Update //third_party/protobuf to version 3.

third_party/protobuf/python/google/protobuf/pyext/descriptor_containers.cc

+// 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.
+
+// Mappings and Sequences of descriptors.
+// Used by Descriptor.fields_by_name, EnumDescriptor.values...
+//
+// They avoid the allocation of a full dictionary or a full list: they simply
+// store a pointer to the parent descriptor, use the C++ Descriptor methods (see
+// google/protobuf/descriptor.h) to retrieve other descriptors, and create
+// Python objects on the fly.
+//
+// The containers fully conform to abc.Mapping and abc.Sequence, and behave just
+// like read-only dictionaries and lists.
+//
+// Because the interface of C++ Descriptors is quite regular, this file actually
+// defines only three types, the exact behavior of a container is controlled by
+// a DescriptorContainerDef structure, which contains functions that uses the
+// public Descriptor API.
+//
+// Note: This DescriptorContainerDef is similar to the "virtual methods table"
+// that a C++ compiler generates for a class. We have to make it explicit
+// because the Python API is based on C, and does not play well with C++
+// inheritance.
+
+#include <Python.h>
+
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/pyext/descriptor_containers.h>
+#include <google/protobuf/pyext/descriptor_pool.h>
+#include <google/protobuf/pyext/descriptor.h>
+#include <google/protobuf/pyext/scoped_pyobject_ptr.h>
+
+#if PY_MAJOR_VERSION >= 3
+  #define PyString_FromStringAndSize PyUnicode_FromStringAndSize
+  #define PyString_FromFormat PyUnicode_FromFormat
+  #define PyInt_FromLong PyLong_FromLong
+  #if PY_VERSION_HEX < 0x03030000
+    #error "Python 3.0 - 3.2 are not supported."
+  #endif
+  #define PyString_AsStringAndSize(ob, charpp, sizep) \
+    (PyUnicode_Check(ob)? \
+       ((*(charpp) = PyUnicode_AsUTF8AndSize(ob, (sizep))) == NULL? -1: 0): \
+       PyBytes_AsStringAndSize(ob, (charpp), (sizep)))
+#endif
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+struct PyContainer;
+
+typedef int (*CountMethod)(PyContainer* self);
+typedef const void* (*GetByIndexMethod)(PyContainer* self, int index);
+typedef const void* (*GetByNameMethod)(PyContainer* self, const string& name);
+typedef const void* (*GetByCamelcaseNameMethod)(PyContainer* self,
+                                                const string& name);
+typedef const void* (*GetByNumberMethod)(PyContainer* self, int index);
+typedef PyObject* (*NewObjectFromItemMethod)(const void* descriptor);
+typedef const string& (*GetItemNameMethod)(const void* descriptor);
+typedef const string& (*GetItemCamelcaseNameMethod)(const void* descriptor);
+typedef int (*GetItemNumberMethod)(const void* descriptor);
+typedef int (*GetItemIndexMethod)(const void* descriptor);
+
+struct DescriptorContainerDef {
+  const char* mapping_name;
+  // Returns the number of items in the container.
+  CountMethod count_fn;
+  // Retrieve item by index (usually the order of declaration in the proto file)
+  // Used by sequences, but also iterators. 0 <= index < Count().
+  GetByIndexMethod get_by_index_fn;
+  // Retrieve item by name (usually a call to some 'FindByName' method).
+  // Used by "by_name" mappings.
+  GetByNameMethod get_by_name_fn;
+  // Retrieve item by camelcase name (usually a call to some
+  // 'FindByCamelcaseName' method). Used by "by_camelcase_name" mappings.
+  GetByCamelcaseNameMethod get_by_camelcase_name_fn;
+  // Retrieve item by declared number (field tag, or enum value).
+  // Used by "by_number" mappings.
+  GetByNumberMethod get_by_number_fn;
+  // Converts a item C++ descriptor to a Python object. Returns a new reference.
+  NewObjectFromItemMethod new_object_from_item_fn;
+  // Retrieve the name of an item. Used by iterators on "by_name" mappings.
+  GetItemNameMethod get_item_name_fn;
+  // Retrieve the camelcase name of an item. Used by iterators on
+  // "by_camelcase_name" mappings.
+  GetItemCamelcaseNameMethod get_item_camelcase_name_fn;
+  // Retrieve the number of an item. Used by iterators on "by_number" mappings.
+  GetItemNumberMethod get_item_number_fn;
+  // Retrieve the index of an item for the container type.
+  // Used by "__contains__".
+  // If not set, "x in sequence" will do a linear search.
+  GetItemIndexMethod get_item_index_fn;
+};
+
+struct PyContainer {
+  PyObject_HEAD
+
+  // The proto2 descriptor this container belongs to the global DescriptorPool.
+  const void* descriptor;
+
+  // A pointer to a static structure with function pointers that control the
+  // behavior of the container. Very similar to the table of virtual functions
+  // of a C++ class.
+  const DescriptorContainerDef* container_def;
+
+  // The kind of container: list, or dict by name or value.
+  enum ContainerKind {
+    KIND_SEQUENCE,
+    KIND_BYNAME,
+    KIND_BYCAMELCASENAME,
+    KIND_BYNUMBER,
+  } kind;
+};
+
+struct PyContainerIterator {
+  PyObject_HEAD
+
+  // The container we are iterating over. Own a reference.
+  PyContainer* container;
+
+  // The current index in the iterator.
