boost/archive/iterators/binary_from_base64.hpp

   1 #ifndef BOOST_ARCHIVE_ITERATORS_BINARY_FROM_BASE64_HPP
   2 #define BOOST_ARCHIVE_ITERATORS_BINARY_FROM_BASE64_HPP
   3
   4 // MS compatible compilers support #pragma once
   5 #if defined(_MSC_VER)
   6 # pragma once
   7 #endif
   8
   9 /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
  10 // binary_from_base64.hpp
  11
  12 // (C) Copyright 2002 Robert Ramey - http://www.rrsd.com .
  13 // Use, modification and distribution is subject to the Boost Software
  14 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  15 // http://www.boost.org/LICENSE_1_0.txt)
  16
  17 //  See http://www.boost.org for updates, documentation, and revision history.
  18
  19 #include <boost/assert.hpp>
  20
  21 #include <boost/serialization/throw_exception.hpp>
  22 #include <boost/serialization/pfto.hpp>
  23 #include <boost/static_assert.hpp>
  24
  25 #include <boost/iterator/transform_iterator.hpp>
  26 #include <boost/archive/iterators/dataflow_exception.hpp>
  27
  28 namespace boost {
  29 namespace archive {
  30 namespace iterators {
  31
  32 /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
  33 // convert base64 characters to binary data
  34
  35 namespace detail {
  36
  37 template<class CharType>
  38 struct to_6_bit {
  39     typedef CharType result_type;
  40     CharType operator()(CharType t) const{
  41         const signed char lookup_table[] = {
  42             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
  43             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
  44             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,
  45             52,53,54,55,56,57,58,59,60,61,-1,-1,-1, 0,-1,-1, // render '=' as 0
  46             -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
  47             15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,
  48             -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
  49             41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1
  50         };
  51         // metrowerks trips this assertion - how come?
  52         #if ! defined(__MWERKS__)
  53         BOOST_STATIC_ASSERT(128 == sizeof(lookup_table));
  54         #endif
  55         signed char value = -1;
  56         if((unsigned)t <= 127)
  57             value = lookup_table[(unsigned)t];
  58         if(-1 == value)
  59             boost::serialization::throw_exception(
  60                 dataflow_exception(dataflow_exception::invalid_base64_character)
  61             );
  62         return value;
  63     }
  64 };
  65
  66 } // namespace detail
  67
  68 // note: what we would like to do is
  69 // template<class Base, class CharType = typename Base::value_type>
  70 //  typedef transform_iterator<
  71 //      from_6_bit<CharType>,
  72 //      transform_width<Base, 6, sizeof(Base::value_type) * 8, CharType>
  73 //  > base64_from_binary;
  74 // but C++ won't accept this.  Rather than using a "type generator" and
  75 // using a different syntax, make a derivation which should be equivalent.
  76 //
  77 // Another issue addressed here is that the transform_iterator doesn't have
  78 // a templated constructor.  This makes it incompatible with the dataflow
  79 // ideal.  This is also addressed here.
  80
  81 template<
  82     class Base,
  83     class CharType = typename boost::iterator_value<Base>::type
  84 >
  85 class binary_from_base64 : public
  86     transform_iterator<
  87         detail::to_6_bit<CharType>,
  88         Base
  89     >
  90 {
  91     friend class boost::iterator_core_access;
  92     typedef transform_iterator<
  93         detail::to_6_bit<CharType>,
  94         Base
  95     > super_t;
  96 public:
  97     // make composible buy using templated constructor
  98     template<class T>
  99     binary_from_base64(BOOST_PFTO_WRAPPER(T)  start) :
 100         super_t(
 101             Base(BOOST_MAKE_PFTO_WRAPPER(static_cast< T >(start))),
 102             detail::to_6_bit<CharType>()
 103         )
 104     {}
 105     // intel 7.1 doesn't like default copy constructor
 106     binary_from_base64(const binary_from_base64 & rhs) :
 107         super_t(
 108             Base(rhs.base_reference()),
 109             detail::to_6_bit<CharType>()
 110         )
 111     {}
 112 //    binary_from_base64(){};
 113 };
 114
 115 } // namespace iterators
 116 } // namespace archive
 117 } // namespace boost
 118
 119 #endif // BOOST_ARCHIVE_ITERATORS_BINARY_FROM_BASE64_HPP