Jeff Thompson | 86b6d64 | 2013-10-17 15:01:56 -0700 | [diff] [blame] | 1 | // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com) |
| 2 | // (C) Copyright 2003-2007 Jonathan Turkanis |
| 3 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 4 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.) |
| 5 | |
| 6 | // See http://www.boost.org/libs/iostreams for documentation. |
| 7 | |
| 8 | // Contains the definitions of the class templates symmetric_filter, |
| 9 | // which models DualUseFilter based on a model of the Symmetric Filter. |
| 10 | |
| 11 | // |
| 12 | // Roughly, a Symmetric Filter is a class type with the following interface: |
| 13 | // |
| 14 | // struct symmetric_filter { |
| 15 | // typedef xxx char_type; |
| 16 | // |
| 17 | // bool filter( const char*& begin_in, const char* end_in, |
| 18 | // char*& begin_out, char* end_out, bool flush ) |
| 19 | // { |
| 20 | // // Consume as many characters as possible from the interval |
| 21 | // // [begin_in, end_in), without exhausting the output range |
| 22 | // // [begin_out, end_out). If flush is true, write as mush output |
| 23 | // // as possible. |
| 24 | // // A return value of true indicates that filter should be called |
| 25 | // // again. More precisely, if flush is false, a return value of |
| 26 | // // false indicates that the natural end of stream has been reached |
| 27 | // // and that all filtered data has been forwarded; if flush is |
| 28 | // // true, a return value of false indicates that all filtered data |
| 29 | // // has been forwarded. |
| 30 | // } |
| 31 | // void close() { /* Reset filter's state. */ } |
| 32 | // }; |
| 33 | // |
| 34 | // Symmetric Filter filters need not be CopyConstructable. |
| 35 | // |
| 36 | |
| 37 | #ifndef NDNBOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED |
| 38 | #define NDNBOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED |
| 39 | |
| 40 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
| 41 | # pragma once |
| 42 | #endif |
| 43 | |
| 44 | #include <ndnboost/assert.hpp> |
| 45 | #include <memory> // allocator, auto_ptr. |
| 46 | #include <ndnboost/config.hpp> // NDNBOOST_DEDUCED_TYPENAME. |
| 47 | #include <ndnboost/iostreams/char_traits.hpp> |
| 48 | #include <ndnboost/iostreams/constants.hpp> // buffer size. |
| 49 | #include <ndnboost/iostreams/detail/buffer.hpp> |
| 50 | #include <ndnboost/iostreams/detail/char_traits.hpp> |
| 51 | #include <ndnboost/iostreams/detail/config/limits.hpp> |
| 52 | #include <ndnboost/iostreams/detail/template_params.hpp> |
| 53 | #include <ndnboost/iostreams/traits.hpp> |
| 54 | #include <ndnboost/iostreams/operations.hpp> // read, write. |
| 55 | #include <ndnboost/iostreams/pipeline.hpp> |
| 56 | #include <ndnboost/preprocessor/iteration/local.hpp> |
| 57 | #include <ndnboost/preprocessor/punctuation/comma_if.hpp> |
| 58 | #include <ndnboost/preprocessor/repetition/enum_binary_params.hpp> |
| 59 | #include <ndnboost/preprocessor/repetition/enum_params.hpp> |
| 60 | #include <ndnboost/shared_ptr.hpp> |
| 61 | |
| 62 | // Must come last. |
| 63 | #include <ndnboost/iostreams/detail/config/disable_warnings.hpp> // MSVC. |
| 64 | |
| 65 | namespace ndnboost { namespace iostreams { |
| 66 | |
| 67 | template< typename SymmetricFilter, |
| 68 | typename Alloc = |
| 69 | std::allocator< |
| 70 | NDNBOOST_DEDUCED_TYPENAME char_type_of<SymmetricFilter>::type |
| 71 | > > |
| 72 | class symmetric_filter { |
| 73 | public: |
| 74 | typedef typename char_type_of<SymmetricFilter>::type char_type; |
| 75 | typedef NDNBOOST_IOSTREAMS_CHAR_TRAITS(char_type) traits_type; |
| 76 | typedef std::basic_string<char_type, traits_type, Alloc> string_type; |
| 77 | struct category |
| 78 | : dual_use, |
| 79 | filter_tag, |
| 80 | multichar_tag, |
| 81 | closable_tag |
| 82 | { }; |
| 83 | |
| 84 | // Expands to a sequence of ctors which forward to impl. |
| 85 | #define NDNBOOST_PP_LOCAL_MACRO(n) \ |
| 86 | NDNBOOST_IOSTREAMS_TEMPLATE_PARAMS(n, T) \ |