+  int index;
+
+  // The kind of container: list, or dict by name or value.
+  enum IterKind {
+    KIND_ITERKEY,
+    KIND_ITERVALUE,
+    KIND_ITERITEM,
+    KIND_ITERVALUE_REVERSED,  // For sequences
+  } kind;
+};
+
+namespace descriptor {
+
+// Returns the C++ item descriptor for a given Python key.
+// When the descriptor is found, return true and set *item.
+// When the descriptor is not found, return true, but set *item to NULL.
+// On error, returns false with an exception set.
+static bool _GetItemByKey(PyContainer* self, PyObject* key, const void** item) {
+  switch (self->kind) {
+    case PyContainer::KIND_BYNAME:
+      {
+        char* name;
+        Py_ssize_t name_size;
+        if (PyString_AsStringAndSize(key, &name, &name_size) < 0) {
+          if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            // Not a string, cannot be in the container.
+            PyErr_Clear();
+            *item = NULL;
+            return true;
+          }
+          return false;
+        }
+        *item = self->container_def->get_by_name_fn(
+            self, string(name, name_size));
+        return true;
+      }
+    case PyContainer::KIND_BYCAMELCASENAME:
+      {
+        char* camelcase_name;
+        Py_ssize_t name_size;
+        if (PyString_AsStringAndSize(key, &camelcase_name, &name_size) < 0) {
+          if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            // Not a string, cannot be in the container.
+            PyErr_Clear();
+            *item = NULL;
+            return true;
+          }
+          return false;
+        }
+        *item = self->container_def->get_by_camelcase_name_fn(
+            self, string(camelcase_name, name_size));
+        return true;
+      }
+    case PyContainer::KIND_BYNUMBER:
+      {
+        Py_ssize_t number = PyNumber_AsSsize_t(key, NULL);
+        if (number == -1 && PyErr_Occurred()) {
+          if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            // Not a number, cannot be in the container.
+            PyErr_Clear();
+            *item = NULL;
+            return true;
+          }
+          return false;
+        }
+        *item = self->container_def->get_by_number_fn(self, number);
+        return true;
+      }
+    default:
+      PyErr_SetNone(PyExc_NotImplementedError);
+      return false;
+  }
+}
+
+// Returns the key of the object at the given index.
+// Used when iterating over mappings.
+static PyObject* _NewKey_ByIndex(PyContainer* self, Py_ssize_t index) {
+  const void* item = self->container_def->get_by_index_fn(self, index);
+  switch (self->kind) {
+    case PyContainer::KIND_BYNAME:
+      {
+        const string& name(self->container_def->get_item_name_fn(item));
+        return PyString_FromStringAndSize(name.c_str(), name.size());
+      }
+    case PyContainer::KIND_BYCAMELCASENAME:
+      {
+        const string& name(
+            self->container_def->get_item_camelcase_name_fn(item));
+        return PyString_FromStringAndSize(name.c_str(), name.size());
+      }
+    case PyContainer::KIND_BYNUMBER:
+      {
+        int value = self->container_def->get_item_number_fn(item);
+        return PyInt_FromLong(value);
+      }
+    default:
+      PyErr_SetNone(PyExc_NotImplementedError);
+      return NULL;
+  }
+}
+
+// Returns the object at the given index.
+// Also used when iterating over mappings.
+static PyObject* _NewObj_ByIndex(PyContainer* self, Py_ssize_t index) {
+  return self->container_def->new_object_from_item_fn(
+      self->container_def->get_by_index_fn(self, index));
+}
+
+static Py_ssize_t Length(PyContainer* self) {
+  return self->container_def->count_fn(self);
+}
+
+// The DescriptorMapping type.
+
+static PyObject* Subscript(PyContainer* self, PyObject* key) {
+  const void* item = NULL;
+  if (!_GetItemByKey(self, key, &item)) {
+    return NULL;
+  }
+  if (!item) {
+    PyErr_SetObject(PyExc_KeyError, key);
+    return NULL;
+  }
+  return self->container_def->new_object_from_item_fn(item);
+}
+
+static int AssSubscript(PyContainer* self, PyObject* key, PyObject* value) {
+  if (_CalledFromGeneratedFile(0)) {
+    return 0;
+  }
+  PyErr_Format(PyExc_TypeError,
+               "'%.200s' object does not support item assignment",
+               Py_TYPE(self)->tp_name);
+  return -1;
+}
+
+static PyMappingMethods MappingMappingMethods = {
+  (lenfunc)Length,               // mp_length
+  (binaryfunc)Subscript,         // mp_subscript
+  (objobjargproc)AssSubscript,   // mp_ass_subscript
+};
+
+static int Contains(PyContainer* self, PyObject* key) {
+  const void* item = NULL;
+  if (!_GetItemByKey(self, key, &item)) {
+    return -1;
+  }
+  if (item) {
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+static PyObject* ContainerRepr(PyContainer* self) {
+  const char* kind = "";
+  switch (self->kind) {
+    case PyContainer::KIND_SEQUENCE:
+      kind = "sequence";
+      break;
+    case PyContainer::KIND_BYNAME:
+      kind = "mapping by name";
+      break;
+    case PyContainer::KIND_BYCAMELCASENAME:
+      kind = "mapping by camelCase name";
+      break;
+    case PyContainer::KIND_BYNUMBER:
+      kind = "mapping by number";
+      break;
+  }
+  return PyString_FromFormat(
+      "<%s %s>", self->container_def->mapping_name, kind);
+}
+
+extern PyTypeObject DescriptorMapping_Type;
+extern PyTypeObject DescriptorSequence_Type;
+
+// A sequence container can only be equal to another sequence container, or (for
+// backward compatibility) to a list containing the same items.
