/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2012 Blender Foundation. All rights reserved. */

/** \file
 * \ingroup pybmesh
 */

#include "BLI_math.h"
#include "BLI_sort.h"

#include "DNA_material_types.h"
#include "DNA_mesh_types.h"
#include "DNA_object_types.h"

#include "BKE_customdata.h"
#include "BKE_global.h"
#include "BKE_lib_id.h"
#include "BKE_mesh.h"
#include "BKE_mesh_runtime.h"

#include "DEG_depsgraph.h"
#include "DEG_depsgraph_query.h"

#include "bmesh.h"

#include <Python.h>

#include "../mathutils/mathutils.h"

#include "../generic/py_capi_utils.h"
#include "../generic/python_utildefines.h"

#include "bmesh_py_types.h" /* own include */
#include "bmesh_py_types_customdata.h"
#include "bmesh_py_types_meshdata.h"
#include "bmesh_py_types_select.h"

static void bm_dealloc_editmode_warn(BPy_BMesh *self);

/* Common Flags
 * ************ */

/* scene does not use BM_* flags. */
PyC_FlagSet bpy_bm_scene_vert_edge_face_flags[] = {
    {1, "VERT"},
    {2, "EDGE"},
    {4, "FACE"},
    {0, NULL},
};

PyC_FlagSet bpy_bm_htype_vert_edge_face_flags[] = {
    {BM_VERT, "VERT"},
    {BM_EDGE, "EDGE"},
    {BM_FACE, "FACE"},
    {0, NULL},
};

PyC_FlagSet bpy_bm_htype_all_flags[] = {
    {BM_VERT, "VERT"},
    {BM_LOOP, "EDGE"},
    {BM_FACE, "FACE"},
    {BM_LOOP, "LOOP"},
    {0, NULL},
};

#define BPY_BM_HFLAG_ALL_STR "('SELECT', 'HIDE', 'SEAM', 'SMOOTH', 'TAG')"

PyC_FlagSet bpy_bm_hflag_all_flags[] = {
    {BM_ELEM_SELECT, "SELECT"},
    {BM_ELEM_HIDDEN, "HIDE"},
    {BM_ELEM_SEAM, "SEAM"},
    {BM_ELEM_SMOOTH, "SMOOTH"},
    {BM_ELEM_TAG, "TAG"},
    {0, NULL},
};

/* py-type definitions
 * ******************* */

/* getseters
 * ========= */

/* bmesh elems
 * ----------- */

PyDoc_STRVAR(bpy_bm_elem_select_doc, "Selected state of this element.\n\n:type: boolean");
PyDoc_STRVAR(bpy_bm_elem_hide_doc, "Hidden state of this element.\n\n:type: boolean");
PyDoc_STRVAR(bpy_bm_elem_tag_doc,
             "Generic attribute scripts can use for own logic\n\n:type: boolean");
PyDoc_STRVAR(bpy_bm_elem_smooth_doc, "Smooth state of this element.\n\n:type: boolean");
PyDoc_STRVAR(bpy_bm_elem_seam_doc, "Seam for UV unwrapping.\n\n:type: boolean");

static PyObject *bpy_bm_elem_hflag_get(BPy_BMElem *self, void *flag)
{
  const char hflag = (char)POINTER_AS_INT(flag);

  BPY_BM_CHECK_OBJ(self);

  return PyBool_FromLong(BM_elem_flag_test(self->ele, hflag));
}

static int bpy_bm_elem_hflag_set(BPy_BMElem *self, PyObject *value, void *flag)
{
  const char hflag = (char)POINTER_AS_INT(flag);
  int param;

  BPY_BM_CHECK_INT(self);

  if ((param = PyC_Long_AsBool(value)) == -1) {
    return -1;
  }

  if (hflag == BM_ELEM_SELECT) {
    BM_elem_select_set(self->bm, self->ele, param);
  }
  else {
    BM_elem_flag_set(self->ele, hflag, param);
  }
  return 0;
}

PyDoc_STRVAR(
    bpy_bm_elem_index_doc,
    "Index of this element.\n"
    "\n"
    ":type: int\n"
    "\n"
    ".. note::\n"
    "\n"
    "   This value is not necessarily valid, while editing the mesh it can become *dirty*.\n"
    "\n"
    "   It's also possible to assign any number to this attribute for a scripts internal logic.\n"
    "\n"
    "   To ensure the value is up to date - see :class:`BMElemSeq.index_update`.\n");
static PyObject *bpy_bm_elem_index_get(BPy_BMElem *self, void *UNUSED(flag))
{
  BPY_BM_CHECK_OBJ(self);

  return PyLong_FromLong(BM_elem_index_get(self->ele));
}

static int bpy_bm_elem_index_set(BPy_BMElem *self, PyObject *value, void *UNUSED(flag))
{
  int param;

