1 | // (C) Copyright Jonathan Turkanis 2003. |
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2 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
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3 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.) |
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4 | |
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5 | // See http://www.boost.org/libs/iostreams for documentation. |
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6 | |
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7 | #ifndef BOOST_IOSTREAMS_SEEK_HPP_INCLUDED |
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8 | #define BOOST_IOSTREAMS_SEEK_HPP_INCLUDED |
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9 | |
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10 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
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11 | # pragma once |
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12 | #endif |
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13 | |
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14 | #include <boost/config.hpp> // DEDUCED_TYPENAME, MSVC. |
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15 | #include <boost/integer_traits.hpp> |
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16 | #include <boost/iostreams/categories.hpp> |
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17 | #include <boost/iostreams/detail/dispatch.hpp> |
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18 | #include <boost/iostreams/detail/ios.hpp> // streamsize, seekdir, openmode. |
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19 | #include <boost/iostreams/detail/streambuf.hpp> |
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20 | #include <boost/iostreams/detail/wrap_unwrap.hpp> |
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21 | #include <boost/iostreams/operations_fwd.hpp> |
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22 | #include <boost/iostreams/positioning.hpp> |
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23 | #include <boost/mpl/if.hpp> |
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24 | |
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25 | // Must come last. |
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26 | #include <boost/iostreams/detail/config/disable_warnings.hpp> |
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27 | |
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28 | namespace boost { namespace iostreams { |
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29 | |
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30 | namespace detail { |
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31 | |
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32 | template<typename T> |
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33 | struct seek_device_impl; |
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34 | |
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35 | template<typename T> |
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36 | struct seek_filter_impl; |
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37 | |
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38 | } // End namespace detail. |
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39 | |
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40 | template<typename T> |
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41 | inline std::streampos |
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42 | seek( T& t, stream_offset off, BOOST_IOS::seekdir way, |
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43 | BOOST_IOS::openmode which = BOOST_IOS::in | BOOST_IOS::out ) |
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44 | { |
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45 | using namespace detail; |
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46 | return seek_device_impl<T>::seek(detail::unwrap(t), off, way, which); |
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47 | } |
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48 | |
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49 | template<typename T, typename Device> |
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50 | inline std::streampos |
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51 | seek( T& t, Device& dev, stream_offset off, BOOST_IOS::seekdir way, |
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52 | BOOST_IOS::openmode which = BOOST_IOS::in | BOOST_IOS::out ) |
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53 | { |
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54 | using namespace detail; |
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55 | return seek_filter_impl<T>::seek(detail::unwrap(t), dev, off, way, which); |
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56 | } |
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57 | |
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58 | namespace detail { |
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59 | |
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60 | //------------------Definition of seek_device_impl----------------------------// |
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61 | |
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62 | template<typename T> |
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63 | struct seek_device_impl |
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64 | : mpl::if_< |
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65 | is_custom<T>, |
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66 | operations<T>, |
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67 | seek_device_impl< |
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68 | BOOST_DEDUCED_TYPENAME |
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69 | dispatch< |
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70 | T, iostream_tag, istream_tag, ostream_tag, |
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71 | streambuf_tag, two_head, any_tag |
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72 | >::type |
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73 | > |
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74 | >::type |
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75 | { }; |
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76 | |
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77 | struct seek_impl_basic_ios { |
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78 | template<typename T> |
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79 | static std::streampos seek( T& t, stream_offset off, |
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80 | BOOST_IOS::seekdir way, |
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81 | BOOST_IOS::openmode which ) |
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82 | { |
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83 | if ( way == BOOST_IOS::beg && |
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84 | ( off < integer_traits<std::streamoff>::const_min || |
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85 | off > integer_traits<std::streamoff>::const_max ) ) |
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86 | { |
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87 | return t.rdbuf()->pubseekpos(offset_to_position(off)); |
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88 | } else { |
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89 | return t.rdbuf()->pubseekoff(off, way, which); |
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90 | } |
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91 | } |
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92 | }; |
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93 | |
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94 | template<> |
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95 | struct seek_device_impl<iostream_tag> : seek_impl_basic_ios { }; |
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96 | |
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97 | template<> |
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98 | struct seek_device_impl<istream_tag> : seek_impl_basic_ios { }; |
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99 | |
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100 | template<> |
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101 | struct seek_device_impl<ostream_tag> : seek_impl_basic_ios { }; |
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102 | |
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103 | template<> |
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104 | struct seek_device_impl<streambuf_tag> { |
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105 | template<typename T> |
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106 | static std::streampos seek( T& t, stream_offset off, |
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107 | BOOST_IOS::seekdir way, |
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108 | BOOST_IOS::openmode which ) |
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109 | { |
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110 | if ( way == BOOST_IOS::beg && |
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111 | ( off < integer_traits<std::streamoff>::const_min || |
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112 | off > integer_traits<std::streamoff>::const_max ) ) |
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113 | { |
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114 | return t.BOOST_IOSTREAMS_PUBSEEKPOS(offset_to_position(off)); |
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115 | } else { |
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116 | return t.BOOST_IOSTREAMS_PUBSEEKOFF(off, way, which); |
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117 | } |
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118 | } |
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119 | }; |
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120 | |
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121 | template<> |
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122 | struct seek_device_impl<two_head> { |
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123 | template<typename T> |
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124 | static std::streampos seek( T& t, stream_offset off, |
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125 | BOOST_IOS::seekdir way, |
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126 | BOOST_IOS::openmode which ) |
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127 | { return t.seek(off, way, which); } |
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128 | }; |
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129 | |
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130 | template<> |
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131 | struct seek_device_impl<any_tag> { |
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132 | template<typename T> |
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133 | static std::streampos seek( T& t, stream_offset off, |
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134 | BOOST_IOS::seekdir way, |
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135 | BOOST_IOS::openmode ) |
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136 | { return t.seek(off, way); } |
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137 | }; |
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138 | |
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139 | //------------------Definition of seek_filter_impl----------------------------// |
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140 | |
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141 | template<typename T> |
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142 | struct seek_filter_impl |
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143 | : mpl::if_< |
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144 | is_custom<T>, |
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145 | operations<T>, |
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146 | seek_filter_impl< |
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147 | BOOST_DEDUCED_TYPENAME |
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148 | dispatch<T, two_head, any_tag>::type |
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149 | > |
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150 | >::type |
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151 | { }; |
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152 | |
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153 | template<> |
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154 | struct seek_filter_impl<two_head> { |
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155 | template<typename T, typename Device> |
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156 | static std::streampos seek( T& t, Device& d, |
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157 | stream_offset off, |
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158 | BOOST_IOS::seekdir way, |
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159 | BOOST_IOS::openmode which ) |
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160 | { return t.seek(d, off, way, which); } |
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161 | }; |
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162 | |
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163 | template<> |
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164 | struct seek_filter_impl<any_tag> { |
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165 | template<typename T, typename Device> |
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166 | static std::streampos seek( T& t, Device& d, |
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167 | stream_offset off, |
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168 | BOOST_IOS::seekdir way, |
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169 | BOOST_IOS::openmode ) |
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170 | { return t.seek(d, off, way); } |
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171 | }; |
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172 | |
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173 | } // End namespace detail. |
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174 | |
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175 | } } // End namespaces iostreams, boost. |
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176 | |
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177 | #include <boost/iostreams/detail/config/enable_warnings.hpp> |
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178 | |
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179 | #endif // #ifndef BOOST_IOSTREAMS_SEEK_HPP_INCLUDED |
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