pyResultConversions.h

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//
// Copyright 2016 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifndef PXR_BASE_TF_PY_RESULT_CONVERSIONS_H
#define PXR_BASE_TF_PY_RESULT_CONVERSIONS_H

#include "pxr/pxr.h"

#include "pxr/base/tf/pyUtils.h"

#include "pxr/external/boost/python/tuple.hpp"
#include "pxr/external/boost/python/list.hpp"
#include "pxr/external/boost/python/dict.hpp"

#include <type_traits>

PXR_NAMESPACE_OPEN_SCOPE

template <typename T> struct Tf_PySequenceToListConverter;
template <typename T> struct Tf_PySequenceToSetConverter;
template <typename T> struct Tf_PyMapToDictionaryConverter;
template <typename T> struct Tf_PySequenceToTupleConverter;
template <typename First, typename Second> struct Tf_PyPairToTupleConverter;

/// \class TfPySequenceToList
///
/// A \c pxr_boost::python result converter generator which converts standard
/// library sequences to lists.
///
/// The way to use this is as a return value policy for a function which
/// returns a sequence or a const reference to a sequence.  For example this
/// function:
/// \code
/// vector<double> getDoubles() {
///     vector<double> ret;
///     ret.push_back(1.0);
///     ret.push_back(2.0);
///     ret.push_back(3.0);
///     return ret;
/// }
/// \endcode
///
/// May be wrapped as:
/// \code
/// def("getDoubles", &getDoubles, return_value_policy<TfPySequenceToList>())
/// \endcode
struct TfPySequenceToList {
    template <typename T>
    struct apply {
        typedef Tf_PySequenceToListConverter<T> type;
    };
};

/// \class TfPySequenceToSet
///
/// A \c pxr_boost::python result converter generator which converts standard
/// library sequences to sets.
///
/// The way to use this is as a return value policy for a function which
/// returns a sequence or a const reference to a sequence.  For example this
/// function:
/// \code
/// unordered_set<double> getDoubles() {
///     unordered_set<double> ret;
///     ret.insert(1.0);
///     ret.insert(2.0);
///     ret.insert(3.0);
///     return ret;
/// }
/// \endcode
///
/// May be wrapped as:
/// \code
/// def("getDoubles", &getDoubles, return_value_policy<TfPySequenceToSet>())
/// \endcode
struct TfPySequenceToSet {
    template <typename T>
    struct apply {
        typedef Tf_PySequenceToSetConverter<T> type;
    };
};

/// \class TfPyMapToDictionary
///
/// A \c pxr_boost::python result converter generator which converts standard
/// library maps to dictionaries.
struct TfPyMapToDictionary {
    template <typename T>
    struct apply {
        typedef Tf_PyMapToDictionaryConverter<T> type;
    };
};

/// \class TfPySequenceToTuple
///
/// A \c pxr_boost::python result converter generator which converts standard
/// library sequences to tuples.
/// \see TfPySequenceToList.
struct TfPySequenceToTuple {
    template <typename T>
    struct apply {
        typedef Tf_PySequenceToTupleConverter<T> type;
    };
};

/// A \c pxr_boost::python result converter generator which converts standard
/// library pairs to tuples.
struct TfPyPairToTuple {
    template <typename T>
    struct apply {
        typedef Tf_PyPairToTupleConverter<typename T::first_type,
                                          typename T::second_type> type;
    };
};

template <typename T>
struct Tf_PySequenceToListConverter {
    typedef std::remove_reference_t<T> SeqType;
    bool convertible() const {
        return true;
    }
    PyObject *operator()(T seq) const {
        return pxr_boost::python::incref(TfPyCopySequenceToList(seq).ptr());
    }
    PyTypeObject *get_pytype() {
        return &PyList_Type;
    }
};

template <typename T>
struct Tf_PySequenceToSetConverter {
    typedef std::remove_reference_t<T> SeqType;
    bool convertible() const {
        return true;
    }
    PyObject *operator()(T seq) const {
        return pxr_boost::python::incref(TfPyCopySequenceToSet(seq).ptr());
    }
    PyTypeObject *get_pytype() {
        return &PySet_Type;
    }
};

template <typename T>
struct Tf_PyMapToDictionaryConverter {
    typedef std::remove_reference_t<T> SeqType;
    // TODO: convertible() should be made more robust by checking that the
    // value_type of the container is pair<const key_type, data_type> 
    bool convertible() const {
        return true;
    }
    PyObject *operator()(T seq) const {
        return pxr_boost::python::incref(TfPyCopyMapToDictionary(seq).ptr());
    }
    PyTypeObject *get_pytype() {
        return &PyDict_Type;
    }
};

template <typename T>
struct Tf_PySequenceToTupleConverter {
    typedef std::remove_reference_t<T> SeqType;
    bool convertible() const {
        return true;
    }
    PyObject *operator()(T seq) const {
        return pxr_boost::python::incref(TfPyCopySequenceToTuple(seq).ptr());
    }
    PyTypeObject *get_pytype() {
        return &PyTuple_Type;
    }
};

template <typename First, typename Second>
struct Tf_PyPairToTupleConverter {
    typedef std::pair<First, Second> PairType;
    bool convertible() const {
        return true;
    }
    PyObject *operator()(PairType const& a) const {
        pxr_boost::python::tuple result =
            pxr_boost::python::make_tuple(a.first, a.second);
        return pxr_boost::python::incref(result.ptr());
    }
    PyTypeObject *get_pytype() {
        return &PyTuple_Type;
    }
};

PXR_NAMESPACE_CLOSE_SCOPE

#endif // TF_RESULT_CONVERSIONS_H