  BPY_BM_CHECK_INT(self);

  if (((param = PyC_Long_AsI32(value)) == -1) && PyErr_Occurred()) {
    /* error is set */
    return -1;
  }

  BM_elem_index_set(self->ele, param); /* set_dirty! */

  /* when setting the index assume its set invalid */
  self->bm->elem_index_dirty |= self->ele->head.htype;

  return 0;
}

/* type specific get/sets
 * ---------------------- */

/* Mesh
 * ^^^^ */

/* doc-strings for all uses of this function */

PyDoc_STRVAR(bpy_bmvertseq_doc,
             "This meshes vert sequence (read-only).\n\n:type: :class:`BMVertSeq`");
static PyObject *bpy_bmvertseq_get(BPy_BMesh *self, void *UNUSED(closure))
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMVertSeq_CreatePyObject(self->bm);
}

PyDoc_STRVAR(bpy_bmedgeseq_doc,
             "This meshes edge sequence (read-only).\n\n:type: :class:`BMEdgeSeq`");
static PyObject *bpy_bmedgeseq_get(BPy_BMesh *self, void *UNUSED(closure))
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMEdgeSeq_CreatePyObject(self->bm);
}

PyDoc_STRVAR(bpy_bmfaceseq_doc,
             "This meshes face sequence (read-only).\n\n:type: :class:`BMFaceSeq`");
static PyObject *bpy_bmfaceseq_get(BPy_BMesh *self, void *UNUSED(closure))
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMFaceSeq_CreatePyObject(self->bm);
}

PyDoc_STRVAR(bpy_bmloopseq_doc,
             "This meshes loops (read-only).\n\n:type: :class:`BMLoopSeq`\n"
             "\n"
             ".. note::\n"
             "\n"
             "   Loops must be accessed via faces, this is only exposed for layer access.\n");
static PyObject *bpy_bmloopseq_get(BPy_BMesh *self, void *UNUSED(closure))
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMLoopSeq_CreatePyObject(self->bm);
}

/* vert */
PyDoc_STRVAR(
    bpy_bmvert_link_edges_doc,
    "Edges connected to this vertex (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMEdge`");
PyDoc_STRVAR(
    bpy_bmvert_link_faces_doc,
    "Faces connected to this vertex (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMFace`");
PyDoc_STRVAR(
    bpy_bmvert_link_loops_doc,
    "Loops that use this vertex (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMLoop`");
/* edge */
PyDoc_STRVAR(bpy_bmedge_verts_doc,
             "Verts this edge uses (always 2), (read-only).\n\n:type: :class:`BMElemSeq` of "
             ":class:`BMVert`");
PyDoc_STRVAR(
    bpy_bmedge_link_faces_doc,
    "Faces connected to this edge, (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMFace`");
PyDoc_STRVAR(
    bpy_bmedge_link_loops_doc,
    "Loops connected to this edge, (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMLoop`");
/* face */
PyDoc_STRVAR(bpy_bmface_verts_doc,
             "Verts of this face, (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMVert`");
PyDoc_STRVAR(bpy_bmface_edges_doc,
             "Edges of this face, (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMEdge`");
PyDoc_STRVAR(bpy_bmface_loops_doc,
             "Loops of this face, (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMLoop`");
/* loop */
PyDoc_STRVAR(
    bpy_bmloops_link_loops_doc,
    "Loops connected to this loop, (read-only).\n\n:type: :class:`BMElemSeq` of :class:`BMLoop`");

static PyObject *bpy_bmelemseq_elem_get(BPy_BMElem *self, void *itype)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMElemSeq_CreatePyObject(self->bm, self, POINTER_AS_INT(itype));
}

PyDoc_STRVAR(bpy_bm_is_valid_doc,
             "True when this element is valid (hasn't been removed).\n\n:type: boolean");
static PyObject *bpy_bm_is_valid_get(BPy_BMGeneric *self)
{
  return PyBool_FromLong(BPY_BM_IS_VALID(self));
}

PyDoc_STRVAR(
    bpy_bmesh_is_wrapped_doc,
    "True when this mesh is owned by blender (typically the editmode BMesh).\n\n:type: boolean");
static PyObject *bpy_bmesh_is_wrapped_get(BPy_BMesh *self)
{
  BPY_BM_CHECK_OBJ(self);

  return PyBool_FromLong(self->flag & BPY_BMFLAG_IS_WRAPPED);
}

PyDoc_STRVAR(bpy_bmesh_select_mode_doc,
             "The selection mode, values can be {'VERT', 'EDGE', 'FACE'}, can't be assigned an "
             "empty set.\n\n:type: set");
static PyObject *bpy_bmesh_select_mode_get(BPy_BMesh *self)
{
  BPY_BM_CHECK_OBJ(self);

  return PyC_FlagSet_FromBitfield(bpy_bm_scene_vert_edge_face_flags, self->bm->selectmode);
}