| 87 | explicit symmetric_filter( \ |
| 88 | int buffer_size NDNBOOST_PP_COMMA_IF(n) \ |
| 89 | NDNBOOST_PP_ENUM_BINARY_PARAMS(n, const T, &t) ) \ |
| 90 | : pimpl_(new impl(buffer_size NDNBOOST_PP_COMMA_IF(n) \ |
| 91 | NDNBOOST_PP_ENUM_PARAMS(n, t))) \ |
| 92 | { NDNBOOST_ASSERT(buffer_size > 0); } \ |
| 93 | /**/ |
| 94 | #define NDNBOOST_PP_LOCAL_LIMITS (0, NDNBOOST_IOSTREAMS_MAX_FORWARDING_ARITY) |
| 95 | #include NDNBOOST_PP_LOCAL_ITERATE() |
| 96 | #undef NDNBOOST_PP_LOCAL_MACRO |
| 97 | |
| 98 | template<typename Source> |
| 99 | std::streamsize read(Source& src, char_type* s, std::streamsize n) |
| 100 | { |
| 101 | using namespace std; |
| 102 | if (!(state() & f_read)) |
| 103 | begin_read(); |
| 104 | |
| 105 | buffer_type& buf = pimpl_->buf_; |
| 106 | int status = (state() & f_eof) != 0 ? f_eof : f_good; |
| 107 | char_type *next_s = s, |
| 108 | *end_s = s + n; |
| 109 | while (true) |
| 110 | { |
| 111 | // Invoke filter if there are unconsumed characters in buffer or if |
| 112 | // filter must be flushed. |
| 113 | bool flush = status == f_eof; |
| 114 | if (buf.ptr() != buf.eptr() || flush) { |
| 115 | const char_type* next = buf.ptr(); |
| 116 | bool done = |
| 117 | !filter().filter(next, buf.eptr(), next_s, end_s, flush); |
| 118 | buf.ptr() = buf.data() + (next - buf.data()); |
| 119 | if (done) |
| 120 | return detail::check_eof( |
| 121 | static_cast<std::streamsize>(next_s - s) |
| 122 | ); |
| 123 | } |
| 124 | |
| 125 | // If no more characters are available without blocking, or |
| 126 | // if read request has been satisfied, return. |
| 127 | if ( (status == f_would_block && buf.ptr() == buf.eptr()) || |
| 128 | next_s == end_s ) |
| 129 | { |
| 130 | return static_cast<std::streamsize>(next_s - s); |
| 131 | } |
| 132 | |
| 133 | // Fill buffer. |
| 134 | if (status == f_good) |
| 135 | status = fill(src); |
| 136 | } |
| 137 | } |
| 138 | |
| 139 | template<typename Sink> |
| 140 | std::streamsize write(Sink& snk, const char_type* s, std::streamsize n) |
| 141 | { |
| 142 | if (!(state() & f_write)) |
| 143 | begin_write(); |
| 144 | |
| 145 | buffer_type& buf = pimpl_->buf_; |
| 146 | const char_type *next_s, *end_s; |
| 147 | for (next_s = s, end_s = s + n; next_s != end_s; ) { |
| 148 | if (buf.ptr() == buf.eptr() && !flush(snk)) |
| 149 | break; |
| 150 | if(!filter().filter(next_s, end_s, buf.ptr(), buf.eptr(), false)) { |
| 151 | flush(snk); |
| 152 | break; |
| 153 | } |
| 154 | } |
| 155 | return static_cast<std::streamsize>(next_s - s); |
| 156 | } |
| 157 | |
| 158 | template<typename Sink> |
| 159 | void close(Sink& snk, NDNBOOST_IOS::openmode mode) |
| 160 | { |
| 161 | if (mode == NDNBOOST_IOS::out) { |
| 162 | |
| 163 | if (!(state() & f_write)) |
| 164 | begin_write(); |
| 165 | |
| 166 | // Repeatedly invoke filter() with no input. |
| 167 | try { |
| 168 | buffer_type& buf = pimpl_->buf_; |
| 169 | char_type dummy; |
| 170 | const char_type* end = &dummy; |
| 171 | bool again = true; |
| 172 | while (again) { |
| 173 | if (buf.ptr() != buf.eptr()) |
| 174 | again = filter().filter( end, end, buf.ptr(), |
| 175 | buf.eptr(), true ); |
| 176 | flush(snk); |
| 177 | } |
| 178 | } catch (...) { |
| 179 | try { close_impl(); } catch (...) { } |
| 180 | throw; |
| 181 | } |
| 182 | close_impl(); |
| 183 | } else { |
| 184 | close_impl(); |
| 185 | } |
| 186 | } |
| 187 | SymmetricFilter& filter() { return *pimpl_; } |
| 188 | string_type unconsumed_input() const; |
| 189 | |
| 190 | // Give impl access to buffer_type on Tru64 |
| 191 | #if !NDNBOOST_WORKAROUND(__DECCXX_VER, NDNBOOST_TESTED_AT(60590042)) |
| 192 | private: |
| 193 | #endif |
| 194 | typedef detail::buffer<char_type, Alloc> buffer_type; |
| 195 | private: |
| 196 | buffer_type& buf() { return pimpl_->buf_; } |
| 197 | const buffer_type& buf() const { return pimpl_->buf_; } |
| 198 | int& state() { return pimpl_->state_; } |
| 199 | void begin_read(); |
| 200 | void begin_write(); |
