PySequenceToVector.h

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2011 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 <boost/python/extract.hpp>
#include <boost/python/object.hpp>
#include <vector>
 
namespace Mantid {
namespace PythonInterface {
namespace // <anonymous>
{
template <typename CType> struct ExtractCType {
  inline CType operator()(PyObject *value) { return boost::python::extract<CType>(value); }
};
 
template <> struct ExtractCType<std::string> {
  inline std::string operator()(PyObject *value) { return boost::python::extract<std::string>(PyObject_Str(value)); }
};
 
} // namespace
 
namespace Converters {
template <typename DestElementType> struct DLLExport PySequenceToVector {
  // Alias definitions
  using TypedVector = std::vector<DestElementType>;
 
  PySequenceToVector(const boost::python::object &value) : m_obj(value) {}
 
  inline TypedVector operator()() {
    TypedVector cvector(srcSize());
    copyTo(cvector);
    return cvector;
  }
 
  inline void copyTo(TypedVector &dest) {
    throwIfSizeMismatched(dest);
    ExtractCType<DestElementType> elementConverter;
    auto length = srcSize();
    for (size_t i = 0; i < length; ++i) {
      dest[i] = elementConverter(PySequence_GetItem(ptr(), i));
    }
  }
 
private:
  inline PyObject *ptr() const { return m_obj.ptr(); }
 
  inline std::size_t srcSize() const { return static_cast<size_t>(PySequence_Size(ptr())); }
 
  inline void throwIfSizeMismatched(const TypedVector &dest) const {
    if (srcSize() != dest.size()) {
      throw std::invalid_argument("Length mismatch between python list & C array. python=" + std::to_string(srcSize()) +
                                  ", C=" + std::to_string(dest.size()));
    }
  }
 
  boost::python::object m_obj;
};
} // namespace Converters
} // namespace PythonInterface
} // namespace Mantid