py_wrappers.cxx

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/**
 * @file py_wrappers.cxx
 * @author rdb
 * @date 2017-11-26
 */

#include "py_wrappers.h"

#ifdef HAVE_PYTHON

#if PY_VERSION_HEX >= 0x03040000
#define _COLLECTIONS_ABC "_collections_abc"
#elif PY_VERSION_HEX >= 0x03030000
#define _COLLECTIONS_ABC "collections.abc"
#else
#define _COLLECTIONS_ABC "_abcoll"
#endif

static void _register_collection(PyTypeObject *type, const char *abc) {
  PyObject *sys_modules = PyImport_GetModuleDict();
  if (sys_modules != nullptr) {
    PyObject *module = PyDict_GetItemString(sys_modules, _COLLECTIONS_ABC);
    if (module != nullptr) {
      PyObject *dict = PyModule_GetDict(module);
      if (module != nullptr) {
#if PY_MAJOR_VERSION >= 3
        static PyObject *register_str = PyUnicode_InternFromString("register");
#else
        static PyObject *register_str = PyString_InternFromString("register");
#endif
        PyObject *sequence = PyDict_GetItemString(dict, abc);
        if (sequence != nullptr) {
          if (PyObject_CallMethodObjArgs(sequence, register_str, (PyObject *)type, nullptr) == nullptr) {
            PyErr_Print();
          }
        }
      }
    }
  }
}

/**
 * These classes are returned from properties that require a subscript
 * interface, ie. something.children[i] = 3.
 */
static void Dtool_WrapperBase_dealloc(PyObject *self) {
  Dtool_WrapperBase *wrap = (Dtool_WrapperBase *)self;
  nassertv(wrap);
  Py_XDECREF(wrap->_self);
}

static PyObject *Dtool_WrapperBase_repr(PyObject *self) {
  Dtool_WrapperBase *wrap = (Dtool_WrapperBase *)self;
  nassertr(wrap, nullptr);

  PyObject *repr = PyObject_Repr(wrap->_self);
  PyObject *result;
#if PY_MAJOR_VERSION >= 3
  result = PyUnicode_FromFormat("<%s[] of %s>", wrap->_name, PyUnicode_AsUTF8(repr));
#else
  result = PyString_FromFormat("<%s[] of %s>", wrap->_name, PyString_AS_STRING(repr));
#endif
  Py_DECREF(repr);
  return result;
}

static PyObject *Dtool_SequenceWrapper_repr(PyObject *self) {
  Dtool_SequenceWrapper *wrap = (Dtool_SequenceWrapper *)self;
  nassertr(wrap, nullptr);

  Py_ssize_t len = -1;
  if (wrap->_len_func != nullptr) {
    len = wrap->_len_func(wrap->_base._self);
  }

  if (len < 0) {
    PyErr_Restore(nullptr, nullptr, nullptr);
    return Dtool_WrapperBase_repr(self);
  }

  PyObject *repr = PyObject_Repr(wrap->_base._self);
  PyObject *result;
#if PY_MAJOR_VERSION >= 3
  result = PyUnicode_FromFormat("<%s[%zd] of %s>", wrap->_base._name, len, PyUnicode_AsUTF8(repr));
#else
  result = PyString_FromFormat("<%s[%zd] of %s>", wrap->_base._name, len, PyString_AS_STRING(repr));
#endif
  Py_DECREF(repr);
  return result;
}

static Py_ssize_t Dtool_SequenceWrapper_length(PyObject *self) {
  Dtool_SequenceWrapper *wrap = (Dtool_SequenceWrapper *)self;
  nassertr(wrap, -1);
  if (wrap->_len_func != nullptr) {
    return wrap->_len_func(wrap->_base._self);
  } else {
    Dtool_Raise_TypeError("property does not support len()");
    return -1;
  }
}

static PyObject *Dtool_SequenceWrapper_getitem(PyObject *self, Py_ssize_t index) {
  Dtool_SequenceWrapper *wrap = (Dtool_SequenceWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_getitem_func, nullptr);
  return wrap->_getitem_func(wrap->_base._self, index);
}

/**
 * Implementation of (x in property)
 */
static int Dtool_SequenceWrapper_contains(PyObject *self, PyObject *value) {
  Dtool_SequenceWrapper *wrap = (Dtool_SequenceWrapper *)self;
  nassertr(wrap, -1);
  nassertr(wrap->_len_func, -1);
  nassertr(wrap->_getitem_func, -1);

  Py_ssize_t length = wrap->_len_func(wrap->_base._self);

  // Iterate through the items, invoking the equality function for each, until
  // we have found the matching one.
  for (Py_ssize_t index = 0; index < length; ++index) {
    PyObject *item = wrap->_getitem_func(wrap->_base._self, index);
    if (item != nullptr) {
      int cmp = PyObject_RichCompareBool(item, value, Py_EQ);
      if (cmp > 0) {
        return 1;
      }
      if (cmp < 0) {
        return -1;
      }
    } else {
      return -1;
    }
  }
  return 0;
}

/**
 * Implementation of property.index(x) which returns the index of the first
 * occurrence of x in the sequence, or raises a ValueError if it isn't found.
 */
static PyObject *Dtool_SequenceWrapper_index(PyObject *self, PyObject *value) {
  Dtool_SequenceWrapper *wrap = (Dtool_SequenceWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_len_func, nullptr);
  nassertr(wrap->_getitem_func, nullptr);

  Py_ssize_t length = wrap->_len_func(wrap->_base._self);

  // Iterate through the items, invoking the equality function for each, until
  // we have found the right one.
  for (Py_ssize_t index = 0; index < length; ++index) {
    PyObject *item = wrap->_getitem_func(wrap->_base._self, index);
    if (item != nullptr) {
      int cmp = PyObject_RichCompareBool(item, value, Py_EQ);
      if (cmp > 0) {
        return Dtool_WrapValue(index);
      }
      if (cmp < 0) {
        return nullptr;
      }
    } else {
      return nullptr;
    }
  }
  // Not found, raise ValueError.
  return PyErr_Format(PyExc_ValueError, "%s.index() did not find value", wrap->_base._name);
}

