pyObjWrapper.h

//
// Copyright 2016 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef PXR_BASE_TF_PY_OBJ_WRAPPER_H
#define PXR_BASE_TF_PY_OBJ_WRAPPER_H

#include "pxr/pxr.h"

#include "pxr/base/tf/api.h"
#include "pxr/base/arch/pragmas.h"

#ifdef PXR_PYTHON_SUPPORT_ENABLED
// Include this header first to pick up additional mitigations
// for build issues when including Python.h
#include "pxr/base/tf/pySafePython.h"

#include <boost/functional/hash.hpp>
#include <boost/python/object_fwd.hpp>
#include <boost/python/object_operators.hpp>

#include <iosfwd>
#include <memory>

#else

#include <type_traits>

#endif

PXR_NAMESPACE_OPEN_SCOPE

// We define the empty stub for ABI compatibility even if Python support is
// enabled so we can make sure size and alignment is the same.
class TfPyObjWrapperStub
{
public:
    static constexpr std::size_t Size = 16;
    static constexpr std::size_t Align = 8;

private:
    ARCH_PRAGMA_PUSH
    ARCH_PRAGMA_UNUSED_PRIVATE_FIELD
    std::aligned_storage<Size, Align>::type _stub;
    ARCH_PRAGMA_POP
};


#ifdef PXR_PYTHON_SUPPORT_ENABLED
class TfPyObjWrapper
    : public boost::python::api::object_operators<TfPyObjWrapper>
{
    typedef boost::python::object object;

public:

    TF_API TfPyObjWrapper();

    TF_API TfPyObjWrapper(object obj);

    object const &Get() const {
        return *_objectPtr;
    }

    TF_API PyObject *ptr() const;

    friend inline size_t hash_value(TfPyObjWrapper const &o) {
        return (size_t) o.ptr();
    }

    TF_API bool operator==(TfPyObjWrapper const &other) const;

    TF_API bool operator!=(TfPyObjWrapper const &other) const;

private:

    // Befriend object_operators to allow it access to implicit conversion to
    // boost::python::object.
    friend class boost::python::api::object_operators<TfPyObjWrapper>;
    operator object const &() const {
        return Get();
    }

    // Store a shared_ptr to a python object.
    std::shared_ptr<object> _objectPtr;
};

static_assert(sizeof(TfPyObjWrapper) == sizeof(TfPyObjWrapperStub),
              "ABI break: Incompatible class sizes.");
static_assert(alignof(TfPyObjWrapper) == alignof(TfPyObjWrapperStub),
              "ABI break: Incompatible class alignments.");

#else // PXR_PYTHON_SUPPORT_ENABLED

class TfPyObjWrapper : TfPyObjWrapperStub
{
};

#endif // PXR_PYTHON_SUPPORT_ENABLED

PXR_NAMESPACE_CLOSE_SCOPE

#endif // PXR_BASE_TF_PY_OBJ_WRAPPER_H