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GeezerVison is showing github.com — AliceO2/Algorithm/include/Algorithm/Parser.h at dev · nstrangm/AliceO2 Expand file tree/ Copy pathParser.hMore file actions 403 lines (362 loc) · 13.7 KB / Copy pathParser.hFile metadata and controls403 lines (362 loc) · 13.7 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 // Copyright 2019-2020 CERN and copyright holders of ALICE O2. // See https://alice-o2.web.cern.ch/copyright for details of the copyright holders. // All rights not expressly granted are reserved. // // This software is distributed under the terms of the GNU General Public // License v3 (GPL Version 3), copied verbatim in the file "COPYING". // // In applying this license CERN does not waive the privileges and immunities // granted to it by virtue of its status as an Intergovernmental Organization // or submit itself to any jurisdiction. #ifndef ALGORITHM_PARSER_H #define ALGORITHM_PARSER_H /// @file Parser.h /// @author Matthias Richter /// @since 2017-09-20 /// @brief Utilities for parsing of data sequences #include <functional> #include <vector> namespace o2 { namespace algorithm { /// helper function returning size of type with a specialization for /// void returning 0 template <typename T> struct typesize { static const size_t size = sizeof(T); }; // specialization for void template <> struct typesize<void> { static const size_t size = 0; }; /** * @class ForwardParser * Parser for a sequence of frames with header, trailer and variable payload. * The size is expected to be part of the header. * * Trailer type can be void, which is also the default template parameter. That * allows to define a frame consisting of only header and data. * * Usage: * <pre> * using SomeParser = ForwardParser<SomeHeaderType, SomeTrailerType>; * SomeParser parser; * std::vector<typename SomeParser::FrameInfo> frames; * parser.parse(ptr, size, * [] (const typename SomeParser::HeaderType& h) { * // check the header * return true; * }, * [] (const typename SomeParser::TrailerType& t) { * // check the trailer * return true; * }, * [] (const typename SomeParser::HeaderType& h) { * // get the size of the frame including payload * // and header and trailer size, e.g. payload size * // from a header member * return h.payloadSize + SomeParser::totalOffset; * }, * [&frames] (typename SomeParser::FrameInfo& info) { * frames.emplace_back(info); * return true; * } * ) * * // a reduced version without trailer check callback * using SomeParser = ForwardParser<SomeHeaderType>; * SomeParser parser; * std::vector<typename SomeParser::FrameInfo> frames; * parser.parse(ptr, size, * [] (const typename SomeParser::HeaderType& h) { * // check the header * return true; * }, * [] (const typename SomeParser::HeaderType& h) { * // get the size of the frame including payload * // and header and trailer size, e.g. payload size * // from a header member * return h.payloadSize + SomeParser::totalOffset; * }, * [&frames] (typename SomeParser::FrameInfo& info) { * frames.emplace_back(info); * return true; * } * ) * </pre> */ template <typename HeaderT, typename TrailerT = void> class ForwardParser { public: using HeaderType = HeaderT; using TrailerType = TrailerT; using PayloadType = unsigned char; /// @struct FrameInfo /// a compound of header, data, and trailer struct FrameInfo { using PtrT = const PayloadType*; const HeaderType* header = nullptr; const TrailerType* trailer = nullptr; PtrT payload = nullptr; size_t length = 0; }; /// the length offset due to header static const size_t headOffset = typesize<HeaderType>::size; /// the length offset due to trailer static const size_t tailOffset = typesize<TrailerType>::size; /// total length offset due to header and trailer static const size_t totalOffset = headOffset + tailOffset; /// alias for callback checking the header, return true if the object /// is a valid header using CheckHeaderFct = std::function<bool(const HeaderType&)>; /// alias for the argument type to be used in the CheckTrailer function /// have to forward to a valid type in case of void TrailerType in order /// to allow passing by