/**
 * Implementation of property.count(x) which returns the number of occurrences
 * of x in the sequence.
 */
static PyObject *Dtool_SequenceWrapper_count(PyObject *self, PyObject *value) {
  Dtool_SequenceWrapper *wrap = (Dtool_SequenceWrapper *)self;
  nassertr(wrap, nullptr);
  Py_ssize_t index = 0;
  if (wrap->_len_func != nullptr) {
    index = wrap->_len_func(wrap->_base._self);
  } else {
    return Dtool_Raise_TypeError("property does not support count()");
  }
  // Iterate through the items, invoking the == operator for each.
  long count = 0;
  nassertr(wrap->_getitem_func, nullptr);
  while (index > 0) {
    --index;
    PyObject *item = wrap->_getitem_func(wrap->_base._self, index);
    if (item == nullptr) {
      return nullptr;
    }
    int cmp = PyObject_RichCompareBool(item, value, Py_EQ);
    if (cmp > 0) {
      ++count;
    }
    if (cmp < 0) {
      return nullptr;
    }
  }
#if PY_MAJOR_VERSION >= 3
  return PyLong_FromLong(count);
#else
  return PyInt_FromLong(count);
#endif
}

/**
 * Implementation of `property[i] = x`
 */
static int Dtool_MutableSequenceWrapper_setitem(PyObject *self, Py_ssize_t index, PyObject *value) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)self;
  nassertr(wrap, -1);
  if (wrap->_setitem_func != nullptr) {
    return wrap->_setitem_func(wrap->_base._self, index, value);
  } else {
    Dtool_Raise_TypeError("property does not support item assignment");
    return -1;
  }
}

/**
 * Implementation of property.clear() which removes all elements in the
 * sequence, starting with the last.
 */
static PyObject *Dtool_MutableSequenceWrapper_clear(PyObject *self, PyObject *) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)self;
  nassertr(wrap, nullptr);
  Py_ssize_t index = 0;
  if (wrap->_len_func != nullptr && wrap->_setitem_func != nullptr) {
    index = wrap->_len_func(wrap->_base._self);
  } else {
    return Dtool_Raise_TypeError("property does not support clear()");
  }

  // Iterate through the items, invoking the delete function for each.  We do
  // this in reverse order, which may be more efficient.
  while (index > 0) {
    --index;
    if (wrap->_setitem_func(wrap->_base._self, index, nullptr) != 0) {
      return nullptr;
    }
  }
  Py_INCREF(Py_None);
  return Py_None;
}

/**
 * Implementation of property.remove(x) which removes the first occurrence of
 * x in the sequence, or raises a ValueError if it isn't found.
 */
static PyObject *Dtool_MutableSequenceWrapper_remove(PyObject *self, PyObject *value) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)self;
  nassertr(wrap, nullptr);
  Py_ssize_t length = 0;
  if (wrap->_len_func != nullptr && wrap->_setitem_func != nullptr) {
    length = wrap->_len_func(wrap->_base._self);
  } else {
    return Dtool_Raise_TypeError("property does not support remove()");
  }

  // Iterate through the items, invoking the equality function for each, until
  // we have found the right one.
  nassertr(wrap->_getitem_func, nullptr);
  for (Py_ssize_t index = 0; index < length; ++index) {
    PyObject *item = wrap->_getitem_func(wrap->_base._self, index);
    if (item != nullptr) {
      int cmp = PyObject_RichCompareBool(item, value, Py_EQ);
      if (cmp > 0) {
        if (wrap->_setitem_func(wrap->_base._self, index, nullptr) == 0) {
          Py_INCREF(Py_None);
          return Py_None;
        } else {
          return nullptr;
        }
      }
      if (cmp < 0) {
        return nullptr;
      }
    } else {
      return nullptr;
    }
  }
  // Not found, raise ValueError.
  return PyErr_Format(PyExc_ValueError, "%s.remove() did not find value", wrap->_base._name);
}

/**
 * Implementation of property.pop([i=-1]) which returns and removes the
 * element at the indicated index in the sequence.  If no index is provided,
 * it removes from the end of the list.
 */
static PyObject *Dtool_MutableSequenceWrapper_pop(PyObject *self, PyObject *args) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)self;
  nassertr(wrap, nullptr);
  if (wrap->_getitem_func == nullptr || wrap->_setitem_func == nullptr ||
      wrap->_len_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support pop()");
  }

  Py_ssize_t length = wrap->_len_func(wrap->_base._self);
  Py_ssize_t index;
  switch (PyTuple_GET_SIZE(args)) {
  case 0:
    index = length - 1;
    break;
  case 1:
    index = PyNumber_AsSsize_t(PyTuple_GET_ITEM(args, 0), PyExc_IndexError);
    if (index == -1 && _PyErr_OCCURRED()) {
      return nullptr;
    }
    if (index < 0) {
      index += length;
    }
    break;
  default:
    return Dtool_Raise_TypeError("pop([i=-1]) takes 0 or 1 arguments");
  }

  if (length <= 0) {
    return PyErr_Format(PyExc_IndexError, "%s.pop() from empty sequence", wrap->_base._name);
  }

  // Index error will be caught by getitem_func.
  PyObject *value = wrap->_getitem_func(wrap->_base._self, index);
  if (value != nullptr) {
    if (wrap->_setitem_func(wrap->_base._self, index, nullptr) != 0) {
      return nullptr;
    }
    return value;
  }
  return nullptr;
}

/**
 * Implementation of property.append(x) which is an alias for
 * property.insert(len(property), x).
 */
static PyObject *Dtool_MutableSequenceWrapper_append(PyObject *self, PyObject *arg) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)self;
  nassertr(wrap, nullptr);
  if (wrap->_insert_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support append()");
  }
  return wrap->_insert_func(wrap->_base._self, (size_t)-1, arg);
}

/**
 * Implementation of property.insert(i, x) which inserts the given item at the
 * given position.
 */
static PyObject *Dtool_MutableSequenceWrapper_insert(PyObject *self, PyObject *args) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)self;
  nassertr(wrap, nullptr);
  if (wrap->_insert_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support insert()");
  }
  if (PyTuple_GET_SIZE(args) != 2) {
    return Dtool_Raise_TypeError("insert() takes exactly 2 arguments");
  }
  Py_ssize_t index = PyNumber_AsSsize_t(PyTuple_GET_ITEM(args, 0), PyExc_IndexError);
  if (index == -1 && _PyErr_OCCURRED()) {
    return nullptr;
  }
  if (index < 0) {
    if (wrap->_len_func != nullptr) {
      index += wrap->_len_func(wrap->_base._self);
    } else {
      return PyErr_Format(PyExc_TypeError, "%s.insert() does not support negative indices", wrap->_base._name);
    }
  }
  return wrap->_insert_func(wrap->_base._self, (ssize_t)std::max(index, (Py_ssize_t)0), PyTuple_GET_ITEM(args, 1));
}

