root/ROOT/RFieldToken.hxx

0001 /// \file ROOT/RFieldToken.hxx
0002 /// \ingroup NTuple
0003 /// \author Jonas Hahnfeld <jonas.hahnfeld@cern.ch>
0004 /// \date 2025-03-19
0005
0006 /*************************************************************************
0007  * Copyright (C) 1995-2025, Rene Brun and Fons Rademakers.               *
0008  * All rights reserved.                                                  *
0009  *                                                                       *
0010  * For the licensing terms see $ROOTSYS/LICENSE.                         *
0011  * For the list of contributors see $ROOTSYS/README/CREDITS.             *
0012  *************************************************************************/
0013
0014 #ifndef ROOT_RFieldToken
0015 #define ROOT_RFieldToken
0016
0017 #include <cstddef> // for std::size_t
0018 #include <cstdint> // for std::uint64_t
0019
0020 namespace ROOT {
0021
0022 class REntry;
0023 class RNTupleModel;
0024
0025 namespace Experimental {
0026 namespace Detail {
0027 class RRawPtrWriteEntry;
0028 } // namespace Detail
0029 } // namespace Experimental
0030
0031 // clang-format off
0032 /**
0033 \class ROOT::RFieldToken
0034 \ingroup NTuple
0035 \brief A field token identifies a (sub)field in an entry
0036
0037 It can be used for fast indexing in REntry's methods, e.g. REntry::BindValue(). The field token can also be created by the model.
0038 */
0039 // clang-format on
0040 class RFieldToken {
0041    friend class REntry;
0042    friend class RNTupleModel;
0043    friend class Experimental::Detail::RRawPtrWriteEntry;
0044
0045    std::size_t fIndex = 0;                      ///< The index of the field (top-level or registered subfield)
0046    std::uint64_t fSchemaId = std::uint64_t(-1); ///< Safety check to prevent tokens from other models being used
0047    RFieldToken(std::size_t index, std::uint64_t schemaId) : fIndex(index), fSchemaId(schemaId) {}
0048
0049 public:
0050    RFieldToken() = default; // The default constructed token cannot be used by any entry
0051 };
0052
0053 } // namespace ROOT
0054
0055 #endif