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 | #include <xutility>
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9 | #if defined(_MSC_VER) && (_MSC_VER >= 1800)
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10 | #include <algorithm>
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11 | #endif
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12 |
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13 | /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
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14 | // transform_width.hpp
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15 |
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16 | // (C) Copyright 2002 Robert Ramey - http://www.rrsd.com .
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17 | // Use, modification and distribution is subject to the Boost Software
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18 | // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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19 | // http://www.boost.org/LICENSE_1_0.txt)
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20 |
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21 | // See http://www.boost.org for updates, documentation, and revision history.
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22 |
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23 | // iterator which takes elements of x bits and returns elements of y bits.
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24 | // used to change streams of 8 bit characters into streams of 6 bit characters.
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25 | // and vice-versa for implementing base64 encodeing/decoding. Be very careful
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26 | // when using and end iterator. end is only reliable detected when the input
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27 | // stream length is some common multiple of x and y. E.G. Base64 6 bit
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28 | // character and 8 bit bytes. Lowest common multiple is 24 => 4 6 bit characters
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29 | // or 3 8 bit characters
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30 |
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31 | #include <boost/config.hpp> // for BOOST_DEDUCED_TYPENAME & PTFO
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32 | #include <boost/serialization/pfto.hpp>
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33 |
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34 | #include <boost/iterator/iterator_adaptor.hpp>
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35 | #include <boost/iterator/iterator_traits.hpp>
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36 |
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37 | namespace boost {
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38 | namespace archive {
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39 | namespace iterators {
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40 |
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41 | /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
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42 | // class used by text archives to translate char strings to wchar_t
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43 | // strings of the currently selected locale
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44 | template<
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45 | class Base,
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46 | int BitsOut,
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47 | int BitsIn,
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48 | class CharType = BOOST_DEDUCED_TYPENAME boost::iterator_value<Base>::type // output character
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49 | >
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50 | class transform_width :
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51 | public boost::iterator_adaptor<
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52 | transform_width<Base, BitsOut, BitsIn, CharType>,
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53 | Base,
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54 | CharType,
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55 | single_pass_traversal_tag,
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56 | CharType
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57 | >
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58 | {
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59 | friend class boost::iterator_core_access;
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60 | typedef BOOST_DEDUCED_TYPENAME boost::iterator_adaptor<
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61 | transform_width<Base, BitsOut, BitsIn, CharType>,
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62 | Base,
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63 | CharType,
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64 | single_pass_traversal_tag,
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65 | CharType
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66 | > super_t;
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67 |
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68 | typedef transform_width<Base, BitsOut, BitsIn, CharType> this_t;
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69 | typedef BOOST_DEDUCED_TYPENAME iterator_value<Base>::type base_value_type;
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70 |
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71 | void fill();
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72 |
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73 | CharType dereference() const {
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74 | if(!m_buffer_out_full)
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75 | const_cast<this_t *>(this)->fill();
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76 | return m_buffer_out;
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77 | }
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78 |
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79 | bool equal_impl(const this_t & rhs){
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80 | if(BitsIn < BitsOut) // discard any left over bits
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81 | return this->base_reference() == rhs.base_reference();
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82 | else{
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83 | // BitsIn > BitsOut // zero fill
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84 | if(this->base_reference() == rhs.base_reference()){
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85 | m_end_of_sequence = true;
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86 | return 0 == m_remaining_bits;
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87 | }
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88 | return false;
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89 | }
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90 | }
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91 |
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92 | // standard iterator interface
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93 | bool equal(const this_t & rhs) const {
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94 | return const_cast<this_t *>(this)->equal_impl(rhs);
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95 | }
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96 |
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97 | void increment(){
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98 | m_buffer_out_full = false;
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99 | }
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100 |
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101 | bool m_buffer_out_full;
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102 | CharType m_buffer_out;
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103 |
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104 | // last read element from input
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105 | base_value_type m_buffer_in;
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106 |
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107 | // number of bits to left in the input buffer.
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108 | unsigned int m_remaining_bits;
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109 |
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110 | // flag to indicate we've reached end of data.
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111 | bool m_end_of_sequence;
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112 |
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113 | public:
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114 | // make composible buy using templated constructor
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115 | template<class T>
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116 | transform_width(BOOST_PFTO_WRAPPER(T) start) :
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117 | super_t(Base(BOOST_MAKE_PFTO_WRAPPER(static_cast< T >(start)))),
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118 | m_buffer_out_full(false),
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119 | m_remaining_bits(0),
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120 | m_end_of_sequence(false)
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121 | {}
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122 | // intel 7.1 doesn't like default copy constructor
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123 | transform_width(const transform_width & rhs) :
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124 | super_t(rhs.base_reference()),
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125 | m_buffer_out_full(rhs.m_buffer_out_full),
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126 | m_remaining_bits(rhs.m_remaining_bits),
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127 | m_buffer_in(rhs.m_buffer_in),
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128 | m_end_of_sequence(false)
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129 | {}
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130 | };
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131 |
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132 | template<
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133 | class Base,
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134 | int BitsOut,
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135 | int BitsIn,
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136 | class CharType
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137 | >
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138 | void transform_width<Base, BitsOut, BitsIn, CharType>::fill() {
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139 | unsigned int missing_bits = BitsOut;
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140 | m_buffer_out = 0;
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141 | do{
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142 | if(0 == m_remaining_bits){
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143 | if(m_end_of_sequence){
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144 | m_buffer_in = 0;
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145 | m_remaining_bits = missing_bits;
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146 | }
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147 | else{
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148 | m_buffer_in = * this->base_reference()++;
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149 | m_remaining_bits = BitsIn;
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150 | }
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151 | }
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152 |
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153 | // append these bits to the next output
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154 | // up to the size of the output
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155 | unsigned int i = std::min(missing_bits, m_remaining_bits);
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156 | // shift interesting bits to least significant position
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157 | base_value_type j = m_buffer_in >> (m_remaining_bits - i);
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158 | // and mask off the un interesting higher bits
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159 | // note presumption of twos complement notation
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160 | j &= (1 << i) - 1;
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161 | // append then interesting bits to the output value
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162 | m_buffer_out <<= i;
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163 | m_buffer_out |= j;
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164 |
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165 | // and update counters
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166 | missing_bits -= i;
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167 | m_remaining_bits -= i;
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168 | }while(0 < missing_bits);
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169 | m_buffer_out_full = true;
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170 | }
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171 |
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172 | } // namespace iterators
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173 | } // namespace archive
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174 | } // namespace boost
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175 |
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176 | #endif // BOOST_ARCHIVE_ITERATORS_TRANSFORM_WIDTH_HPP
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