Chris@16: #ifndef BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
Chris@16: #define BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
Chris@16: 
Chris@16: // MS compatible compilers support #pragma once
Chris@101: #if defined(_MSC_VER)
Chris@16: # pragma once
Chris@16: #endif
Chris@16: 
Chris@16: /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
Chris@16: // transform_width.hpp
Chris@16: 
Chris@16: // (C) Copyright 2002 Robert Ramey - http://www.rrsd.com . 
Chris@16: // Use, modification and distribution is subject to the Boost Software
Chris@16: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: //  See http://www.boost.org for updates, documentation, and revision history.
Chris@16: 
Chris@16: // iterator which takes elements of x bits and returns elements of y bits.
Chris@16: // used to change streams of 8 bit characters into streams of 6 bit characters.
Chris@16: // and vice-versa for implementing base64 encodeing/decoding. Be very careful
Chris@16: // when using and end iterator.  end is only reliable detected when the input
Chris@16: // stream length is some common multiple of x and y.  E.G. Base64 6 bit
Chris@16: // character and 8 bit bytes. Lowest common multiple is 24 => 4 6 bit characters
Chris@16: // or 3 8 bit characters
Chris@16: 
Chris@16: #include <boost/serialization/pfto.hpp>
Chris@16: 
Chris@16: #include <boost/iterator/iterator_adaptor.hpp>
Chris@16: #include <boost/iterator/iterator_traits.hpp>
Chris@16: 
Chris@101: #include <algorithm> // std::min
Chris@101: 
Chris@16: namespace boost { 
Chris@16: namespace archive {
Chris@16: namespace iterators {
Chris@16: 
Chris@16: /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
Chris@16: // class used by text archives to translate char strings to wchar_t
Chris@16: // strings of the currently selected locale
Chris@16: template<
Chris@16:     class Base, 
Chris@16:     int BitsOut, 
Chris@16:     int BitsIn, 
Chris@101:     class CharType = typename boost::iterator_value<Base>::type // output character
Chris@16: >
Chris@16: class transform_width : 
Chris@16:     public boost::iterator_adaptor<
Chris@16:         transform_width<Base, BitsOut, BitsIn, CharType>,
Chris@16:         Base,
Chris@16:         CharType,
Chris@16:         single_pass_traversal_tag,
Chris@16:         CharType
Chris@16:     >
Chris@16: {
Chris@16:     friend class boost::iterator_core_access;
Chris@101:     typedef typename boost::iterator_adaptor<
Chris@16:         transform_width<Base, BitsOut, BitsIn, CharType>,
Chris@16:         Base,
Chris@16:         CharType,
Chris@16:         single_pass_traversal_tag,
Chris@16:         CharType
Chris@16:     > super_t;
Chris@16: 
Chris@16:     typedef transform_width<Base, BitsOut, BitsIn, CharType> this_t;
Chris@101:     typedef typename iterator_value<Base>::type base_value_type;
Chris@16: 
Chris@16:     void fill();
Chris@16: 
Chris@16:     CharType dereference() const {
Chris@16:         if(!m_buffer_out_full)
Chris@16:             const_cast<this_t *>(this)->fill();
Chris@16:         return m_buffer_out;
Chris@16:     }
Chris@16: 
Chris@16:     bool equal_impl(const this_t & rhs){
Chris@16:         if(BitsIn < BitsOut) // discard any left over bits
Chris@16:             return this->base_reference() == rhs.base_reference();
Chris@16:         else{
Chris@16:             // BitsIn > BitsOut  // zero fill
Chris@16:             if(this->base_reference() == rhs.base_reference()){
Chris@16:                 m_end_of_sequence = true;
Chris@16:                 return 0 == m_remaining_bits;
Chris@16:             }
Chris@16:             return false;
Chris@16:         }
Chris@16:     }
Chris@16: 
Chris@16:     // standard iterator interface
Chris@16:     bool equal(const this_t & rhs) const {
Chris@16:         return const_cast<this_t *>(this)->equal_impl(rhs);
Chris@16:     }
Chris@16: 
Chris@16:     void increment(){
Chris@16:         m_buffer_out_full = false;
Chris@16:     }
Chris@16: 
Chris@16:     bool m_buffer_out_full;
Chris@16:     CharType m_buffer_out;
Chris@16: 
Chris@16:     // last read element from input
Chris@16:     base_value_type m_buffer_in;
Chris@16: 
Chris@16:     // number of bits to left in the input buffer.