+// Returns 1 if equal, 0 if unequal, -1 on error.
+static int DescriptorSequence_Equal(PyContainer* self, PyObject* other) {
+  // Check the identity of C++ pointers.
+  if (PyObject_TypeCheck(other, &DescriptorSequence_Type)) {
+    PyContainer* other_container = reinterpret_cast<PyContainer*>(other);
+    if (self->descriptor == other_container->descriptor &&
+        self->container_def == other_container->container_def &&
+        self->kind == other_container->kind) {
+      return 1;
+    } else {
+      return 0;
+    }
+  }
+
+  // If other is a list
+  if (PyList_Check(other)) {
+    // return list(self) == other
+    int size = Length(self);
+    if (size != PyList_Size(other)) {
+      return false;
+    }
+    for (int index = 0; index < size; index++) {
+      ScopedPyObjectPtr value1(_NewObj_ByIndex(self, index));
+      if (value1 == NULL) {
+        return -1;
+      }
+      PyObject* value2 = PyList_GetItem(other, index);
+      if (value2 == NULL) {
+        return -1;
+      }
+      int cmp = PyObject_RichCompareBool(value1.get(), value2, Py_EQ);
+      if (cmp != 1)  // error or not equal
+          return cmp;
+    }
+    // All items were found and equal
+    return 1;
+  }
+
+  // Any other object is different.
+  return 0;
+}
+
+// A mapping container can only be equal to another mapping container, or (for
+// backward compatibility) to a dict containing the same items.
+// Returns 1 if equal, 0 if unequal, -1 on error.
+static int DescriptorMapping_Equal(PyContainer* self, PyObject* other) {
+  // Check the identity of C++ pointers.
+  if (PyObject_TypeCheck(other, &DescriptorMapping_Type)) {
+    PyContainer* other_container = reinterpret_cast<PyContainer*>(other);
+    if (self->descriptor == other_container->descriptor &&
+        self->container_def == other_container->container_def &&
+        self->kind == other_container->kind) {
+      return 1;
+    } else {
+      return 0;
+    }
+  }
+
+  // If other is a dict
+  if (PyDict_Check(other)) {
+    // equivalent to dict(self.items()) == other
+    int size = Length(self);
+    if (size != PyDict_Size(other)) {
+      return false;
+    }
+    for (int index = 0; index < size; index++) {
+      ScopedPyObjectPtr key(_NewKey_ByIndex(self, index));
+      if (key == NULL) {
+        return -1;
+      }
+      ScopedPyObjectPtr value1(_NewObj_ByIndex(self, index));
+      if (value1 == NULL) {
+        return -1;
+      }
+      PyObject* value2 = PyDict_GetItem(other, key.get());
+      if (value2 == NULL) {
+        // Not found in the other dictionary
+        return 0;
+      }
+      int cmp = PyObject_RichCompareBool(value1.get(), value2, Py_EQ);
+      if (cmp != 1)  // error or not equal
+          return cmp;
+    }
+    // All items were found and equal
+    return 1;
+  }
+
+  // Any other object is different.
+  return 0;
+}
+
+static PyObject* RichCompare(PyContainer* self, PyObject* other, int opid) {
+  if (opid != Py_EQ && opid != Py_NE) {
+    Py_INCREF(Py_NotImplemented);
+    return Py_NotImplemented;
+  }
+
+  int result;
+
+  if (self->kind == PyContainer::KIND_SEQUENCE) {
+    result = DescriptorSequence_Equal(self, other);
+  } else {
+    result = DescriptorMapping_Equal(self, other);
+  }
+  if (result < 0) {
+    return NULL;
+  }
+  if (result ^ (opid == Py_NE)) {
+    Py_RETURN_TRUE;
+  } else {
+    Py_RETURN_FALSE;
+  }
+}
+
+static PySequenceMethods MappingSequenceMethods = {
+    0,                      // sq_length
+    0,                      // sq_concat
+    0,                      // sq_repeat
+    0,                      // sq_item
+    0,                      // sq_slice
+    0,                      // sq_ass_item
+    0,                      // sq_ass_slice
+    (objobjproc)Contains,   // sq_contains
+};
+
+static PyObject* Get(PyContainer* self, PyObject* args) {
+  PyObject* key;
+  PyObject* default_value = Py_None;
+  if (!PyArg_UnpackTuple(args, "get", 1, 2, &key, &default_value)) {
+    return NULL;
+  }
+
+  const void* item;
+  if (!_GetItemByKey(self, key, &item)) {
+    return NULL;
+  }
+  if (item == NULL) {
+    Py_INCREF(default_value);
+    return default_value;
+  }
+  return self->container_def->new_object_from_item_fn(item);
+}
+
+static PyObject* Keys(PyContainer* self, PyObject* args) {
+  Py_ssize_t count = Length(self);
+  ScopedPyObjectPtr list(PyList_New(count));
+  if (list == NULL) {
+    return NULL;
+  }
+  for (Py_ssize_t index = 0; index < count; ++index) {
+    PyObject* key = _NewKey_ByIndex(self, index);
+    if (key == NULL) {
+      return NULL;
+    }
+    PyList_SET_ITEM(list.get(), index, key);
+  }
+  return list.release();
+}
+
+static PyObject* Values(PyContainer* self, PyObject* args) {
+  Py_ssize_t count = Length(self);
+  ScopedPyObjectPtr list(PyList_New(count));
+  if (list == NULL) {
+    return NULL;
+  }
+  for (Py_ssize_t index = 0; index < count; ++index) {
+    PyObject* value = _NewObj_ByIndex(self, index);
