python/google/protobuf/pyext/map_container.h

// Protocol Buffers - Google's data interchange format
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#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_MAP_CONTAINER_H__
#define GOOGLE_PROTOBUF_PYTHON_CPP_MAP_CONTAINER_H__

#include <Python.h>

#include <memory>

#include <google/protobuf/descriptor.h>
#include <google/protobuf/message.h>
#include <google/protobuf/pyext/message.h>

namespace google {
namespace protobuf {

class Message;

namespace python {

struct CMessageClass;

// This struct is used directly for ScalarMap, and is the base class of
// MessageMapContainer, which is used for MessageMap.
struct MapContainer {
  PyObject_HEAD;

  // This is the top-level C++ Message object that owns the whole
  // proto tree.  Every Python MapContainer 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.
  CMessage::OwnerRef owner;

  // Pointer to the C++ Message that contains this container.  The
  // MapContainer does not own this pointer.
  const Message* message;

  // Use to get a mutable message when necessary.
  Message* GetMutableMessage();

  // Weak reference to a parent CMessage object (i.e. may be NULL.)
  //
  // Used to make sure all ancestors are also mutable when first
  // modifying the container.
  CMessage* parent;

  // Pointer to the parent's descriptor that describes this
  // field.  Used together with the parent's message when making a
  // default message instance mutable.
  // The pointer is owned by the global DescriptorPool.
  const FieldDescriptor* parent_field_descriptor;
  const FieldDescriptor* key_field_descriptor;
  const FieldDescriptor* value_field_descriptor;

  // We bump this whenever we perform a mutation, to invalidate existing
  // iterators.
  uint64 version;

  // Releases the messages in the container to a new message.
  //
  // Returns 0 on success, -1 on failure.
  int Release();

  // Set the owner field of self and any children of self.
  void SetOwner(const CMessage::OwnerRef& new_owner) { owner = new_owner; }
};

struct MessageMapContainer : public MapContainer {
  // The type used to create new child messages.
  CMessageClass* message_class;

  // A dict mapping Message* -> CMessage.
  PyObject* message_dict;
};

bool InitMapContainers();

extern PyTypeObject* MessageMapContainer_Type;
extern PyTypeObject* ScalarMapContainer_Type;
extern PyTypeObject MapIterator_Type;  // Both map types use the same iterator.

// Builds a MapContainer object, from a parent message and a
// field descriptor.
extern PyObject* NewScalarMapContainer(
    CMessage* parent, const FieldDescriptor* parent_field_descriptor);

// Builds a MessageMap object, from a parent message and a
// field descriptor.
extern PyObject* NewMessageMapContainer(
    CMessage* parent, const FieldDescriptor* parent_field_descriptor,
    CMessageClass* message_class);

}  // namespace python
}  // namespace protobuf

}  // namespace google
#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_MAP_CONTAINER_H__