G4AnyType.hh

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//
// G4AnyType
//
// Class description:
//
// The class G4AnyType represents any data type.
// The class only holds a reference to the type and not the value.
 
// See http://www.boost.org/libs/any for Documentation.
// Copyright Kevlin Henney, 2000, 2001, 2002. All rights reserved.
//
// Permission to use, copy, modify, and distribute this software for any
// purpose is hereby granted without fee, provided that this copyright and
// permissions notice appear in all copies and derivatives.
//
// This software is provided "as is" without express or implied warranty.
// What:  variant At boost::any
// who:   contributed by Kevlin Henney,
//        with features contributed and bugs found by
//        Ed Brey, Mark Rodgers, Peter Dimov, and James Curran
// when:  July 2001
// --------------------------------------------------------------------
#ifndef G4AnyType_hh
#define G4AnyType_hh 1
 
#include "G4UIcommand.hh"
 
#include <algorithm>
#include <iostream>
#include <sstream>
#include <typeinfo>
 
class G4String;
namespace CLHEP
{
class Hep3Vector;
}
 
class G4AnyType
{
  public:
    /** Constructors */
 
    G4AnyType() = default;
 
    template<typename ValueType>
    G4AnyType(ValueType& value) : fContent(new Ref<ValueType>(value))
    {}
 
    /** Copy Constructor */
 
    G4AnyType(const G4AnyType& other)
      : fContent(other.fContent != nullptr ? other.fContent->Clone() : nullptr)
    {}
 
    /** Destructor */
 
    ~G4AnyType() { delete fContent; }
 
    /** bool operator */
 
    operator bool() { return !Empty(); }
 
    /** Modifiers */
 
    G4AnyType& Swap(G4AnyType& rhs)
    {
      std::swap(fContent, rhs.fContent);
      return *this;
    }
 
    template<typename ValueType>
    G4AnyType& operator=(const ValueType& rhs)
    {
      G4AnyType(rhs).Swap(*this);
      return *this;
    }
 
    G4AnyType& operator=(const G4AnyType& rhs)
    {
      G4AnyType(rhs).Swap(*this);
      return *this;
    }
 
    /** Queries */
 
    G4bool Empty() const { return fContent == nullptr; }
 
    const std::type_info& TypeInfo() const
    {
      return fContent != nullptr ? fContent->TypeInfo() : typeid(void);
    }
 
    /** Address */
 
    void* Address() const { return fContent != nullptr ? fContent->Address() : nullptr; }
 
    /** String conversions */
 
    std::string ToString() const { return fContent->ToString(); }
 
    void FromString(const std::string& val) { fContent->FromString(val); }
 
  private:
    class Placeholder
    {
      public:
        Placeholder() = default;
 
        virtual ~Placeholder() = default;
 
        /** Queries */
 
        virtual const std::type_info& TypeInfo() const = 0;
 
        virtual Placeholder* Clone() const = 0;
 
        virtual void* Address() const = 0;
 
        /** ToString */
 
        virtual std::string ToString() const = 0;
 
        /** FromString */
 
        virtual void FromString(const std::string& val) = 0;
    };
 
    template<typename ValueType>
    class Ref : public Placeholder
    {
      public:
        /** Constructor */
 
        Ref(ValueType& value) : fRef(value) {}
 
        /** Query */
 
        const std::type_info& TypeInfo() const override { return typeid(ValueType); }
 
        /** Clone */
 
        Placeholder* Clone() const override { return new Ref(fRef); }
 
        /** Address */
 
        void* Address() const override { return (void*)(&fRef); }
 
        /** ToString */
 
        std::string ToString() const override
        {
          std::stringstream ss;
          ss << fRef;
          return ss.str();
        }
 
        /** FromString */
 
        void FromString(const std::string& val) override
        {
          std::stringstream ss(val);
          ss >> fRef;
        }
 
        ValueType& fRef;  // representation
    };
 
    /** representation */
 
    template<typename ValueType>
    friend ValueType* any_cast(G4AnyType*);
 
    Placeholder* fContent = nullptr;
};
 
//
// Specializations
//
 
template<>
inline void G4AnyType::Ref<bool>::FromString(const std::string& val)
{
  fRef = G4UIcommand::ConvertToBool(val.c_str());
}
 
template<>
inline void G4AnyType::Ref<G4String>::FromString(const std::string& val)
{
  if (val[0] == '"') {
    fRef = val.substr(1, val.size() - 2);
  }
  else {
    fRef = val;
  }
}
 
template<>
inline void G4AnyType::Ref<G4ThreeVector>::FromString(const std::string& val)
{
  fRef = G4UIcommand::ConvertTo3Vector(val.c_str());
}
 
/**
 * @class G4BadAnyCast G4AnyType.h Reflex/G4AnyType.h
 * @author K. Henney
 */
class G4BadAnyCast : public std::bad_cast
{
  public:
    G4BadAnyCast() = default;
 
    const char* what() const throw() override
    {
      return "G4BadAnyCast: failed conversion using any_cast";
    }
};
 
/** value */
 
template<typename ValueType>
ValueType* any_cast(G4AnyType* operand)
{
  return operand && operand->TypeInfo() == typeid(ValueType)
           ? &static_cast<G4AnyType::Ref<ValueType>*>(operand->fContent)->fRef
           : nullptr;
}
 
template<typename ValueType>
const ValueType* any_cast(const G4AnyType* operand)
{
  return any_cast<ValueType>(const_cast<G4AnyType*>(operand));
}
 
template<typename ValueType>
ValueType any_cast(const G4AnyType& operand)
{
  const ValueType* result = any_cast<ValueType>(&operand);
  if (!result) {
    throw G4BadAnyCast();
  }
  return *result;
}
 
#endif