RField.hxx

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/// \file ROOT/RField.hxx
/// \ingroup NTuple ROOT7
/// \author Jakob Blomer <jblomer@cern.ch>
/// \date 2018-10-09
/// \warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback
/// is welcome!
 
/*************************************************************************
 * Copyright (C) 1995-2019, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#ifndef ROOT7_RField
#define ROOT7_RField
 
#include <ROOT/RError.hxx>
#include <ROOT/RFieldBase.hxx>
#include <ROOT/RNTupleSerialize.hxx>
#include <ROOT/RNTupleUtil.hxx>
#include <ROOT/RSpan.hxx>
#include <string_view>
#include <ROOT/TypeTraits.hxx>
 
#include <TGenericClassInfo.h>
 
#include <algorithm>
#include <array>
#include <cstddef>
#include <iostream>
#include <memory>
#include <string>
#include <type_traits>
#include <typeinfo>
#include <vector>
 
class TClass;
class TEnum;
class TObject;
class TVirtualStreamerInfo;
 
namespace ROOT {
 
class TSchemaRule;
 
namespace Experimental {
 
class RNTupleCollectionWriter;
class REntry;
 
namespace Detail {
class RFieldVisitor;
} // namespace Detail
 
/// The container field for an ntuple model, which itself has no physical representation.
/// Therefore, the zero field must not be connected to a page source or sink.
class RFieldZero final : public RFieldBase {
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const override;
   void ConstructValue(void *) const final {}
 
public:
   RFieldZero() : RFieldBase("", "", ENTupleStructure::kRecord, false /* isSimple */) {}
 
   using RFieldBase::Attach;
   size_t GetValueSize() const final { return 0; }
   size_t GetAlignment() const final { return 0; }
 
   void AcceptVisitor(Detail::RFieldVisitor &visitor) const final;
};
 
/// Used in RFieldBase::Check() to record field creation failures.
class RInvalidField final : public RFieldBase {
   std::string fError;
 
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const final
   {
      return std::make_unique<RInvalidField>(newName, GetTypeName(), fError);
   }
   void ConstructValue(void *) const final {}
 
public:
   RInvalidField(std::string_view name, std::string_view type, std::string_view error)
      : RFieldBase(name, type, ENTupleStructure::kLeaf, false /* isSimple */), fError(error)
   {
   }
 
   const std::string &GetError() const { return fError; }
 
   size_t GetValueSize() const final { return 0; }
   size_t GetAlignment() const final { return 0; }
}; // RInvalidField
 
/// The field for a class with dictionary
class RClassField : public RFieldBase {
private:
   enum ESubFieldRole {
      kBaseClass,
      kDataMember,
   };
   struct RSubFieldInfo {
      ESubFieldRole fRole;
      std::size_t fOffset;
   };
   /// Prefix used in the subfield names generated for base classes
   static constexpr const char *kPrefixInherited{":"};
 
   class RClassDeleter : public RDeleter {
   private:
      TClass *fClass;
 
   public:
      explicit RClassDeleter(TClass *cl) : fClass(cl) {}
      void operator()(void *objPtr, bool dtorOnly) final;
   };
 
   TClass *fClass;
   /// Additional information kept for each entry in `fSubFields`
   std::vector<RSubFieldInfo> fSubFieldsInfo;
   std::size_t fMaxAlignment = 1;
 
private:
   RClassField(std::string_view fieldName, std::string_view className, TClass *classp);
   void Attach(std::unique_ptr<RFieldBase> child, RSubFieldInfo info);
   /// Register post-read callbacks corresponding to a list of ROOT I/O customization rules. `classp` is used to
   /// fill the `TVirtualObject` instance passed to the user function.
   void AddReadCallbacksFromIORules(const std::span<const TSchemaRule *> rules, TClass *classp = nullptr);
 
