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	/*
	* Copyright (c) 1996, 2021, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.io;

	import java.nio.CharBuffer;
	import java.nio.charset.Charset;
	import java.nio.charset.CharsetDecoder;
	import sun.nio.cs.StreamDecoder;


	/**
	* An InputStreamReader is a bridge from byte streams to character streams: It
	* reads bytes and decodes them into characters using a specified {@link
	* java.nio.charset.Charset charset}. The charset that it uses
	* may be specified by name or may be given explicitly, or the platform's
	* {@link Charset#defaultCharset() default charset} may be accepted.
	*
	* <p> Each invocation of one of an InputStreamReader's read() methods may
	* cause one or more bytes to be read from the underlying byte-input stream.
	* To enable the efficient conversion of bytes to characters, more bytes may
	* be read ahead from the underlying stream than are necessary to satisfy the
	* current read operation.
	*
	* <p> For top efficiency, consider wrapping an InputStreamReader within a
	* BufferedReader. For example:
	*
	* <pre>
	* BufferedReader in
	* = new BufferedReader(new InputStreamReader(anInputStream));
	* </pre>
	*
	* @see BufferedReader
	* @see InputStream
	* @see java.nio.charset.Charset
	*
	* @author Mark Reinhold
	* @since 1.1
	*/

	public class InputStreamReader extends Reader {

	private final StreamDecoder sd;

	/**
	* Creates an InputStreamReader that uses the
	* {@link Charset#defaultCharset() default charset}.
	*
	* @param in An InputStream
	*
	* @see Charset#defaultCharset()
	*/
	public InputStreamReader(InputStream in) {
	super(in);
	sd = StreamDecoder.forInputStreamReader(in, this,
	Charset.defaultCharset()); // ## check lock object
	}

	/**
	* Creates an InputStreamReader that uses the named charset.
	*
	* @param in
	* An InputStream
	*
	* @param charsetName
	* The name of a supported
	* {@link java.nio.charset.Charset charset}
	*
	* @throws UnsupportedEncodingException
	* If the named charset is not supported
	*/
	public InputStreamReader(InputStream in, String charsetName)
	throws UnsupportedEncodingException
	{
	super(in);
	if (charsetName == null)
	throw new NullPointerException("charsetName");
	sd = StreamDecoder.forInputStreamReader(in, this, charsetName);
	}

	/**
	* Creates an InputStreamReader that uses the given charset.
	*
	* @param in An InputStream
	* @param cs A charset
	*
	* @since 1.4
	*/
	public InputStreamReader(InputStream in, Charset cs) {
	super(in);
	if (cs == null)
	throw new NullPointerException("charset");
	sd = StreamDecoder.forInputStreamReader(in, this, cs);
	}

	/**
	* Creates an InputStreamReader that uses the given charset decoder.
	*
	* @param in An InputStream
	* @param dec A charset decoder
	*
	* @since 1.4
	*/
	public InputStreamReader(InputStream in, CharsetDecoder dec) {
	super(in);
	if (dec == null)
	throw new NullPointerException("charset decoder");
	sd = StreamDecoder.forInputStreamReader(in, this, dec);
	}

	/**
	* Returns the name of the character encoding being used by this stream.
	*
	* <p> If the encoding has an historical name then that name is returned;
	* otherwise the encoding's canonical name is returned.
	*
	* <p> If this instance was created with the {@link
	* #InputStreamReader(InputStream, String)} constructor then the returned
	* name, being unique for the encoding, may differ from the name passed to
	* the constructor. This method will return {@code null} if the
	* stream has been closed.
	* </p>
	* @return The historical name of this encoding, or
	* {@code null} if the stream has been closed
	*
	* @see java.nio.charset.Charset
	*
	* @revised 1.4
	*/
	public String getEncoding() {
	return sd.getEncoding();
	}

	public int read(CharBuffer target) throws IOException {
	return sd.read(target);
	}

	/**
	* Reads a single character.
	*
	* @return The character read, or -1 if the end of the stream has been
	* reached
	*
	* @throws IOException If an I/O error occurs
	*/
	public int read() throws IOException {
	return sd.read();
	}

	/**
	* {@inheritDoc}
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	public int read(char[] cbuf, int off, int len) throws IOException {
	return sd.read(cbuf, off, len);
	}

	/**
	* Tells whether this stream is ready to be read. An InputStreamReader is
	* ready if its input buffer is not empty, or if bytes are available to be
	* read from the underlying byte stream.
	*
	* @throws IOException If an I/O error occurs
	*/
	public boolean ready() throws IOException {
	return sd.ready();
	}

	public void close() throws IOException {
	sd.close();
	}
	}

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