407 lines
13 KiB
Java
407 lines
13 KiB
Java
/* gnu.classpath.tools.NotifyingInputStreamReader
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Copyright (C) 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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package gnu.classpath.tools;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.Reader;
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import java.nio.ByteBuffer;
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import java.nio.CharBuffer;
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import java.nio.charset.Charset;
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import java.nio.charset.CharsetDecoder;
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import java.nio.charset.CoderResult;
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import java.nio.charset.IllegalCharsetNameException;
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import java.nio.charset.UnsupportedCharsetException;
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import java.util.Iterator;
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import java.util.LinkedHashSet;
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import java.util.Set;
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/**
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* Similar to {@link java.io.InputStreamReader}, but can give
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* notification when malformed input is encountered.
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*
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* <p> Users of this class can register interest in the event of
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* malformed input by calling {@link
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* #addMalformedInputListener}. Each time a run of malformed input
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* data is encountered, all listener objects are notified. For
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* instance, this allows the calling code to inform the user about
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* problems in the input stream. </p>
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*
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* <p> <strong>Background:</strong> The default
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* <code>InputStreamReader</code> implementation will ignore
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* malformed input, silently replacing it with the default
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* replacement string (usually the question mark). Alternatively, you
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* can configure a <code>CharsetDecoder</code> for the default
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* <char>InputStreamReader</code> implementation, instructing it to
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* ignore malformed input without replacing it; to replace it with a
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* different string; or to throw an exception when malformed input is
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* encountered. However, you cannot configure an
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* <code>InputStreamReader</code> to gracefully handle malformed data
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* but notify the client code about such
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* problems. <code>NotifyingInputStreamReader</code> fills this
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* gap. </p>
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*
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* @author Julian Scheid
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*/
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public class NotifyingInputStreamReader
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extends Reader
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{
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/**
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* The default size (in bytes) for byteBuf, i.e. the size of data
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* chunks read from the underlying input stream.
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*/
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private static final int DEFAULT_INPUT_BUFFER_SIZE = 64;
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/**
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* The default size (in chars) for charBuf. This should be large
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* enough to hold a decoded chunk of input data for the Charset
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* with the minimum number of bytes per character. Since the
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* minimum number of bytes per character for usual Charsets is
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* one, this number should be identical to
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* DEFAULT_INPUT_BUFFER_SIZE.
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*/
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private static final int DEFAULT_OUTPUT_BUFFER_SIZE = 64;
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/**
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* The underlying InputStream.
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*/
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private InputStream in;
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/**
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* The CharsetDecoder used to decode the underlying stream.
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*/
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private CharsetDecoder decoder;
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/**
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* Holds bytes already read from the underlying stream, but not
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* yet decoded.
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*/
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private ByteBuffer byteBuffer;
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/**
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* Holds characters already decoded, but not yet fetched via
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* read().
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*/
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private CharBuffer charBuffer;
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/**
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* This is the primitive byte array wrapped in byteBuffer for
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* passing to to InputStream.read().
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*/
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private byte[] readBuffer;
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/**
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* Keeps track of the current line number (1-based).
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*/
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private int lineNumber = 1;
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/**
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* Keeps track of the current column number (0-based).
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*/
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private int columnNumber = 0;
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/**
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* Becomes true as soon as EOF has been reached in the underlying
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* InputStream. At this point, byteBuffer contains the last chunk
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* of data from the underlying InputStream.
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*/
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private boolean allInputConsumed = false;
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/**
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* Becomes true as soon as the decoder has been supplied with the
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* last chunk of data from the InputStream after EOF has been
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* reached. At this point, the last chunk of data has been drained
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* from the byteBuffer.
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*/
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private boolean decodingFinished = false;
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/**
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* Becomes true as soon as the decoder has been flushed. At this
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* point, the last chunk of character data has been written to the
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* charBuffer.
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*/
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private boolean flushed = false;
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/**
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* Stores all registered MalformedInputListeners.
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*/
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private Set listeners = new LinkedHashSet();
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/**
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* Initializes a new instance for reading from the given
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* InputStream using the default encoding. The default encoding is
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* currently determined by looking at the system property
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* <code>file.encoding</code>. If this property isn't set,
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* <code>ISO-8859-1</code> is used as a fallback.
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*
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* <p>This method should use {@link Charset.defaultCharset()}
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* instead, but this isn't implemented in Classpath at the
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* moment.</p>
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*
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* @param in the <code>InputStream</code> to read from.
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*/
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public NotifyingInputStreamReader(InputStream in)
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{
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this(in, System.getProperty("file.encoding", "ISO-8859-1"));
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}
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/**
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* Initializes a new instance for reading from the given
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* InputStream using the specified charset.
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*
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* @param in the <code>InputStream</code> to read from.
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* @param charsetName the canonical name or an alias of a
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* <code>Charset</code>.
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*
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* @throws IllegalCharsetNameException if there is no
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* <code>Charset</code> with the given canonical name or alias.
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*
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* @throws UnsupportedCharsetException if there is no support for
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* the specified <code>Charset</code> in the runtime environment.
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*/
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public NotifyingInputStreamReader(InputStream in, String charsetName)
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throws IllegalCharsetNameException, UnsupportedCharsetException
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{
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this(in, Charset.forName(charsetName));
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}
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/**
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* Initializes a new instance for reading from the given
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* InputStream using the specified charset.
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*
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* @param in the <code>InputStream</code> to read from.
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* @param charset the <code>Charset</code> to use for decoding
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* characters.
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*/
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public NotifyingInputStreamReader(InputStream in, Charset charset)
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{
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this(in, charset.newDecoder());
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}
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/**
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* Initializes a new instance for reading from the given
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* InputStream using the specified charset decoder.
