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include/boost/archive/iterators/transform_width.hpp  view on Meta::CPAN

#ifndef BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
#define BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP

// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif

/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
// transform_width.hpp

// (C) Copyright 2002 Robert Ramey - http://www.rrsd.com . 
// Use, modification and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

//  See http://www.boost.org for updates, documentation, and revision history.

// iterator which takes elements of x bits and returns elements of y bits.
// used to change streams of 8 bit characters into streams of 6 bit characters.
// and vice-versa for implementing base64 encodeing/decoding. Be very careful
// when using and end iterator.  end is only reliable detected when the input
// stream length is some common multiple of x and y.  E.G. Base64 6 bit
// character and 8 bit bytes. Lowest common multiple is 24 => 4 6 bit characters
// or 3 8 bit characters

#include <boost/config.hpp> // for BOOST_DEDUCED_TYPENAME & PTFO
#include <boost/pfto.hpp>

#include <boost/iterator/iterator_adaptor.hpp>
#include <boost/iterator/iterator_traits.hpp>

namespace boost { 
namespace archive {
namespace iterators {

/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
// class used by text archives to translate char strings to wchar_t
// strings of the currently selected locale
template<
    class Base, 
    int BitsOut, 
    int BitsIn, 
    class CharType = BOOST_DEDUCED_TYPENAME boost::iterator_value<Base>::type // output character
>
class transform_width : 
    public boost::iterator_adaptor<
        transform_width<Base, BitsOut, BitsIn, CharType>,
        Base,
        CharType,
        single_pass_traversal_tag,
        CharType
    >
{
    friend class boost::iterator_core_access;
    typedef BOOST_DEDUCED_TYPENAME boost::iterator_adaptor<
        transform_width<Base, BitsOut, BitsIn, CharType>,
        Base,
        CharType,
        single_pass_traversal_tag,
        CharType
    > super_t;

    typedef transform_width<Base, BitsOut, BitsIn, CharType> this_t;
    typedef BOOST_DEDUCED_TYPENAME iterator_value<Base>::type base_value_type;

    CharType fill();

    CharType dereference_impl(){
        if(! m_full){
            m_current_value = fill();
            m_full = true;
        }
        return m_current_value;
    }

    CharType dereference() const {
        return const_cast<this_t *>(this)->dereference_impl();
    }

    // test for iterator equality
    bool equal(const this_t & rhs) const {
        return
            this->base_reference() == rhs.base_reference();
        ;
    }

    void increment(){
        m_displacement += BitsOut;

        while(m_displacement >= BitsIn){
            m_displacement -= BitsIn;
            if(0 == m_displacement)
                m_bufferfull = false;
            if(! m_bufferfull){
                // note: suspect that this is not invoked for borland
                ++(this->base_reference());
            }
        }