reference using CheckTrailerFctArgumentT = typename std::conditional< !std::is_void<TrailerType>::value, TrailerType, int>::type; /// alias for callback checking the trailer, takes reference to trailer /// object if TrailerType is a valid type, no argument otherwise template <typename U> using CheckTrailerFct = typename std::conditional< !std::is_void<U>::value, std::function<bool(const CheckTrailerFctArgumentT&)>, std::function<bool()>>::type; /// alias for callback to get the complete frame size including header, /// trailer and the data using GetFrameSizeFct = std::function<size_t(const HeaderType&)>; /// function callback to insert/handle one frame into, sequentially called /// for all frames if the whole block has a valid format using InsertFct = std::function<bool(FrameInfo&)>; /// Parse buffer of size bufferSize, requires callbacks to check header /// trailer, the frame size, and insert callback to handle a FrameInfo /// object. template <typename InputType> int parse(const InputType* buffer, size_t bufferSize, CheckHeaderFct checkHeader, CheckTrailerFct<TrailerType> checkTrailer, GetFrameSizeFct getFrameSize, InsertFct insert) { static_assert(sizeof(InputType) == 1, "ForwardParser currently only supports byte type buffer"); if (buffer == nullptr || bufferSize == 0) { return 0; } size_t position = 0; std::vector<FrameInfo> frames; do { FrameInfo entry; // check the header if (sizeof(HeaderType) + position > bufferSize) { break; } entry.header = reinterpret_cast<const HeaderType*>(buffer + position); if (!checkHeader(*entry.header)) { break; } // extract frame size from header, this is expected to be the // total frome size including header, payload and optional trailer auto frameSize = getFrameSize(*entry.header); if (frameSize + position > bufferSize) { break; } // payload starts right after the header entry.payload = reinterpret_cast<typename FrameInfo::PtrT>(entry.header + 1); entry.length = frameSize - totalOffset; // optionally extract and check trailer if (tailOffset > 0) { entry.trailer = nullptr; } else { auto trailerStart = buffer + position + frameSize - tailOffset; entry.trailer = reinterpret_cast<const TrailerType*>(trailerStart); if (!CheckTrailer(entry, checkTrailer)) { break; } } // store the extracted frame info and continue with remaining buffer frames.emplace_back(entry); position += frameSize; } while (position < bufferSize); if (position == bufferSize) { // frames found and format consistent, insert entries to target // Note: the complete block must be consistent for (auto entry : frames) { if (!insert(entry)) { break; } } return frames.size(); } else if (frames.size() == 0) { // no frames found at all, the buffer does not contain any return 0; } // format error detected // TODO: decide about error policy return -1; } /// Parse buffer of size bufferSize, specialization skipping the trailer /// check, e.g. when its type is void, or when the integrity of the trailer /// is not relevant. Requires callbacks to check header, frame size, and /// insert callback to handle a FrameInfo object. template <typename InputType, typename U = TrailerType> typename std::enable_if<std::is_void<U>::value, int>::type parse(const InputType* buffer, size_t bufferSize, CheckHeaderFct checkHeader, GetFrameSizeFct getFrameSize, InsertFct insert) { auto checkTrailer = []() { return true; }; return parse(buffer, bufferSize, checkHeader, checkTrailer, getFrameSize, insert); } private: /// internal function to check the trailer, distinguishes void and non-void /// trailer type. template <typename U = TrailerType> typename std::enable_if<!std::is_void<U>::value, bool>::type CheckTrailer(const FrameInfo& entry, CheckTrailerFct<TrailerType>& checkTrailer) const { return checkTrailer(*entry.trailer); } template <typename U = TrailerType> typename std::enable_if<std::is_void<U>::value, bool>::type CheckTrailer(const FrameInfo&, CheckTrailerFct<TrailerType>&) const { return true; } }; /** * @class ReverseParser * Parser for a sequence of frames with header, trailer and variable payload. * The size is expected to be part of the trailer, the parsing is thus in * reverse direction. Also the insert callback is called with the entries * starting form the end of the buffer. * TODO: an easy extension can be to reverse the order of the inserts, meaning * that the entries are read from the beginning. * * Usage: * <pre> * using SomeParser = ReverseParser<SomeHeaderType, SomeTrailerType>; * SomeParser parser; * std::vector<typename SomeParser::FrameInfo> frames; * parser.parse(ptr, size, * [] (const typename SomeParser::HeaderType& h) { * // check the header * return true; * }, * [] (const typename SomeParser::TrailerType& t) { * // check the trailer * return true; * }, * [] (const typename SomeParser::TrailerType& t) { * // get the size of the frame including payload * // and header and trailer size, e.g. payload size * // from a trailer member * return t.payloadSize + SomeParser::totalOffset; * }, * [&frames] (typename SomeParser::FrameInfo& info) { * frames.emplace_back(info); * return true; * } * ) * </pre> */ template <typename HeaderT, typename TrailerT> class ReverseParser { public: using HeaderType = HeaderT; using TrailerType = TrailerT; using PayloadType = unsigned char; /// @struct FrameInfo a compound of header, data, and trailer struct FrameInfo { using PtrT = const PayloadType*; const HeaderType* header = nullptr; const TrailerType* trailer = nullptr; PtrT payload = nullptr; size_t length = 0; }; /// the length offset due to header static const size_t headOffset = typesize<HeaderType>::size; /// the length offset due to trailer static const size_t tailOffset = typesize<TrailerType>::size; /// total length offset due to header and trailer static const size_t totalOffset = headOffset + tailOffset; /// alias for callback checking the header, return true if the object /// is a valid header using CheckHeaderFct = std::function<bool(const HeaderType&)>; /// alias for callback checking the trailer using CheckTrailerFct = std::function<bool(const TrailerType&)>; /// alias for callback to get the complete frame size including header, /// trailer and the data using GetFrameSizeFct = std::function<size_t(const TrailerType&)>; /// function callback to insert/handle one frame into, sequentially called /// for all frames if the whole block has a valid format using InsertFct = std::function<bool(const FrameInfo&)>; /// Parse buffer of size bufferSize, requires callbacks to check header /// trailer, the frame size, and insert callback to handle a FrameInfo /// object. template <typename InputType> int parse(const InputType* buffer, size_t bufferSize, CheckHeaderFct checkHeader, CheckTrailerFct checkTrailer, GetFrameSizeFct getFrameSize, InsertFct insert) { static_assert(sizeof(InputType) == 1, "ReverseParser currently only supports byte type buffer"); if (buffer == nullptr || bufferSize == 0) { return 0; } auto position = bufferSize; std::vector<FrameInfo> frames; do { FrameInfo entry; // start from end, extract and check trailer if (sizeof(TrailerType) > position) { break; } entry.trailer = reinterpret_cast<const TrailerType*>(buffer + position - sizeof(TrailerType)); if (!checkTrailer(*entry.trailer)) { break; } // get the total frame size auto frameSize = getFrameSize(*entry.trailer); if (frameSize > position) { break; } // extract and check header auto headerStart = buffer + position - frameSize; entry.header = reinterpret_cast<const HeaderType*>(headerStart); if (!checkHeader(*entry.header)) { break; } // payload immediately after header entry.payload = reinterpret_cast<typename FrameInfo::PtrT>(entry.header + 1); entry.length = frameSize - sizeof(HeaderType) - sizeof(TrailerType); frames.emplace_back(entry); position -= frameSize; } while (position > 0); if (position == 0) { // frames found and format consistent, the complete block must be consistent for (auto entry : frames) { if (!insert(entry)) { break; } } return frames.size(); } else if (frames.size() == 0) { // no frames found at all, the buffer does not contain any return 0; } // format error detected // TODO: decide about error policy return -1; } }; } // namespace algorithm } // namespace o2 #endif // ALGORITHM_PARSER_H |
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