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const final;
 
   void ConstructValue(void *where) const override;
   std::unique_ptr<RDeleter> GetDeleter() const final { return std::make_unique<RClassDeleter>(fClass); }
 
   std::size_t AppendImpl(const void *from) final;
   void ReadGlobalImpl(NTupleSize_t globalIndex, void *to) final;
   void ReadInClusterImpl(RClusterIndex clusterIndex, void *to) final;
   void OnConnectPageSource() final;
 
public:
   RClassField(std::string_view fieldName, std::string_view className);
   RClassField(RClassField &&other) = default;
   RClassField &operator=(RClassField &&other) = default;
   ~RClassField() override = default;
 
   std::vector<RValue> SplitValue(const RValue &value) const final;
   size_t GetValueSize() const override;
   size_t GetAlignment() const final { return fMaxAlignment; }
   std::uint32_t GetTypeVersion() const final;
   std::uint32_t GetTypeChecksum() const final;
   void AcceptVisitor(Detail::RFieldVisitor &visitor) const override;
};
 
/// The field for a class in unsplit mode, which is using ROOT standard streaming
class RUnsplitField final : public RFieldBase {
private:
   class RUnsplitDeleter : public RDeleter {
   private:
      TClass *fClass;
 
   public:
      explicit RUnsplitDeleter(TClass *cl) : fClass(cl) {}
      void operator()(void *objPtr, bool dtorOnly) final;
   };
 
   TClass *fClass = nullptr;
   Internal::RNTupleSerializer::StreamerInfoMap_t fStreamerInfos; ///< streamer info records seen during writing
   ClusterSize_t fIndex;                                          ///< number of bytes written in the current cluster
 
private:
   // Note that className may be different from classp->GetName(), e.g. through different canonicalization of RNTuple
   // vs. TClass. Also, classp may be nullptr for types unsupported by the ROOT I/O.
   RUnsplitField(std::string_view fieldName, std::string_view className, TClass *classp);
 
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const final;
 
   const RColumnRepresentations &GetColumnRepresentations() const final;
   void GenerateColumns() final;
   void GenerateColumns(const RNTupleDescriptor &) final;
 
   void ConstructValue(void *where) const final;
   std::unique_ptr<RDeleter> GetDeleter() const final { return std::make_unique<RUnsplitDeleter>(fClass); }
 
   std::size_t AppendImpl(const void *from) final;
   void ReadGlobalImpl(NTupleSize_t globalIndex, void *to) final;
 
   void CommitClusterImpl() final { fIndex = 0; }
 
   bool HasExtraTypeInfo() const final { return true; }
   // Returns the list of seen streamer infos
   RExtraTypeInfoDescriptor GetExtraTypeInfo() const final;
 
public:
   RUnsplitField(std::string_view fieldName, std::string_view className, std::string_view typeAlias = "");
   RUnsplitField(RUnsplitField &&other) = default;
   RUnsplitField &operator=(RUnsplitField &&other) = default;
   ~RUnsplitField() override = default;
 
   size_t GetValueSize() const final;
   size_t GetAlignment() const final;
   std::uint32_t GetTypeVersion() const final;
   std::uint32_t GetTypeChecksum() const final;
   void AcceptVisitor(Detail::RFieldVisitor &visitor) const final;
};
 
/// The field for an unscoped or scoped enum with dictionary
class REnumField : public RFieldBase {
private:
   REnumField(std::string_view fieldName, std::string_view enumName, TEnum *enump);
   REnumField(std::string_view fieldName, std::string_view enumName, std::unique_ptr<RFieldBase> intField);
 
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const final;
 
   void ConstructValue(void *where) const final { CallConstructValueOn(*fSubFields[0], where); }
 
   std::size_t AppendImpl(const void *from) final { return CallAppendOn(*fSubFields[0], from); }
   void ReadGlobalImpl(NTupleSize_t globalIndex, void *to) final { CallReadOn(*fSubFields[0], globalIndex, to); }
   void ReadInClusterImpl(RClusterIndex clusterIndex, void *to) final { CallReadOn(*fSubFields[0], clusterIndex, to); }
 
public:
   REnumField(std::string_view fieldName, std::string_view enumName);
   REnumField(REnumField &&other) = default;
   REnumField &operator=(REnumField &&other) = default;
   ~REnumField() override = default;
 
   std::vector<RValue> SplitValue(const RValue &value) const final;
   size_t GetValueSize() const final { return fSubFields[0]->GetValueSize(); }
   size_t GetAlignment() const final { return fSubFields[0]->GetAlignment(); }
   void AcceptVisitor(Detail::RFieldVisitor &visitor) const final;
};
 
