+++ /dev/null
-/* PushbackReader.java -- An character stream that can unread chars
- Copyright (C) 1998, 2000, 2001 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>FilterReader</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 char, but this can be overridden
- * by the creator of the stream.
- *
- * @version 0.0
- *
- * @author Aaron M. Renn (arenn@urbanophile.com)
- * @author Warren Levy <warrenl@cygnus.com>
- */
-public class PushbackReader extends FilterReader
-{
- /**
- * 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
- */
- private char[] buf;
-
- /**
- * This is the position in the buffer from which the next char 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
- */
- private int pos;
-
- /**
- * This method initializes a <code>PushbackReader</code> to read from the
- * specified subordinate <code>Reader</code> with a default pushback buffer
- * size of 1.
- *
- * @code in The subordinate stream to read from
- */
- public PushbackReader(Reader in)
- {
- this(in, DEFAULT_BUFFER_SIZE);
- }
-
- /**
- * This method initializes a <code>PushbackReader</code> to read from the
- * specified subordinate <code>Reader</code> with the specified buffer
- * size
- *
- * @param in The subordinate <code>Reader</code> to read from
- * @param bufsize The pushback buffer size to use
- */
- public PushbackReader(Reader in, int bufsize)
- {
- super(in);
-
- if (bufsize < 0)
- throw new IllegalArgumentException("buffer size must be positive");
-
- buf = new char[bufsize];
- pos = bufsize;
- }
-
- /**
- * This method closes the stream and frees any associated resources.
- *
- * @exception IOException If an error occurs.
- */
- public void close() throws IOException
- {
- synchronized (lock)
- {
- buf = null;
- super.close();
- }
- }
-
- /**
- * This method throws an exception when called since this class does
- * not support mark/reset.
- *
- * @param read_limit Not used.
- *
- * @exception IOException Always thrown to indicate mark/reset not supported.
- */
- public void mark(int read_limit) throws IOException
- {
- throw new IOException("mark not supported in this class");
- }
-
- /**
- * 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("reset not supported in this class");
- }
-
- /**
- * This method determines whether or not this stream is ready to be read.
- * If it returns <code>false</code> to indicate that the stream is not
- * ready, any attempt to read from the stream could (but is not
- * guaranteed to) block.
- * <p>
- * This stream is ready to read if there are either chars waiting to be
- * read in the pushback buffer or if the underlying stream is ready to
- * be read.
- *
- * @return <code>true</code> if this stream is ready to be read, <code>false</code> otherwise
- *
- * @exception IOException If an error occurs
- */
- public boolean ready() throws IOException
- {
- synchronized (lock)
- {
- if (buf == null)
- throw new IOException ("stream closed");
-
- if (((buf.length - pos) > 0) || super.ready())
- return(true);
- else
- return(false);
- }
- }
-
- // Don't delete this method just because the spec says it shouldn't be there!
- // See the CVS log for details.
- /**
- * This method skips the specified number of chars in the stream. It
- * returns the actual number of chars skipped, which may be less than the
- * requested amount.
- * <p>
- * This method first discards chars from the buffer, then calls the
- * <code>skip</code> method on the underlying <code>Reader</code> to
- * skip additional chars if necessary.
- *
- * @param num_chars The requested number of chars to skip
- *
- * @return The actual number of chars skipped.
- *
- * @exception IOException If an error occurs
- */
- public long skip(long num_chars) throws IOException
- {
- synchronized (lock)
- {
- if (num_chars <= 0)
- return(0);
-
- if ((buf.length - pos) >= num_chars)
- {
- pos += num_chars;
- return(num_chars);
- }
-
- int chars_discarded = buf.length - pos;
- pos = buf.length;
-
- long chars_skipped = in.skip(num_chars - chars_discarded);
-
- return(chars_discarded + chars_skipped);
- }
- }
-
- /**
- * This method reads an unsigned char from the input stream and returns it
- * as an int in the range of 0-65535. This method also will return -1 if
- * the end of the stream has been reached. The char returned will be read
- * from the pushback buffer, unless the buffer is empty, in which case
- * the char will be read from the underlying stream.
- * <p>
- * This method will block until the char can be read.
- *
- * @return The char read or -1 if end of stream
- *
- * @exception IOException If an error occurs
- */
- public int read() throws IOException
- {
- synchronized (lock)
- {
- if (buf == null)
- throw new IOException("stream closed");
-
- if (pos == buf.length)
- return(super.read());
-
- ++pos;
- return((buf[pos - 1] & 0xFFFF));
- }
- }
-
- /**
- * This method read chars 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> chars. This method can
- * return before reading the number of chars requested. The actual number
- * of chars 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 chars from the pushback buffer in order to
- * satisfy the read request. If the pushback buffer cannot provide all
- * of the chars requested, the remaining chars are read from the
- * underlying stream.
- *
- * @param buf The array into which the chars read should be stored
- * @param offset 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.
- *
- * @exception IOException If an error occurs.
- */
- public synchronized int read(char[] b, int offset, int len) throws IOException
- {
- synchronized (lock)
- {
- if (buf == null)
- throw new IOException("stream closed");
-
- if (offset < 0 || len < 0 || offset + len > b.length)
- throw new ArrayIndexOutOfBoundsException();
-
- int numBytes = Math.min(buf.length - pos, len);
- if (numBytes > 0)
- {
- System.arraycopy (buf, pos, b, offset, numBytes);
- pos += numBytes;
- return numBytes;
- }
-
- return super.read(b, offset, len);
- }
- }
-
- /**
- * This method pushes a single char of data into the pushback buffer.
- * The char pushed back is the one that will be returned as the first char
- * 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 char to be pushed back, passed as an int
- *
- * @exception IOException If the pushback buffer is full.
- */
- public void unread(int b) throws IOException
- {
- synchronized (lock)
- {
- if (buf == null)
- throw new IOException("stream closed");
- if (pos == 0)
- throw new IOException("Pushback buffer is full");
-
- --pos;
- buf[pos] = (char)(b & 0xFFFF);
- }
- }
-
- /**
- * This method pushes all of the chars in the passed char array into
- * the pushback buffer. These chars are pushed in reverse order so that
- * the next char read from the stream after this operation will be
- * <code>buf[0]</code> followed by <code>buf[1]</code>, etc.
- * <p>
- * If the pushback buffer cannot hold all of the requested chars, an
- * exception is thrown.
- *
- * @param buf The char array to be pushed back
- *
- * @exception IOException If the pushback buffer is full
- */
- public synchronized void unread(char[] buf) throws IOException
- {
- unread(buf, 0, buf.length);
- }
-
- /**
- * This method pushed back chars from the passed in array into the pushback
- * buffer. The chars from <code>buf[offset]</code> to <code>buf[offset + len]</code>
- * are pushed in reverse order so that the next char read from the stream
- * after this operation will be <code>buf[offset]</code> followed by
- * <code>buf[offset + 1]</code>, etc.
- * <p>
- * If the pushback buffer cannot hold all of the requested chars, an
- * exception is thrown.
- *
- * @param buf The char array to be pushed back
- * @param offset The index into the array where the chars to be push start
- * @param len The number of chars to be pushed.
- *
- * @exception IOException If the pushback buffer is full
- */
- public synchronized void unread(char[] b, int offset, int len)
- throws IOException
- {
- synchronized (lock)
- {
- if (buf == null)
- throw new IOException("stream closed");
- if (pos < len)
- throw new IOException("Pushback buffer is full");
-
- // Note the order that these chars 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. 1397.
- System.arraycopy(b, offset, 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;
- }
- }
-}
projects / msp430-gcc.git / blobdiff