* java/io/PushbackReader.java: Reformat.
From-SVN: r51291
This commit is contained in:
Bryce McKinlay
Bryce McKinlay
parent
1bd6476f2e
commit
e89268b691
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@ -1,3 +1,7 @@
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2002-03-24 Bryce McKinlay <bryce@waitaki.otago.ac.nz>
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* java/io/PushbackReader.java: Reformat.
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2002-03-24 Tom Tromey <tromey@redhat.com>
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* java/awt/TextComponent.java (TextComponent): Editable by
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@ -39,402 +39,342 @@ exception statement from your version. */
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package java.io;
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/**
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* This subclass of <code>FilterReader</code> provides the ability to
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* unread data from a stream. It maintains an internal buffer of unread
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* data that is supplied to the next read operation. This is conceptually
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* similar to mark/reset functionality, except that in this case the
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* position to reset the stream to does not need to be known in advance.
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* <p>
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* The default pushback buffer size one char, but this can be overridden
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* by the creator of the stream.
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*
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* @version 0.0
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Warren Levy <warrenl@cygnus.com>
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*/
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* This subclass of <code>FilterReader</code> provides the ability to
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* unread data from a stream. It maintains an internal buffer of unread
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* data that is supplied to the next read operation. This is conceptually
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* similar to mark/reset functionality, except that in this case the
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* position to reset the stream to does not need to be known in advance.
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* <p>
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* The default pushback buffer size one char, but this can be overridden
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* by the creator of the stream.
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*
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* @version 0.0
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Warren Levy <warrenl@cygnus.com>
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*/
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public class PushbackReader extends FilterReader
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{
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/**
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* This is the default buffer size
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*/
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private static final int DEFAULT_BUFFER_SIZE = 1;
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/*************************************************************************/
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/**
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* This is the buffer that is used to store the pushed back data
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*/
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private char[] buf;
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/*
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* Class Variables
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*/
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/**
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* This is the position in the buffer from which the next char will be
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* read. Bytes are stored in reverse order in the buffer, starting from
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* <code>buf[buf.length - 1]</code> to <code>buf[0]</code>. Thus when
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* <code>pos</code> is 0 the buffer is full and <code>buf.length</code> when
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* it is empty
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*/
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private int pos;
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/**
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* This is the default buffer size
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*/
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private static final int DEFAULT_BUFFER_SIZE = 1;
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/**
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* This method initializes a <code>PushbackReader</code> to read from the
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* specified subordinate <code>Reader</code> with a default pushback buffer
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* size of 1.
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*
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* @code in The subordinate stream to read from
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*/
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public PushbackReader(Reader in)
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{
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this(in, DEFAULT_BUFFER_SIZE);
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}
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/*************************************************************************/
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/**
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* This method initializes a <code>PushbackReader</code> to read from the
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* specified subordinate <code>Reader</code> with the specified buffer
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* size
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*
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* @param in The subordinate <code>Reader</code> to read from
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* @param bufsize The pushback buffer size to use
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*/
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public PushbackReader(Reader in, int bufsize)
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{
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super(in);
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/*
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* Instance Variables
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*/
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if (bufsize < 0)
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throw new IllegalArgumentException("buffer size must be positive");
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/**
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* This is the buffer that is used to store the pushed back data
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*/
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private char[] buf;
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buf = new char[bufsize];
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pos = bufsize;
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}
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/**
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* This is the position in the buffer from which the next char will be
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* read. Bytes are stored in reverse order in the buffer, starting from
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* <code>buf[buf.length - 1]</code> to <code>buf[0]</code>. Thus when
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* <code>pos</code> is 0 the buffer is full and <code>buf.length</code> when
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* it is empty
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*/
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private int pos;
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/**
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* This method closes the stream and frees any associated resources.
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*
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* @exception IOException If an error occurs.
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*/
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public void close() throws IOException
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{
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synchronized (lock)
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{
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buf = null;
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super.close();
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}
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}
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/*************************************************************************/
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/**
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* This method throws an exception when called since this class does
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* not support mark/reset.
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*
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* @param read_limit Not used.
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*
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* @exception IOException Always thrown to indicate mark/reset not supported.
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*/
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public void mark(int read_limit) throws IOException
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{
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throw new IOException("mark not supported in this class");
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}
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/*
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* Constructors
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*/
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/**
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* This method returns <code>false</code> to indicate that it does not support
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* mark/reset functionality.