static int bpy_bmesh_select_mode_set(BPy_BMesh *self, PyObject *value)
{
  int flag = 0;
  BPY_BM_CHECK_INT(self);

  if (PyC_FlagSet_ToBitfield(bpy_bm_scene_vert_edge_face_flags, value, &flag, "bm.select_mode") ==
      -1) {
    return -1;
  }
  if (flag == 0) {
    PyErr_SetString(PyExc_TypeError, "bm.select_mode: can't assign an empty value");
    return -1;
  }

  self->bm->selectmode = flag;
  return 0;
}

PyDoc_STRVAR(bpy_bmesh_select_history_doc,
             "Sequence of selected items (the last is displayed as active).\n\n:type: "
             ":class:`BMEditSelSeq`");
static PyObject *bpy_bmesh_select_history_get(BPy_BMesh *self)
{
  BPY_BM_CHECK_OBJ(self);

  return BPy_BMEditSel_CreatePyObject(self->bm);
}

static int bpy_bmesh_select_history_set(BPy_BMesh *self, PyObject *value)
{
  BPY_BM_CHECK_INT(self);

  return BPy_BMEditSel_Assign(self, value);
}

/* Vert
 * ^^^^ */

PyDoc_STRVAR(bpy_bmvert_co_doc,
             "The coordinates for this vertex as a 3D, wrapped vector.\n\n:type: "
             ":class:`mathutils.Vector`");
static PyObject *bpy_bmvert_co_get(BPy_BMVert *self)
{
  BPY_BM_CHECK_OBJ(self);
  return Vector_CreatePyObject_wrap(self->v->co, 3, NULL);
}

static int bpy_bmvert_co_set(BPy_BMVert *self, PyObject *value)
{
  BPY_BM_CHECK_INT(self);

  if (mathutils_array_parse(self->v->co, 3, 3, value, "BMVert.co") != -1) {
    return 0;
  }

  return -1;
}

PyDoc_STRVAR(
    bpy_bmvert_normal_doc,
    "The normal for this vertex as a 3D, wrapped vector.\n\n:type: :class:`mathutils.Vector`");
static PyObject *bpy_bmvert_normal_get(BPy_BMVert *self)
{
  BPY_BM_CHECK_OBJ(self);
  return Vector_CreatePyObject_wrap(self->v->no, 3, NULL);
}

static int bpy_bmvert_normal_set(BPy_BMVert *self, PyObject *value)
{
  BPY_BM_CHECK_INT(self);

  if (mathutils_array_parse(self->v->no, 3, 3, value, "BMVert.normal") != -1) {
    return 0;
  }

  return -1;
}

PyDoc_STRVAR(bpy_bmvert_is_manifold_doc,
             "True when this vertex is manifold (read-only).\n\n:type: boolean");
static PyObject *bpy_bmvert_is_manifold_get(BPy_BMVert *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_vert_is_manifold(self->v));
}

PyDoc_STRVAR(bpy_bmvert_is_wire_doc,
             "True when this vertex is not connected to any faces (read-only).\n\n:type: boolean");
static PyObject *bpy_bmvert_is_wire_get(BPy_BMVert *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_vert_is_wire(self->v));
}

PyDoc_STRVAR(
    bpy_bmvert_is_boundary_doc,
    "True when this vertex is connected to boundary edges (read-only).\n\n:type: boolean");
static PyObject *bpy_bmvert_is_boundary_get(BPy_BMVert *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_vert_is_boundary(self->v));
}

/* Edge
 * ^^^^ */

PyDoc_STRVAR(bpy_bmedge_is_manifold_doc,
             "True when this edge is manifold (read-only).\n\n:type: boolean");
static PyObject *bpy_bmedge_is_manifold_get(BPy_BMEdge *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_edge_is_manifold(self->e));
}

PyDoc_STRVAR(bpy_bmedge_is_contiguous_doc,
             "True when this edge is manifold, between two faces with the same winding "
             "(read-only).\n\n:type: boolean");
static PyObject *bpy_bmedge_is_contiguous_get(BPy_BMEdge *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_edge_is_contiguous(self->e));
}

PyDoc_STRVAR(bpy_bmedge_is_convex_doc,
             "True when this edge joins two convex faces, depends on a valid face normal "
             "(read-only).\n\n:type: boolean");
static PyObject *bpy_bmedge_is_convex_get(BPy_BMEdge *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_edge_is_convex(self->e));
}

PyDoc_STRVAR(bpy_bmedge_is_wire_doc,
             "True when this edge is not connected to any faces (read-only).\n\n:type: boolean");
static PyObject *bpy_bmedge_is_wire_get(BPy_BMEdge *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_edge_is_wire(self->e));
}