/// Classes with dictionaries that can be inspected by TClass
template <typename T, typename = void>
class RField final : public RClassField {
protected:
   void ConstructValue(void *where) const final
   {
      if constexpr (std::is_default_constructible_v<T>) {
         new (where) T();
      } else {
         // If there is no default constructor, try with the IO constructor
         new (where) T(static_cast<TRootIOCtor *>(nullptr));
      }
   }
 
public:
   static std::string TypeName() { return ROOT::Internal::GetDemangledTypeName(typeid(T)); }
   RField(std::string_view name) : RClassField(name, TypeName())
   {
      static_assert(std::is_class_v<T>, "no I/O support for this basic C++ type");
   }
   RField(RField &&other) = default;
   RField &operator=(RField &&other) = default;
   ~RField() override = default;
};
 
template <typename T>
class RField<T, typename std::enable_if<std::is_enum_v<T>>::type> : public REnumField {
public:
   static std::string TypeName() { return ROOT::Internal::GetDemangledTypeName(typeid(T)); }
   RField(std::string_view name) : REnumField(name, TypeName()) {}
   RField(RField &&other) = default;
   RField &operator=(RField &&other) = default;
   ~RField() override = default;
};
 
/// The collection field is only used for writing; when reading, untyped collections are projected to an std::vector
class RCollectionField final : public ROOT::Experimental::RFieldBase {
private:
   /// Save the link to the collection ntuple in order to reset the offset counter when committing the cluster
   std::shared_ptr<RNTupleCollectionWriter> fCollectionWriter;
 
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const final;
   const RColumnRepresentations &GetColumnRepresentations() const final;
   void GenerateColumns() final;
   void GenerateColumns(const RNTupleDescriptor &desc) final;
   void ConstructValue(void *) const final {}
 
   std::size_t AppendImpl(const void *from) final;
   void ReadGlobalImpl(NTupleSize_t globalIndex, void *to) final;
 
   void CommitClusterImpl() final;
 
public:
   static std::string TypeName() { return ""; }
   RCollectionField(std::string_view name, std::shared_ptr<RNTupleCollectionWriter> collectionWriter,
                    std::unique_ptr<RFieldZero> collectionParent);
   RCollectionField(RCollectionField &&other) = default;
   RCollectionField &operator=(RCollectionField &&other) = default;
   ~RCollectionField() override = default;
 
   size_t GetValueSize() const final { return sizeof(ClusterSize_t); }
   size_t GetAlignment() const final { return alignof(ClusterSize_t); }
};
 
/// An artificial field that transforms an RNTuple column that contains the offset of collections into
/// collection sizes. It is only used for reading, e.g. as projected field or as an artificial field that provides the
/// "number of" RDF columns for collections (e.g. `R_rdf_sizeof_jets` for a collection named `jets`).
/// It is used in the templated RField<RNTupleCardinality<SizeT>> form, which represents the collection sizes either
/// as 32bit unsigned int (std::uint32_t) or as 64bit unsigned int (std::uint64_t).
class RCardinalityField : public RFieldBase {
protected:
   RCardinalityField(std::string_view fieldName, std::string_view typeName)
      : RFieldBase(fieldName, typeName, ENTupleStructure::kLeaf, false /* isSimple */)
   {
   }
 
   const RColumnRepresentations &GetColumnRepresentations() const final;
   // Field is only used for reading
   void GenerateColumns() final { throw RException(R__FAIL("Cardinality fields must only be used for reading")); }
   void GenerateColumns(const RNTupleDescriptor &) final;
 
public:
   RCardinalityField(RCardinalityField &&other) = default;
   RCardinalityField &operator=(RCardinalityField &&other) = default;
   ~RCardinalityField() override = default;
 
   void AcceptVisitor(Detail::RFieldVisitor &visitor) const final;
 
   const RField<RNTupleCardinality<std::uint32_t>> *As32Bit() const;
   const RField<RNTupleCardinality<std::uint64_t>> *As64Bit() const;
};
 
template <typename T>
class RSimpleField : public RFieldBase {
protected:
   void GenerateColumns() final { GenerateColumnsImpl<T>(); }
   void GenerateColumns(const RNTupleDescriptor &desc) final { GenerateColumnsImpl<T>(desc); }
 
   void ConstructValue(void *where) const final { new (where) T{0}; }
 
public:
   RSimpleField(std::string_view name, std::string_view type)
      : RFieldBase(name, type, ENTupleStructure::kLeaf, true /* isSimple */)
   {
      fTraits |= kTraitTrivialType;
   }
   RSimpleField(RSimpleField &&other) = default;
   RSimpleField &operator=(RSimpleField &&other) = default;
   ~RSimpleField() override = default;
 