/**
 * Implementation of property.extend(seq) which is equivalent to:
 * @code
 * for x in seq:
 *   property.append(seq)
 * @endcode
 */
static PyObject *Dtool_MutableSequenceWrapper_extend(PyObject *self, PyObject *arg) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)self;
  nassertr(wrap, nullptr);
  if (wrap->_insert_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support extend()");
  }
  PyObject *iter = PyObject_GetIter(arg);
  if (iter == nullptr) {
    return nullptr;
  }
  PyObject *next = PyIter_Next(iter);
  PyObject *retval = nullptr;
  while (next != nullptr) {
    retval = wrap->_insert_func(wrap->_base._self, (size_t)-1, next);
    Py_DECREF(next);
    if (retval == nullptr) {
      Py_DECREF(iter);
      return nullptr;
    }
    Py_DECREF(retval);
    next = PyIter_Next(iter);
  }

  Py_DECREF(iter);
  Py_INCREF(Py_None);
  return Py_None;
}

/**
 * Implementation of `x in mapping`.
 */
static int Dtool_MappingWrapper_contains(PyObject *self, PyObject *key) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, -1);
  nassertr(wrap->_getitem_func, -1);
  PyObject *value = wrap->_getitem_func(wrap->_base._self, key);
  if (value != nullptr) {
    Py_DECREF(value);
    return 1;
  } else if (_PyErr_OCCURRED() == PyExc_KeyError ||
             _PyErr_OCCURRED() == PyExc_TypeError) {
    PyErr_Restore(nullptr, nullptr, nullptr);
    return 0;
  } else {
    return -1;
  }
}

static PyObject *Dtool_MappingWrapper_getitem(PyObject *self, PyObject *key) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_getitem_func, nullptr);
  return wrap->_getitem_func(wrap->_base._self, key);
}

/**
 * Implementation of iter(property) that returns an iterable over all the
 * keys.
 */
static PyObject *Dtool_MappingWrapper_iter(PyObject *self) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);

  if (wrap->_keys._len_func == nullptr || wrap->_keys._getitem_func == nullptr) {
    return PyErr_Format(PyExc_TypeError, "%s is not iterable", wrap->_base._name);
  }

  Dtool_SequenceWrapper *keys = Dtool_NewSequenceWrapper(wrap->_base._self, wrap->_base._name);
  if (keys != nullptr) {
    keys->_len_func = wrap->_keys._len_func;
    keys->_getitem_func = wrap->_keys._getitem_func;
    return PySeqIter_New((PyObject *)keys);
  } else {
    return nullptr;
  }
}

/**
 * Implementation of property.get(key[,def=None]) which returns the value with
 * the given key in the mapping, or the given default value (which defaults to
 * None) if the key isn't found in the mapping.
 */
static PyObject *Dtool_MappingWrapper_get(PyObject *self, PyObject *args) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_getitem_func, nullptr);
  Py_ssize_t size = PyTuple_GET_SIZE(args);
  if (size != 1 && size != 2) {
    return PyErr_Format(PyExc_TypeError, "%s.get() takes 1 or 2 arguments", wrap->_base._name);
  }
  PyObject *defvalue = Py_None;
  if (size >= 2) {
    defvalue = PyTuple_GET_ITEM(args, 1);
  }
  PyObject *key = PyTuple_GET_ITEM(args, 0);
  PyObject *value = wrap->_getitem_func(wrap->_base._self, key);
  if (value != nullptr) {
    return value;
  } else if (_PyErr_OCCURRED() == PyExc_KeyError) {
    PyErr_Restore(nullptr, nullptr, nullptr);
    Py_INCREF(defvalue);
    return defvalue;
  } else {
    return nullptr;
  }
}

/**
 * This is returned by mapping.keys().
 */
static PyObject *Dtool_MappingWrapper_Keys_repr(PyObject *self) {
  Dtool_WrapperBase *wrap = (Dtool_WrapperBase *)self;
  nassertr(wrap, nullptr);

  PyObject *repr = PyObject_Repr(wrap->_self);
  PyObject *result;
#if PY_MAJOR_VERSION >= 3
  result = PyUnicode_FromFormat("<%s.keys() of %s>", wrap->_name, PyUnicode_AsUTF8(repr));
#else
  result = PyString_FromFormat("<%s.keys() of %s>", wrap->_name, PyString_AS_STRING(repr));
#endif
  Py_DECREF(repr);
  return result;
}

/**
 * Implementation of property.keys(...) that returns a view of all the keys.
 */
static PyObject *Dtool_MappingWrapper_keys(PyObject *self, PyObject *) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);

  if (wrap->_keys._len_func == nullptr || wrap->_keys._getitem_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support keys()");
  }

  Dtool_MappingWrapper *keys = (Dtool_MappingWrapper *)PyObject_MALLOC(sizeof(Dtool_MappingWrapper));
  if (keys == nullptr) {
    return PyErr_NoMemory();
  }

  static PySequenceMethods seq_methods = {
    Dtool_SequenceWrapper_length,
    nullptr, // sq_concat
    nullptr, // sq_repeat
    Dtool_SequenceWrapper_getitem,
    nullptr, // sq_slice
    nullptr, // sq_ass_item
    nullptr, // sq_ass_slice
    Dtool_SequenceWrapper_contains,
    nullptr, // sq_inplace_concat
    nullptr, // sq_inplace_repeat
  };

  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "sequence wrapper",
    sizeof(Dtool_SequenceWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    Dtool_MappingWrapper_Keys_repr,
    nullptr, // tp_as_number
    &seq_methods,
    nullptr, // tp_as_mapping
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    PySeqIter_New,
    nullptr, // tp_iternext
    nullptr, // tp_methods
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  static bool registered = false;
  if (!registered) {
    registered = true;

    if (PyType_Ready(&wrapper_type) < 0) {
      return nullptr;
    }

    // If the collections.abc module is loaded, register this as a subclass.
    _register_collection((PyTypeObject *)&wrapper_type, "MappingView");
  }

  (void)PyObject_INIT(keys, &wrapper_type);
  Py_XINCREF(wrap->_base._self);
  keys->_base._self = wrap->_base._self;
  keys->_base._name = wrap->_base._name;
  keys->_keys._len_func = wrap->_keys._len_func;
  keys->_keys._getitem_func = wrap->_keys._getitem_func;
  keys->_getitem_func = wrap->_getitem_func;
  keys->_setitem_func = nullptr;
  return (PyObject *)keys;
}

/**
 * This is returned by mapping.values().
 */
static PyObject *Dtool_MappingWrapper_Values_repr(PyObject *self) {
  Dtool_WrapperBase *wrap = (Dtool_WrapperBase *)self;
  nassertr(wrap, nullptr);

  PyObject *repr = PyObject_Repr(wrap->_self);
  PyObject *result;
#if PY_MAJOR_VERSION >= 3
  result = PyUnicode_FromFormat("<%s.values() of %s>", wrap->_name, PyUnicode_AsUTF8(repr));
#else
  result = PyString_FromFormat("<%s.values() of %s>", wrap->_name, PyString_AS_STRING(repr));
#endif
  Py_DECREF(repr);
  return result;
}

static PyObject *Dtool_MappingWrapper_Values_getitem(PyObject *self, Py_ssize_t index) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_keys._getitem_func, nullptr);

  PyObject *key = wrap->_keys._getitem_func(wrap->_base._self, index);
  if (key != nullptr) {
    PyObject *value = wrap->_getitem_func(wrap->_base._self, key);
    Py_DECREF(key);
    return value;
  }
  return nullptr;
}

/**
 * Implementation of property.values(...) that returns a view of the values.
 */
static PyObject *Dtool_MappingWrapper_values(PyObject *self, PyObject *) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_getitem_func, nullptr);

  if (wrap->_keys._len_func == nullptr || wrap->_keys._getitem_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support values()");
  }

  Dtool_MappingWrapper *values = (Dtool_MappingWrapper *)PyObject_MALLOC(sizeof(Dtool_MappingWrapper));
  if (values == nullptr) {
    return PyErr_NoMemory();
  }

  static PySequenceMethods seq_methods = {
    Dtool_SequenceWrapper_length,
    nullptr, // sq_concat
    nullptr, // sq_repeat
    Dtool_MappingWrapper_Values_getitem,
    nullptr, // sq_slice
    nullptr, // sq_ass_item
    nullptr, // sq_ass_slice
    Dtool_MappingWrapper_contains,
    nullptr, // sq_inplace_concat
    nullptr, // sq_inplace_repeat
  };

  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "sequence wrapper",
    sizeof(Dtool_MappingWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    Dtool_MappingWrapper_Values_repr,
    nullptr, // tp_as_number
    &seq_methods,
    nullptr, // tp_as_mapping
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    PySeqIter_New,
    nullptr, // tp_iternext
    nullptr, // tp_methods
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  static bool registered = false;
  if (!registered) {
    registered = true;

    if (PyType_Ready(&wrapper_type) < 0) {
      return nullptr;
    }

    // If the collections.abc module is loaded, register this as a subclass.
    _register_collection((PyTypeObject *)&wrapper_type, "ValuesView");
  }

  (void)PyObject_INIT(values, &wrapper_type);
  Py_XINCREF(wrap->_base._self);
  values->_base._self = wrap->_base._self;
  values->_base._name = wrap->_base._name;
  values->_keys._len_func = wrap->_keys._len_func;
  values->_keys._getitem_func = wrap->_keys._getitem_func;
  values->_getitem_func = wrap->_getitem_func;
  values->_setitem_func = nullptr;
  return (PyObject *)values;
}

/**
 * This is returned by mapping.items().
 */
static PyObject *Dtool_MappingWrapper_Items_repr(PyObject *self) {
  Dtool_WrapperBase *wrap = (Dtool_WrapperBase *)self;
  nassertr(wrap, nullptr);

  PyObject *repr = PyObject_Repr(wrap->_self);
  PyObject *result;
#if PY_MAJOR_VERSION >= 3
  result = PyUnicode_FromFormat("<%s.items() of %s>", wrap->_name, PyUnicode_AsUTF8(repr));
#else
  result = PyString_FromFormat("<%s.items() of %s>", wrap->_name, PyString_AS_STRING(repr));
#endif
  Py_DECREF(repr);
  return result;
}

static PyObject *Dtool_MappingWrapper_Items_getitem(PyObject *self, Py_ssize_t index) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_keys._getitem_func, nullptr);

  PyObject *key = wrap->_keys._getitem_func(wrap->_base._self, index);
  if (key != nullptr) {
    PyObject *value = wrap->_getitem_func(wrap->_base._self, key);
    if (value != nullptr) {
      // PyTuple_SET_ITEM steals the reference.
      PyObject *item = PyTuple_New(2);
      PyTuple_SET_ITEM(item, 0, key);
      PyTuple_SET_ITEM(item, 1, value);
      return item;
    } else {
      Py_DECREF(key);
    }
  }
  return nullptr;
}

/**
 * Implementation of property.items(...) that returns an iterable yielding a
 * `(key, value)` tuple for every item.
 */
static PyObject *Dtool_MappingWrapper_items(PyObject *self, PyObject *) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_getitem_func, nullptr);

  if (wrap->_keys._len_func == nullptr || wrap->_keys._getitem_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support items()");
  }

  Dtool_MappingWrapper *items = (Dtool_MappingWrapper *)PyObject_MALLOC(sizeof(Dtool_MappingWrapper));
  if (items == nullptr) {
    return PyErr_NoMemory();
  }

  static PySequenceMethods seq_methods = {
    Dtool_SequenceWrapper_length,
    nullptr, // sq_concat
    nullptr, // sq_repeat
    Dtool_MappingWrapper_Items_getitem,
    nullptr, // sq_slice
    nullptr, // sq_ass_item
    nullptr, // sq_ass_slice
    Dtool_MappingWrapper_contains,
    nullptr, // sq_inplace_concat
    nullptr, // sq_inplace_repeat
  };

