source: NonGTP/Boost/boost/archive/iterators/binary_from_base64.hpp @ 857

Revision 857, 3.8 KB checked in by igarcia, 19 years ago (diff)
Line 
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) && (_MSC_VER >= 1020)
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 <cassert>
20
21#include <boost/config.hpp> // for BOOST_DEDUCED_TYPENAME
22#include <boost/throw_exception.hpp>
23#include <boost/pfto.hpp>
24
25#include <boost/iterator/transform_iterator.hpp>
26#include <boost/archive/iterators/dataflow_exception.hpp>
27
28namespace boost {
29namespace archive {
30namespace iterators {
31
32/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
33// convert base64 characters to binary data
34
35namespace detail {
36
37template<class CharType>
38struct to_6_bit {
39    typedef CharType result_type;
40    CharType operator()(CharType t) const{
41        const 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,-1,-1,-1,
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        signed char value = -1;
52        if((unsigned)t <= 127)
53            value = lookup_table[(unsigned)t];
54        if(-1 == value)
55            boost::throw_exception(
56                dataflow_exception(dataflow_exception::invalid_base64_character)
57            );
58        return value;
59    }
60};
61
62} // namespace detail
63
64// note: what we would like to do is
65// template<class Base, class CharType = BOOST_DEDUCED_TYPENAME Base::value_type>
66//  typedef transform_iterator<
67//      from_6_bit<CharType>,
68//      transform_width<Base, 6, sizeof(Base::value_type) * 8, CharType>
69//  > base64_from_binary;
70// but C++ won't accept this.  Rather than using a "type generator" and
71// using a different syntax, make a derivation which should be equivalent.
72//
73// Another issue addressed here is that the transform_iterator doesn't have
74// a templated constructor.  This makes it incompatible with the dataflow
75// ideal.  This is also addressed here.
76
77template<
78    class Base,
79    class CharType = BOOST_DEDUCED_TYPENAME boost::iterator_value<Base>::type
80>
81class binary_from_base64 : public
82    transform_iterator<
83        detail::to_6_bit<CharType>,
84        Base
85    >
86{
87    friend class boost::iterator_core_access;
88    typedef transform_iterator<
89        detail::to_6_bit<CharType>,
90        Base
91    > super_t;
92public:
93    // make composible buy using templated constructor
94    template<class T>
95    binary_from_base64(BOOST_PFTO_WRAPPER(T)  start) :
96        super_t(
97            Base(BOOST_MAKE_PFTO_WRAPPER(static_cast<T>(start))),
98            detail::to_6_bit<CharType>()
99        )
100    {}
101    // intel 7.1 doesn't like default copy constructor
102    binary_from_base64(const binary_from_base64 & rhs) :
103        super_t(
104            Base(rhs.base_reference()),
105            detail::to_6_bit<CharType>()
106        )
107    {}
108//    binary_from_base64(){};
109};
110
111} // namespace iterators
112} // namespace archive
113} // namespace boost
114
115#endif // BOOST_ARCHIVE_ITERATORS_BINARY_FROM_BASE64_HPP
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