Teuchos_any.hpp

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#ifndef TEUCHOS_ANY_HPP
#define TEUCHOS_ANY_HPP

#include <utility>
#include <type_traits>
#include <exception>

#include "Teuchos_Assert.hpp"
#include "Teuchos_TypeNameTraits.hpp"

//
// This file was taken from the boost library which contained the
// following notice:
//
// *************************************************************
//
// what:  variant type 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
//
// 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.
//
// *************************************************************
//
// RAB modified the file for use in Teuchos.  I changed the nature of
// the any_cast<> to be easier to use.
//

namespace Teuchos {

template<class T>
struct is_comparable
{
    template<class X>
    static auto test(int) -> decltype(std::declval<X>() == std::declval<X>(),
                                      void(), std::true_type());
    template<class X>
    static auto test(...) -> std::false_type;
    using type = decltype(test<T>(0));
};

template<class T>
struct is_printable
{
    template<class X>
    static auto test(int) -> decltype(std::declval<std::ostream&>() << std::declval<X>(),
                                      void(), std::true_type());
    template<class X>
    static auto test(...) -> std::false_type;
    using type = decltype(test<T>(0));
};

template <class T, class ok = typename is_comparable<T>::type>
struct compare;

template <class T>
struct compare<T, std::false_type> {
  bool operator()(T const&, T const&) const {
    TEUCHOS_TEST_FOR_EXCEPTION(true, std::runtime_error,
        "Trying to compare type " << typeid(T).name() << " which is not comparable");
#ifndef __CUDACC__
    return false;
#endif
  }
};

template <class T>
struct compare<T, std::true_type> {
  bool operator()(T const& a, T const& b) const {
    return a == b;
  }
};

template <class T, class ok = typename is_printable<T>::type>
struct print;

template <class T>
struct print<T, std::false_type> {
  std::ostream& operator()(std::ostream& s, T const&) const {
    TEUCHOS_TEST_FOR_EXCEPTION(true, std::runtime_error,
        "Trying to print type " << typeid(T).name() << " which is not printable");
#ifndef __CUDACC__
    return s;
#endif
  }
};

template <class T>
struct print<T, std::true_type> {
  std::ostream& operator()(std::ostream& a, T const& b) const {
    return a << b;
  }
};

class TEUCHOSCORE_LIB_DLL_EXPORT any
{
public:
  any()
    : content(0)
    {}

  template<typename ValueType>
  explicit any(ValueType&& value)
    : content(new holder<std::decay_t<ValueType>>(std::forward<ValueType>(value)))
    {}

  any(const any & other)
    : content(other.content ? other.content->clone() : 0)
    {}

  any(any&& other)
    : content(std::exchange(other.content,nullptr))
    {}

  ~any()
    {
      delete content;
    }

  any & swap(any & rhs)
    {
      std::swap(content, rhs.content);
      return *this;
    }

  template<typename ValueType>
  any & operator=(const ValueType & rhs)
    {
      any(rhs).swap(*this);
      return *this;
    }

  any & operator=(const any & rhs)
    {
      any(rhs).swap(*this);
      return *this;
    }

  any& operator=(any&& other)
  {
    if(this != &other) {
      delete this->content;
      this->content = std::exchange(other.content, nullptr);
    }
    return *this;
  }

  TEUCHOS_DEPRECATED
  bool empty() const
  {
    return ! this->has_value();
  }

  bool has_value() const { return this->content != nullptr; }

  const std::type_info & type() const
    {
      return content ? content->type() : typeid(void);
    }

  std::string typeName() const
    {
      return content ? content->typeName() : "NONE";
    }

  bool same( const any &other ) const
    {
      if( !this->has_value() && !other.has_value() )
        return true;
      else if( this->has_value() && !other.has_value() )
        return false;
      else if( !this->has_value() && other.has_value() )
        return false;
      // this->has_value() && other.has_value()
      return content->same(*other.content);
    }

  void print(std::ostream& os) const
    {
      if (content) content->print(os);
    }