PyDoc_STRVAR(bpy_bmedge_is_boundary_doc,
             "True when this edge is at the boundary of a face (read-only).\n\n:type: boolean");
static PyObject *bpy_bmedge_is_boundary_get(BPy_BMEdge *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_edge_is_boundary(self->e));
}

/* Face
 * ^^^^ */

PyDoc_STRVAR(
    bpy_bmface_normal_doc,
    "The normal for this face as a 3D, wrapped vector.\n\n:type: :class:`mathutils.Vector`");
static PyObject *bpy_bmface_normal_get(BPy_BMFace *self)
{
  BPY_BM_CHECK_OBJ(self);
  return Vector_CreatePyObject_wrap(self->f->no, 3, NULL);
}

static int bpy_bmface_normal_set(BPy_BMFace *self, PyObject *value)
{
  BPY_BM_CHECK_INT(self);

  if (mathutils_array_parse(self->f->no, 3, 3, value, "BMFace.normal") != -1) {
    return 0;
  }

  return -1;
}

PyDoc_STRVAR(bpy_bmface_material_index_doc, "The face's material index.\n\n:type: int");
static PyObject *bpy_bmface_material_index_get(BPy_BMFace *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyLong_FromLong(self->f->mat_nr);
}

static int bpy_bmface_material_index_set(BPy_BMFace *self, PyObject *value)
{
  int param;

  BPY_BM_CHECK_INT(self);

  if (((param = PyC_Long_AsI32(value)) == -1) && PyErr_Occurred()) {
    /* error is set */
    return -1;
  }

  if ((param < 0) || (param > MAXMAT)) {
    /* normally we clamp but in this case raise an error */
    PyErr_SetString(PyExc_ValueError, "material index outside of usable range (0 - 32766)");
    return -1;
  }

  self->f->mat_nr = (short)param;
  return 0;
}

/* Loop
 * ^^^^ */

PyDoc_STRVAR(bpy_bmloop_vert_doc, "The loop's vertex (read-only).\n\n:type: :class:`BMVert`");
static PyObject *bpy_bmloop_vert_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMVert_CreatePyObject(self->bm, self->l->v);
}

PyDoc_STRVAR(
    bpy_bmloop_edge_doc,
    "The loop's edge (between this loop and the next), (read-only).\n\n:type: :class:`BMEdge`");
static PyObject *bpy_bmloop_edge_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMEdge_CreatePyObject(self->bm, self->l->e);
}

PyDoc_STRVAR(bpy_bmloop_face_doc,
             "The face this loop makes (read-only).\n\n:type: :class:`BMFace`");
static PyObject *bpy_bmloop_face_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMFace_CreatePyObject(self->bm, self->l->f);
}

PyDoc_STRVAR(bpy_bmloop_link_loop_next_doc,
             "The next face corner (read-only).\n\n:type: :class:`BMLoop`");
static PyObject *bpy_bmloop_link_loop_next_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMLoop_CreatePyObject(self->bm, self->l->next);
}

PyDoc_STRVAR(bpy_bmloop_link_loop_prev_doc,
             "The previous face corner (read-only).\n\n:type: :class:`BMLoop`");
static PyObject *bpy_bmloop_link_loop_prev_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMLoop_CreatePyObject(self->bm, self->l->prev);
}

PyDoc_STRVAR(bpy_bmloop_link_loop_radial_next_doc,
             "The next loop around the edge (read-only).\n\n:type: :class:`BMLoop`");
static PyObject *bpy_bmloop_link_loop_radial_next_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMLoop_CreatePyObject(self->bm, self->l->radial_next);
}

PyDoc_STRVAR(bpy_bmloop_link_loop_radial_prev_doc,
             "The previous loop around the edge (read-only).\n\n:type: :class:`BMLoop`");
static PyObject *bpy_bmloop_link_loop_radial_prev_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return BPy_BMLoop_CreatePyObject(self->bm, self->l->radial_prev);
}

PyDoc_STRVAR(bpy_bmloop_is_convex_doc,
             "True when this loop is at the convex corner of a face, depends on a valid face "
             "normal (read-only).\n\n:type: boolean");
static PyObject *bpy_bmloop_is_convex_get(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyBool_FromLong(BM_loop_is_convex(self->l));
}