Chris@16:     unsigned int m_remaining_bits;
Chris@16: 
Chris@16:     // flag to indicate we've reached end of data.
Chris@16:     bool m_end_of_sequence;
Chris@16: 
Chris@16: public:
Chris@16:     // make composible buy using templated constructor
Chris@16:     template<class T>
Chris@16:     transform_width(BOOST_PFTO_WRAPPER(T) start) : 
Chris@16:         super_t(Base(BOOST_MAKE_PFTO_WRAPPER(static_cast< T >(start)))),
Chris@16:         m_buffer_out_full(false),
Chris@101:         // To disable GCC warning, but not truly necessary 
Chris@101: 	    //(m_buffer_in will be initialized later before being 
Chris@101: 	    //used because m_remaining_bits == 0)
Chris@101:         m_buffer_in(0), 
Chris@16:         m_remaining_bits(0),
Chris@16:         m_end_of_sequence(false)
Chris@16:     {}
Chris@16:     // intel 7.1 doesn't like default copy constructor
Chris@16:     transform_width(const transform_width & rhs) : 
Chris@16:         super_t(rhs.base_reference()),
Chris@16:         m_buffer_out_full(rhs.m_buffer_out_full),
Chris@101:         m_buffer_out(rhs.m_buffer_out),
Chris@101:         m_buffer_in(rhs.m_buffer_in),
Chris@16:         m_remaining_bits(rhs.m_remaining_bits),
Chris@16:         m_end_of_sequence(false)
Chris@16:     {}
Chris@16: };
Chris@16: 
Chris@16: template<
Chris@16:     class Base, 
Chris@16:     int BitsOut, 
Chris@16:     int BitsIn, 
Chris@16:     class CharType
Chris@16: >
Chris@16: void transform_width<Base, BitsOut, BitsIn, CharType>::fill() {
Chris@16:     unsigned int missing_bits = BitsOut;
Chris@16:     m_buffer_out = 0;
Chris@16:     do{
Chris@16:         if(0 == m_remaining_bits){
Chris@16:             if(m_end_of_sequence){
Chris@16:                 m_buffer_in = 0;
Chris@16:                 m_remaining_bits = missing_bits;
Chris@16:             }
Chris@16:             else{
Chris@16:                 m_buffer_in = * this->base_reference()++;
Chris@16:                 m_remaining_bits = BitsIn;
Chris@16:             }
Chris@16:         }
Chris@16: 
Chris@16:         // append these bits to the next output
Chris@16:         // up to the size of the output
Chris@16:         unsigned int i = std::min(missing_bits, m_remaining_bits);
Chris@16:         // shift interesting bits to least significant position
Chris@16:         base_value_type j = m_buffer_in >> (m_remaining_bits - i);
Chris@16:         // and mask off the un interesting higher bits
Chris@16:         // note presumption of twos complement notation
Chris@16:         j &= (1 << i) - 1;
Chris@16:         // append then interesting bits to the output value
Chris@16:         m_buffer_out <<= i;
Chris@16:         m_buffer_out |= j;
Chris@16: 
Chris@16:         // and update counters
Chris@16:         missing_bits -= i;
Chris@16:         m_remaining_bits -= i;
Chris@16:     }while(0 < missing_bits);
Chris@16:     m_buffer_out_full = true;
Chris@16: }
Chris@16: 
Chris@16: } // namespace iterators
Chris@16: } // namespace archive
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP