G4AnyType.hh

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//
// $Id: G4UImessenger.hh,v 1.9 2006-06-29 19:08:19 gunter Exp $
//
// 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
// where: tested with BCC 5.5, MSVC 6.0, and g++ 2.95

#ifndef G4AnyType_h
#define G4AnyType_h 1

#include <algorithm>
#include <typeinfo>
#include <iostream>
#include <sstream>

class G4String;
namespace CLHEP {
  class Hep3Vector;
}

class  G4AnyType {  
public:
  G4AnyType():
  fContent(0) {}
  
  template <typename ValueType> G4AnyType(ValueType &value):
  fContent(new Ref<ValueType>(value)) {}
  
  G4AnyType(const G4AnyType &other):
  fContent(other.fContent ? other.fContent->Clone() : 0) {}
  
  ~G4AnyType() {
    delete fContent;
  }
  
  operator bool() {
    return !Empty();
  }
  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;
  }
  bool Empty() const {
    return !fContent;
  }
  const std::type_info& TypeInfo() const {
    return fContent ? fContent->TypeInfo() : typeid(void);
  }
  void* Address() const {
    return fContent ? fContent->Address() : 0;
  }
  std::string ToString() const {
    return fContent->ToString();
  }
  void FromString(const std::string& val) {
    fContent->FromString(val);
  }
private:
  class Placeholder {
  public:
    Placeholder() {}
    virtual ~Placeholder() {}
    virtual const std::type_info& TypeInfo() const = 0;
    virtual Placeholder* Clone() const = 0;
    virtual void* Address() const = 0;
    virtual std::string ToString() const = 0;
    virtual void FromString(const std::string& val) = 0;
  };
  
  template <typename ValueType> class Ref: public Placeholder {
  public:
    Ref(ValueType& value): fRef(value) {}
    virtual const std::type_info& TypeInfo() const {
      return typeid(ValueType);
    }
    virtual Placeholder* Clone() const {
      return new Ref(fRef);
    }
    virtual void* Address() const {
      return (void*) (&fRef);
    }
    virtual std::string ToString() const {
      std::stringstream s;
      s << fRef;
      return s.str();
    }
    virtual void FromString(const std::string& val) {
      std::stringstream s(val);
      s >> fRef;
    }
    ValueType& fRef;
  };
  template <typename ValueType> friend ValueType* any_cast(G4AnyType*);
  Placeholder* fContent;
};

template<> void G4AnyType::Ref<bool>::FromString(const std::string& val);
template<> void G4AnyType::Ref<G4String>::FromString(const std::string& val);
template<> void G4AnyType::Ref<CLHEP::Hep3Vector>::FromString(const std::string& val);

class G4BadAnyCast: public std::bad_cast {
public:
  G4BadAnyCast() {}
  
  virtual const char* what() const throw() {
    return "G4BadAnyCast: failed conversion using any_cast";
  }
};

template <typename ValueType> ValueType* any_cast(G4AnyType* operand) {
  return operand && operand->TypeInfo() == typeid(ValueType)
  ? &static_cast<G4AnyType::Ref<ValueType>*>(operand->fContent)->fRef : 0;
}
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