); - - if (numBytes > 0) - { - System.arraycopy (buf, pos, b, off, numBytes); - pos += numBytes; - len -= numBytes; - off += numBytes; - } - - if (len > 0) - { - len = super.read(b, off, len); - if (len == -1) //EOF - return numBytes > 0 ? numBytes : -1; - numBytes += len; - } - return numBytes; - } - - /** - * This method pushes a single byte of data into the pushback buffer. - * The byte pushed back is the one that will be returned as the first byte - * of the next read. - * <p> - * If the pushback buffer is full, this method throws an exception. - * <p> - * The argument to this method is an <code>int</code>. Only the low - * eight bits of this value are pushed back. - * - * @param b The byte to be pushed back, passed as an int - * - * @exception IOException If the pushback buffer is full. - */ - public synchronized void unread(int b) throws IOException - { - if (pos <= 0) - throw new IOException("Insufficient space in pushback buffer"); - - buf[--pos] = (byte) b; - } - - /** - * This method pushes all of the bytes in the passed byte array into - * the pushback bfer. These bytes are pushed in reverse order so that - * the next byte read from the stream after this operation will be - * <code>b[0]</code> followed by <code>b[1]</code>, etc. - * <p> - * If the pushback buffer cannot hold all of the requested bytes, an - * exception is thrown. - * - * @param b The byte array to be pushed back - * - * @exception IOException If the pushback buffer is full - */ - public synchronized void unread(byte[] b) throws IOException - { - unread(b, 0, b.length); - } - - /** - * This method pushed back bytes from the passed in array into the - * pushback buffer. The bytes from <code>b[offset]</code> to - * <code>b[offset + len]</code> are pushed in reverse order so that - * the next byte read from the stream after this operation will be - * <code>b[offset]</code> followed by <code>b[offset + 1]</code>, - * etc. - * <p> - * If the pushback buffer cannot hold all of the requested bytes, an - * exception is thrown. - * - * @param b The byte array to be pushed back - * @param off The index into the array where the bytes to be push start - * @param len The number of bytes to be pushed. - * - * @exception IOException If the pushback buffer is full - */ - public synchronized void unread(byte[] b, int off, int len) - throws IOException - { - if (pos < len) - throw new IOException("Insufficient space in pushback buffer"); - - // Note the order that these bytes are being added is the opposite - // of what would be done if they were added to the buffer one at a time. - // See the Java Class Libraries book p. 1390. - System.arraycopy(b, off, buf, pos - len, len); - - // Don't put this into the arraycopy above, an exception might be thrown - // and in that case we don't want to modify pos. - pos -= len; - } - - /** - * This method skips the specified number of bytes in the stream. It - * returns the actual number of bytes skipped, which may be less than the - * requested amount. - * <p> - * This method first discards bytes from the buffer, then calls the - * <code>skip</code> method on the underlying <code>InputStream</code> to - * skip additional bytes if necessary. - * - * @param n The requested number of bytes to skip - * - * @return The actual number of bytes skipped. - * - * @exception IOException If an error occurs - * - * @since 1.2 - */ - public synchronized long skip(long n) throws IOException - { - final long origN = n; - - if (n > 0L) - { - int numread = (int) Math.min((long) (buf.length - pos), n); - pos += numread; - n -= numread; - if (n > 0) - n -= super.skip(n); - } - - return origN - n; - } -} |