# dlib C++ Library - pybind_utils.h

    // Copyright (C) 2013  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_PYBIND_UtILS_Hh_
    #define DLIB_PYBIND_UtILS_Hh_

    #include <pybind11/pybind11.h>
    #include <vector>
    #include <string>
    #include <dlib/serialize.h>
    #include <array>

    namespace py = pybind11;

    namespace dlib
    {

        template <typename T>
        std::vector<T> python_list_to_vector (
            const py::list& obj
        )
        /*!
            ensures
                - converts a python object into a std::vector<T> and returns it.
        !*/
        {
            std::vector<T> vect(len(obj));
            for (unsigned long i = 0; i < vect.size(); ++i)
            {
                vect[i] = obj[i].cast<T>();
            }
            return vect;
        }

        template <typename T,size_t N>
        std::array<T,N> python_list_to_array (
            const py::list& the_list
        )
        /*!
            ensures
                - converts a python object into a std::array<T,N> and returns it.
        !*/
        {
            DLIB_CASSERT(len(the_list) == N, "Expected a list of " << N << " things.");
            std::array<T,N> vect;
            for (unsigned long i = 0; i < vect.size(); ++i)
            {
                vect[i] = the_list[i].cast<T>();
            }
            return vect;
        }

        template <typename T>
        py::list vector_to_python_list (
            const std::vector<T>& vect
        )
        /*!
            ensures
                - converts a std::vector<T> into a python list object.
        !*/
        {
            py::list obj;
            for (unsigned long i = 0; i < vect.size(); ++i)
                obj.append(vect[i]);
            return obj;
        }

        template <typename T>
        void extend_vector_with_python_list (
            std::vector<T> &v,
            const py::list &l
        )
        /*!
            ensures
                - appends items from a python list to the end of std::vector<T>.
        !*/
        {
            for (const auto &item : l)
                v.push_back(item.cast<T>());
        }

    // ----------------------------------------------------------------------------------------

        template <typename T>
        std::shared_ptr<T> load_object_from_file (
            const std::string& filename
        )
        /*!
            ensures
                - deserializes an object of type T from the given file and returns it.
        !*/
        {
            std::ifstream fin(filename.c_str(), std::ios::binary);
            if (!fin)
                throw dlib::error("Unable to open " + filename);
            auto obj = std::make_shared<T>();
            deserialize(*obj, fin);
            return obj;
        }
    }

    // ----------------------------------------------------------------------------------------

    #endif // DLIB_PYBIND_UtILS_Hh_