include/GaudiKernel/AnyDataWrapper.h

0001 /***********************************************************************************\
0002 * (c) Copyright 1998-2019 CERN for the benefit of the LHCb and ATLAS collaborations *
0003 *                                                                                   *
0004 * This software is distributed under the terms of the Apache version 2 licence,     *
0005 * copied verbatim in the file "LICENSE".                                            *
0006 *                                                                                   *
0007 * In applying this licence, CERN does not waive the privileges and immunities       *
0008 * granted to it by virtue of its status as an Intergovernmental Organization        *
0009 * or submit itself to any jurisdiction.                                             *
0010 \***********************************************************************************/
0011 #pragma once
0012 #include "GaudiKernel/DataObject.h"
0013 #include <cstddef>
0014 #include <iterator>
0015 #include <optional>
0016 #include <utility>
0017
0018 namespace details {
0019   using std::size;
0020
0021   template <typename T, typename... Args>
0022   constexpr auto size( const T&, Args&&... ) noexcept {
0023     static_assert( sizeof...( Args ) == 0, "No extra args please" );
0024     return std::nullopt;
0025   }
0026 } // namespace details
0027
0028 // ugly hack to circumvent the usage of std::any
0029 struct GAUDI_API AnyDataWrapperBase : DataObject {
0030   virtual std::optional<std::size_t> size() const = 0;
0031 };
0032
0033 template <typename T>
0034 class GAUDI_API AnyDataWrapper : public AnyDataWrapperBase {
0035 protected:
0036   T m_data;
0037
0038 public:
0039   AnyDataWrapper( T&& data ) : m_data{ std::move( data ) } {};
0040   AnyDataWrapper( AnyDataWrapper&& )                 = delete;
0041   AnyDataWrapper( AnyDataWrapper const& )            = delete;
0042   AnyDataWrapper& operator=( AnyDataWrapper&& )      = delete;
0043   AnyDataWrapper& operator=( AnyDataWrapper const& ) = delete;
0044
0045   const T& getData() const { return m_data; }
0046   T&       getData() { return m_data; }
0047
0048   std::optional<std::size_t> size() const override {
0049     using ::details::size;
0050     return size( getData() );
0051   }
0052 };
0053
0054 template <typename ViewType, typename OwnedType>
0055 class GAUDI_API AnyDataWithViewWrapper : public AnyDataWrapper<ViewType> {
0056   OwnedType m_owned;
0057
0058 public:
0059   AnyDataWithViewWrapper( OwnedType&& data ) : AnyDataWrapper<ViewType>{ {} }, m_owned{ std::move( data ) } {
0060     AnyDataWrapper<ViewType>::m_data = ViewType{ std::as_const( m_owned ) };
0061   }
0062   AnyDataWithViewWrapper( AnyDataWithViewWrapper&& )                 = delete;
0063   AnyDataWithViewWrapper( AnyDataWithViewWrapper const& )            = delete;
0064   AnyDataWithViewWrapper& operator=( AnyDataWithViewWrapper&& )      = delete;
0065   AnyDataWithViewWrapper& operator=( AnyDataWithViewWrapper const& ) = delete;
0066 };