PythonStdPairUtils.h

Go to the documentation of this file.

// PythonStdPairUtils.h:
// ---------------------
//

#ifndef __PYIPSDKBASE_PYTHONSTDPAIRUTILS_H__
#define __PYIPSDKBASE_PYTHONSTDPAIRUTILS_H__

#include <vector>
#include <boost/python/iterator.hpp>
#include <boost/python/self.hpp>
#include <boost/python/operators.hpp>
#include <boost/python/tuple.hpp>
#include <iostream>


namespace std {

    // default ostream operator for std::pair
    template<typename T1, typename T2>
    static std::ostream&
    operator<< (std::ostream& os, const std::pair<T1, T2>& pairData)
    {
        os << "{" << pairData.first << ", " << pairData.second << "}";

        return os;
    }
}


namespace ipsdk {
namespace python {


// from https://stackoverflow.com/questions/16497889/how-to-expose-stdpair-to-python-using-boostpython/41593748
template<typename T1, typename T2>
struct PairToPythonConverter
{
    static PyObject* convert(const std::pair<T1, T2>& pair)
    {
        return boost::python::incref(boost::python::make_tuple(pair.first, pair.second).ptr());
    }
};

template<typename T1, typename T2>
struct PythonToPairConverter
{
    static void* convertible(PyObject* obj)
    {
        if (!PyTuple_CheckExact(obj)) return 0;
        if (PyTuple_Size(obj) != 2) return 0;
        return obj;
    }
 
   static void construct(PyObject* obj, boost::python::converter::rvalue_from_python_stage1_data* data)
    {
        boost::python::tuple tuple(boost::python::borrowed(obj));
        void* storage = ((boost::python::converter::rvalue_from_python_storage<std::pair<T1, T2> >*) data)->storage.bytes;
        new (storage) std::pair<T1, T2>(boost::python::extract<T1>(tuple[0]), boost::python::extract<T2>(tuple[1]));
        data->convertible = storage;
    }
};

// export pair
template<typename PairType>
void
export_pair(const char* py_name)
{
    typedef typename PairType::first_type T1;
    typedef typename PairType::second_type T2;
    boost::python::type_info info = boost::python::type_id<PairType>(); 
    const boost::python::converter::registration* reg = boost::python::converter::registry::query(info);
    if (reg == 0 || reg->m_to_python == 0) {

        boost::python::to_python_converter<PairType, PairToPythonConverter<T1, T2> > toPython;
        boost::python::converter::registry::push_back(
            &PythonToPairConverter<T1, T2>::convertible,
            &PythonToPairConverter<T1, T2>::construct,
            boost::python::type_id<PairType>());
    }
}


} // end of namespace python
} // end of namespace ipsdk

#endif // __PYIPSDKBASE_PYTHONSTDPAIRUTILS_H__