/* ElemSeq
 * ^^^^^^^ */

/* NOTE: use for bmvert/edge/face/loop seq's use these, not bmelemseq directly. */
PyDoc_STRVAR(bpy_bmelemseq_layers_vert_doc,
             "custom-data layers (read-only).\n\n:type: :class:`BMLayerAccessVert`");
PyDoc_STRVAR(bpy_bmelemseq_layers_edge_doc,
             "custom-data layers (read-only).\n\n:type: :class:`BMLayerAccessEdge`");
PyDoc_STRVAR(bpy_bmelemseq_layers_face_doc,
             "custom-data layers (read-only).\n\n:type: :class:`BMLayerAccessFace`");
PyDoc_STRVAR(bpy_bmelemseq_layers_loop_doc,
             "custom-data layers (read-only).\n\n:type: :class:`BMLayerAccessLoop`");
static PyObject *bpy_bmelemseq_layers_get(BPy_BMElemSeq *self, void *htype)
{
  BPY_BM_CHECK_OBJ(self);

  return BPy_BMLayerAccess_CreatePyObject(self->bm, POINTER_AS_INT(htype));
}

/* FaceSeq
 * ^^^^^^^ */

PyDoc_STRVAR(bpy_bmfaceseq_active_doc, "active face.\n\n:type: :class:`BMFace` or None");
static PyObject *bpy_bmfaceseq_active_get(BPy_BMElemSeq *self, void *UNUSED(closure))
{
  BMesh *bm = self->bm;
  BPY_BM_CHECK_OBJ(self);

  if (bm->act_face) {
    return BPy_BMElem_CreatePyObject(bm, (BMHeader *)bm->act_face);
  }

  Py_RETURN_NONE;
}

static int bpy_bmfaceseq_active_set(BPy_BMElem *self, PyObject *value, void *UNUSED(closure))
{
  BMesh *bm = self->bm;
  if (value == Py_None) {
    bm->act_face = NULL;
    return 0;
  }
  if (BPy_BMFace_Check(value)) {
    BPY_BM_CHECK_SOURCE_INT(bm, "faces.active = f", value);

    bm->act_face = ((BPy_BMFace *)value)->f;
    return 0;
  }

  PyErr_Format(PyExc_TypeError,
               "faces.active = f: expected BMFace or None, not %.200s",
               Py_TYPE(value)->tp_name);
  return -1;
}

static PyGetSetDef bpy_bmesh_getseters[] = {
    {"verts", (getter)bpy_bmvertseq_get, (setter)NULL, bpy_bmvertseq_doc, NULL},
    {"edges", (getter)bpy_bmedgeseq_get, (setter)NULL, bpy_bmedgeseq_doc, NULL},
    {"faces", (getter)bpy_bmfaceseq_get, (setter)NULL, bpy_bmfaceseq_doc, NULL},
    {"loops", (getter)bpy_bmloopseq_get, (setter)NULL, bpy_bmloopseq_doc, NULL},
    {"select_mode",
     (getter)bpy_bmesh_select_mode_get,
     (setter)bpy_bmesh_select_mode_set,
     bpy_bmesh_select_mode_doc,
     NULL},

    {"select_history",
     (getter)bpy_bmesh_select_history_get,
     (setter)bpy_bmesh_select_history_set,
     bpy_bmesh_select_history_doc,
     NULL},

    /* readonly checks */
    {"is_wrapped",
     (getter)bpy_bmesh_is_wrapped_get,
     (setter)NULL,
     bpy_bmesh_is_wrapped_doc,
     NULL}, /* as with mathutils */
    {"is_valid", (getter)bpy_bm_is_valid_get, (setter)NULL, bpy_bm_is_valid_doc, NULL},

    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};

static PyGetSetDef bpy_bmvert_getseters[] = {
    /* generic */
    {"select",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_select_doc,
     (void *)BM_ELEM_SELECT},
    {"hide",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_hide_doc,
     (void *)BM_ELEM_HIDDEN},
    {"tag",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_tag_doc,
     (void *)BM_ELEM_TAG},
    {"index",
     (getter)bpy_bm_elem_index_get,
     (setter)bpy_bm_elem_index_set,
     bpy_bm_elem_index_doc,
     NULL},

    {"co", (getter)bpy_bmvert_co_get, (setter)bpy_bmvert_co_set, bpy_bmvert_co_doc, NULL},
    {"normal",
     (getter)bpy_bmvert_normal_get,
     (setter)bpy_bmvert_normal_set,
     bpy_bmvert_normal_doc,
     NULL},

    /* connectivity data */
    {"link_edges",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmvert_link_edges_doc,
     (void *)BM_EDGES_OF_VERT},
    {"link_faces",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmvert_link_faces_doc,
     (void *)BM_FACES_OF_VERT},
    {"link_loops",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmvert_link_loops_doc,
     (void *)BM_LOOPS_OF_VERT},

    /* readonly checks */
    {"is_manifold",
     (getter)bpy_bmvert_is_manifold_get,
     (setter)NULL,
     bpy_bmvert_is_manifold_doc,
     NULL},
    {"is_wire", (getter)bpy_bmvert_is_wire_get, (setter)NULL, bpy_bmvert_is_wire_doc, NULL},
    {"is_boundary",
     (getter)bpy_bmvert_is_boundary_get,
     (setter)NULL,
     bpy_bmvert_is_boundary_doc,
     NULL},
    {"is_valid", (getter)bpy_bm_is_valid_get, (setter)NULL, bpy_bm_is_valid_doc, NULL},

