Support for binding tools to event and/or conditions data

Support for binding tools to event and/or conditions data

GaudiAlg/include/GaudiAlg/FunctionalTool.h

+/*****************************************************************************\
+* (c) Copyright 2021 CERN for the benefit of the LHCb Collaboration           *
+*                                                                             *
+* This software is distributed under the terms of the GNU General Public      *
+* Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING".   *
+*                                                                             *
+* In applying this licence, 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.                                       *
+\*****************************************************************************/
+#include "GaudiAlg/FunctionalDetails.h"
+#include "GaudiKernel/IBinder.h"
+
+namespace Gaudi::Functional{
+namespace details {
+  // add a baseclass in case it isn't defined yet...
+  template <typename Tr, typename Base = FixTESPath<AlgTool>>
+  using add_base_t =
+      std::conditional_t<Gaudi::cpp17::is_detected_v<detail2::BaseClass_t, Tr>, Tr,
+                         Traits::use_<Tr,BaseClass_t<Base>>>;
+
+
+template <typename Signature, typename Traits>
+struct ToolBinder;
+
+template <typename IFace, typename... Args, typename Traits >
+class ToolBinder<Gaudi::Interface::BoxedInterface<IFace>( Args const&... ), Traits>
+    : public extends<details::BaseClass_t<Traits>, Gaudi::Interface::IBinder<IFace>> {
+
+  constexpr static std::size_t N = sizeof...( Args );
+
+  template <typename IArgs, std::size_t... I>
+  ToolBinder( std::string type, std::string name, const IInterface* parent, IArgs&& args, std::index_sequence<I...> )
+    : extends<details::BaseClass_t<Traits>, Gaudi::Interface::IBinder<IFace>> {
+       std::move( type ),
+                                                                                                    std::move( name ),
+                                                                                                    parent }
+      , m_handles{ std::tuple_cat( std::forward_as_tuple( this ), std::get<I>( args ) )... } {}
+
+  std::tuple<details::InputHandle_t<Traits, Args>...> m_handles;
+
+public:
+  using KeyValue = std::pair<std::string, std::string>;
+  ToolBinder( std::string type, std::string name, const IInterface* parent,
+              Gaudi::Functional::details::RepeatValues_<KeyValue, N> const& inputs )
+      : ToolBinder{ std::move( type ), std::move( name ), parent, inputs, std::make_index_sequence<N>{} } {}
+
+  virtual Gaudi::Interface::BoxedInterface<IFace> bind( const Args&... args ) const = 0;
+
+  Gaudi::Interface::BoxedInterface<IFace> operator()( EventContext const& ctx ) const override final {
+    return std::apply(
+        [&]( auto const&... arg ) {
+          using namespace details;
+          return this->bind( get( arg, *this, ctx )... );
+        },
+        m_handles );
+  }
+
+  template <std::size_t N = 0>
+  decltype( auto ) inputLocation() const {
+    using namespace details;
+    return getKey( std::get<N>( m_handles ) );
+  }
+  template <typename T>
+  decltype( auto ) inputLocation() const {
+    using namespace details;
+    return getKey( std::get<InputHandle_t<Traits, std::decay_t<T>>>( m_handles ) );
+  }
+};
+} // namespace details
+
+template <typename Signature, typename Traits_ = Traits::use_<Traits::BaseClass_t<AlgTool>> >
+using ToolBinder = details::ToolBinder<Signature,Traits_>;
+
+}