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#ifndef DataFormats_Portable_interface_PortableHostObjectReadRules_h
#define DataFormats_Portable_interface_PortableHostObjectReadRules_h
#include <TGenericClassInfo.h>
#include <TVirtualObject.h>
#include "DataFormats/Portable/interface/PortableHostObject.h"
#include "FWCore/Utilities/interface/concatenate.h"
#include "FWCore/Utilities/interface/stringize.h"
// read function for PortableHostObject, called for every event
template <typename T>
static void readPortableHostObject_v1(char *target, TVirtualObject *from_buffer) {
// extract the actual types
using Object = T;
using Product = typename Object::Product;
// valid only for PortableHostObject<T>
static_assert(std::is_same_v<Object, PortableHostObject<Product>>);
// proxy for the object being read from file
struct OnFile {
Product *product_;
};
// address in memory of the buffer containing the object being read from file
char *address = static_cast<char *>(from_buffer->GetObject());
// offset of the "product_" data member
static ptrdiff_t product_offset = from_buffer->GetClass()->GetDataMemberOffset("product_");
// pointer to the Product object being read from file
OnFile onfile = {*(Product **)(address + product_offset)};
// pointer to the Object object being constructed in memory
Object *newObj = (Object *)target;
// move the data from the on-file layout to the newly constructed object
Object::ROOTReadStreamer(newObj, *onfile.product_);
}
// put set_PortableHostObject_read_rules in the ROOT namespace to let it forward declare GenerateInitInstance
namespace ROOT {
// set the read rules for PortableHostObject<T>;
// this is called only once, when the dictionary is loaded.
template <typename T>
static bool set_PortableHostObject_read_rules(std::string const &type) {
// forward declaration
TGenericClassInfo *GenerateInitInstance(T const *);
// build the read rules
std::vector<ROOT::Internal::TSchemaHelper> readrules(1);
ROOT::Internal::TSchemaHelper &rule = readrules[0];
rule.fTarget = "buffer_,product_";
rule.fSourceClass = type;
rule.fSource = type + "::Product* product_;";
rule.fCode = type + "::ROOTReadStreamer(newObj, *onfile.product_)";
rule.fVersion = "[1-]";
rule.fChecksum = "";
rule.fInclude = "";
rule.fEmbed = false;
rule.fFunctionPtr = reinterpret_cast<void *>(::readPortableHostObject_v1<T>);
rule.fAttributes = "";
// set the read rules
TGenericClassInfo *instance = GenerateInitInstance((T const *)nullptr);
instance->SetReadRules(readrules);
return true;
}
} // namespace ROOT
#define SET_PORTABLEHOSTOBJECT_READ_RULES(OBJECT) \
static bool EDM_CONCATENATE(set_PortableHostObject_read_rules_done_at_, __LINE__) [[maybe_unused]] = \
ROOT::set_PortableHostObject_read_rules<OBJECT>(EDM_STRINGIZE(OBJECT))
#endif // DataFormats_Portable_interface_PortableHostObjectReadRules_h
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