+++ /dev/null
-/* PushbackInputStream.java -- An input stream that can unread bytes
- Copyright (C) 1998, 1999, 2001, 2002 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., 59 Temple Place, Suite 330, Boston, MA
-02111-1307 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
- {
- return (buf.length - pos) + super.available();
- }
-
- /**
- * 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
- * <cdoe>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 num_bytes 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;
- n -= super.skip(n);
- }
-
- return origN - n;
- }
-}
projects / msp430-gcc.git / blobdiff