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 | // Contains the definitions of the class templates symmetric_filter,
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8 | // which models DualUseFilter based on a model of the Symmetric Filter.
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9 |
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10 | //
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11 | // Roughly, a Symmetric Filter is a class type with the following interface:
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12 | //
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13 | // struct symmetric_filter {
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14 | // typedef xxx char_type;
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15 | //
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16 | // bool filter( const char*& begin_in, const char* end_in,
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17 | // char*& begin_out, char* end_out, bool flush )
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18 | // {
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19 | // // Consume as many characters as possible from the interval
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20 | // // [begin_in, end_in), without exhausting the output range
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21 | // // [begin_out, end_out). If flush is true, write as mush output
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22 | // // as possible.
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23 | // // A return value of true indicates that filter should be called
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24 | // // again. More precisely, if flush is false, a return value of
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25 | // // false indicates that the natural end of stream has been reached
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26 | // // and that all filtered data has been forwarded; if flush is
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27 | // // true, a return value of false indicates that all filtered data
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28 | // // has been forwarded.
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29 | // }
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30 | // void close() { /* Reset filter's state. */ }
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31 | // };
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32 | //
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33 | // Symmetric Filter filters need not be CopyConstructable.
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34 | //
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35 |
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36 | #ifndef BOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED
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37 | #define BOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED
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38 |
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39 | #if defined(_MSC_VER) && (_MSC_VER >= 1020)
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40 | # pragma once
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41 | #endif
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42 |
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43 | #include <cassert>
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44 | #include <memory> // allocator, auto_ptr.
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45 | #include <boost/config.hpp> // BOOST_DEDUCED_TYPENAME.
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46 | #include <boost/iostreams/char_traits.hpp>
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47 | #include <boost/iostreams/constants.hpp> // buffer size.
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48 | #include <boost/iostreams/detail/buffer.hpp>
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49 | #include <boost/iostreams/detail/char_traits.hpp>
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50 | #include <boost/iostreams/detail/closer.hpp>
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51 | #include <boost/iostreams/detail/config/limits.hpp>
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52 | #include <boost/iostreams/detail/template_params.hpp>
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53 | #include <boost/iostreams/traits.hpp>
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54 | #include <boost/iostreams/operations.hpp> // read, write.
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55 | #include <boost/iostreams/pipeline.hpp>
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56 | #include <boost/preprocessor/iteration/local.hpp>
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57 | #include <boost/preprocessor/punctuation/comma_if.hpp>
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58 | #include <boost/preprocessor/repetition/enum_binary_params.hpp>
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59 | #include <boost/preprocessor/repetition/enum_params.hpp>
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60 | #include <boost/shared_ptr.hpp>
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61 |
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62 | // Must come last.
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63 | #include <boost/iostreams/detail/config/disable_warnings.hpp> // MSVC.
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64 |
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65 | namespace boost { namespace iostreams {
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66 |
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67 | template< typename SymmetricFilter,
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68 | typename Alloc =
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69 | std::allocator<
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70 | BOOST_DEDUCED_TYPENAME char_type_of<SymmetricFilter>::type
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71 | > >
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72 | class symmetric_filter {
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73 | public:
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74 | typedef typename char_type_of<SymmetricFilter>::type char_type;
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75 | typedef std::basic_string<char_type> string_type;
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76 | struct category
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77 | : dual_use,
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78 | filter_tag,
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79 | multichar_tag,
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80 | closable_tag
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81 | { };
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82 |
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83 | // Expands to a sequence of ctors which forward to impl.
