1 | // |
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2 | // UnufferedStreamBuf.h |
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3 | // |
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4 | // $Id: //poco/1.3/Foundation/include/Poco/UnbufferedStreamBuf.h#3 $ |
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5 | // |
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6 | // Library: Foundation |
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7 | // Package: Streams |
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8 | // Module: StreamBuf |
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9 | // |
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10 | // Definition of template BasicUnbufferedStreamBuf and class UnbufferedStreamBuf. |
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11 | // |
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12 | // Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH. |
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13 | // and Contributors. |
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14 | // |
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15 | // Permission is hereby granted, free of charge, to any person or organization |
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16 | // obtaining a copy of the software and accompanying documentation covered by |
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17 | // this license (the "Software") to use, reproduce, display, distribute, |
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18 | // execute, and transmit the Software, and to prepare derivative works of the |
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19 | // Software, and to permit third-parties to whom the Software is furnished to |
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20 | // do so, all subject to the following: |
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21 | // |
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22 | // The copyright notices in the Software and this entire statement, including |
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23 | // the above license grant, this restriction and the following disclaimer, |
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24 | // must be included in all copies of the Software, in whole or in part, and |
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25 | // all derivative works of the Software, unless such copies or derivative |
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26 | // works are solely in the form of machine-executable object code generated by |
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27 | // a source language processor. |
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28 | // |
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29 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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30 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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31 | // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT |
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32 | // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE |
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33 | // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, |
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34 | // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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35 | // DEALINGS IN THE SOFTWARE. |
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36 | // |
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37 | |
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38 | |
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39 | #ifndef Foundation_UnbufferedStreamBuf_INCLUDED |
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40 | #define Foundation_UnbufferedStreamBuf_INCLUDED |
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41 | |
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42 | |
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43 | #include "Poco/Foundation.h" |
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44 | #include "Poco/StreamUtil.h" |
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45 | #include <streambuf> |
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46 | #include <iosfwd> |
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47 | #include <ios> |
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48 | |
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49 | |
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50 | namespace Poco { |
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51 | |
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52 | |
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53 | template <typename ch, typename tr> |
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54 | class BasicUnbufferedStreamBuf: public std::basic_streambuf<ch, tr> |
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55 | /// This is an implementation of an unbuffered streambuf |
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56 | /// that greatly simplifies the implementation of |
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57 | /// custom streambufs of various kinds. |
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58 | /// Derived classes only have to override the methods |
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59 | /// readFromDevice() or writeToDevice(). |
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60 | { |
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61 | protected: |
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62 | typedef std::basic_streambuf<ch, tr> Base; |
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63 | typedef std::basic_ios<ch, tr> IOS; |
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64 | typedef ch char_type; |
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65 | typedef tr char_traits; |
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66 | typedef typename Base::int_type int_type; |
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67 | typedef typename Base::pos_type pos_type; |
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68 | typedef typename Base::off_type off_type; |
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69 | typedef typename IOS::openmode openmode; |
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70 | |
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71 | public: |
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72 | BasicUnbufferedStreamBuf(): |
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73 | _pb(char_traits::eof()), |
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74 | _ispb(false) |
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75 | { |
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76 | this->setg(0, 0, 0); |
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77 | this->setp(0, 0); |
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78 | } |
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79 | |
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80 | ~BasicUnbufferedStreamBuf() |
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81 | { |
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82 | } |
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83 | |
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84 | virtual int_type overflow(int_type c) |
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85 | { |
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86 | if (c != char_traits::eof()) |
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87 | return writeToDevice(char_traits::to_char_type(c)); |
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88 | else |
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89 | return c; |
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90 | } |
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91 | |
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92 | virtual int_type underflow() |
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93 | { |
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94 | if (_ispb) |
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95 | { |
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96 | return _pb; |
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97 | } |
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98 | else |
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99 | { |
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100 | int_type c = readFromDevice(); |
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101 | if (c != char_traits::eof()) |
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102 | { |
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103 | _ispb = true; |
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104 | _pb = c; |
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105 | } |
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106 | return c; |
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107 | } |
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108 | } |
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109 | |
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110 | virtual int_type uflow() |
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111 | { |
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112 | if (_ispb) |
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113 | { |
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114 | _ispb = false; |
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115 | return _pb; |
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116 | } |
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117 | else |
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118 | { |
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119 | int_type c = readFromDevice(); |
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120 | if (c != char_traits::eof()) |
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121 | { |
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122 | _pb = c; |
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123 | } |
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124 | return c; |
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125 | } |
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126 | } |
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127 | |
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128 | virtual int_type pbackfail(int_type c) |
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129 | { |
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130 | if (_ispb) |
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131 | { |
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132 | return char_traits::eof(); |
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133 | } |
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134 | else |
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135 | { |
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136 | _ispb = true; |
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137 | _pb = c; |
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138 | return c; |
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139 | } |
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140 | } |
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141 | |
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142 | virtual std::streamsize xsgetn(char_type* p, std::streamsize count) |
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143 | /// Some platforms (for example, Compaq C++) have buggy implementations of |
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144 | /// xsgetn that handle null buffers incorrectly. |
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145 | /// Anyway, it does not hurt to provide an optimized implementation |
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146 | /// of xsgetn for this streambuf implementation. |
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147 | { |
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148 | std::streamsize copied = 0; |
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149 | while (count > 0) |
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150 | { |
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151 | int_type c = uflow(); |
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152 | if (c == char_traits::eof()) break; |
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153 | *p++ = char_traits::to_char_type(c); |
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154 | ++copied; |
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155 | --count; |
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156 | } |
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157 | return copied; |
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158 | } |
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159 | |
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160 | protected: |
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161 | static int_type charToInt(char_type c) |
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162 | { |
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163 | return char_traits::to_int_type(c); |
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164 | } |
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165 | |
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166 | private: |
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167 | virtual int_type readFromDevice() |
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168 | { |
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169 | return char_traits::eof(); |
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170 | } |
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171 | |
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172 | virtual int_type writeToDevice(char_type) |
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173 | { |
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174 | return char_traits::eof(); |
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175 | } |
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176 | |
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177 | int_type _pb; |
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178 | bool _ispb; |
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179 | |
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180 | BasicUnbufferedStreamBuf(const BasicUnbufferedStreamBuf&); |
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181 | BasicUnbufferedStreamBuf& operator = (const BasicUnbufferedStreamBuf&); |
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182 | }; |
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183 | |
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184 | |
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185 | // |
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186 | // We provide an instantiation for char |
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187 | // |
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188 | typedef BasicUnbufferedStreamBuf<char, std::char_traits<char> > UnbufferedStreamBuf; |
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189 | |
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190 | |
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191 | } // namespace Poco |
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192 | |
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193 | |
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194 | #endif // Foundation_UnbufferedStreamBuf_INCLUDED |
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