  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "sequence wrapper",
    sizeof(Dtool_MappingWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    Dtool_MappingWrapper_Items_repr,
    nullptr, // tp_as_number
    &seq_methods,
    nullptr, // tp_as_mapping
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    PySeqIter_New,
    nullptr, // tp_iternext
    nullptr, // tp_methods
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  static bool registered = false;
  if (!registered) {
    registered = true;

    if (PyType_Ready(&wrapper_type) < 0) {
      return nullptr;
    }

    // If the collections.abc module is loaded, register this as a subclass.
    _register_collection((PyTypeObject *)&wrapper_type, "MappingView");
  }

  (void)PyObject_INIT(items, &wrapper_type);
  Py_XINCREF(wrap->_base._self);
  items->_base._self = wrap->_base._self;
  items->_base._name = wrap->_base._name;
  items->_keys._len_func = wrap->_keys._len_func;
  items->_keys._getitem_func = wrap->_keys._getitem_func;
  items->_getitem_func = wrap->_getitem_func;
  items->_setitem_func = nullptr;
  return (PyObject *)items;
}

/**
 * Implementation of `property[key] = value`
 */
static int Dtool_MutableMappingWrapper_setitem(PyObject *self, PyObject *key, PyObject *value) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap->_setitem_func != nullptr, -1);
  return wrap->_setitem_func(wrap->_base._self, key, value);
}

/**
 * Implementation of property.pop(key[,def=None]) which is the same as get()
 * except that it also removes the element from the mapping.
 */
static PyObject *Dtool_MutableMappingWrapper_pop(PyObject *self, PyObject *args) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  if (wrap->_getitem_func == nullptr || wrap->_setitem_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support pop()");
  }

  Py_ssize_t size = PyTuple_GET_SIZE(args);
  if (size != 1 && size != 2) {
    return PyErr_Format(PyExc_TypeError, "%s.pop() takes 1 or 2 arguments", wrap->_base._name);
  }
  PyObject *defvalue = Py_None;
  if (size >= 2) {
    defvalue = PyTuple_GET_ITEM(args, 1);
  }

  PyObject *key = PyTuple_GET_ITEM(args, 0);
  PyObject *value = wrap->_getitem_func(wrap->_base._self, key);
  if (value != nullptr) {
    // OK, now set unset this value.
    if (wrap->_setitem_func(wrap->_base._self, key, nullptr) == 0) {
      return value;
    } else {
      Py_DECREF(value);
      return nullptr;
    }
  } else if (_PyErr_OCCURRED() == PyExc_KeyError) {
    PyErr_Restore(nullptr, nullptr, nullptr);
    Py_INCREF(defvalue);
    return defvalue;
  } else {
    return nullptr;
  }
}

/**
 * Implementation of property.popitem() which returns and removes an arbitrary
 * (key, value) pair from the mapping.  Useful for destructive iteration.
 */
static PyObject *Dtool_MutableMappingWrapper_popitem(PyObject *self, PyObject *) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  if (wrap->_getitem_func == nullptr || wrap->_setitem_func == nullptr ||
      wrap->_keys._len_func == nullptr || wrap->_keys._getitem_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support popitem()");
  }

  Py_ssize_t length = wrap->_keys._len_func(wrap->_base._self);
  if (length < 1) {
    return PyErr_Format(PyExc_KeyError, "%s is empty", wrap->_base._name);
  }

  PyObject *key = wrap->_keys._getitem_func(wrap->_base._self, length - 1);
  if (key != nullptr) {
    PyObject *value = wrap->_getitem_func(wrap->_base._self, key);
    if (value != nullptr) {
      // OK, now set unset this value.
      if (wrap->_setitem_func(wrap->_base._self, key, nullptr) == 0) {
        PyObject *item = PyTuple_New(2);
        PyTuple_SET_ITEM(item, 0, key);
        PyTuple_SET_ITEM(item, 1, value);
        return item;
      }
      Py_DECREF(value);
    }
  }
  return nullptr;
}

/*
 * Implementation of property.clear() which removes all elements in the
 * mapping.
 */
static PyObject *Dtool_MutableMappingWrapper_clear(PyObject *self, PyObject *) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);
  Py_ssize_t index = 0;
  if (wrap->_keys._len_func != nullptr && wrap->_keys._getitem_func != nullptr &&
      wrap->_setitem_func != nullptr) {
    index = wrap->_keys._len_func(wrap->_base._self);
  } else {
    return Dtool_Raise_TypeError("property does not support clear()");
  }

  // Iterate through the items, invoking the delete function for each.  We do
  // this in reverse order, which may be more efficient.
  while (index > 0) {
    --index;
    PyObject *key = wrap->_keys._getitem_func(wrap->_base._self, index);
    if (key != nullptr) {
      int result = wrap->_setitem_func(wrap->_base._self, key, nullptr);
      Py_DECREF(key);
      if (result != 0) {
        return nullptr;
      }
    }
  }
  Py_INCREF(Py_None);
  return Py_None;
}

/**
 * Implementation of property.setdefault(key[,def=None]) which is the same as
 * get() except that it also writes the default value back to the mapping if
 * the key was not found is missing.
 */
static PyObject *Dtool_MutableMappingWrapper_setdefault(PyObject *self, PyObject *args) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);

  if (wrap->_getitem_func == nullptr || wrap->_setitem_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support setdefault()");
  }

  Py_ssize_t size = PyTuple_GET_SIZE(args);
  if (size != 1 && size != 2) {
    return PyErr_Format(PyExc_TypeError, "%s.setdefault() takes 1 or 2 arguments", wrap->_base._name);
  }
  PyObject *defvalue = Py_None;
  if (size >= 2) {
    defvalue = PyTuple_GET_ITEM(args, 1);
  }
  PyObject *key = PyTuple_GET_ITEM(args, 0);
  PyObject *value = wrap->_getitem_func(wrap->_base._self, key);
  if (value != nullptr) {
    return value;
  } else if (_PyErr_OCCURRED() == PyExc_KeyError) {
    PyErr_Restore(nullptr, nullptr, nullptr);
    if (wrap->_setitem_func(wrap->_base._self, key, defvalue) == 0) {
      Py_INCREF(defvalue);
      return defvalue;
    }
  }
  return nullptr;
}