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84 | #define BOOST_PP_LOCAL_MACRO(n) \
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85 | BOOST_IOSTREAMS_TEMPLATE_PARAMS(n, T) \
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86 | explicit symmetric_filter( \
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87 | int buffer_size BOOST_PP_COMMA_IF(n) \
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88 | BOOST_PP_ENUM_BINARY_PARAMS(n, const T, &t) ) \
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89 | : pimpl_(new impl(buffer_size BOOST_PP_COMMA_IF(n) \
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90 | BOOST_PP_ENUM_PARAMS(n, t))) \
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91 | { } \
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92 | /**/
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93 | #define BOOST_PP_LOCAL_LIMITS (0, BOOST_IOSTREAMS_MAX_FORWARDING_ARITY)
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94 | #include BOOST_PP_LOCAL_ITERATE()
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95 | #undef BOOST_PP_LOCAL_MACRO
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96 |
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97 | template<typename Source>
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98 | std::streamsize read(Source& src, char_type* s, std::streamsize n)
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99 | {
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100 | using namespace std;
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101 | if (!(state() & f_read))
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102 | begin_read();
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103 |
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104 | buffer_type& buf = pimpl_->buf_;
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105 | int status = (state() & f_eof) != 0 ? f_eof : f_good;
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106 | char_type *next_s = s,
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107 | *end_s = s + n;
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108 | while (true)
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109 | {
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110 | // Invoke filter if there are unconsumed characters in buffer or if
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111 | // filter must be flushed.
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112 | bool flush = status == f_eof;
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113 | if (buf.ptr() != buf.eptr() || flush) {
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114 | const char_type* next = buf.ptr();
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115 | bool done =
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116 | !filter().filter(next, buf.eptr(), next_s, end_s, flush);
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117 | buf.ptr() = buf.data() + (next - buf.data());
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118 | if (done)
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119 | return detail::check_eof(static_cast<streamsize>(next_s - s));
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120 | }
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121 |
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122 | // If no more characters are available without blocking, or
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123 | // if read request has been satisfied, return.
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124 | if ( status == f_would_block && buf.ptr() == buf.eptr() ||
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125 | next_s == end_s )
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126 | {
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127 | return static_cast<streamsize>(next_s - s);
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128 | }
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129 |
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130 | // Fill buffer.
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131 | if (status == f_good)
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132 | status = fill(src);
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133 | }
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134 | }
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135 |
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136 | template<typename Sink>
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137 | std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
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138 | {
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139 | if (!(state() & f_write))
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140 | begin_write();
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141 |
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142 | buffer_type& buf = pimpl_->buf_;
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143 | const char_type *next_s, *end_s;
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144 | for (next_s = s, end_s = s + n; next_s != end_s; ) {
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145 | if (buf.ptr() == buf.eptr() && !flush(snk))
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146 | break;
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147 | filter().filter(next_s, end_s, buf.ptr(), buf.eptr(), false);
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148 | }
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149 | return static_cast<std::streamsize>(next_s - s);
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150 | }
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151 |
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152 | // Give detail::closer<> permission to call close().
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153 | typedef symmetric_filter<SymmetricFilter, Alloc> self;
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154 | friend struct detail::closer<self>;
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155 |
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156 | template<typename Sink>
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157 | void close(Sink& snk, BOOST_IOS::openmode which)
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158 | {
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159 | using namespace std;
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160 | if ((state() & f_read) && (which & BOOST_IOS::in))
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161 | close();
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162 | if ((state() & f_write) && (which & BOOST_IOS::out)) {
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163 |
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164 | // Repeatedly invoke filter() with no input.
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165 | detail::closer<self> closer(*this);
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166 | buffer_type& buf = pimpl_->buf_;
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167 | char dummy;
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168 | const char* end = &dummy;
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169 | bool again = true;
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170 | while (again) {
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171 | if (buf.ptr() != buf.eptr())
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172 | again = filter().filter(end, end, buf.ptr(), buf.eptr(), true);
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173 | flush(snk);
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174 | }
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175 | }
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176 | }
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177 | SymmetricFilter& filter() { return *pimpl_; }
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178 | string_type unconsumed_input() const;
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179 |
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180 | // Give impl access to buffer_type on Tru64
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181 | #if !BOOST_WORKAROUND(__DECCXX_VER, BOOST_TESTED_AT(60590042))
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182 | private:
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183 | #endif
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184 | typedef detail::buffer<char_type, Alloc> buffer_type;
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185 | private:
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186 | buffer_type& buf() { return pimpl_->buf_; }
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187 | const buffer_type& buf() const { return pimpl_->buf_; }
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188 | int& state() { return pimpl_->state_; }
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189 | void begin_read();
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190 | void begin_write();
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191 |
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192 | template<typename Source>
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193 | int fill(Source& src)
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194 | {
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195 | std::streamsize amt = iostreams::read(src, buf().data(), buf().size());
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196 | if (amt == -1) {
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197 | state() |= f_eof;
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198 | return f_eof;
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199 | }
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200 | buf().set(0, amt);
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201 | return amt == buf().size() ? f_good : f_would_block;
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202 | }
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203 |
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204 | // Attempts to write the contents of the buffer the given Sink.
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205 | // Returns true if at least on character was written.
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206 | template<typename Sink>
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207 | bool flush(Sink& snk)
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208 | {
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209 | typedef typename iostreams::category_of<Sink>::type category;
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210 | typedef is_convertible<category, output> can_write;
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211 | return flush(snk, can_write());
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212 | }
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213 |
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214 | template<typename Sink>
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215 | bool flush(Sink& snk, mpl::true_)
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216 | {
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217 | using std::streamsize;
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218 | typedef char_traits<char_type> traits_type;
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219 | streamsize amt =
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220 | static_cast<streamsize>(buf().ptr() - buf().data());
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221 | streamsize result =
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222 | boost::iostreams::write(snk, buf().data(), amt);
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223 | if (result < amt && result > 0)
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224 | traits_type::move(buf().data(), buf().data() + result, amt - result);
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225 | buf().set(amt - result, buf().size());
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226 | return result != 0;
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227 | }
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228 |
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229 | template<typename Sink>
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230 | bool flush(Sink& snk, mpl::false_) { return true;}
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231 |
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232 | void close();
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233 |
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234 | enum flag_type {
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235 | f_read = 1,
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236 | f_write = f_read << 1,
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237 | f_eof = f_write << 1,
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238 | f_good,
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239 | f_would_block
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240 | };
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241 |
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242 | struct impl : SymmetricFilter {
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243 |
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244 | // Expands to a sequence of ctors which forward to SymmetricFilter.
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245 | #define BOOST_PP_LOCAL_MACRO(n) \
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246 | BOOST_IOSTREAMS_TEMPLATE_PARAMS(n, T) \
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247 | impl( int buffer_size BOOST_PP_COMMA_IF(n) \
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248 | BOOST_PP_ENUM_BINARY_PARAMS(n, const T, &t) ) \
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249 | : SymmetricFilter(BOOST_PP_ENUM_PARAMS(n, t)), \
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250 | buf_(buffer_size), state_(0) \
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251 | { } \
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252 | /**/
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253 | #define BOOST_PP_LOCAL_LIMITS (0, BOOST_IOSTREAMS_MAX_FORWARDING_ARITY)
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254 | #include BOOST_PP_LOCAL_ITERATE()
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255 | #undef BOOST_PP_LOCAL_MACRO
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256 |
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257 | buffer_type buf_;
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258 | int state_;
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259 | };
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260 |
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261 | shared_ptr<impl> pimpl_;
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262 | };
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263 | BOOST_IOSTREAMS_PIPABLE(symmetric_filter, 2)
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264 |
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265 | //------------------Implementation of symmetric_filter----------------//
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266 |
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267 | template<typename SymmetricFilter, typename Alloc>
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268 | void symmetric_filter<SymmetricFilter, Alloc>::begin_read()
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269 | {
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270 | assert(!(state() & f_write));
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271 | state() |= f_read;
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272 | buf().set(0, 0);
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273 | }
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274 |
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275 | template<typename SymmetricFilter, typename Alloc>
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276 | void symmetric_filter<SymmetricFilter, Alloc>::begin_write()
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277 | {
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278 | assert(!(state() & f_read));
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279 | state() |= f_write;
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280 | buf().set(0, buf().size());
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281 | }
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282 |
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283 | template<typename SymmetricFilter, typename Alloc>
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284 | void symmetric_filter<SymmetricFilter, Alloc>::close()
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285 | {
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286 | state() = 0;
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287 | buf().set(0, 0);
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288 | filter().close();
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289 | }
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290 |
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291 | template<typename SymmetricFilter, typename Alloc>
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292 | typename symmetric_filter<SymmetricFilter, Alloc>::string_type
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293 | symmetric_filter<SymmetricFilter, Alloc>::unconsumed_input() const
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294 | { return string_type(buf().ptr(), buf().eptr()); }
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295 |
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296 | //----------------------------------------------------------------------------//
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297 |
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298 | } } // End namespaces iostreams, boost.
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299 |
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300 | #include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC.
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301 |
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302 | #endif // #ifndef BOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED
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