+    if (value == NULL) {
+      return NULL;
+    }
+    PyList_SET_ITEM(list.get(), index, value);
+  }
+  return list.release();
+}
+
+static PyObject* Items(PyContainer* self, PyObject* args) {
+  Py_ssize_t count = Length(self);
+  ScopedPyObjectPtr list(PyList_New(count));
+  if (list == NULL) {
+    return NULL;
+  }
+  for (Py_ssize_t index = 0; index < count; ++index) {
+    ScopedPyObjectPtr obj(PyTuple_New(2));
+    if (obj == NULL) {
+      return NULL;
+    }
+    PyObject* key = _NewKey_ByIndex(self, index);
+    if (key == NULL) {
+      return NULL;
+    }
+    PyTuple_SET_ITEM(obj.get(), 0, key);
+    PyObject* value = _NewObj_ByIndex(self, index);
+    if (value == NULL) {
+      return NULL;
+    }
+    PyTuple_SET_ITEM(obj.get(), 1, value);
+    PyList_SET_ITEM(list.get(), index, obj.release());
+  }
+  return list.release();
+}
+
+static PyObject* NewContainerIterator(PyContainer* mapping,
+                                      PyContainerIterator::IterKind kind);
+
+static PyObject* Iter(PyContainer* self) {
+  return NewContainerIterator(self, PyContainerIterator::KIND_ITERKEY);
+}
+static PyObject* IterKeys(PyContainer* self, PyObject* args) {
+  return NewContainerIterator(self, PyContainerIterator::KIND_ITERKEY);
+}
+static PyObject* IterValues(PyContainer* self, PyObject* args) {
+  return NewContainerIterator(self, PyContainerIterator::KIND_ITERVALUE);
+}
+static PyObject* IterItems(PyContainer* self, PyObject* args) {
+  return NewContainerIterator(self, PyContainerIterator::KIND_ITERITEM);
+}
+
+static PyMethodDef MappingMethods[] = {
+  { "get", (PyCFunction)Get, METH_VARARGS, },
+  { "keys", (PyCFunction)Keys, METH_NOARGS, },
+  { "values", (PyCFunction)Values, METH_NOARGS, },
+  { "items", (PyCFunction)Items, METH_NOARGS, },
+  { "iterkeys", (PyCFunction)IterKeys, METH_NOARGS, },
+  { "itervalues", (PyCFunction)IterValues, METH_NOARGS, },
+  { "iteritems", (PyCFunction)IterItems, METH_NOARGS, },
+  {NULL}
+};
+
+PyTypeObject DescriptorMapping_Type = {
+  PyVarObject_HEAD_INIT(&PyType_Type, 0)
+  "DescriptorMapping",                  // tp_name
+  sizeof(PyContainer),                  // tp_basicsize
+  0,                                    // tp_itemsize
+  0,                                    // tp_dealloc
+  0,                                    // tp_print
+  0,                                    // tp_getattr
+  0,                                    // tp_setattr
+  0,                                    // tp_compare
+  (reprfunc)ContainerRepr,              // tp_repr
+  0,                                    // tp_as_number
+  &MappingSequenceMethods,              // tp_as_sequence
+  &MappingMappingMethods,               // tp_as_mapping
+  0,                                    // tp_hash
+  0,                                    // tp_call
+  0,                                    // tp_str
+  0,                                    // tp_getattro
+  0,                                    // tp_setattro
+  0,                                    // tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                   // tp_flags
+  0,                                    // tp_doc
+  0,                                    // tp_traverse
+  0,                                    // tp_clear
+  (richcmpfunc)RichCompare,             // tp_richcompare
+  0,                                    // tp_weaklistoffset
+  (getiterfunc)Iter,                    // tp_iter
+  0,                                    // tp_iternext
+  MappingMethods,                       // tp_methods
+  0,                                    // tp_members
+  0,                                    // tp_getset
+  0,                                    // tp_base
+  0,                                    // tp_dict
+  0,                                    // tp_descr_get
+  0,                                    // tp_descr_set
+  0,                                    // tp_dictoffset
+  0,                                    // tp_init
+  0,                                    // tp_alloc
+  0,                                    // tp_new
+  0,                                    // tp_free
+};
+
+// The DescriptorSequence type.
+
+static PyObject* GetItem(PyContainer* self, Py_ssize_t index) {
+  if (index < 0) {
+    index += Length(self);
+  }
+  if (index < 0 || index >= Length(self)) {
+    PyErr_SetString(PyExc_IndexError, "index out of range");
+    return NULL;
+  }
+  return _NewObj_ByIndex(self, index);
+}
+
+// Returns the position of the item in the sequence, of -1 if not found.
+// This function never fails.
+int Find(PyContainer* self, PyObject* item) {
+  // The item can only be in one position: item.index.
+  // Check that self[item.index] == item, it's faster than a linear search.
+  //
+  // This assumes that sequences are only defined by syntax of the .proto file:
+  // a specific item belongs to only one sequence, depending on its position in
+  // the .proto file definition.
