// Copyright CERN and copyright holders of ALICE O2. This software is // distributed under the terms of the GNU General Public License v3 (GPL // Version 3), copied verbatim in the file "COPYING". // // See http://alice-o2.web.cern.ch/license for full licensing information. // // 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_HEADERSTACK_H #define ALGORITHM_HEADERSTACK_H /// @file HeaderStack.h /// @author Matthias Richter /// @since 2017-09-19 /// @brief Utilities for the O2 header stack // the implemented functionality relies on o2::header::get defined in // DataHeader.h; all O2 headers inherit from BaseHeader, this is required // to check the consistency of the header stack, also the next-header-flag // is part of the BaseHeader #include "Headers/DataHeader.h" // for o2::header::get namespace o2 { namespace algorithm { /** * Generic utility for the O2 header stack, redirect to header specific callbacks * * The O2 header stack consists of one or more headers. The DataHeader is the * first one and mandatory. Other optional headers can be recursively extracted * from a buffer with one call to this utility function. For each header a pair * of type and callback has to be provided. The header type can be provided as * a dummy parameter, the callback with a lambda or any callable object. * * Usage: * dispatchHeaderStackCallback(ptr, size, * MyHeader(), * [] (const auto & h) { * // do something with h * } */ template < typename PtrType, typename SizeType, typename HeaderType, typename HeaderCallbackType, typename... MoreTypes> void dispatchHeaderStackCallback(PtrType ptr, SizeType size, HeaderType header, HeaderCallbackType onHeader, MoreTypes&&... types); // template specialization: handler for one pair of type and callback template < typename PtrType, typename SizeType, typename HeaderType, typename HeaderCallbackType> void dispatchHeaderStackCallback(PtrType ptr, SizeType size, HeaderType /*dummy*/, HeaderCallbackType onHeader) { const HeaderType* h = o2::header::get(ptr, size); if (h) { onHeader(*h); } } // an empty function in case no StackTypes have been provided to call template void dispatchHeaderStackCallback(PtrType ptr, SizeType size) { } // actual implementation template < typename PtrType, typename SizeType, typename HeaderType, typename HeaderCallbackType, typename... MoreTypes> void dispatchHeaderStackCallback(PtrType ptr, SizeType size, HeaderType header, HeaderCallbackType onHeader, MoreTypes&&... types) { // call for current dispatchHeaderStackCallback(ptr, size, header, onHeader); // call for next dispatchHeaderStackCallback(ptr, size, types...); } /** * Generic utility for the O2 header stack, extract headers * * The O2 header stack consists of one or more headers. The DataHeader is the * first one and mandatory. Other optional headers can be recursively extracted * from a buffer with one call to this utility function. For each header to be * extracted, a variable can be passed be reference. If a header of corresponding * type is in the stack, its content will be assigned to the variable. * * Usage: * DataHeader dataheader; * TriggerHeader triggerheader * parseHeaderStack(ptr, size, * dataheader, * triggerheader */ template < typename PtrType, typename SizeType, typename HeaderType, typename... MoreTypes> void parseHeaderStack(PtrType ptr, SizeType size, HeaderType& header, MoreTypes&&... types); // template specialization: handler for one type template < typename PtrType, typename SizeType, typename HeaderType> void parseHeaderStack(PtrType ptr, SizeType size, HeaderType& header) { const HeaderType* h = o2::header::get(ptr, size); if (h) { header = *h; } } // an empty function in case no StackTypes have been provided to call template void parseHeaderStack(PtrType ptr, SizeType size) { } // generic implementation template < typename PtrType, typename SizeType, typename HeaderType, typename... MoreTypes> void parseHeaderStack(PtrType ptr, SizeType size, HeaderType& header, MoreTypes&&... types) { // call for current parseHeaderStack(ptr, size, header); // call for next parseHeaderStack(ptr, size, types...); } }; // namespace algorithm }; // namespace o2 #endif //ALGORITHM_HEADERSTACK_H