| 201 | |
| 202 | template<typename Source> |
| 203 | int fill(Source& src) |
| 204 | { |
| 205 | std::streamsize amt = iostreams::read(src, buf().data(), buf().size()); |
| 206 | if (amt == -1) { |
| 207 | state() |= f_eof; |
| 208 | return f_eof; |
| 209 | } |
| 210 | buf().set(0, amt); |
| 211 | return amt != 0 ? f_good : f_would_block; |
| 212 | } |
| 213 | |
| 214 | // Attempts to write the contents of the buffer the given Sink. |
| 215 | // Returns true if at least on character was written. |
| 216 | template<typename Sink> |
| 217 | bool flush(Sink& snk) |
| 218 | { |
| 219 | typedef typename iostreams::category_of<Sink>::type category; |
| 220 | typedef is_convertible<category, output> can_write; |
| 221 | return flush(snk, can_write()); |
| 222 | } |
| 223 | |
| 224 | template<typename Sink> |
| 225 | bool flush(Sink& snk, mpl::true_) |
| 226 | { |
| 227 | std::streamsize amt = |
| 228 | static_cast<std::streamsize>(buf().ptr() - buf().data()); |
| 229 | std::streamsize result = |
| 230 | ndnboost::iostreams::write(snk, buf().data(), amt); |
| 231 | if (result < amt && result > 0) |
| 232 | traits_type::move(buf().data(), buf().data() + result, amt - result); |
| 233 | buf().set(amt - result, buf().size()); |
| 234 | return result != 0; |
| 235 | } |
| 236 | |
| 237 | template<typename Sink> |
| 238 | bool flush(Sink&, mpl::false_) { return true;} |
| 239 | |
| 240 | void close_impl(); |
| 241 | |
| 242 | enum flag_type { |
| 243 | f_read = 1, |
| 244 | f_write = f_read << 1, |
| 245 | f_eof = f_write << 1, |
| 246 | f_good, |
| 247 | f_would_block |
| 248 | }; |
| 249 | |
| 250 | struct impl : SymmetricFilter { |
| 251 | |
| 252 | // Expands to a sequence of ctors which forward to SymmetricFilter. |
| 253 | #define NDNBOOST_PP_LOCAL_MACRO(n) \ |
| 254 | NDNBOOST_IOSTREAMS_TEMPLATE_PARAMS(n, T) \ |
| 255 | impl( int buffer_size NDNBOOST_PP_COMMA_IF(n) \ |
| 256 | NDNBOOST_PP_ENUM_BINARY_PARAMS(n, const T, &t) ) \ |
| 257 | : SymmetricFilter(NDNBOOST_PP_ENUM_PARAMS(n, t)), \ |
| 258 | buf_(buffer_size), state_(0) \ |
| 259 | { } \ |
| 260 | /**/ |
| 261 | #define NDNBOOST_PP_LOCAL_LIMITS (0, NDNBOOST_IOSTREAMS_MAX_FORWARDING_ARITY) |
| 262 | #include NDNBOOST_PP_LOCAL_ITERATE() |
| 263 | #undef NDNBOOST_PP_LOCAL_MACRO |
| 264 | |
| 265 | buffer_type buf_; |
| 266 | int state_; |
| 267 | }; |
| 268 | |
| 269 | shared_ptr<impl> pimpl_; |
| 270 | }; |
| 271 | NDNBOOST_IOSTREAMS_PIPABLE(symmetric_filter, 2) |
| 272 | |
| 273 | //------------------Implementation of symmetric_filter----------------// |
| 274 | |
| 275 | template<typename SymmetricFilter, typename Alloc> |
| 276 | void symmetric_filter<SymmetricFilter, Alloc>::begin_read() |
| 277 | { |
| 278 | NDNBOOST_ASSERT(!(state() & f_write)); |
| 279 | state() |= f_read; |
| 280 | buf().set(0, 0); |
| 281 | } |
| 282 | |
| 283 | template<typename SymmetricFilter, typename Alloc> |
| 284 | void symmetric_filter<SymmetricFilter, Alloc>::begin_write() |
| 285 | { |
| 286 | NDNBOOST_ASSERT(!(state() & f_read)); |
| 287 | state() |= f_write; |
| 288 | buf().set(0, buf().size()); |
| 289 | } |
| 290 | |
| 291 | template<typename SymmetricFilter, typename Alloc> |
| 292 | void symmetric_filter<SymmetricFilter, Alloc>::close_impl() |
| 293 | { |
| 294 | state() = 0; |
| 295 | buf().set(0, 0); |
| 296 | filter().close(); |
| 297 | } |
| 298 | |
| 299 | template<typename SymmetricFilter, typename Alloc> |
| 300 | typename symmetric_filter<SymmetricFilter, Alloc>::string_type |
| 301 | symmetric_filter<SymmetricFilter, Alloc>::unconsumed_input() const |
| 302 | { return string_type(buf().ptr(), buf().eptr()); } |
| 303 | |
| 304 | //----------------------------------------------------------------------------// |
| 305 | |
| 306 | } } // End namespaces iostreams, boost. |
| 307 | |
| 308 | #include <ndnboost/iostreams/detail/config/enable_warnings.hpp> // MSVC. |
| 309 | |
| 310 | #endif // #ifndef NDNBOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED |