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// 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_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<HeaderType*>(ptr, size);
if (h) {
onHeader(*h);
}
}
// an empty function in case no StackTypes have been provided to call
template <typename PtrType, typename SizeType>
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<HeaderType*>(ptr, size);
if (h) {
header = *h;
}
}
// an empty function in case no StackTypes have been provided to call
template <typename PtrType, typename SizeType>
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