+  const void* descriptor_ptr = PyDescriptor_AsVoidPtr(item);
+  if (descriptor_ptr == NULL) {
+    // Not a descriptor, it cannot be in the list.
+    return -1;
+  }
+  if (self->container_def->get_item_index_fn) {
+    int index = self->container_def->get_item_index_fn(descriptor_ptr);
+    if (index < 0 || index >= Length(self)) {
+      // This index is not from this collection.
+      return -1;
+    }
+    if (self->container_def->get_by_index_fn(self, index) != descriptor_ptr) {
+      // The descriptor at this index is not the same.
+      return -1;
+    }
+    // self[item.index] == item, so return the index.
+    return index;
+  } else {
+    // Fall back to linear search.
+    int length = Length(self);
+    for (int index=0; index < length; index++) {
+      if (self->container_def->get_by_index_fn(self, index) == descriptor_ptr) {
+        return index;
+      }
+    }
+    // Not found
+    return -1;
+  }
+}
+
+// Implements list.index(): the position of the item is in the sequence.
+static PyObject* Index(PyContainer* self, PyObject* item) {
+  int position = Find(self, item);
+  if (position < 0) {
+    // Not found
+    PyErr_SetNone(PyExc_ValueError);
+    return NULL;
+  } else {
+    return PyInt_FromLong(position);
+  }
+}
+// Implements "list.__contains__()": is the object in the sequence.
+static int SeqContains(PyContainer* self, PyObject* item) {
+  int position = Find(self, item);
+  if (position < 0) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+// Implements list.count(): number of occurrences of the item in the sequence.
+// An item can only appear once in a sequence. If it exists, return 1.
+static PyObject* Count(PyContainer* self, PyObject* item) {
+  int position = Find(self, item);
+  if (position < 0) {
+    return PyInt_FromLong(0);
+  } else {
+    return PyInt_FromLong(1);
+  }
+}
+
+static PyObject* Append(PyContainer* self, PyObject* args) {
+  if (_CalledFromGeneratedFile(0)) {
+    Py_RETURN_NONE;
+  }
+  PyErr_Format(PyExc_TypeError,
+               "'%.200s' object is not a mutable sequence",
+               Py_TYPE(self)->tp_name);
+  return NULL;
+}
+
+static PyObject* Reversed(PyContainer* self, PyObject* args) {
+  return NewContainerIterator(self,
+                              PyContainerIterator::KIND_ITERVALUE_REVERSED);
+}
+
+static PyMethodDef SeqMethods[] = {
+  { "index", (PyCFunction)Index, METH_O, },
+  { "count", (PyCFunction)Count, METH_O, },
+  { "append", (PyCFunction)Append, METH_O, },
+  { "__reversed__", (PyCFunction)Reversed, METH_NOARGS, },
+  {NULL}
+};
+
+static PySequenceMethods SeqSequenceMethods = {
+    (lenfunc)Length,          // sq_length
+    0,                        // sq_concat
+    0,                        // sq_repeat
+    (ssizeargfunc)GetItem,    // sq_item
+    0,                        // sq_slice
+    0,                        // sq_ass_item
+    0,                        // sq_ass_slice
+    (objobjproc)SeqContains,  // sq_contains
+};
+
+PyTypeObject DescriptorSequence_Type = {
+  PyVarObject_HEAD_INIT(&PyType_Type, 0)
+  "DescriptorSequence",                 // tp_name
+  sizeof(PyContainer),                  // tp_basicsize
+  0,                                    // tp_itemsize
+  0,                                    // tp_dealloc
+  0,                                    // tp_print
+  0,                                    // tp_getattr
+  0,                                    // tp_setattr
+  0,                                    // tp_compare
+  (reprfunc)ContainerRepr,              // tp_repr
+  0,                                    // tp_as_number
+  &SeqSequenceMethods,                  // tp_as_sequence
+  0,                                    // tp_as_mapping
+  0,                                    // tp_hash
+  0,                                    // tp_call
+  0,                                    // tp_str
+  0,                                    // tp_getattro
+  0,                                    // tp_setattro
+  0,                                    // tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                   // tp_flags
+  0,                                    // tp_doc
+  0,                                    // tp_traverse
+  0,                                    // tp_clear
+  (richcmpfunc)RichCompare,             // tp_richcompare
+  0,                                    // tp_weaklistoffset
+  0,                                    // tp_iter
+  0,                                    // tp_iternext
+  SeqMethods,                           // tp_methods
+  0,                                    // tp_members
+  0,                                    // tp_getset
+  0,                                    // tp_base
+  0,                                    // tp_dict
+  0,                                    // tp_descr_get
+  0,                                    // tp_descr_set
+  0,                                    // tp_dictoffset
+  0,                                    // tp_init
+  0,                                    // tp_alloc
+  0,                                    // tp_new
+  0,                                    // tp_free
+};
+
+static PyObject* NewMappingByName(
+    DescriptorContainerDef* container_def, const void* descriptor) {
+  PyContainer* self = PyObject_New(PyContainer, &DescriptorMapping_Type);
+  if (self == NULL) {
+    return NULL;
+  }
+  self->descriptor = descriptor;
+  self->container_def = container_def;
+  self->kind = PyContainer::KIND_BYNAME;
+  return reinterpret_cast<PyObject*>(self);
+}
+
+static PyObject* NewMappingByCamelcaseName(
+    DescriptorContainerDef* container_def, const void* descriptor) {
+  PyContainer* self = PyObject_New(PyContainer, &DescriptorMapping_Type);
+  if (self == NULL) {
+    return NULL;
+  }
+  self->descriptor = descriptor;
+  self->container_def = container_def;
+  self->kind = PyContainer::KIND_BYCAMELCASENAME;
+  return reinterpret_cast<PyObject*>(self);
+}
+
+static PyObject* NewMappingByNumber(
+    DescriptorContainerDef* container_def, const void* descriptor) {
+  if (container_def->get_by_number_fn == NULL ||
+      container_def->get_item_number_fn == NULL) {
+    PyErr_SetNone(PyExc_NotImplementedError);
+    return NULL;
+  }
+  PyContainer* self = PyObject_New(PyContainer, &DescriptorMapping_Type);
+  if (self == NULL) {
+    return NULL;
+  }
+  self->descriptor = descriptor;
+  self->container_def = container_def;
+  self->kind = PyContainer::KIND_BYNUMBER;
+  return reinterpret_cast<PyObject*>(self);
+}
+
+static PyObject* NewSequence(
+    DescriptorContainerDef* container_def, const void* descriptor) {
+  PyContainer* self = PyObject_New(PyContainer, &DescriptorSequence_Type);
+  if (self == NULL) {
+    return NULL;
+  }
+  self->descriptor = descriptor;
+  self->container_def = container_def;
+  self->kind = PyContainer::KIND_SEQUENCE;
+  return reinterpret_cast<PyObject*>(self);
+}
+
+// Implement iterators over PyContainers.