   T *Map(NTupleSize_t globalIndex) { return fPrincipalColumn->Map<T>(globalIndex); }
   T *Map(RClusterIndex clusterIndex) { return fPrincipalColumn->Map<T>(clusterIndex); }
   T *MapV(NTupleSize_t globalIndex, NTupleSize_t &nItems) { return fPrincipalColumn->MapV<T>(globalIndex, nItems); }
   T *MapV(RClusterIndex clusterIndex, NTupleSize_t &nItems) { return fPrincipalColumn->MapV<T>(clusterIndex, nItems); }
 
   size_t GetValueSize() const final { return sizeof(T); }
   size_t GetAlignment() const final { return alignof(T); }
};
 
////////////////////////////////////////////////////////////////////////////////
/// Template specializations for concrete C++ types
////////////////////////////////////////////////////////////////////////////////
 
} // namespace Experimental
} // namespace ROOT
 
#include "RField/RFieldFundamental.hxx"
#include "RField/RFieldProxiedCollection.hxx"
#include "RField/RFieldRecord.hxx"
#include "RField/RFieldSequenceContainer.hxx"
#include "RField/RFieldSTLMisc.hxx"
 
namespace ROOT {
namespace Experimental {
 
template <>
class RField<ClusterSize_t> final : public RSimpleField<ClusterSize_t> {
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const final
   {
      return std::make_unique<RField>(newName);
   }
 
   const RColumnRepresentations &GetColumnRepresentations() const final;
 
public:
   static std::string TypeName() { return "ROOT::Experimental::ClusterSize_t"; }
   explicit RField(std::string_view name) : RSimpleField(name, TypeName()) {}
   RField(RField &&other) = default;
   RField &operator=(RField &&other) = default;
   ~RField() override = default;
 
   /// Special help for offset fields
   void GetCollectionInfo(NTupleSize_t globalIndex, RClusterIndex *collectionStart, ClusterSize_t *size)
   {
      fPrincipalColumn->GetCollectionInfo(globalIndex, collectionStart, size);
   }
   void GetCollectionInfo(RClusterIndex clusterIndex, RClusterIndex *collectionStart, ClusterSize_t *size)
   {
      fPrincipalColumn->GetCollectionInfo(clusterIndex, collectionStart, size);
   }
   void AcceptVisitor(Detail::RFieldVisitor &visitor) const final;
};
 
template <typename SizeT>
class RField<RNTupleCardinality<SizeT>> final : public RCardinalityField {
protected:
   std::unique_ptr<ROOT::Experimental::RFieldBase> CloneImpl(std::string_view newName) const final
   {
      return std::make_unique<RField<RNTupleCardinality<SizeT>>>(newName);
   }
   void ConstructValue(void *where) const final { new (where) RNTupleCardinality<SizeT>(0); }
 
public:
   static std::string TypeName() { return "ROOT::Experimental::RNTupleCardinality<" + RField<SizeT>::TypeName() + ">"; }
   explicit RField(std::string_view name) : RCardinalityField(name, TypeName()) {}
   RField(RField &&other) = default;
   RField &operator=(RField &&other) = default;
   ~RField() override = default;
 
   size_t GetValueSize() const final { return sizeof(RNTupleCardinality<SizeT>); }
   size_t GetAlignment() const final { return alignof(RNTupleCardinality<SizeT>); }
 
   /// Get the number of elements of the collection identified by globalIndex
   void ReadGlobalImpl(NTupleSize_t globalIndex, void *to) final
   {
      RClusterIndex collectionStart;
      ClusterSize_t size;
      fPrincipalColumn->GetCollectionInfo(globalIndex, &collectionStart, &size);
      *static_cast<RNTupleCardinality<SizeT> *>(to) = size;
   }
 
