[857] | 1 | #ifndef BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
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| 2 | #define BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
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| 3 |
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| 4 | // MS compatible compilers support #pragma once
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| 5 | #if defined(_MSC_VER) && (_MSC_VER >= 1020)
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| 6 | # pragma once
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| 7 | #endif
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| 8 |
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| 9 | /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
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| 10 | // transform_width.hpp
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| 11 |
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| 12 | // (C) Copyright 2002 Robert Ramey - http://www.rrsd.com .
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| 13 | // Use, modification and distribution is subject to the Boost Software
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| 14 | // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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| 15 | // http://www.boost.org/LICENSE_1_0.txt)
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| 16 |
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| 17 | // See http://www.boost.org for updates, documentation, and revision history.
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| 18 |
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| 19 | // iterator which takes elements of x bits and returns elements of y bits.
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| 20 | // used to change streams of 8 bit characters into streams of 6 bit characters.
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| 21 | // and vice-versa for implementing base64 encodeing/decoding. Be very careful
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| 22 | // when using and end iterator. end is only reliable detected when the input
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| 23 | // stream length is some common multiple of x and y. E.G. Base64 6 bit
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| 24 | // character and 8 bit bytes. Lowest common multiple is 24 => 4 6 bit characters
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| 25 | // or 3 8 bit characters
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| 26 |
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| 27 | #include <boost/config.hpp> // for BOOST_DEDUCED_TYPENAME & PTFO
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| 28 | #include <boost/pfto.hpp>
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| 29 |
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| 30 | #include <boost/iterator/iterator_adaptor.hpp>
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| 31 | #include <boost/iterator/iterator_traits.hpp>
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| 32 |
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| 33 | namespace boost {
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| 34 | namespace archive {
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| 35 | namespace iterators {
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| 36 |
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| 37 | /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
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| 38 | // class used by text archives to translate char strings to wchar_t
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| 39 | // strings of the currently selected locale
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| 40 | template<
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| 41 | class Base,
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| 42 | int BitsOut,
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| 43 | int BitsIn,
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| 44 | class CharType = BOOST_DEDUCED_TYPENAME boost::iterator_value<Base>::type // output character
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| 45 | >
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| 46 | class transform_width :
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| 47 | public boost::iterator_adaptor<
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| 48 | transform_width<Base, BitsOut, BitsIn, CharType>,
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| 49 | Base,
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| 50 | CharType,
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| 51 | single_pass_traversal_tag,
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| 52 | CharType
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| 53 | >
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| 54 | {
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| 55 | friend class boost::iterator_core_access;
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| 56 | typedef BOOST_DEDUCED_TYPENAME boost::iterator_adaptor<
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| 57 | transform_width<Base, BitsOut, BitsIn, CharType>,
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| 58 | Base,
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| 59 | CharType,
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| 60 | single_pass_traversal_tag,
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| 61 | CharType
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| 62 | > super_t;
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| 63 |
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| 64 | typedef transform_width<Base, BitsOut, BitsIn, CharType> this_t;
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| 65 | typedef BOOST_DEDUCED_TYPENAME iterator_value<Base>::type base_value_type;
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| 66 |
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| 67 | CharType fill();
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| 68 |
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| 69 | CharType dereference_impl(){
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| 70 | if(! m_full){
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| 71 | m_current_value = fill();
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| 72 | m_full = true;
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| 73 | }
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| 74 | return m_current_value;
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| 75 | }
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| 76 |
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| 77 | CharType dereference() const {
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| 78 | return const_cast<this_t *>(this)->dereference_impl();
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| 79 | }
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| 80 |
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| 81 | // test for iterator equality
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| 82 | bool equal(const this_t & rhs) const {
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| 83 | return
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| 84 | this->base_reference() == rhs.base_reference();
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| 85 | ;
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| 86 | }
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| 87 |
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| 88 | void increment(){
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| 89 | m_displacement += BitsOut;
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| 90 |
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| 91 | while(m_displacement >= BitsIn){
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| 92 | m_displacement -= BitsIn;
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| 93 | if(0 == m_displacement)
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| 94 | m_bufferfull = false;
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| 95 | if(! m_bufferfull){
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| 96 | // note: suspect that this is not invoked for borland
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| 97 | ++(this->base_reference());
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| 98 | }
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| 99 | }
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| 100 | m_full = false;
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| 101 | }
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| 102 |
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| 103 | CharType m_current_value;
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| 104 | // number of bits left in current input character buffer
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| 105 | unsigned int m_displacement;
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| 106 | base_value_type m_buffer;
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| 107 | // flag to current output character is ready - just used to save time
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| 108 | bool m_full;
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| 109 | // flag to indicate that m_buffer has data
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| 110 | bool m_bufferfull;
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| 111 |
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| 112 | public:
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| 113 | // make composible buy using templated constructor
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| 114 | template<class T>
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| 115 | transform_width(BOOST_PFTO_WRAPPER(T) start) :
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| 116 | super_t(Base(BOOST_MAKE_PFTO_WRAPPER(static_cast<T>(start)))),
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| 117 | m_displacement(0),
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| 118 | m_full(false),
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| 119 | m_bufferfull(false)
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| 120 | {}
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| 121 | // intel 7.1 doesn't like default copy constructor
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| 122 | transform_width(const transform_width & rhs) :
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| 123 | super_t(rhs.base_reference()),
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| 124 | m_current_value(rhs.m_current_value),
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| 125 | m_displacement(rhs.m_displacement),
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| 126 | m_buffer(rhs.m_buffer),
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| 127 | m_full(rhs.m_full),
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| 128 | m_bufferfull(rhs.m_bufferfull)
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| 129 | {}
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| 130 | };
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| 131 |
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| 132 | template<class Base, int BitsOut, int BitsIn, class CharType>
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| 133 | CharType transform_width<Base, BitsOut, BitsIn, CharType>::fill(){
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| 134 | CharType retval = 0;
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| 135 | unsigned int missing_bits = BitsOut;
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| 136 | for(;;){
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| 137 | unsigned int bcount;
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| 138 | if(! m_bufferfull){
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| 139 | m_buffer = * this->base_reference();
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| 140 | m_bufferfull = true;
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| 141 | bcount = BitsIn;
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| 142 | }
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| 143 | else
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| 144 | bcount = BitsIn - m_displacement;
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| 145 | unsigned int i = (std::min)(bcount, missing_bits);
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| 146 | // shift interesting bits to least significant position
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| 147 | unsigned int j = m_buffer >> (bcount - i);
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| 148 | // strip off uninteresting bits
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| 149 | // (note presumption of two's complement arithmetic)
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| 150 | j &= ~(-(1 << i));
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| 151 | // append then interesting bits to the output value
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| 152 | retval <<= i;
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| 153 | retval |= j;
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| 154 | missing_bits -= i;
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| 155 | if(0 == missing_bits)
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| 156 | break;
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| 157 | // note: suspect that this is not invoked for borland 5.51
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| 158 | ++(this->base_reference());
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| 159 | m_bufferfull = false;
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| 160 | }
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| 161 | return retval;
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| 162 | }
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| 163 |
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| 164 | } // namespace iterators
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| 165 | } // namespace archive
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| 166 | } // namespace boost
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| 167 |
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| 168 | #endif // BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
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