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	/*
	* Copyright (c) 2012, 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 jdk.internal.util.xml.impl;

	import java.io.Reader;
	import java.io.InputStream;
	import java.io.IOException;
	import java.io.UnsupportedEncodingException;

	/**
	* UTF-8 transformed UCS-2 character stream reader.
	*
	* This reader converts UTF-8 transformed UCS-2 characters to Java characters.
	* The UCS-2 subset of UTF-8 transformation is described in RFC-2279 #2
	* "UTF-8 definition":
	* 0000 0000-0000 007F 0xxxxxxx
	* 0000 0080-0000 07FF 110xxxxx 10xxxxxx
	* 0000 0800-0000 FFFF 1110xxxx 10xxxxxx 10xxxxxx
	*
	* This reader will return incorrect last character on broken UTF-8 stream.
	*/
	public class ReaderUTF8 extends Reader {

	private InputStream is;

	/**
	* Constructor.
	*
	* @param is A byte input stream.
	*/
	public ReaderUTF8(InputStream is) {
	this.is = is;
	}

	/**
	* Reads characters into a portion of an array.
	*
	* @param cbuf Destination buffer.
	* @param off Offset at which to start storing characters.
	* @param len Maximum number of characters to read.
	* @exception IOException If any IO errors occur.
	* @exception UnsupportedEncodingException If UCS-4 character occur in the stream.
	*/
	public int read(char[] cbuf, int off, int len) throws IOException {
	int num = 0;
	int val;
	while (num < len) {
	if ((val = is.read()) < 0) {
	return (num != 0) ? num : -1;
	}
	switch (val & 0xf0) {
	case 0xc0:
	case 0xd0:
	cbuf[off++] = (char) (((val & 0x1f) << 6) \| (is.read() & 0x3f));
	break;

	case 0xe0:
	cbuf[off++] = (char) (((val & 0x0f) << 12)
	\| ((is.read() & 0x3f) << 6) \| (is.read() & 0x3f));
	break;

	case 0xf0: // UCS-4 character
	throw new UnsupportedEncodingException("UTF-32 (or UCS-4) encoding not supported.");

	default:
	cbuf[off++] = (char) val;
	break;
	}
	num++;
	}
	return num;
	}

	/**
	* Reads a single character.
	*
	* @return The character read, as an integer in the range 0 to 65535
	* (0x00-0xffff), or -1 if the end of the stream has been reached.
	* @exception IOException If any IO errors occur.
	* @exception UnsupportedEncodingException If UCS-4 character occur in the stream.
	*/
	public int read() throws IOException {
	int val;
	if ((val = is.read()) < 0) {
	return -1;
	}
	switch (val & 0xf0) {
	case 0xc0:
	case 0xd0:
	val = ((val & 0x1f) << 6) \| (is.read() & 0x3f);
	break;

	case 0xe0:
	val = ((val & 0x0f) << 12)
	\| ((is.read() & 0x3f) << 6) \| (is.read() & 0x3f);
	break;

	case 0xf0: // UCS-4 character
	throw new UnsupportedEncodingException();

	default:
	break;
	}
	return val;
	}

	/**
	* Closes the stream.
	*
	* @exception IOException If any IO errors occur.
	*/
	public void close() throws IOException {
	is.close();
	}
	}

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