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#ifndef BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
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#define BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER)
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# pragma once
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#endif
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/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
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// transform_width.hpp
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// (C) Copyright 2002 Robert Ramey - http://www.rrsd.com . 
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// Use, modification and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//  See http://www.boost.org for updates, documentation, and revision history.
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// iterator which takes elements of x bits and returns elements of y bits.
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// used to change streams of 8 bit characters into streams of 6 bit characters.
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// and vice-versa for implementing base64 encodeing/decoding. Be very careful
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// when using and end iterator.  end is only reliable detected when the input
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// stream length is some common multiple of x and y.  E.G. Base64 6 bit
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// character and 8 bit bytes. Lowest common multiple is 24 => 4 6 bit characters
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// or 3 8 bit characters
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#include <boost/iterator/iterator_adaptor.hpp>
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#include <boost/iterator/iterator_traits.hpp>
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#include <algorithm> // std::min
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namespace boost { 
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namespace archive {
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namespace iterators {
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/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
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// class used by text archives to translate char strings to wchar_t
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// strings of the currently selected locale
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template<
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    class Base, 
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    int BitsOut, 
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    int BitsIn, 
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    class CharType = typename boost::iterator_value<Base>::type // output character
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>
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class transform_width : 
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    public boost::iterator_adaptor<
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        transform_width<Base, BitsOut, BitsIn, CharType>,
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        Base,
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        CharType,
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        single_pass_traversal_tag,
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        CharType
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    >
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{
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    friend class boost::iterator_core_access;
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    typedef typename boost::iterator_adaptor<
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        transform_width<Base, BitsOut, BitsIn, CharType>,
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        Base,
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        CharType,
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        single_pass_traversal_tag,
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        CharType
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    > super_t;
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    typedef transform_width<Base, BitsOut, BitsIn, CharType> this_t;
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    typedef typename iterator_value<Base>::type base_value_type;
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    void fill();
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    CharType dereference() const {
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        if(!m_buffer_out_full)
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            const_cast<this_t *>(this)->fill();
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        return m_buffer_out;
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    }
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    bool equal_impl(const this_t & rhs){
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        if(BitsIn < BitsOut) // discard any left over bits
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            return this->base_reference() == rhs.base_reference();
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        else{
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            // BitsIn > BitsOut  // zero fill
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            if(this->base_reference() == rhs.base_reference()){
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                m_end_of_sequence = true;
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                return 0 == m_remaining_bits;
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            }
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            return false;
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        }
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    }
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    // standard iterator interface
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    bool equal(const this_t & rhs) const {
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        return const_cast<this_t *>(this)->equal_impl(rhs);
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    }
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    void increment(){
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        m_buffer_out_full = false;
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    }
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    bool m_buffer_out_full;
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    CharType m_buffer_out;
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    // last read element from input
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    base_value_type m_buffer_in;
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    // number of bits to left in the input buffer.
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    unsigned int m_remaining_bits;
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    // flag to indicate we've reached end of data.
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    bool m_end_of_sequence;
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public:
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    // make composible buy using templated constructor
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    template<class T>
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    transform_width(T start) : 
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        super_t(Base(static_cast< T >(start))),
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        m_buffer_out_full(false),
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        // To disable GCC warning, but not truly necessary 
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            //(m_buffer_in will be initialized later before being 
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            //used because m_remaining_bits == 0)
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        m_buffer_in(0), 
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        m_remaining_bits(0),
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        m_end_of_sequence(false)
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    {}
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    // intel 7.1 doesn't like default copy constructor
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    transform_width(const transform_width & rhs) : 
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        super_t(rhs.base_reference()),
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        m_buffer_out_full(rhs.m_buffer_out_full),
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        m_buffer_out(rhs.m_buffer_out),
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        m_buffer_in(rhs.m_buffer_in),
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        m_remaining_bits(rhs.m_remaining_bits),
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        m_end_of_sequence(false)
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    {}
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};
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template<
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    class Base, 
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    int BitsOut, 
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    int BitsIn, 
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    class CharType
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>
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void transform_width<Base, BitsOut, BitsIn, CharType>::fill() {
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    unsigned int missing_bits = BitsOut;
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    m_buffer_out = 0;
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    do{
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        if(0 == m_remaining_bits){
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            if(m_end_of_sequence){
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                m_buffer_in = 0;
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                m_remaining_bits = missing_bits;
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            }
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            else{
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                m_buffer_in = * this->base_reference()++;
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                m_remaining_bits = BitsIn;
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            }
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        }
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        // append these bits to the next output
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        // up to the size of the output
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        unsigned int i = (std::min)(missing_bits, m_remaining_bits);
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        // shift interesting bits to least significant position
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        base_value_type j = m_buffer_in >> (m_remaining_bits - i);
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        // and mask off the un interesting higher bits
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        // note presumption of twos complement notation
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        j &= (1 << i) - 1;
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        // append then interesting bits to the output value
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        m_buffer_out <<= i;
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        m_buffer_out |= j;
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        // and update counters
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        missing_bits -= i;
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        m_remaining_bits -= i;
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    }while(0 < missing_bits);
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    m_buffer_out_full = true;
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}
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} // namespace iterators
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} // namespace archive
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} // namespace boost
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#endif // BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP