path: root/python/google/protobuf/pyext/repeated_composite_container.h

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// Author: anuraag@google.com (Anuraag Agrawal)
// Author: tibell@google.com (Johan Tibell)

#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_REPEATED_COMPOSITE_CONTAINER_H__
#define GOOGLE_PROTOBUF_PYTHON_CPP_REPEATED_COMPOSITE_CONTAINER_H__

#include <Python.h>

#include <memory>
#include <string>
#include <vector>

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

namespace google {
namespace protobuf {

class FieldDescriptor;
class Message;

namespace python {

struct CMessageClass;

// A RepeatedCompositeContainer can be in one of two states: attached
// or released.
//
// When in the attached state all modifications to the container are
// done both on the 'message' and on the 'child_messages'
// list.  In this state all Messages referred to by the children in
// 'child_messages' are owner by the 'owner'.
//
// When in the released state 'message', 'owner', 'parent', and
// 'parent_field_descriptor' are NULL.
typedef struct RepeatedCompositeContainer {
  PyObject_HEAD;

  // This is the top-level C++ Message object that owns the whole
  // proto tree.  Every Python RepeatedCompositeContainer 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;

  // Weak reference to parent object. May be NULL. Used to make sure
  // the parent is writable before modifying the
  // RepeatedCompositeContainer.
  CMessage* parent;

  // A descriptor used to modify the underlying 'message'.
  // The pointer is owned by the global DescriptorPool.
  const FieldDescriptor* parent_field_descriptor;

  // Pointer to the C++ Message that contains this container.  The
  // RepeatedCompositeContainer does not own this pointer.
  //
  // If NULL, this message has been released from its parent (by
  // calling Clear() or ClearField() on the parent.
  Message* message;

  // The type used to create new child messages.
  CMessageClass* child_message_class;

  // A list of child messages.
  PyObject* child_messages;
} RepeatedCompositeContainer;

extern PyTypeObject RepeatedCompositeContainer_Type;

namespace repeated_composite_container {

// Builds a RepeatedCompositeContainer object, from a parent message and a
// field descriptor.
PyObject *NewContainer(
    CMessage* parent,
    const FieldDescriptor* parent_field_descriptor,
    CMessageClass *child_message_class);

// Appends a new CMessage to the container and returns it.  The
// CMessage is initialized using the content of kwargs.
//
// Returns a new reference if successful; returns NULL and sets an
// exception if unsuccessful.
PyObject* Add(RepeatedCompositeContainer* self,
              PyObject* args,
              PyObject* kwargs);

// Appends all the CMessages in the input iterator to the container.
//
// Returns None if successful; returns NULL and sets an exception if
// unsuccessful.
PyObject* Extend(RepeatedCompositeContainer* self, PyObject* value);

// Appends a new message to the container for each message in the
// input iterator, merging each data element in. Equivalent to extend.
//
// Returns None if successful; returns NULL and sets an exception if
// unsuccessful.
PyObject* MergeFrom(RepeatedCompositeContainer* self, PyObject* other);

// Accesses messages in the container.
//
// Returns a new reference to the message for an integer parameter.
// Returns a new reference to a list of messages for a slice.
PyObject* Subscript(RepeatedCompositeContainer* self, PyObject* slice);

// Deletes items from the container (cannot be used for assignment).
//
// Returns 0 on success, -1 on failure.
int AssignSubscript(RepeatedCompositeContainer* self,
                    PyObject* slice,
                    PyObject* value);

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

// Returns 0 on success, -1 on failure.
int SetOwner(RepeatedCompositeContainer* self,
             const CMessage::OwnerRef& new_owner);

// Removes the last element of the repeated message field 'field' on
// the Message 'parent', and transfers the ownership of the released
// Message to 'target'.
//
// Corresponds to reflection api method ReleaseMessage.
void ReleaseLastTo(Message* message,
                   const FieldDescriptor* field,
                   CMessage* target);

}  // namespace repeated_composite_container
}  // namespace python
}  // namespace protobuf
}  // namespace google

#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_REPEATED_COMPOSITE_CONTAINER_H__