+
+static void Iterator_Dealloc(PyContainerIterator* self) {
+  Py_CLEAR(self->container);
+  Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
+}
+
+static PyObject* Iterator_Next(PyContainerIterator* self) {
+  int count = self->container->container_def->count_fn(self->container);
+  if (self->index >= count) {
+    // Return NULL with no exception to indicate the end.
+    return NULL;
+  }
+  int index = self->index;
+  self->index += 1;
+  switch (self->kind) {
+    case PyContainerIterator::KIND_ITERKEY:
+      return _NewKey_ByIndex(self->container, index);
+    case PyContainerIterator::KIND_ITERVALUE:
+      return _NewObj_ByIndex(self->container, index);
+    case PyContainerIterator::KIND_ITERVALUE_REVERSED:
+      return _NewObj_ByIndex(self->container, count - index - 1);
+    case PyContainerIterator::KIND_ITERITEM:
+      {
+        PyObject* obj = PyTuple_New(2);
+        if (obj == NULL) {
+          return NULL;
+        }
+        PyObject* key = _NewKey_ByIndex(self->container, index);
+        if (key == NULL) {
+          Py_DECREF(obj);
+          return NULL;
+        }
+        PyTuple_SET_ITEM(obj, 0, key);
+        PyObject* value = _NewObj_ByIndex(self->container, index);
+        if (value == NULL) {
+          Py_DECREF(obj);
+          return NULL;
+        }
+        PyTuple_SET_ITEM(obj, 1, value);
+        return obj;
+      }
+    default:
+      PyErr_SetNone(PyExc_NotImplementedError);
+      return NULL;
+  }
+}
+
+static PyTypeObject ContainerIterator_Type = {
+  PyVarObject_HEAD_INIT(&PyType_Type, 0)
+  "DescriptorContainerIterator",        // tp_name
+  sizeof(PyContainerIterator),          // tp_basicsize
+  0,                                    // tp_itemsize
+  (destructor)Iterator_Dealloc,         // tp_dealloc
+  0,                                    // tp_print
+  0,                                    // tp_getattr
+  0,                                    // tp_setattr
+  0,                                    // tp_compare
+  0,                                    // tp_repr
+  0,                                    // tp_as_number
+  0,                                    // tp_as_sequence
+  0,                                    // tp_as_mapping
+  0,                                    // tp_hash
+  0,                                    // tp_call
+  0,                                    // tp_str
+  0,                                    // tp_getattro
+  0,                                    // tp_setattro
+  0,                                    // tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                   // tp_flags
+  0,                                    // tp_doc
+  0,                                    // tp_traverse
+  0,                                    // tp_clear
+  0,                                    // tp_richcompare
+  0,                                    // tp_weaklistoffset
+  PyObject_SelfIter,                    // tp_iter
+  (iternextfunc)Iterator_Next,          // tp_iternext
+  0,                                    // tp_methods
+  0,                                    // tp_members
+  0,                                    // tp_getset
+  0,                                    // tp_base
+  0,                                    // tp_dict
+  0,                                    // tp_descr_get
+  0,                                    // tp_descr_set
+  0,                                    // tp_dictoffset
+  0,                                    // tp_init
+  0,                                    // tp_alloc
+  0,                                    // tp_new
+  0,                                    // tp_free
+};
+
+static PyObject* NewContainerIterator(PyContainer* container,
+                                      PyContainerIterator::IterKind kind) {
+  PyContainerIterator* self = PyObject_New(PyContainerIterator,
+                                           &ContainerIterator_Type);
+  if (self == NULL) {
+    return NULL;
+  }
+  Py_INCREF(container);
+  self->container = container;
+  self->kind = kind;
+  self->index = 0;
+
+  return reinterpret_cast<PyObject*>(self);
+}
+
+}  // namespace descriptor
+
+// Now define the real collections!