#ifndef DOXYGEN_SHOULD_SKIP_THIS


  class placeholder
  {
  public:
    virtual ~placeholder() {}
    virtual const std::type_info & type() const = 0;
    virtual std::string typeName() const = 0;
    virtual placeholder * clone() const = 0;
    virtual bool same( const placeholder &other ) const = 0;
    virtual void print(std::ostream & os) const = 0;
  };

  template<typename ValueType>
  class holder : public placeholder
  {
  public:
    template <typename U>
    holder(U&& value)
      : held(std::forward<U>(value))
      {}
    const std::type_info & type() const
      { return typeid(ValueType); }
    std::string typeName() const
      { return TypeNameTraits<ValueType>::name(); }
    placeholder * clone() const
      { return new holder(held); }
    bool same( const placeholder &other ) const
      {
        if( type() != other.type() ) {
          return false;
        }
        // type() == other.type()
        const ValueType
          &other_held = dynamic_cast<const holder<ValueType>&>(other).held;
        return ::Teuchos::compare<ValueType>{}(held, other_held);
      }
    void print(std::ostream & os) const
      { ::Teuchos::print<ValueType>{}(os, held); }
    ValueType held;
  };


public:
  // Danger: This is made public to allow any_cast to be non-friend
  placeholder* access_content()
    { return content; }
  const placeholder* access_content() const
    { return content; }
#endif

private:

  // /////////////////////////
  // Private data members

  placeholder * content;

};

class bad_any_cast : public std::runtime_error
{
public:
  bad_any_cast( const std::string msg ) : std::runtime_error(msg) {}
};

template<typename ValueType>
ValueType& any_cast(any &operand)
{
  const std::string ValueTypeName = TypeNameTraits<ValueType>::name();
  TEUCHOS_TEST_FOR_EXCEPTION(
    operand.type() != typeid(ValueType), bad_any_cast,
    "any_cast<"<<ValueTypeName<<">(operand): Error, cast to type "
    << "any::holder<"<<ValueTypeName<<"> failed since the actual underlying type is \'"
    << typeName(*operand.access_content()) << "!"
    );
  TEUCHOS_TEST_FOR_EXCEPTION(
    !operand.access_content(), bad_any_cast
    ,"any_cast<"<<ValueTypeName<<">(operand): Error, cast to type "
    << "any::holder<"<<ValueTypeName<<"> failed because the content is NULL"
    );
  any::holder<ValueType>
    *dyn_cast_content = dynamic_cast<any::holder<ValueType>*>(operand.access_content());
  TEUCHOS_TEST_FOR_EXCEPTION(
    !dyn_cast_content, std::logic_error
    ,"any_cast<"<<ValueTypeName <<">(operand): Error, cast to type "
    << "any::holder<"<<ValueTypeName<<"> failed but should not have and the actual underlying type is \'"
    << typeName(*operand.access_content()) << "!"
    << "  The problem might be related to incompatible RTTI systems in static and shared libraries!"
    );
  return dyn_cast_content->held;
}

template<typename ValueType>
const ValueType& any_cast(const any &operand)
{
  return any_cast<ValueType>(const_cast<any&>(operand));
}

template <typename ValueType>
ValueType* any_cast(any* operand)
{
  return &any_cast<ValueType>(*operand);
}

template <typename ValueType>
ValueType any_cast(any&& operand)
{
  using U = std::remove_cv_t<std::remove_reference_t<ValueType>>;
  static_assert(std::is_constructible_v<ValueType, U>);
  return static_cast<ValueType>(std::move(*any_cast<U>(&operand)));
}

template<typename ValueType>
ValueType& any_ref_cast(any &operand)
{
  return Teuchos::any_cast<ValueType>(operand);
}

inline std::string toString(const any &rhs)
{
  std::ostringstream oss;
  rhs.print(oss);
  return oss.str();
}

inline bool operator==( const any &a, const any &b )
{
  return a.same(b);
}

inline bool operator!=( const any &a, const any &b )
{
  return !a.same(b);
}

inline std::ostream & operator<<(std::ostream & os, const any &rhs)
{
  rhs.print(os);
  return os;
}

inline void swap(Teuchos::any& a, Teuchos::any& b) {
  a.swap(b);
}

template <typename T>
T & make_any_ref(any &rhs)
{
  any(T()).swap(rhs);
  return any_cast<T>(rhs);
}

} // namespace Teuchos

#endif // TEUCHOS_ANY_HPP