// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// This file can be included by other C++ libraries, typically extension modules
// which want to interact with the Python Messages coming from the "cpp"
// implementation of protocol buffers.
//
// Usage:
// Declare a (probably static) variable to hold the API:
// const PyProto_API* py_proto_api;
// In some initialization function, write:
// py_proto_api = static_cast<const PyProto_API*>(PyCapsule_Import(
// PyProtoAPICapsuleName(), 0));
// if (!py_proto_api) { ...handle ImportError... }
// Then use the methods of the returned class:
// py_proto_api->GetMessagePointer(...);
#ifndef GOOGLE_PROTOBUF_PYTHON_PROTO_API_H__
#define GOOGLE_PROTOBUF_PYTHON_PROTO_API_H__
#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include <google/protobuf/descriptor_database.h>
#include <google/protobuf/message.h>
namespace google {
namespace protobuf {
namespace python {
// Note on the implementation:
// This API is designed after
// https://docs.python.org/3/extending/extending.html#providing-a-c-api-for-an-extension-module
// The class below contains no mutable state, and all methods are "const";
// we use a C++ class instead of a C struct with functions pointers just because
// the code looks more readable.
struct PyProto_API {
// The API object is created at initialization time and never freed.
// This destructor is never called.
virtual ~PyProto_API() {}
// Operations on Messages.
// If the passed object is a Python Message, returns its internal pointer.
// Otherwise, returns NULL with an exception set.
virtual const Message* GetMessagePointer(PyObject* msg) const = 0;
// If the passed object is a Python Message, returns a mutable pointer.
// Otherwise, returns NULL with an exception set.
// This function will succeed only if there are no other Python objects
// pointing to the message, like submessages or repeated containers.
// With the current implementation, only empty messages are in this case.
virtual Message* GetMutableMessagePointer(PyObject* msg) const = 0;
// If the passed object is a Python Message Descriptor, returns its internal
// pointer.
// Otherwise, returns NULL with an exception set.
virtual const Descriptor* MessageDescriptor_AsDescriptor(
PyObject* desc) const = 0;
// If the passed object is a Python Enum Descriptor, returns its internal
// pointer.
// Otherwise, returns NULL with an exception set.
virtual const EnumDescriptor* EnumDescriptor_AsDescriptor(
PyObject* enum_desc) const = 0;
// Expose the underlying DescriptorPool and MessageFactory to enable C++ code
// to create Python-compatible message.
virtual const DescriptorPool* GetDefaultDescriptorPool() const = 0;
virtual MessageFactory* GetDefaultMessageFactory() const = 0;
// Allocate a new protocol buffer as a python object for the provided
// descriptor. This function works even if no Python module has been imported
// for the corresponding protocol buffer class.
// The factory is usually null; when provided, it is the MessageFactory which
// owns the Python class, and will be used to find and create Extensions for
// this message.
// When null is returned, a python error has already been set.
virtual PyObject* NewMessage(const Descriptor* descriptor,
PyObject* py_message_factory) const = 0;
// Allocate a new protocol buffer where the underlying object is owned by C++.
// The factory must currently be null. This function works even if no Python
// module has been imported for the corresponding protocol buffer class.
// When null is returned, a python error has already been set.
//
// Since this call returns a python object owned by C++, some operations
// are risky, and it must be used carefully. In particular:
// * Avoid modifying the returned object from the C++ side while there are
// existing python references to it or it's subobjects.
// * Avoid using python references to this object or any subobjects after the
// C++ object has been freed.
// * Calling this with the same C++ pointer will result in multiple distinct
// python objects referencing the same C++ object.
virtual PyObject* NewMessageOwnedExternally(
Message* msg, PyObject* py_message_factory) const = 0;
// Returns a new reference for the given DescriptorPool.
// The returned object does not manage the C++ DescriptorPool: it is the
// responsibility of the caller to keep it alive.
// As long as the returned Python DescriptorPool object is kept alive,
// functions that process C++ descriptors or messages created from this pool
// can work and return their Python counterparts.
virtual PyObject* DescriptorPool_FromPool(
const google::protobuf::DescriptorPool* pool) const = 0;
};
inline const char* PyProtoAPICapsuleName() {
static const char kCapsuleName[] =
"google.protobuf.pyext._message.proto_API";
return kCapsuleName;
}
} // namespace python
} // namespace protobuf
} // namespace google
#endif // GOOGLE_PROTOBUF_PYTHON_PROTO_API_H__
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