/**
 * Implementation of property.update(...) which sets multiple values in one
 * go.  It accepts either a single dictionary or keyword arguments, not both.
 */
static PyObject *Dtool_MutableMappingWrapper_update(PyObject *self, PyObject *args, PyObject *kwargs) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)self;
  nassertr(wrap, nullptr);

  if (wrap->_getitem_func == nullptr || wrap->_setitem_func == nullptr) {
    return Dtool_Raise_TypeError("property does not support update()");
  }

  // We accept either a dict argument or keyword arguments, but not both.
  PyObject *dict;
  switch (PyTuple_GET_SIZE(args)) {
  case 0:
    if (kwargs == nullptr) {
      // This is legal.
      Py_INCREF(Py_None);
      return Py_None;
    }
    dict = kwargs;
    break;
  case 1:
    if (PyDict_Check(PyTuple_GET_ITEM(args, 0)) && (kwargs == nullptr || Py_SIZE(kwargs) == 0)) {
      dict = PyTuple_GET_ITEM(args, 0);
      break;
    }
    // Fall through
  default:
    return PyErr_Format(PyExc_TypeError, "%s.update() takes either a dict argument or keyword arguments", wrap->_base._name);
  }

  PyObject *key, *value;
  Py_ssize_t pos = 0;
  while (PyDict_Next(dict, &pos, &key, &value)) {
    if (wrap->_setitem_func(wrap->_base._self, key, value) != 0) {
      return nullptr;
    }
  }
  Py_INCREF(Py_None);
  return Py_None;
}

/**
 * This variant defines only a generator interface.
 */
static PyObject *Dtool_GeneratorWrapper_iternext(PyObject *self) {
  Dtool_GeneratorWrapper *wrap = (Dtool_GeneratorWrapper *)self;
  nassertr(wrap, nullptr);
  nassertr(wrap->_iternext_func, nullptr);
  return wrap->_iternext_func(wrap->_base._self);
}

/**
 * This is a variant of the Python getset mechanism that permits static
 * properties.
 */
static void
Dtool_StaticProperty_dealloc(PyDescrObject *descr) {
  _PyObject_GC_UNTRACK(descr);
  Py_XDECREF(descr->d_type);
  Py_XDECREF(descr->d_name);
//#if PY_MAJOR_VERSION >= 3
//  Py_XDECREF(descr->d_qualname);
//#endif
  PyObject_GC_Del(descr);
}

static PyObject *
Dtool_StaticProperty_repr(PyDescrObject *descr, const char *format) {
#if PY_MAJOR_VERSION >= 3
  return PyUnicode_FromFormat("<attribute '%s' of '%s'>",
                              PyUnicode_AsUTF8(descr->d_name),
                              descr->d_type->tp_name);
#else
  return PyString_FromFormat("<attribute '%s' of '%s'>",
                             PyString_AS_STRING(descr->d_name),
                             descr->d_type->tp_name);
#endif
}

static int
Dtool_StaticProperty_traverse(PyObject *self, visitproc visit, void *arg) {
  PyDescrObject *descr = (PyDescrObject *)self;
  Py_VISIT(descr->d_type);
  return 0;
}

static PyObject *
Dtool_StaticProperty_get(PyGetSetDescrObject *descr, PyObject *obj, PyObject *type) {
  if (descr->d_getset->get != nullptr) {
    return descr->d_getset->get(obj, descr->d_getset->closure);
  } else {
    return PyErr_Format(PyExc_AttributeError,
                        "attribute '%s' of type '%.100s' is not readable",
#if PY_MAJOR_VERSION >= 3
                        PyUnicode_AsUTF8(((PyDescrObject *)descr)->d_name),
#else
                        PyString_AS_STRING(((PyDescrObject *)descr)->d_name),
#endif
                        ((PyDescrObject *)descr)->d_type->tp_name);
  }
}

static int
Dtool_StaticProperty_set(PyGetSetDescrObject *descr, PyObject *obj, PyObject *value) {
  if (descr->d_getset->set != nullptr) {
    return descr->d_getset->set(obj, value, descr->d_getset->closure);
  } else {
    PyErr_Format(PyExc_AttributeError,
                 "attribute '%s' of type '%.100s' is not writable",
#if PY_MAJOR_VERSION >= 3
                 PyUnicode_AsUTF8(((PyDescrObject *)descr)->d_name),
#else
                 PyString_AS_STRING(((PyDescrObject *)descr)->d_name),
#endif
                 ((PyDescrObject *)descr)->d_type->tp_name);
    return -1;
  }
}

/**
 * This wraps around a property that exposes a sequence interface.
 */
Dtool_SequenceWrapper *Dtool_NewSequenceWrapper(PyObject *self, const char *name) {
  Dtool_SequenceWrapper *wrap = (Dtool_SequenceWrapper *)PyObject_MALLOC(sizeof(Dtool_SequenceWrapper));
  if (wrap == nullptr) {
    return (Dtool_SequenceWrapper *)PyErr_NoMemory();
  }

  static PySequenceMethods seq_methods = {
    Dtool_SequenceWrapper_length,
    nullptr, // sq_concat
    nullptr, // sq_repeat
    Dtool_SequenceWrapper_getitem,
    nullptr, // sq_slice
    nullptr, // sq_ass_item
    nullptr, // sq_ass_slice
    Dtool_SequenceWrapper_contains,
    nullptr, // sq_inplace_concat
    nullptr, // sq_inplace_repeat
  };

  static PyMethodDef methods[] = {
    {"index", &Dtool_SequenceWrapper_index, METH_O, nullptr},
    {"count", &Dtool_SequenceWrapper_count, METH_O, nullptr},
    {nullptr, nullptr, 0, nullptr}
  };

  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "sequence wrapper",
    sizeof(Dtool_SequenceWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    Dtool_SequenceWrapper_repr,
    nullptr, // tp_as_number
    &seq_methods,
    nullptr, // tp_as_mapping
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    PySeqIter_New,
    nullptr, // tp_iternext
    methods,
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  static bool registered = false;
  if (!registered) {
    registered = true;

    if (PyType_Ready(&wrapper_type) < 0) {
      return nullptr;
    }

    // If the collections.abc module is loaded, register this as a subclass.
    _register_collection((PyTypeObject *)&wrapper_type, "Sequence");
  }

  (void)PyObject_INIT(wrap, &wrapper_type);
  Py_XINCREF(self);
  wrap->_base._self = self;
  wrap->_base._name = name;
  wrap->_len_func = nullptr;
  wrap->_getitem_func = nullptr;
  return wrap;
}