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*
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* @return This method returns <code>false</code> to indicate that this class does not support mark/reset functionality
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*
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*/
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public boolean markSupported()
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{
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return(false);
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}
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/**
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* This method initializes a <code>PushbackReader</code> to read from the
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* specified subordinate <code>Reader</code> with a default pushback buffer
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* size of 1.
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*
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* @code in The subordinate stream to read from
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*/
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public
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PushbackReader(Reader in)
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{
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this(in, DEFAULT_BUFFER_SIZE);
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/**
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* This method always throws an IOException in this class because
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* mark/reset functionality is not supported.
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*
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* @exception IOException Always thrown for this class
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*/
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public void reset() throws IOException
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{
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throw new IOException("reset not supported in this class");
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}
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/**
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* This method determines whether or not this stream is ready to be read.
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* If it returns <code>false</code> to indicate that the stream is not
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* ready, any attempt to read from the stream could (but is not
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* guaranteed to) block.
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* <p>
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* This stream is ready to read if there are either chars waiting to be
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* read in the pushback buffer or if the underlying stream is ready to
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* be read.
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*
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* @return <code>true</code> if this stream is ready to be read, <code>false</code> otherwise
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*
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* @exception IOException If an error occurs
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*/
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public boolean ready() throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException ("stream closed");
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if (((buf.length - pos) > 0) || super.ready())
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return(true);
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else
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return(false);
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}
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}
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// Don't delete this method just because the spec says it shouldn't be there!
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// See the CVS log for details.
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/**
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* This method skips the specified number of chars in the stream. It
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* returns the actual number of chars skipped, which may be less than the
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* requested amount.
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* <p>
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* This method first discards chars from the buffer, then calls the
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* <code>skip</code> method on the underlying <code>Reader</code> to
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* skip additional chars if necessary.
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*
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* @param num_chars The requested number of chars to skip
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*
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* @return The actual number of chars skipped.
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*
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* @exception IOException If an error occurs
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*/
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public long skip(long num_chars) throws IOException
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{
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synchronized (lock)
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{
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if (num_chars <= 0)
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return(0);
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if ((buf.length - pos) >= num_chars)
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{
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pos += num_chars;
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return(num_chars);
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}
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int chars_discarded = buf.length - pos;
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pos = buf.length;
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long chars_skipped = in.skip(num_chars - chars_discarded);
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return(chars_discarded + chars_skipped);
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}
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}
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/**
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* This method reads an unsigned char from the input stream and returns it
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* as an int in the range of 0-65535. This method also will return -1 if
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* the end of the stream has been reached. The char returned will be read
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* from the pushback buffer, unless the buffer is empty, in which case
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* the char will be read from the underlying stream.
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* <p>
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* This method will block until the char can be read.
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*
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* @return The char read or -1 if end of stream
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*
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* @exception IOException If an error occurs
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*/
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public int read() throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("stream closed");
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if (pos == buf.length)
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return(super.read());
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++pos;
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return((buf[pos - 1] & 0xFFFF));
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}
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}
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/**
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* This method read chars from a stream and stores them into a caller
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* supplied buffer. It starts storing the data at index <code>offset</code> into
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* the buffer and attempts to read <code>len</code> chars. This method can
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* return before reading the number of chars requested. The actual number
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* of chars read is returned as an int. A -1 is returned to indicate the
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* end of the stream.
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* <p>
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* This method will block until some data can be read.
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* <p>
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* This method first reads chars from the pushback buffer in order to
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* satisfy the read request. If the pushback buffer cannot provide all
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* of the chars requested, the remaining chars are read from the
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* underlying stream.
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*
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* @param buf The array into which the chars read should be stored
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* @param offset The offset into the array to start storing chars
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* @param len The requested number of chars to read
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*
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* @return The actual number of chars read, or -1 if end of stream.
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*
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* @exception IOException If an error occurs.
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*/
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public synchronized int read(char[] b, int offset, int len) throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("stream closed");
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if (offset < 0 || len < 0 || offset + len > b.length)
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throw new ArrayIndexOutOfBoundsException();
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int numBytes = Math.min(buf.length - pos, len);
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if (numBytes > 0)
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{
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System.arraycopy (buf, pos, b, offset, numBytes);
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pos += numBytes;
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return numBytes;
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}
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return super.read(b, offset, len);
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}
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}
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/**
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* This method pushes a single char of data into the pushback buffer.
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* The char pushed back is the one that will be returned as the first char
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* of the next read.
