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	/*
	* Copyright (c) 2006, 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 com.sun.xml.internal.stream.writers;

	import java.io.IOException;
	import java.io.Writer;
	import com.sun.org.apache.xerces.internal.util.XMLStringBuffer;

	/**
	* XMLWriter
	*
	* <code>XMLWriter</code> is not thread safe.
	*
	* For efficiency this writer buffers the input. Use <code>flush()</code> function
	* to explicitly write the data to underlying stream.
	*
	* This writer is designed in such a way that it atleast buffers the input to the
	* <code>size</code> specified. Unless <code>flush</code> is called, it guarantees that
	* data in chunks of size equal to or more than <code>size</code> specified will be written.
	*
	*
	* <code>XMLWriter</code> instance can be reused. <code>setWriter()</code> internally clears the
	* buffer and stores the reference to newly supplied <code>Writer</code> instance.
	*
	* @author Neeraj Bajaj Sun Microsystems, inc.
	*/
	public class XMLWriter extends Writer {

	private Writer writer ;
	private int size ;
	//keep the size of internal buffer more than 'size' required to avoid resizing
	private XMLStringBuffer buffer = new XMLStringBuffer(6 * (1 << 11) ); // 6 KB
	private static final int THRESHHOLD_LENGTH = 1 << 12 ; // 4 KB
	private static final boolean DEBUG = false;

	/** Creates the instance of <code>XMLWriter</code>
	*/

	public XMLWriter(Writer writer){
	this(writer, THRESHHOLD_LENGTH);
	}

	/**
	* Creates the instnace of <code>XMLWriter</code>.
	*
	* atleast buffers the input to the
	* <code>size</code> specified.
	*/
	public XMLWriter(Writer writer, int size){
	this.writer = writer ;
	this.size = size;
	}

	/**
	* Write a single character. The character to be written is contained in
	* the 16 low-order bits of the given integer value; the 16 high-order bits
	* are ignored.
	*
	* <p> Subclasses that intend to support efficient single-character output
	* should override this method.
	*
	* @param c int specifying a character to be written.
	* @exception IOException If an I/O error occurs
	*/

	public void write(int c) throws IOException {
	ensureOpen();
	buffer.append((char)c);
	conditionalWrite();
	}

	/**
	* Write an array of characters.
	*
	* @param cbuf Array of characters to be written
	*
	* @exception IOException If an I/O error occurs
	*/

	public void write(char cbuf[]) throws IOException {
	write(cbuf, 0, cbuf.length);
	}

	/**
	* Write a portion of an array of characters.
	*
	* @param cbuf Array of characters
	* @param off Offset from which to start writing characters
	* @param len Number of characters to write
	*
	* @exception IOException If an I/O error occurs
	*/

	public void write(char cbuf[], int off, int len) throws IOException{
	ensureOpen();
	//optimization: if data size to be written is more than the 'size' specified,
	//do not buffer the data but write the data straight to the underlying stream
	if(len > size){
	//first write the data that may be present in the buffer
	writeBufferedData();
	//write directly to stream
	writer.write(cbuf, off, len);
	}else{
	buffer.append(cbuf, off, len);
	conditionalWrite();
	}
	}

	/**
	* Write a portion of a string.
	*
	* @param str A String
	* @param off Offset from which to start writing characters
	* @param len Number of characters to write
	*
	* @exception IOException If an I/O error occurs
	*/
	public void write(String str, int off, int len) throws IOException {
	write(str.toCharArray(), off, len);
	}

	/**
	* Write a string.
	*
	* @param str String to be written
	*
	* @exception IOException If an I/O error occurs
	*/
	public void write(String str) throws IOException {
	//optimization: if data size to be written is more than the 'size' specified,
	//do not buffer the data but write the data straight to the underlying stream - nb.
	if(str.length() > size){
	//first write the data that may be present in the buffer
	writeBufferedData();
	//write directly to stream
	writer.write(str);
	}else{
	buffer.append(str);
	conditionalWrite();
	}
	}

	/**
	* Close the stream, flushing it first. Once a stream has been closed,
	* further write() or flush() invocations will cause an IOException to be
	* thrown. Closing a previously-closed stream, however, has no effect.
	*
	* @exception IOException If an I/O error occurs
	*/
	public void close() throws IOException {
	if(writer == null) return;
	//flush it first
	flush();
	writer.close();
	writer = null ;
	}

	/**
	* Flush the stream. If the stream has saved any characters from the
	* various write() methods in a buffer, write them immediately to their
	* intended destination. Then, if that destination is another character or
	* byte stream, flush it. Thus one flush() invocation will flush all the
	* buffers in a chain of Writers and OutputStreams.
	*
	* @exception IOException If an I/O error occurs
	*/

	public void flush() throws IOException {
	ensureOpen();
	//write current data present in the buffer
	writeBufferedData();
	writer.flush();
	}

	/** Reset this Writer.
	*
	* see @setWriter()
	*/
	public void reset(){
	this.writer = null;
	buffer.clear();
	this.size = THRESHHOLD_LENGTH;
	}

	/**
	* Set the given <code>Writer</code>.
	*
	* @param Writer Writer.
	*/
	public void setWriter(Writer writer){
	this.writer = writer;
	buffer.clear();
	this.size = THRESHHOLD_LENGTH;
	}

	/** Set the given <code>Writer</code>
	*
	* @param Writer Writer.
	* @param int Writer will buffer the character data size, after that data is written to stream.
	*/
	public void setWriter(Writer writer, int size){
	this.writer = writer;
	this.size = size;
	}

	/**
	* Returns underlying <code>Writer</code>
	*/
	protected Writer getWriter() {
	return writer;
	}

	/** write the buffer data, if the buffer size has increased the size specified
	*/
	private void conditionalWrite() throws IOException {
	if(buffer.length > size){
	if(DEBUG){
	System.out.println("internal buffer length " + buffer.length + " increased size limit : " + size);
	System.out.println("Data: ('" + new String(buffer.ch, buffer.offset, buffer.length) + "')");
	}
	writeBufferedData();
	}
	}

	/** Write the data present in the buffer to the writer.
	* buffer is cleared after write operation.
	*/
	private void writeBufferedData() throws IOException {
	writer.write(buffer.ch, buffer.offset, buffer.length);
	buffer.clear();
	}

	/** Check to make sure that the stream has not been closed */
	private void ensureOpen() throws IOException {
	if (writer == null)throw new IOException("Stream closed");
	}
	}

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