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- // 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__
- #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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