GenericHandle.h

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#ifndef FWCore_Framework_GenericHandle_h
#define FWCore_Framework_GenericHandle_h
// -*- C++ -*-
//
// Package:     Framework
// Class  :     GenericHandle
//
//
// Original Author:  Chris Jones
//         Created:  Sat Jan  7 15:40:43 EST 2006
//

// user include files
#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Utilities/interface/ObjectWithDict.h"
#include "FWCore/Utilities/interface/TypeWithDict.h"

// system include files
#include <string>

// forward declarations
namespace edm {
  struct GenericObject {};

  template <>
  class Handle<GenericObject> {
  public:
    Handle(std::string const& iName) : type_(TypeWithDict::byName(iName)), prod_(), prov_(nullptr) {
      if (!bool(type_)) {
        Exception::throwThis(errors::NotFound,
                             "Handle<GenericObject> told to use uknown type '",
                             iName.c_str(),
                             "'.\n Please check spelling or that a module uses this type in the job.");
      }
    }

    Handle(TypeWithDict const& iType) : type_(iType), prod_(), prov_(nullptr) {
      if (!bool(iType)) {
        Exception::throwThis(errors::NotFound, "Handle<GenericObject> given an invalid type");
      }
    }

    Handle(Handle<GenericObject> const& h)
        : type_(h.type_), prod_(h.prod_), prov_(h.prov_), whyFailedFactory_(h.whyFailedFactory_) {}

    Handle(ObjectWithDict const& prod, Provenance const* prov, ProductID const&)
        : type_(prod.typeOf()), prod_(prod), prov_(prov) {
      assert(prod_);
      assert(prov_);
    }

    //~Handle();

    void swap(Handle<GenericObject>& other) {
      // use unqualified swap for user defined classes
      using std::swap;
      swap(type_, other.type_);
      std::swap(prod_, other.prod_);
      swap(prov_, other.prov_);
      swap(whyFailedFactory_, other.whyFailedFactory_);
    }

    Handle<GenericObject>& operator=(Handle<GenericObject> const& rhs) {
      Handle<GenericObject> temp(rhs);
      this->swap(temp);
      return *this;
    }

    bool isValid() const { return prod_ && nullptr != prov_; }

    bool failedToGet() const { return bool(whyFailedFactory_); }
    ObjectWithDict const* product() const {
      if (this->failedToGet()) {
        whyFailedFactory_->make()->raise();
      }
      return &prod_;
    }
    ObjectWithDict const* operator->() const { return this->product(); }
    ObjectWithDict const& operator*() const { return *(this->product()); }

    TypeWithDict const& type() const { return type_; }
    Provenance const* provenance() const { return prov_; }

    ProductID id() const { return prov_->productID(); }

    void clear() {
      prov_ = nullptr;
      whyFailedFactory_ = nullptr;
    }

    void setWhyFailedFactory(std::shared_ptr<HandleExceptionFactory> const& iWhyFailed) {
      whyFailedFactory_ = iWhyFailed;
    }

  private:
    TypeWithDict type_;
    ObjectWithDict prod_;
    Provenance const* prov_;
    std::shared_ptr<HandleExceptionFactory> whyFailedFactory_;
  };

  typedef Handle<GenericObject> GenericHandle;

  void convert_handle(BasicHandle&& orig, Handle<GenericObject>& result);

  template <>
  bool edm::Event::getByLabel<GenericObject>(std::string const& label,
                                             std::string const& productInstanceName,
                                             Handle<GenericObject>& result) const;

  template <>
  bool edm::Event::getByLabel(edm::InputTag const& tag, Handle<GenericObject>& result) const;

}  // namespace edm
#endif