PHengLEI-NCCR/phenglei/3rdparty/Sacado/include/Sacado_mpl_is_convertible.hpp

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2.6 KiB
C++

// @HEADER
// ***********************************************************************
//
// Sacado Package
// Copyright (2006) Sandia Corporation
//
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
//
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
// USA
// Questions? Contact David M. Gay (dmgay@sandia.gov) or Eric T. Phipps
// (etphipp@sandia.gov).
//
// ***********************************************************************
// @HEADER
#ifndef SACADO_MPL_IS_CONVERTIBLE_HPP
#define SACADO_MPL_IS_CONVERTIBLE_HPP
#include "Sacado_ConfigDefs.h"
#ifdef HAVE_SACADO_CXX11
#include <type_traits>
namespace Sacado {
namespace mpl {
using std::is_convertible;
}
}
#else
namespace Sacado {
namespace mpl {
//
// A simplified implementation of boost type-trait
// is_convertible<From,To>. We use this in a much more limited context
// within Sacado, and so the easy implementation should always work.
// We assume From and To are "scalar" types, e.g., are not pointer or
// reference types.
//
struct convertible_impl {
typedef char yes; // sizeof(yes) == 1
typedef char (&no)[2]; // sizeof(no) == 2
// A function that takes anything convertible to a To
template <typename To> static yes tester(To);
// Overload resolution prefers anything over ...
template <typename To> static no tester(...);
// Check if From is convertible to To
template <typename From, typename To>
struct checker {
static From& f;
static const bool value = sizeof(tester<To>(f)) == sizeof(yes);
};
};
template <typename From, typename To>
struct is_convertible {
static const bool value = convertible_impl::checker<From,To>::value;
};
}
}
#endif
#endif // SACADO_MPL_IS_CONVERTIBLE_HPP