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//
//  ========================================================================
//  Copyright (c) 1995-2012 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util;


/* ------------------------------------------------------------ */
/** UTF-8 StringBuilder.
 *
 * This class wraps a standard {@link java.lang.StringBuilder} and provides methods to append
 * UTF-8 encoded bytes, that are converted into characters.
 *
 * This class is stateful and up to 4 calls to {@link #append(byte)} may be needed before
 * state a character is appended to the string buffer.
 *
 * The UTF-8 decoding is done by this class and no additional buffers or Readers are used.
 * The UTF-8 code was inspired by http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
 *
 */
public class Utf8StringBuilder extends Utf8Appendable
{
    final StringBuilder _buffer;

    public Utf8StringBuilder()
    {
        super(new StringBuilder());
        _buffer=(StringBuilder)_appendable;
    }

    public Utf8StringBuilder(int capacity)
    {
        super(new StringBuilder(capacity));
        _buffer=(StringBuilder)_appendable;
    }

    @Override
    public int length()
    {
        return _buffer.length();
    }

    @Override
    public void reset()
    {
        super.reset();
        _buffer.setLength(0);
    }

    public StringBuilder getStringBuilder()
    {
        checkState();
        return _buffer;
    }

    @Override
    public String toString()
    {
        checkState();
        return _buffer.toString();
    }

    private void checkState()
    {
        if (!isUtf8SequenceComplete())
            throw new IllegalArgumentException("Tried to read incomplete UTF8 decoded String");
    }
}