    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};

static PyGetSetDef bpy_bmedge_getseters[] = {
    /* generic */
    {"select",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_select_doc,
     (void *)BM_ELEM_SELECT},
    {"hide",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_hide_doc,
     (void *)BM_ELEM_HIDDEN},
    {"tag",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_tag_doc,
     (void *)BM_ELEM_TAG},
    {"index",
     (getter)bpy_bm_elem_index_get,
     (setter)bpy_bm_elem_index_set,
     bpy_bm_elem_index_doc,
     NULL},

    {"smooth",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_smooth_doc,
     (void *)BM_ELEM_SMOOTH},
    {"seam",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_seam_doc,
     (void *)BM_ELEM_SEAM},

    /* connectivity data */
    {"verts",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmedge_verts_doc,
     (void *)BM_VERTS_OF_EDGE},

    {"link_faces",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmedge_link_faces_doc,
     (void *)BM_FACES_OF_EDGE},
    {"link_loops",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmedge_link_loops_doc,
     (void *)BM_LOOPS_OF_EDGE},

    /* readonly checks */
    {"is_manifold",
     (getter)bpy_bmedge_is_manifold_get,
     (setter)NULL,
     bpy_bmedge_is_manifold_doc,
     NULL},
    {"is_contiguous",
     (getter)bpy_bmedge_is_contiguous_get,
     (setter)NULL,
     bpy_bmedge_is_contiguous_doc,
     NULL},
    {"is_convex", (getter)bpy_bmedge_is_convex_get, (setter)NULL, bpy_bmedge_is_convex_doc, NULL},
    {"is_wire", (getter)bpy_bmedge_is_wire_get, (setter)NULL, bpy_bmedge_is_wire_doc, NULL},
    {"is_boundary",
     (getter)bpy_bmedge_is_boundary_get,
     (setter)NULL,
     bpy_bmedge_is_boundary_doc,
     NULL},
    {"is_valid", (getter)bpy_bm_is_valid_get, (setter)NULL, bpy_bm_is_valid_doc, NULL},

    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};

static PyGetSetDef bpy_bmface_getseters[] = {
    /* generic */
    {"select",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_select_doc,
     (void *)BM_ELEM_SELECT},
    {"hide",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_hide_doc,
     (void *)BM_ELEM_HIDDEN},
    {"tag",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_tag_doc,
     (void *)BM_ELEM_TAG},
    {"index",
     (getter)bpy_bm_elem_index_get,
     (setter)bpy_bm_elem_index_set,
     bpy_bm_elem_index_doc,
     NULL},

    {"smooth",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_smooth_doc,
     (void *)BM_ELEM_SMOOTH},

    {"normal",
     (getter)bpy_bmface_normal_get,
     (setter)bpy_bmface_normal_set,
     bpy_bmface_normal_doc,
     NULL},

    {"material_index",
     (getter)bpy_bmface_material_index_get,
     (setter)bpy_bmface_material_index_set,
     bpy_bmface_material_index_doc,
     NULL},

    /* connectivity data */
    {"verts",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmface_verts_doc,
     (void *)BM_VERTS_OF_FACE},
    {"edges",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmface_edges_doc,
     (void *)BM_EDGES_OF_FACE},
    {"loops",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmface_loops_doc,
     (void *)BM_LOOPS_OF_FACE},

    /* readonly checks */
    {"is_valid", (getter)bpy_bm_is_valid_get, (setter)NULL, bpy_bm_is_valid_doc, NULL},

    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};

static PyGetSetDef bpy_bmloop_getseters[] = {
/* generic */
/* flags are available but not used for loops. */
#if 0
    {"select",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_select_doc,
     (void *)BM_ELEM_SELECT},
    {"hide",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_hide_doc,
     (void *)BM_ELEM_HIDDEN},
#endif
    {"tag",
     (getter)bpy_bm_elem_hflag_get,
     (setter)bpy_bm_elem_hflag_set,
     bpy_bm_elem_tag_doc,
     (void *)BM_ELEM_TAG},
    {"index",
     (getter)bpy_bm_elem_index_get,
     (setter)bpy_bm_elem_index_set,
     bpy_bm_elem_index_doc,
     NULL},

    {"vert", (getter)bpy_bmloop_vert_get, (setter)NULL, bpy_bmloop_vert_doc, NULL},
    {"edge", (getter)bpy_bmloop_edge_get, (setter)NULL, bpy_bmloop_edge_doc, NULL},
    {"face", (getter)bpy_bmloop_face_get, (setter)NULL, bpy_bmloop_face_doc, NULL},

