python/google/protobuf/pyext/extension_dict.h

// Protocol Buffers - Google's data interchange format
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// Author: anuraag@google.com (Anuraag Agrawal)
// Author: tibell@google.com (Johan Tibell)

#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_EXTENSION_DICT_H__
#define GOOGLE_PROTOBUF_PYTHON_CPP_EXTENSION_DICT_H__

#include <Python.h>

#include <memory>
#ifndef _SHARED_PTR_H
#include <google/protobuf/stubs/shared_ptr.h>
#endif

namespace google {
namespace protobuf {

class Message;
class FieldDescriptor;

#ifdef _SHARED_PTR_H
using std::shared_ptr;
#else
using internal::shared_ptr;
#endif

namespace python {

struct CMessage;

typedef struct ExtensionDict {
  PyObject_HEAD;

  // This is the top-level C++ Message object that owns the whole
  // proto tree.  Every Python container class holds a
  // reference to it in order to keep it alive as long as there's a
  // Python object that references any part of the tree.
  shared_ptr<Message> owner;

  // Weak reference to parent message. Used to make sure
  // the parent is writable when an extension field is modified.
  CMessage* parent;

  // Pointer to the C++ Message that this ExtensionDict extends.
  // Not owned by us.
  Message* message;

  // A dict of child messages, indexed by Extension descriptors.
  // Similar to CMessage::composite_fields.
  PyObject* values;
} ExtensionDict;

extern PyTypeObject ExtensionDict_Type;

namespace extension_dict {

// Builds an Extensions dict for a specific message.
ExtensionDict* NewExtensionDict(CMessage *parent);

// Gets the number of extension values in this ExtensionDict as a python object.
//
// Returns a new reference.
PyObject* len(ExtensionDict* self);

// Releases extensions referenced outside this dictionary to keep outside
// references alive.
//
// Returns 0 on success, -1 on failure.
int ReleaseExtension(ExtensionDict* self,
                     PyObject* extension,
                     const FieldDescriptor* descriptor);

// Gets an extension from the dict for the given extension descriptor.
//
// Returns a new reference.
PyObject* subscript(ExtensionDict* self, PyObject* key);

// Assigns a value to an extension in the dict. Can only be used for singular
// simple types.
//
// Returns 0 on success, -1 on failure.
int ass_subscript(ExtensionDict* self, PyObject* key, PyObject* value);

// Clears an extension from the dict. Will release the extension if there
// is still an external reference left to it.
//
// Returns None on success.
PyObject* ClearExtension(ExtensionDict* self,
                                       PyObject* extension);

// Gets an extension from the dict given the extension name as opposed to
// descriptor.
//
// Returns a new reference.
PyObject* _FindExtensionByName(ExtensionDict* self, PyObject* name);

}  // namespace extension_dict
}  // namespace python
}  // namespace protobuf

}  // namespace google
#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_EXTENSION_DICT_H__