/**
 * This wraps around a property that exposes a mutable sequence interface.
 */
Dtool_MutableSequenceWrapper *Dtool_NewMutableSequenceWrapper(PyObject *self, const char *name) {
  Dtool_MutableSequenceWrapper *wrap = (Dtool_MutableSequenceWrapper *)PyObject_MALLOC(sizeof(Dtool_MutableSequenceWrapper));
  if (wrap == nullptr) {
    return (Dtool_MutableSequenceWrapper *)PyErr_NoMemory();
  }

  static PySequenceMethods seq_methods = {
    Dtool_SequenceWrapper_length,
    nullptr, // sq_concat
    nullptr, // sq_repeat
    Dtool_SequenceWrapper_getitem,
    nullptr, // sq_slice
    Dtool_MutableSequenceWrapper_setitem,
    nullptr, // sq_ass_slice
    Dtool_SequenceWrapper_contains,
    Dtool_MutableSequenceWrapper_extend,
    nullptr, // sq_inplace_repeat
  };

  static PyMethodDef methods[] = {
    {"index", &Dtool_SequenceWrapper_index, METH_O, nullptr},
    {"count", &Dtool_SequenceWrapper_count, METH_O, nullptr},
    {"clear", &Dtool_MutableSequenceWrapper_clear, METH_NOARGS, nullptr},
    {"pop", &Dtool_MutableSequenceWrapper_pop, METH_VARARGS, nullptr},
    {"remove", &Dtool_MutableSequenceWrapper_remove, METH_O, nullptr},
    {"append", &Dtool_MutableSequenceWrapper_append, METH_O, nullptr},
    {"insert", &Dtool_MutableSequenceWrapper_insert, METH_VARARGS, nullptr},
    {"extend", &Dtool_MutableSequenceWrapper_extend, METH_O, nullptr},
    {nullptr, nullptr, 0, nullptr}
  };

  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "sequence wrapper",
    sizeof(Dtool_MutableSequenceWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    Dtool_SequenceWrapper_repr,
    nullptr, // tp_as_number
    &seq_methods,
    nullptr, // tp_as_mapping
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    PySeqIter_New,
    nullptr, // tp_iternext
    methods,
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  static bool registered = false;
  if (!registered) {
    registered = true;

    if (PyType_Ready(&wrapper_type) < 0) {
      return nullptr;
    }

    // If the collections.abc module is loaded, register this as a subclass.
    _register_collection((PyTypeObject *)&wrapper_type, "MutableSequence");
  }

  (void)PyObject_INIT(wrap, &wrapper_type);
  Py_XINCREF(self);
  wrap->_base._self = self;
  wrap->_base._name = name;
  wrap->_len_func = nullptr;
  wrap->_getitem_func = nullptr;
  wrap->_setitem_func = nullptr;
  wrap->_insert_func = nullptr;
  return wrap;
}

/**
 * This wraps around a mapping interface, with getitem function.
 */
Dtool_MappingWrapper *Dtool_NewMappingWrapper(PyObject *self, const char *name) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)PyObject_MALLOC(sizeof(Dtool_MappingWrapper));
  if (wrap == nullptr) {
    return (Dtool_MappingWrapper *)PyErr_NoMemory();
  }

  static PySequenceMethods seq_methods = {
    Dtool_SequenceWrapper_length,
    nullptr, // sq_concat
    nullptr, // sq_repeat
    nullptr, // sq_item
    nullptr, // sq_slice
    nullptr, // sq_ass_item
    nullptr, // sq_ass_slice
    Dtool_MappingWrapper_contains,
    nullptr, // sq_inplace_concat
    nullptr, // sq_inplace_repeat
  };

  static PyMappingMethods map_methods = {
    Dtool_SequenceWrapper_length,
    Dtool_MappingWrapper_getitem,
    nullptr, // mp_ass_subscript
  };

  static PyMethodDef methods[] = {
    {"get", &Dtool_MappingWrapper_get, METH_VARARGS, nullptr},
    {"keys", &Dtool_MappingWrapper_keys, METH_NOARGS, nullptr},
    {"values", &Dtool_MappingWrapper_values, METH_NOARGS, nullptr},
    {"items", &Dtool_MappingWrapper_items, METH_NOARGS, nullptr},
    {nullptr, nullptr, 0, nullptr}
  };

  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "mapping wrapper",
    sizeof(Dtool_MappingWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    Dtool_WrapperBase_repr,
    nullptr, // tp_as_number
    &seq_methods,
    &map_methods,
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    Dtool_MappingWrapper_iter,
    nullptr, // tp_iternext
    methods,
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  static bool registered = false;
  if (!registered) {
    registered = true;

    if (PyType_Ready(&wrapper_type) < 0) {
      return nullptr;
    }

    // If the collections.abc module is loaded, register this as a subclass.
    _register_collection((PyTypeObject *)&wrapper_type, "Mapping");
  }

  (void)PyObject_INIT(wrap, &wrapper_type);
  Py_XINCREF(self);
  wrap->_base._self = self;
  wrap->_base._name = name;
  wrap->_keys._len_func = nullptr;
  wrap->_keys._getitem_func = nullptr;
  wrap->_getitem_func = nullptr;
  wrap->_setitem_func = nullptr;
  return wrap;
}

