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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 |