+
+namespace message_descriptor {
+
+typedef const Descriptor* ParentDescriptor;
+
+static ParentDescriptor GetDescriptor(PyContainer* self) {
+  return reinterpret_cast<ParentDescriptor>(self->descriptor);
+}
+
+namespace fields {
+
+typedef const FieldDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->field_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindFieldByName(name);
+}
+
+static ItemDescriptor GetByCamelcaseName(PyContainer* self,
+                                         const string& name) {
+  return GetDescriptor(self)->FindFieldByCamelcaseName(name);
+}
+
+static ItemDescriptor GetByNumber(PyContainer* self, int number) {
+  return GetDescriptor(self)->FindFieldByNumber(number);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->field(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyFieldDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static const string& GetItemCamelcaseName(ItemDescriptor item) {
+  return item->camelcase_name();
+}
+
+static int GetItemNumber(ItemDescriptor item) {
+  return item->number();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "MessageFields",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)GetByCamelcaseName,
+  (GetByNumberMethod)GetByNumber,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)GetItemCamelcaseName,
+  (GetItemNumberMethod)GetItemNumber,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace fields
+
+PyObject* NewMessageFieldsByName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByName(&fields::ContainerDef, descriptor);
+}
+
+PyObject* NewMessageFieldsByCamelcaseName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByCamelcaseName(&fields::ContainerDef,
+                                               descriptor);
+}
+
+PyObject* NewMessageFieldsByNumber(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByNumber(&fields::ContainerDef, descriptor);
+}
+
+PyObject* NewMessageFieldsSeq(ParentDescriptor descriptor) {
+  return descriptor::NewSequence(&fields::ContainerDef, descriptor);
+}
+
+namespace nested_types {
+
+typedef const Descriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->nested_type_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindNestedTypeByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->nested_type(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyMessageDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "MessageNestedTypes",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace nested_types
+
+PyObject* NewMessageNestedTypesSeq(ParentDescriptor descriptor) {
+  return descriptor::NewSequence(&nested_types::ContainerDef, descriptor);
+}
+
+PyObject* NewMessageNestedTypesByName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByName(&nested_types::ContainerDef, descriptor);
+}
+
+namespace enums {
+
+typedef const EnumDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->enum_type_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindEnumTypeByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->enum_type(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyEnumDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "MessageNestedEnums",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace enums
+
+PyObject* NewMessageEnumsByName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByName(&enums::ContainerDef, descriptor);
+}
+
+PyObject* NewMessageEnumsSeq(ParentDescriptor descriptor) {
+  return descriptor::NewSequence(&enums::ContainerDef, descriptor);
+}
+
+namespace enumvalues {
+
+// This is the "enum_values_by_name" mapping, which collects values from all
+// enum types in a message.
+//
+// Note that the behavior of the C++ descriptor is different: it will search and
+// return the first value that matches the name, whereas the Python
+// implementation retrieves the last one.
+
+typedef const EnumValueDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  int count = 0;
+  for (int i = 0; i < GetDescriptor(self)->enum_type_count(); ++i) {
+    count += GetDescriptor(self)->enum_type(i)->value_count();
+  }
+  return count;
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindEnumValueByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  // This is not optimal, but the number of enums *types* in a given message
+  // is small.  This function is only used when iterating over the mapping.
+  const EnumDescriptor* enum_type = NULL;
+  int enum_type_count = GetDescriptor(self)->enum_type_count();
+  for (int i = 0; i < enum_type_count; ++i) {
+    enum_type = GetDescriptor(self)->enum_type(i);
+    int enum_value_count = enum_type->value_count();
+    if (index < enum_value_count) {
+      // Found it!
+      break;
+    }
+    index -= enum_value_count;
+  }
+  // The next statement cannot overflow, because this function is only called by
+  // internal iterators which ensure that 0 <= index < Count().
+  return enum_type->value(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyEnumValueDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "MessageEnumValues",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)NULL,
+};
+
+}  // namespace enumvalues
+
+PyObject* NewMessageEnumValuesByName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByName(&enumvalues::ContainerDef, descriptor);
+}
+
+namespace extensions {
+
+typedef const FieldDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->extension_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindExtensionByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->extension(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyFieldDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "MessageExtensions",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace extensions
+
+PyObject* NewMessageExtensionsByName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByName(&extensions::ContainerDef, descriptor);
+}
+
+PyObject* NewMessageExtensionsSeq(ParentDescriptor descriptor) {
+  return descriptor::NewSequence(&extensions::ContainerDef, descriptor);
+}
+
+namespace oneofs {
+
+typedef const OneofDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->oneof_decl_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindOneofByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->oneof_decl(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyOneofDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "MessageOneofs",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace oneofs
+
+PyObject* NewMessageOneofsByName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByName(&oneofs::ContainerDef, descriptor);
+}
+
+PyObject* NewMessageOneofsSeq(ParentDescriptor descriptor) {
+  return descriptor::NewSequence(&oneofs::ContainerDef, descriptor);
+}
+
+}  // namespace message_descriptor
+
+namespace enum_descriptor {
+
+typedef const EnumDescriptor* ParentDescriptor;
+
+static ParentDescriptor GetDescriptor(PyContainer* self) {