/**
 * This wraps around a mapping interface, with getitem/setitem functions.
 */
Dtool_MappingWrapper *Dtool_NewMutableMappingWrapper(PyObject *self, const char *name) {
  Dtool_MappingWrapper *wrap = (Dtool_MappingWrapper *)PyObject_MALLOC(sizeof(Dtool_MappingWrapper));
  if (wrap == nullptr) {
    return (Dtool_MappingWrapper *)PyErr_NoMemory();
  }

  static PySequenceMethods seq_methods = {
    Dtool_SequenceWrapper_length,
    nullptr, // sq_concat
    nullptr, // sq_repeat
    nullptr, // sq_item
    nullptr, // sq_slice
    nullptr, // sq_ass_item
    nullptr, // sq_ass_slice
    Dtool_MappingWrapper_contains,
    nullptr, // sq_inplace_concat
    nullptr, // sq_inplace_repeat
  };

  static PyMappingMethods map_methods = {
    Dtool_SequenceWrapper_length,
    Dtool_MappingWrapper_getitem,
    Dtool_MutableMappingWrapper_setitem,
  };

  static PyMethodDef methods[] = {
    {"get", &Dtool_MappingWrapper_get, METH_VARARGS, nullptr},
    {"pop", &Dtool_MutableMappingWrapper_pop, METH_VARARGS, nullptr},
    {"popitem", &Dtool_MutableMappingWrapper_popitem, METH_NOARGS, nullptr},
    {"clear", &Dtool_MutableMappingWrapper_clear, METH_VARARGS, nullptr},
    {"setdefault", &Dtool_MutableMappingWrapper_setdefault, METH_VARARGS, nullptr},
    {"update", (PyCFunction) &Dtool_MutableMappingWrapper_update, METH_VARARGS | METH_KEYWORDS, nullptr},
    {"keys", &Dtool_MappingWrapper_keys, METH_NOARGS, nullptr},
    {"values", &Dtool_MappingWrapper_values, METH_NOARGS, nullptr},
    {"items", &Dtool_MappingWrapper_items, METH_NOARGS, nullptr},
    {nullptr, nullptr, 0, nullptr}
  };

  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "mapping wrapper",
    sizeof(Dtool_MappingWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    Dtool_WrapperBase_repr,
    nullptr, // tp_as_number
    &seq_methods,
    &map_methods,
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    Dtool_MappingWrapper_iter,
    nullptr, // tp_iternext
    methods,
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  static bool registered = false;
  if (!registered) {
    registered = true;

    if (PyType_Ready(&wrapper_type) < 0) {
      return nullptr;
    }

    // If the collections.abc module is loaded, register this as a subclass.
    _register_collection((PyTypeObject *)&wrapper_type, "MutableMapping");
  }

  (void)PyObject_INIT(wrap, &wrapper_type);
  Py_XINCREF(self);
  wrap->_base._self = self;
  wrap->_base._name = name;
  wrap->_keys._len_func = nullptr;
  wrap->_keys._getitem_func = nullptr;
  wrap->_getitem_func = nullptr;
  wrap->_setitem_func = nullptr;
  return wrap;
}

/**
 * Creates a generator that invokes a given function with the given self arg.
 */
PyObject *
Dtool_NewGenerator(PyObject *self, iternextfunc gen_next) {
  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(nullptr, 0)
    "generator wrapper",
    sizeof(Dtool_GeneratorWrapper),
    0, // tp_itemsize
    Dtool_WrapperBase_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_compare
    nullptr, // tp_repr
    nullptr, // tp_as_number
    nullptr, // tp_as_sequence
    nullptr, // tp_as_mapping
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    PyObject_GenericSetAttr,
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES,
    nullptr, // tp_doc
    nullptr, // tp_traverse
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    PyObject_SelfIter,
    Dtool_GeneratorWrapper_iternext,
    nullptr, // tp_methods
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    nullptr, // tp_descr_get
    nullptr, // tp_descr_set
    0, // tp_dictoffset
    nullptr, // tp_init
    PyType_GenericAlloc,
    nullptr, // tp_new
    PyObject_Del,
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  if (PyType_Ready(&wrapper_type) < 0) {
    return nullptr;
  }

  Dtool_GeneratorWrapper *gen;
  gen = (Dtool_GeneratorWrapper *)PyType_GenericAlloc(&wrapper_type, 0);
  if (gen != nullptr) {
    Py_INCREF(self);
    gen->_base._self = self;
    gen->_iternext_func = gen_next;
  }
  return (PyObject *)gen;
}

/**
 * This is a variant of the Python getset mechanism that permits static
 * properties.
 */
PyObject *
Dtool_NewStaticProperty(PyTypeObject *type, const PyGetSetDef *getset) {
  static PyTypeObject wrapper_type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "getset_descriptor",
    sizeof(PyGetSetDescrObject),
    0, // tp_itemsize
    (destructor)Dtool_StaticProperty_dealloc,
    nullptr, // tp_print
    nullptr, // tp_getattr
    nullptr, // tp_setattr
    nullptr, // tp_reserved
    (reprfunc)Dtool_StaticProperty_repr,
    nullptr, // tp_as_number
    nullptr, // tp_as_sequence
    nullptr, // tp_as_mapping
    nullptr, // tp_hash
    nullptr, // tp_call
    nullptr, // tp_str
    PyObject_GenericGetAttr,
    nullptr, // tp_setattro
    nullptr, // tp_as_buffer
    Py_TPFLAGS_DEFAULT,
    nullptr, // tp_doc
    Dtool_StaticProperty_traverse,
    nullptr, // tp_clear
    nullptr, // tp_richcompare
    0, // tp_weaklistoffset
    nullptr, // tp_iter
    nullptr, // tp_iternext
    nullptr, // tp_methods
    nullptr, // tp_members
    nullptr, // tp_getset
    nullptr, // tp_base
    nullptr, // tp_dict
    (descrgetfunc)Dtool_StaticProperty_get,
    (descrsetfunc)Dtool_StaticProperty_set,
    0, // tp_dictoffset
    nullptr, // tp_init
    nullptr, // tp_alloc
    nullptr, // tp_new
    nullptr, // tp_del
    nullptr, // tp_is_gc
    nullptr, // tp_bases
    nullptr, // tp_mro
    nullptr, // tp_cache
    nullptr, // tp_subclasses
    nullptr, // tp_weaklist
    nullptr, // tp_del
  };

  if (PyType_Ready(&wrapper_type) < 0) {
    return nullptr;
  }

  PyGetSetDescrObject *descr;
  descr = (PyGetSetDescrObject *)PyType_GenericAlloc(&wrapper_type, 0);
  if (descr != nullptr) {
    Py_XINCREF(type);
    descr->d_getset = (PyGetSetDef *)getset;
#if PY_MAJOR_VERSION >= 3
    descr->d_common.d_type = type;
    descr->d_common.d_name = PyUnicode_InternFromString(getset->name);
#if PY_VERSION_HEX >= 0x03030000
    descr->d_common.d_qualname = nullptr;
#endif
#else
    descr->d_type = type;
    descr->d_name = PyString_InternFromString(getset->name);
#endif
  }
  return (PyObject *)descr;
}

#endif  // HAVE_PYTHON