    /* connectivity data */
    {"link_loops",
     (getter)bpy_bmelemseq_elem_get,
     (setter)NULL,
     bpy_bmloops_link_loops_doc,
     (void *)BM_LOOPS_OF_LOOP},
    {"link_loop_next",
     (getter)bpy_bmloop_link_loop_next_get,
     (setter)NULL,
     bpy_bmloop_link_loop_next_doc,
     NULL},
    {"link_loop_prev",
     (getter)bpy_bmloop_link_loop_prev_get,
     (setter)NULL,
     bpy_bmloop_link_loop_prev_doc,
     NULL},
    {"link_loop_radial_next",
     (getter)bpy_bmloop_link_loop_radial_next_get,
     (setter)NULL,
     bpy_bmloop_link_loop_radial_next_doc,
     NULL},
    {"link_loop_radial_prev",
     (getter)bpy_bmloop_link_loop_radial_prev_get,
     (setter)NULL,
     bpy_bmloop_link_loop_radial_prev_doc,
     NULL},

    /* readonly checks */
    {"is_convex", (getter)bpy_bmloop_is_convex_get, (setter)NULL, bpy_bmloop_is_convex_doc, NULL},
    {"is_valid", (getter)bpy_bm_is_valid_get, (setter)NULL, bpy_bm_is_valid_doc, NULL},

    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};

static PyGetSetDef bpy_bmvertseq_getseters[] = {
    {"layers",
     (getter)bpy_bmelemseq_layers_get,
     (setter)NULL,
     bpy_bmelemseq_layers_vert_doc,
     (void *)BM_VERT},
    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};
static PyGetSetDef bpy_bmedgeseq_getseters[] = {
    {"layers",
     (getter)bpy_bmelemseq_layers_get,
     (setter)NULL,
     bpy_bmelemseq_layers_edge_doc,
     (void *)BM_EDGE},
    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};
static PyGetSetDef bpy_bmfaceseq_getseters[] = {
    {"layers",
     (getter)bpy_bmelemseq_layers_get,
     (setter)NULL,
     bpy_bmelemseq_layers_face_doc,
     (void *)BM_FACE},
    /* face only */
    {"active",
     (getter)bpy_bmfaceseq_active_get,
     (setter)bpy_bmfaceseq_active_set,
     bpy_bmfaceseq_active_doc,
     NULL},
    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};
static PyGetSetDef bpy_bmloopseq_getseters[] = {
    {"layers",
     (getter)bpy_bmelemseq_layers_get,
     (setter)NULL,
     bpy_bmelemseq_layers_loop_doc,
     (void *)BM_LOOP},
    {NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};

/* Methods
 * ======= */

/* Mesh
 * ---- */

PyDoc_STRVAR(bpy_bmesh_copy_doc,
             ".. method:: copy()\n"
             "\n"
             "   :return: A copy of this BMesh.\n"
             "   :rtype: :class:`BMesh`\n");
static PyObject *bpy_bmesh_copy(BPy_BMesh *self)
{
  BMesh *bm;
  BMesh *bm_copy;

  BPY_BM_CHECK_OBJ(self);

  bm = self->bm;

  bm_copy = BM_mesh_copy(bm);

  if (bm_copy) {
    return BPy_BMesh_CreatePyObject(bm_copy, BPY_BMFLAG_NOP);
  }

  PyErr_SetString(PyExc_SystemError, "Unable to copy BMesh, internal error");
  return NULL;
}

PyDoc_STRVAR(bpy_bmesh_clear_doc,
             ".. method:: clear()\n"
             "\n"
             "   Clear all mesh data.\n");
static PyObject *bpy_bmesh_clear(BPy_BMesh *self)
{
  BMesh *bm;

  BPY_BM_CHECK_OBJ(self);

  bm = self->bm;

  BM_mesh_clear(bm);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(
    bpy_bmesh_free_doc,
    ".. method:: free()\n"
    "\n"
    "   Explicitly free the BMesh data from memory, causing exceptions on further access.\n"
    "\n"
    "   .. note::\n"
    "\n"
    "      The BMesh is freed automatically, typically when the script finishes executing.\n"
    "      However in some cases its hard to predict when this will be and its useful to\n"
    "      explicitly free the data.\n");
static PyObject *bpy_bmesh_free(BPy_BMesh *self)
{
  if (self->bm) {
    BMesh *bm = self->bm;

    bm_dealloc_editmode_warn(self);

    if ((self->flag & BPY_BMFLAG_IS_WRAPPED) == 0) {
      BM_mesh_free(bm);
    }

    bpy_bm_generic_invalidate((BPy_BMGeneric *)self);
  }

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmesh_to_mesh_doc,
             ".. method:: to_mesh(mesh)\n"
             "\n"
             "   Writes this BMesh data into an existing Mesh datablock.\n"
             "\n"
             "   :arg mesh: The mesh data to write into.\n"
             "   :type mesh: :class:`Mesh`\n");
static PyObject *bpy_bmesh_to_mesh(BPy_BMesh *self, PyObject *args)
{
  PyObject *py_mesh;
  Mesh *me;
  BMesh *bm;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "O:to_mesh", &py_mesh) ||
      !(me = PyC_RNA_AsPointer(py_mesh, "Mesh"))) {
    return NULL;
  }