   /// Get the number of elements of the collection identified by clusterIndex
   void ReadInClusterImpl(RClusterIndex clusterIndex, void *to) final
   {
      RClusterIndex collectionStart;
      ClusterSize_t size;
      fPrincipalColumn->GetCollectionInfo(clusterIndex, &collectionStart, &size);
      *static_cast<RNTupleCardinality<SizeT> *>(to) = size;
   }
 
   std::size_t ReadBulkImpl(const RBulkSpec &bulkSpec) final
   {
      RClusterIndex collectionStart;
      ClusterSize_t collectionSize;
      fPrincipalColumn->GetCollectionInfo(bulkSpec.fFirstIndex, &collectionStart, &collectionSize);
 
      auto typedValues = static_cast<RNTupleCardinality<SizeT> *>(bulkSpec.fValues);
      typedValues[0] = collectionSize;
 
      auto lastOffset = collectionStart.GetIndex() + collectionSize;
      ClusterSize_t::ValueType nRemainingEntries = bulkSpec.fCount - 1;
      std::size_t nEntries = 1;
      while (nRemainingEntries > 0) {
         NTupleSize_t nItemsUntilPageEnd;
         auto offsets = fPrincipalColumn->MapV<ClusterSize_t>(bulkSpec.fFirstIndex + nEntries, nItemsUntilPageEnd);
         std::size_t nBatch = std::min(nRemainingEntries, nItemsUntilPageEnd);
         for (std::size_t i = 0; i < nBatch; ++i) {
            typedValues[nEntries + i] = offsets[i] - lastOffset;
            lastOffset = offsets[i];
         }
         nRemainingEntries -= nBatch;
         nEntries += nBatch;
      }
      return RBulkSpec::kAllSet;
   }
};
 
/// TObject requires special handling of the fBits and fUniqueID members
template <>
class RField<TObject> final : public RFieldBase {
   static std::size_t GetOffsetOfMember(const char *name);
   static std::size_t GetOffsetUniqueID() { return GetOffsetOfMember("fUniqueID"); }
   static std::size_t GetOffsetBits() { return GetOffsetOfMember("fBits"); }
 
protected:
   std::unique_ptr<RFieldBase> CloneImpl(std::string_view newName) const final;
 
   void ConstructValue(void *where) const override;
   std::unique_ptr<RDeleter> GetDeleter() const final { return std::make_unique<RTypedDeleter<TObject>>(); }
 
   std::size_t AppendImpl(const void *from) final;
   void ReadGlobalImpl(NTupleSize_t globalIndex, void *to) final;
 
   void OnConnectPageSource() final;
 
public:
   static std::string TypeName() { return "TObject"; }
 
   RField(std::string_view fieldName);
   RField(RField &&other) = default;
   RField &operator=(RField &&other) = default;
   ~RField() override = default;
 
   std::vector<RValue> SplitValue(const RValue &value) const final;
   size_t GetValueSize() const final;
   size_t GetAlignment() const final;
   std::uint32_t GetTypeVersion() const final;
   std::uint32_t GetTypeChecksum() const final;
   void AcceptVisitor(Detail::RFieldVisitor &visitor) const final;
};
 
// Has to be implemented after the definition of all RField<T> types
// The void type is specialized in RField.cxx
 
template <typename T>
std::unique_ptr<T, typename RFieldBase::RCreateObjectDeleter<T>::deleter> RFieldBase::CreateObject() const
{
   if (GetTypeName() != RField<T>::TypeName()) {
      throw RException(
         R__FAIL("type mismatch for field " + GetFieldName() + ": " + GetTypeName() + " vs. " + RField<T>::TypeName()));
   }
   return std::unique_ptr<T>(static_cast<T *>(CreateObjectRawPtr()));
}
 
template <>
struct RFieldBase::RCreateObjectDeleter<void> {
   using deleter = RCreateObjectDeleter<void>;
   void operator()(void *);
};
 
template <>
std::unique_ptr<void, typename RFieldBase::RCreateObjectDeleter<void>::deleter>
ROOT::Experimental::RFieldBase::CreateObject<void>() const;
 
} // namespace Experimental
} // namespace ROOT
 
#endif