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* <p>
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* If the pushback buffer is full, this method throws an exception.
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* <p>
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* The argument to this method is an <code>int</code>. Only the low eight bits
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* of this value are pushed back.
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*
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* @param b The char to be pushed back, passed as an int
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*
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* @exception IOException If the pushback buffer is full.
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*/
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public void unread(int b) throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("stream closed");
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if (pos == 0)
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throw new IOException("Pushback buffer is full");
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--pos;
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buf[pos] = (char)(b & 0xFFFF);
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}
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}
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/**
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* This method pushes all of the chars in the passed char array into
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* the pushback buffer. These chars are pushed in reverse order so that
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* the next char read from the stream after this operation will be
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* <code>buf[0]</code> followed by <code>buf[1]</code>, etc.
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* <p>
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* If the pushback buffer cannot hold all of the requested chars, an
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* exception is thrown.
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*
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* @param buf The char array to be pushed back
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*
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* @exception IOException If the pushback buffer is full
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*/
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public synchronized void unread(char[] buf) throws IOException
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{
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unread(buf, 0, buf.length);
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}
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/**
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* This method pushed back chars from the passed in array into the pushback
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* buffer. The chars from <code>buf[offset]</code> to <code>buf[offset + len]</code>
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* are pushed in reverse order so that the next char read from the stream
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* after this operation will be <code>buf[offset]</code> followed by
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* <code>buf[offset + 1]</code>, etc.
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* <p>
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* If the pushback buffer cannot hold all of the requested chars, an
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* exception is thrown.
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*
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* @param buf The char array to be pushed back
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* @param offset The index into the array where the chars to be push start
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* @param len The number of chars to be pushed.
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*
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* @exception IOException If the pushback buffer is full
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*/
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public synchronized void unread(char[] b, int offset, int len)
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throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("stream closed");
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if (pos < len)
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throw new IOException("Pushback buffer is full");
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// Note the order that these chars are being added is the opposite
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// of what would be done if they were added to the buffer one at a time.
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// See the Java Class Libraries book p. 1397.
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System.arraycopy(b, offset, buf, pos - len, len);
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// Don't put this into the arraycopy above, an exception might be thrown
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// and in that case we don't want to modify pos.
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pos -= len;
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}
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}
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}
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/*************************************************************************/
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/**
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* This method initializes a <code>PushbackReader</code> to read from the
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* specified subordinate <code>Reader</code> with the specified buffer
|
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* size
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*
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* @param in The subordinate <code>Reader</code> to read from
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* @param bufsize The pushback buffer size to use
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*/
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public
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PushbackReader(Reader in, int bufsize)
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{
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super(in);
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if (bufsize < 0)
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throw new IllegalArgumentException("buffer size must be positive");
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buf = new char[bufsize];
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pos = bufsize;
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}
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/*************************************************************************/
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/*
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* Instance Methods
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*/
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/**
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* This method closes the stream and frees any associated resources.
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*
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* @exception IOException If an error occurs.
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*/
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public void
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close() throws IOException
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{
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synchronized (lock)
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{
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buf = null;
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super.close();
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}
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}
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/*************************************************************************/
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/**
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* This method throws an exception when called since this class does
|
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* not support mark/reset.
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*
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* @param read_limit Not used.
|
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*
|
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* @exception IOException Always thrown to indicate mark/reset not supported.
|
||||
*/
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public void
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mark(int read_limit) throws IOException
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{
|
||||
throw new IOException("mark not supported in this class");
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}
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/*************************************************************************/
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/**
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* 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
|
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*
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*/
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public boolean
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markSupported()
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{
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return(false);
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}
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/*************************************************************************/
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/**
|
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* This method always throws an IOException in this class because
|
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* mark/reset functionality is not supported.
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||||
*
|
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* @exception IOException Always thrown for this class
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*/
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public void
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reset() throws IOException
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{
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throw new IOException("reset not supported in this class");
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}
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/*************************************************************************/
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/**
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* 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)
|
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{
|
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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);
|
||||
} // synchronized
|
||||
}
|
||||
|
||||
/*************************************************************************/
|
||||
|
||||
/**
|
||||
* 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);
|
||||
} // synchronized
|
||||
}
|
||||
|
||||
/*************************************************************************/
|
||||
|
||||
/**
|
||||
* 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;
|
||||
}
|
||||
}
|
||||
|
||||
} // class PushbackReader
|
||||
|
|
|
|||
Loading…
Reference in New Issue