+  return reinterpret_cast<ParentDescriptor>(self->descriptor);
+}
+
+namespace enumvalues {
+
+typedef const EnumValueDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->value_count();
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->value(index);
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindValueByName(name);
+}
+
+static ItemDescriptor GetByNumber(PyContainer* self, int number) {
+  return GetDescriptor(self)->FindValueByNumber(number);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyEnumValueDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemNumber(ItemDescriptor item) {
+  return item->number();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "EnumValues",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)GetByNumber,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)GetItemNumber,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace enumvalues
+
+PyObject* NewEnumValuesByName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByName(&enumvalues::ContainerDef, descriptor);
+}
+
+PyObject* NewEnumValuesByNumber(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByNumber(&enumvalues::ContainerDef, descriptor);
+}
+
+PyObject* NewEnumValuesSeq(ParentDescriptor descriptor) {
+  return descriptor::NewSequence(&enumvalues::ContainerDef, descriptor);
+}
+
+}  // namespace enum_descriptor
+
+namespace oneof_descriptor {
+
+typedef const OneofDescriptor* ParentDescriptor;
+
+static ParentDescriptor GetDescriptor(PyContainer* self) {
+  return reinterpret_cast<ParentDescriptor>(self->descriptor);
+}
+
+namespace fields {
+
+typedef const FieldDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->field_count();
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->field(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyFieldDescriptor_FromDescriptor(item);
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index_in_oneof();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "OneofFields",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)NULL,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)NULL,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace fields
+
+PyObject* NewOneofFieldsSeq(ParentDescriptor descriptor) {
+  return descriptor::NewSequence(&fields::ContainerDef, descriptor);
+}
+
+}  // namespace oneof_descriptor
+
+namespace file_descriptor {
+
+typedef const FileDescriptor* ParentDescriptor;
+
+static ParentDescriptor GetDescriptor(PyContainer* self) {
+  return reinterpret_cast<ParentDescriptor>(self->descriptor);
+}
+
+namespace messages {
+
+typedef const Descriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->message_type_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindMessageTypeByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->message_type(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyMessageDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "FileMessages",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace messages
+
+PyObject* NewFileMessageTypesByName(const FileDescriptor* descriptor) {
+  return descriptor::NewMappingByName(&messages::ContainerDef, descriptor);
+}
+
+namespace enums {
+
+typedef const EnumDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->enum_type_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindEnumTypeByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->enum_type(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyEnumDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "FileEnums",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace enums
+
+PyObject* NewFileEnumTypesByName(const FileDescriptor* descriptor) {
+  return descriptor::NewMappingByName(&enums::ContainerDef, descriptor);
+}
+
+namespace extensions {
+
+typedef const FieldDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->extension_count();
+}
+
+static ItemDescriptor GetByName(PyContainer* self, const string& name) {
+  return GetDescriptor(self)->FindExtensionByName(name);
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->extension(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyFieldDescriptor_FromDescriptor(item);
+}
+
+static const string& GetItemName(ItemDescriptor item) {
+  return item->name();
+}
+
+static int GetItemIndex(ItemDescriptor item) {
+  return item->index();
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "FileExtensions",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)GetItemIndex,
+};
+
+}  // namespace extensions
+
+PyObject* NewFileExtensionsByName(const FileDescriptor* descriptor) {
+  return descriptor::NewMappingByName(&extensions::ContainerDef, descriptor);
+}
+
+namespace dependencies {
+
+typedef const FileDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->dependency_count();
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->dependency(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyFileDescriptor_FromDescriptor(item);
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "FileDependencies",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)NULL,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)NULL,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)NULL,
+};
+
+}  // namespace dependencies
+
+PyObject* NewFileDependencies(const FileDescriptor* descriptor) {
+  return descriptor::NewSequence(&dependencies::ContainerDef, descriptor);
+}
+
+namespace public_dependencies {
+
+typedef const FileDescriptor* ItemDescriptor;
+
+static int Count(PyContainer* self) {
+  return GetDescriptor(self)->public_dependency_count();
+}
+
+static ItemDescriptor GetByIndex(PyContainer* self, int index) {
+  return GetDescriptor(self)->public_dependency(index);
+}
+
+static PyObject* NewObjectFromItem(ItemDescriptor item) {
+  return PyFileDescriptor_FromDescriptor(item);
+}
+
+static DescriptorContainerDef ContainerDef = {
+  "FilePublicDependencies",
+  (CountMethod)Count,
+  (GetByIndexMethod)GetByIndex,
+  (GetByNameMethod)NULL,
+  (GetByCamelcaseNameMethod)NULL,
+  (GetByNumberMethod)NULL,
+  (NewObjectFromItemMethod)NewObjectFromItem,
+  (GetItemNameMethod)NULL,
+  (GetItemCamelcaseNameMethod)NULL,
+  (GetItemNumberMethod)NULL,
+  (GetItemIndexMethod)NULL,
+};
+
+}  // namespace public_dependencies
+
+PyObject* NewFilePublicDependencies(const FileDescriptor* descriptor) {
+  return descriptor::NewSequence(&public_dependencies::ContainerDef,
+                                 descriptor);
+}
+
+}  // namespace file_descriptor
+
+
+// Register all implementations
+
+bool InitDescriptorMappingTypes() {
+  if (PyType_Ready(&descriptor::DescriptorMapping_Type) < 0)
+    return false;
+  if (PyType_Ready(&descriptor::DescriptorSequence_Type) < 0)
+    return false;
+  if (PyType_Ready(&descriptor::ContainerIterator_Type) < 0)
+    return false;
+  return true;
+}
+
+}  // namespace python
+}  // namespace protobuf
+}  // namespace google