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Diffstat (limited to 'libjava/java/io/PushbackReader.java')
| -rw-r--r-- | libjava/java/io/PushbackReader.java | 384 |
1 files changed, 0 insertions, 384 deletions
diff --git a/libjava/java/io/PushbackReader.java b/libjava/java/io/PushbackReader.java deleted file mode 100644 index 04bccc70fc5..00000000000 --- a/libjava/java/io/PushbackReader.java +++ /dev/null @@ -1,384 +0,0 @@ -/* PushbackReader.java -- An character stream that can unread chars - Copyright (C) 1998, 2000, 2001, 2003, 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>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. - * - * @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. - * - * @param 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 buffer The array into which the chars read should be stored - * @param offset The offset into the array to start storing chars - * @param length 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[] buffer, int offset, int length) - throws IOException - { - synchronized (lock) - { - if (buf == null) - throw new IOException("stream closed"); - - if (offset < 0 || length < 0 || offset + length > buffer.length) - throw new ArrayIndexOutOfBoundsException(); - - int numBytes = Math.min(buf.length - pos, length); - if (numBytes > 0) - { - System.arraycopy (buf, pos, buffer, offset, numBytes); - pos += numBytes; - return numBytes; - } - - return super.read(buffer, offset, length); - } - } - - /** - * 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 buffer The char array to be pushed back - * @param offset The index into the array where the chars to be push start - * @param length The number of chars to be pushed. - * - * @exception IOException If the pushback buffer is full - */ - public synchronized void unread(char[] buffer, int offset, int length) - throws IOException - { - synchronized (lock) - { - if (buf == null) - throw new IOException("stream closed"); - if (pos < length) - 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(buffer, offset, buf, pos - length, length); - - // 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 -= length; - } - } -} - |