AsType.h

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2012 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#pragma once
 
#include <boost/mpl/and.hpp>
#include <boost/python/detail/prefix.hpp>
#include <boost/python/to_python_value.hpp>
#include <type_traits>
 
namespace Mantid {
namespace PythonInterface {
namespace Policies {
// Utility code to help out
namespace {
 
//-----------------------------------------------------------------------
// Polciy implementation
//-----------------------------------------------------------------------
 
// The entry point for the policy is in the struct AsType below. It does
// a check as to whether the return type is valid, if so it forwards the
// call to this struct
template <typename ReturnType, typename InputType> struct AsTypeImpl {
 
  inline PyObject *operator()(const InputType &p) const {
    using namespace boost::python;
    return to_python_value<ReturnType>()(ReturnType(p));
  }
 
  inline PyTypeObject const *get_pytype() const {
    using namespace boost::python;
    return converter::registered<ReturnType>::converters.to_python_target_type();
  }
};
 
// Error handler for shared pointer types. If return type is wrong then user
// sees the name of this
// class in the output, which hopefully gives a clue as to what is going on
template <typename T> struct AsType_Requires_New_Type_Automatically_Convertible_To_Original {};
 
} // namespace
 
template <class ReturnType> struct AsType {
  template <class InputType> struct apply {
    // Deduce if type is correct for policy, needs to be convertible to
    // ReturnType
    using type =
        typename boost::mpl::if_c<std::is_convertible<InputType, ReturnType>::value, AsTypeImpl<ReturnType, InputType>,
                                  AsType_Requires_New_Type_Automatically_Convertible_To_Original<InputType>>::type;
  };
};
 
} // namespace Policies
} // namespace PythonInterface
} // namespace Mantid