VectorToNumpy.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 "MantidKernel/System.h"
#include "MantidPythonInterface/core/Converters/CloneToNDArray.h"
#include "MantidPythonInterface/core/Converters/VectorToNDArray.h"
#include "MantidPythonInterface/core/NDArray.h"
 
#include <boost/mpl/and.hpp>
#include <boost/mpl/if.hpp>
#include <type_traits>
#include <vector>
 
namespace Mantid {
namespace PythonInterface {
namespace Policies {
 
namespace // anonymous
{
//-----------------------------------------------------------------------
// MPL helper structs
//-----------------------------------------------------------------------
template <typename T> struct is_std_vector : std::false_type {};
 
template <typename T> struct is_std_vector<std::vector<T>> : std::true_type {};
 
//-----------------------------------------------------------------------
// VectorRefToNumpyImpl - Policy for reference returns
//-----------------------------------------------------------------------
template <typename VectorType, typename ConversionPolicy> struct VectorRefToNumpyImpl {
  inline PyObject *operator()(const VectorType &cvector) const {
    return Converters::VectorToNDArray<typename VectorType::value_type, ConversionPolicy>()(cvector);
  }
 
  inline PyTypeObject const *get_pytype() const { return ndarrayType(); }
};
 
template <typename T> struct VectorRefToNumpy_Requires_Reference_To_StdVector_Return_Type {};
} // namespace
 
template <typename ConversionPolicy> struct VectorRefToNumpy {
  // The boost::python framework calls return_value_policy::apply<T>::type
  template <class T> struct apply {
    // Typedef that removes and const or reference qualifiers from the type
    using non_const_type = typename std::remove_const<typename std::remove_reference<T>::type>::type;
    // MPL compile-time check that T is a reference to a std::vector
    using type = typename boost::mpl::if_c<is_std_vector<non_const_type>::value,
                                           VectorRefToNumpyImpl<non_const_type, ConversionPolicy>,
                                           VectorRefToNumpy_Requires_Reference_To_StdVector_Return_Type<T>>::type;
  };
};
 
//-----------------------------------------------------------------------
// VectorToNumpy return_value_policy
//-----------------------------------------------------------------------
namespace {
template <typename VectorType> struct VectorToNumpyImpl {
  inline PyObject *operator()(const VectorType &cvector) const {
    return Converters::VectorToNDArray<typename VectorType::value_type, Converters::Clone>()(cvector);
  }
 
  inline PyTypeObject const *get_pytype() const { return ndarrayType(); }
};
 
template <typename T> struct VectorToNumpy_Requires_StdVector_Return {};
} // namespace
 
struct VectorToNumpy {
  // The boost::python framework calls return_value_policy::apply<T>::type
  template <class T> struct apply {
    // Typedef that removes any const from the type
    using non_const_type = typename std::remove_const<typename std::remove_reference<T>::type>::type;
    // MPL compile-time check that T is a std::vector
    using type = typename boost::mpl::if_c<is_std_vector<non_const_type>::value,
                                           VectorRefToNumpyImpl<non_const_type, Converters::Clone>,
                                           VectorToNumpy_Requires_StdVector_Return<T>>::type;
  };
};
} // namespace Policies
} // namespace PythonInterface
} // namespace Mantid