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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef SHARE_VM_METAPROGRAMMING_ISDERIVED_HPP
#define SHARE_VM_METAPROGRAMMING_ISDERIVED_HPP

#include "memory/allocation.hpp"
#include "metaprogramming/integralConstant.hpp"
#include "metaprogramming/isSame.hpp"

// The IsDerived metafunction checks if a DerivedType is derived from a BaseType
// or not. This will return false when used on a forward declared class.
// Note that due to the ODR rule of C++, this metafunction must be used with care
// in contexts where the DerivedType is guaranteed to be fully known.

template <typename DerivedType, typename BaseType>
struct IsDerivedHelper: public StackObj {
  operator BaseType* () const;
  operator DerivedType* ();
};

template <typename DerivedType, typename BaseType>
struct IsDerivedImpl: public AllStatic {
  typedef char yes[1];
  typedef char no[2];

  template <typename T>
  static yes& test(DerivedType*, T);
  static no& test(BaseType*, int);

  static const bool value = IsSame<DerivedType, BaseType>::value ||
    sizeof(test(IsDerivedHelper<DerivedType, BaseType>(), 0)) == sizeof(yes);
};

template <typename DerivedType, typename BaseType>
struct IsDerived: public IntegralConstant<bool, IsDerivedImpl<DerivedType, BaseType>::value> {};

#endif // SHARE_VM_METAPROGRAMMING_ISDERIVED_HPP