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*
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* <strong>Note:</strong> the
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* <code>NotifyingInputStreamReader</code> will not exhibit the
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* advertised behaviour if you changed the action to take on
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* malformed input in the specified
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* <code>CharsetDecoder</code>. In other words, you should not
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* call {@link CharsetDecoder.onMalformedInput(CodingErrorAction)}
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* on the specified decoder before or while this reader is being
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* used unless you know what you're doing.
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*
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* @param in the <code>InputStream</code> to read from.
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* @param charset the <code>CharsetDecoder</code> to use for
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* decoding characters.
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*/
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public NotifyingInputStreamReader(InputStream in, CharsetDecoder decoder)
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{
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this.in = in;
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this.decoder = decoder;
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this.charBuffer = CharBuffer.wrap(new char[DEFAULT_INPUT_BUFFER_SIZE]);
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this.charBuffer.position(charBuffer.limit());
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this.readBuffer = new byte[DEFAULT_OUTPUT_BUFFER_SIZE];
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this.byteBuffer = ByteBuffer.wrap(readBuffer);
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this.byteBuffer.position(byteBuffer.limit());
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}
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public void close()
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throws IOException
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{
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in.close();
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}
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/**
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* Fill charBuffer with new character data. This method returns if
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* either the charBuffer has been filled completely with decoded
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* character data, or if EOF is reached in the underlying
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* InputStream. When this method returns, charBuffer is flipped
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* and ready to be read from.
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*/
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private void fillCharBuf()
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throws IOException
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{
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charBuffer.clear();
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outer:
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while (!flushed) {
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CoderResult coderResult;
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int charBufferPositionBefore = charBuffer.position();
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if (!decodingFinished) {
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coderResult = decoder.decode(byteBuffer, charBuffer, allInputConsumed);
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if (allInputConsumed) {
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decodingFinished = true;
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}
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}
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else {
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coderResult = decoder.flush(charBuffer);
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flushed = coderResult.isUnderflow();
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}
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int charBufferPositionAfter = charBuffer.position();
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for (int i=charBufferPositionBefore; i<charBufferPositionAfter; ++i) {
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if (10 == charBuffer.get(i)) {
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++ lineNumber;
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columnNumber = 0;
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}
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else {
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++ columnNumber;
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}
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}
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if (coderResult.isOverflow()) {
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break;
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}
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else if (coderResult.isUnderflow()) {
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if (!allInputConsumed) {
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int nRemainingBytes = 0;
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if (byteBuffer.position() > 0) {
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nRemainingBytes = Math.max(0, byteBuffer.limit() - byteBuffer.position());
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}
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if (nRemainingBytes > 0) {
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byteBuffer.get(readBuffer, 0, nRemainingBytes);
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}
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byteBuffer.rewind();
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int nread = in.read(readBuffer, nRemainingBytes,
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readBuffer.length - nRemainingBytes);
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if (nread < 0) {
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allInputConsumed = true;
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}
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byteBuffer.limit(nRemainingBytes + Math.max(0, nread));
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}
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else {
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break;
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}
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}
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else if (coderResult.isMalformed()) {
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fireMalformedInputEncountered(coderResult.length());
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String replacement = decoder.replacement();
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for (int i=0; i<coderResult.length(); ++i) {
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if (charBuffer.remaining() > replacement.length()) {
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charBuffer.put(replacement);
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byteBuffer.position(byteBuffer.position() + 1);
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columnNumber ++;
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}
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else {
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break outer;
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}
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}
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}
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else if (coderResult.isUnmappable()) {
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// This should not happen, since unmappable input bytes
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// trigger a "malformed" event instead.
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coderResult.throwException();
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}
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else {
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// This should only happen if run in a future environment
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// where additional events apart from underflow, overflow,
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// malformed and unmappable can be generated.
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coderResult.throwException();
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}
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}
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charBuffer.flip();
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}
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/**
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* Fire a MalformedInputEvent, notifying all registered listeners.
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*/
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private void fireMalformedInputEncountered(int length)
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{
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MalformedInputEvent event
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= new MalformedInputEvent(this, lineNumber, columnNumber, length);
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Iterator it = listeners.iterator();
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while (it.hasNext()) {
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MalformedInputListener listener
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= (MalformedInputListener)it.next();
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listener.malformedInputEncountered(event);
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}
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}
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public int read(char[] cbuf, int offset, int length)
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throws IOException
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{
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if (flushed) {
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return -1;
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}
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else {
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int nread = 0;
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while (nread < length && !flushed) {
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while (charBuffer.hasRemaining() && nread < length) {
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int copyLen = Math.min(length - nread,
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charBuffer.remaining());
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charBuffer.get(cbuf, offset + nread, copyLen);
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nread += copyLen;
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}
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if (nread < length) {
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fillCharBuf();
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}
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}
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return nread;
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}
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}
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public int read()
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throws IOException
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{
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while (!flushed) {
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if (charBuffer.hasRemaining()) {
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return charBuffer.get();
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}
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else {
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fillCharBuf();
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}
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}
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return -1;
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}
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/**
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* Returns whether this reader is ready. The reader is ready if
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* there is data in the internal buffer, or if additional data can
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* be read from the underlying InputStream.
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*/
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public boolean ready()
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{
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return charBuffer.hasRemaining() || !flushed;
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}
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/**
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* Register a <code>MalformedInputListener</code> which should be
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* notified when malformed input is encountered.
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*/
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public void addMalformedInputListener(MalformedInputListener listener)
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{
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this.listeners.add(listener);
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}
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/**
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* Unregister a previously registered
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* <code>MalformedInputListener</code> if it should no longer be
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* notified when malformed input is encountered.
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*/
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public void removeMalformedInputListener(MalformedInputListener listener)
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{
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this.listeners.remove(listener);
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}
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}
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