1 | // (C) Copyright Jonathan Turkanis 2005.
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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_LINE_FILTER_HPP_INCLUDED
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8 | #define BOOST_IOSTREAMS_LINE_FILTER_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 <algorithm> // min.
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15 | #include <cassert>
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16 | #include <memory> // allocator.
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17 | #include <string>
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18 | #include <boost/config.hpp> // BOOST_STATIC_CONSTANT.
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19 | #include <boost/iostreams/categories.hpp>
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20 | #include <boost/iostreams/detail/closer.hpp>
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21 | #include <boost/iostreams/detail/ios.hpp> // openmode, streamsize.
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22 | #include <boost/iostreams/pipeline.hpp>
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23 |
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24 | // Must come last.
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25 | #include <boost/iostreams/detail/config/disable_warnings.hpp> // VC7.1 C4244.
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26 |
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27 | namespace boost { namespace iostreams {
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28 |
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29 | //
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30 | // Template name: line_filter.
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31 | // Template paramters:
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32 | // Ch - The character type.
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33 | // Alloc - The allocator type.
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34 | // Description: Filter which processes data one line at a time.
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35 | //
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36 | template< typename Ch,
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37 | typename Alloc =
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38 | #if BOOST_WORKAROUND(__GNUC__, < 3)
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39 | typename std::basic_string<Ch>::allocator_type
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40 | #else
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41 | std::allocator<Ch>
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42 | #endif
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43 | >
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44 | class basic_line_filter {
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45 | private:
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46 | typedef typename std::basic_string<Ch>::traits_type string_traits;
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47 | public:
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48 | typedef Ch char_type;
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49 | typedef char_traits<char_type> traits_type;
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50 | typedef std::basic_string<
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51 | Ch,
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52 | string_traits,
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53 | Alloc
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54 | > string_type;
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55 | struct category
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56 | : dual_use,
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57 | filter_tag,
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58 | multichar_tag,
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59 | closable_tag
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60 | { };
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61 | protected:
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62 | basic_line_filter() : pos_(string_type::npos), state_(0) { }
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63 | public:
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64 | virtual ~basic_line_filter() { }
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65 |
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66 | template<typename Source>
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67 | std::streamsize read(Source& src, char_type* s, std::streamsize n)
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68 | {
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69 | using namespace std;
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70 | assert(!(state_ & f_write));
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71 | state_ |= f_read;
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72 |
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73 | // Handle unfinished business.
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74 | streamsize result = 0;
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75 | if (!cur_line_.empty() && (result = read_line(s, n)) == n)
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76 | return n;
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77 |
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78 | typename traits_type::int_type status = traits_type::good();
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79 | while (result < n && !traits_type::is_eof(status)) {
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80 |
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81 | // Call next_line() to retrieve a line of filtered test, and
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82 | // read_line() to copy it into buffer s.
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83 | if (traits_type::would_block(status = next_line(src)))
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84 | return result;
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85 | result += read_line(s + result, n - result);
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86 | }
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87 |
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88 | return detail::check_eof(result);
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89 | }
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90 |
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91 | template<typename Sink>
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92 | std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
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93 | {
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94 | using namespace std;
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95 | assert(!(state_ & f_read));
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96 | state_ |= f_write;
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97 |
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98 | // Handle unfinished business.
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99 | if (pos_ != string_type::npos && !write_line(snk))
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100 | return 0;
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101 |
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102 | const char_type *cur = s, *next;
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103 | while (true) {
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104 |
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105 | // Search for the next full line in [cur, s + n), filter it
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106 | // and write it to snk.
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107 | typename string_type::size_type rest = n - (cur - s);
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108 | if ((next = traits_type::find(cur, rest, traits_type::newline()))) {
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109 | cur_line_.append(cur, next - cur);
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110 | cur = next + 1;
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111 | if (!write_line(snk))
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112 | return static_cast<std::streamsize>(cur - s);
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113 | } else {
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114 | cur_line_.append(cur, rest);
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115 | return n;
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116 | }
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117 | }
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118 | }
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119 |
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120 | typedef basic_line_filter<Ch, Alloc> self;
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121 | friend struct detail::closer<self>;
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122 |
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123 | template<typename Sink>
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124 | void close(Sink& snk, BOOST_IOS::openmode which)
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125 | {
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126 | if ((state_ & f_read) && (which & BOOST_IOS::in))
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127 | close();
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128 |
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129 | if ((state_ & f_write) && (which & BOOST_IOS::out)) {
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130 | detail::closer<self> closer(*this);
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131 | if (!cur_line_.empty())
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132 | write_line(snk);
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133 | }
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134 | }
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135 | private:
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136 | virtual string_type do_filter(const string_type& line) = 0;
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137 |
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138 | // Copies filtered characters fron the current line into
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139 | // the given buffer.
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140 | std::streamsize read_line(char_type* s, std::streamsize n)
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141 | {
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142 | using namespace std;
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143 | streamsize result =
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144 | (std::min) (n, static_cast<streamsize>(cur_line_.size()));
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145 | traits_type::copy(s, cur_line_.data(), result);
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146 | cur_line_.erase(0, result);
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147 | return result;
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148 | }
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149 |
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150 | // Attempts to retrieve a line of text from the given source; returns
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151 | // an int_type as a good/eof/would_block status code.
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152 | template<typename Source>
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153 | typename traits_type::int_type next_line(Source& src)
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154 | {
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155 | using namespace std;
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156 | typename traits_type::int_type c;
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157 | while ( traits_type::is_good(c = iostreams::get(src)) &&
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158 | c != traits_type::newline() )
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159 | {
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160 | cur_line_ += traits_type::to_int_type(c);
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161 | }
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162 | if (!traits_type::would_block(c)) {
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163 | if (!cur_line_.empty() || c == traits_type::newline())
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164 | cur_line_ = do_filter(cur_line_);
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165 | if (c == traits_type::newline())
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166 | cur_line_ += c;
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167 | }
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168 | return c; // status indicator.
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169 | }
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170 |
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171 | // Filters the current line and attemps to write it to the given sink.
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172 | // Returns true for success.
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173 | template<typename Sink>
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174 | bool write_line(Sink& snk)
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175 | {
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176 | string_type line = do_filter(cur_line_) + traits_type::newline();
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177 | std::streamsize amt = static_cast<std::streamsize>(line.size());
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178 | bool result = iostreams::write(snk, line.data(), amt) == amt;
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179 | if (result)
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180 | clear();
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181 | return result;
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182 | }
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183 |
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184 | void close()
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185 | {
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186 | clear();
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187 | state_ = 0;
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188 | }
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189 |
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190 | void clear()
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191 | {
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192 | cur_line_.erase();
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193 | pos_ = string_type::npos;
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194 | }
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195 |
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196 | enum flag_type {
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197 | f_read = 1,
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198 | f_write = f_read << 1
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199 | };
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200 |
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201 | string_type cur_line_;
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202 | typename string_type::size_type pos_;
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203 | int state_;
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204 | };
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205 | BOOST_IOSTREAMS_PIPABLE(basic_line_filter, 2)
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206 |
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207 | typedef basic_line_filter<char> line_filter;
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208 | typedef basic_line_filter<wchar_t> wline_filter;
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209 |
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210 | } } // End namespaces iostreams, boost.
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211 |
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212 | #include <boost/iostreams/detail/config/enable_warnings.hpp>
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213 |
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214 | #endif // #ifndef BOOST_IOSTREAMS_LINE_FILTER_HPP_INCLUDED
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