  /* we could allow this but its almost certainly _not_ what script authors want */
  if (me->edit_mesh) {
    PyErr_Format(PyExc_ValueError, "to_mesh(): Mesh '%s' is in editmode", me->id.name + 2);
    return NULL;
  }

  bm = self->bm;

  struct Main *bmain = NULL;
  struct BMeshToMeshParams params = {
      .update_shapekey_indices = true,
  };
  if (me->id.tag & LIB_TAG_NO_MAIN) {
    /* Mesh might be coming from a self-contained source like object.to_mesh(). No need to remap
     * anything in this case. */
  }
  else {
    BLI_assert(BKE_id_is_in_global_main(&me->id));
    bmain = G_MAIN; /* XXX UGLY! */
    params.calc_object_remap = true;
  }

  BM_mesh_bm_to_me(bmain, bm, me, &params);

  /* we could have the user do this but if they forget blender can easy crash
   * since the references arrays for the objects derived meshes are now invalid */
  DEG_id_tag_update(&me->id, ID_RECALC_GEOMETRY_ALL_MODES);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmesh_from_object_doc,
             ".. method:: from_object(object, depsgraph, cage=False, face_normals=True, "
             "vertex_normals=True)\n"
             "\n"
             "   Initialize this bmesh from existing object data-block (only meshes are currently "
             "supported).\n"
             "\n"
             "   :arg object: The object data to load.\n"
             "   :type object: :class:`Object`\n"
             "   :arg cage: Get the mesh as a deformed cage.\n"
             "   :type cage: boolean\n"
             "   :arg face_normals: Calculate face normals.\n"
             "   :type face_normals: boolean\n"
             "   :arg vertex_normals: Calculate vertex normals.\n"
             "   :type vertex_normals: boolean\n");
static PyObject *bpy_bmesh_from_object(BPy_BMesh *self, PyObject *args, PyObject *kw)
{
  static const char *kwlist[] = {
      "object", "depsgraph", "cage", "face_normals", "vertex_normals", NULL};
  PyObject *py_object;
  PyObject *py_depsgraph;
  Object *ob, *ob_eval;
  struct Depsgraph *depsgraph;
  struct Scene *scene_eval;
  Mesh *me_eval;
  BMesh *bm;
  bool use_cage = false;
  bool use_fnorm = true;
  bool use_vert_normal = true;
  const CustomData_MeshMasks data_masks = CD_MASK_BMESH;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTupleAndKeywords(args,
                                   kw,
                                   "OO|$O&O&O&:from_object",
                                   (char **)kwlist,
                                   &py_object,
                                   &py_depsgraph,
                                   PyC_ParseBool,
                                   &use_cage,
                                   PyC_ParseBool,
                                   &use_fnorm,
                                   PyC_ParseBool,
                                   &use_vert_normal) ||
      !(ob = PyC_RNA_AsPointer(py_object, "Object")) ||
      !(depsgraph = PyC_RNA_AsPointer(py_depsgraph, "Depsgraph"))) {
    return NULL;
  }

  if (ob->type != OB_MESH) {
    PyErr_SetString(PyExc_ValueError,
                    "from_object(...): currently only mesh objects are supported");
    return NULL;
  }

  const bool use_render = DEG_get_mode(depsgraph) == DAG_EVAL_RENDER;
  scene_eval = DEG_get_evaluated_scene(depsgraph);
  ob_eval = DEG_get_evaluated_object(depsgraph, ob);
  bool need_free = false;

  /* Write the display mesh into the dummy mesh */
  if (use_render) {
    if (use_cage) {
      PyErr_SetString(PyExc_ValueError,
                      "from_object(...): cage arg is unsupported when dependency graph "
                      "evaluation mode is RENDER");
      return NULL;
    }

    me_eval = BKE_mesh_new_from_object(depsgraph, ob_eval, true, false);
    need_free = true;
  }
  else {
    if (use_cage) {
      me_eval = mesh_get_eval_deform(depsgraph, scene_eval, ob_eval, &data_masks);
    }
    else {
      me_eval = mesh_get_eval_final(depsgraph, scene_eval, ob_eval, &data_masks);
    }
  }

  if (me_eval == NULL) {
    PyErr_Format(PyExc_ValueError,
                 "from_object(...): Object '%s' has no usable mesh data",
                 ob->id.name + 2);
    return NULL;
  }

  bm = self->bm;

  BM_mesh_bm_from_me(bm,
                     me_eval,
                     (&(struct BMeshFromMeshParams){
                         .calc_face_normal = use_fnorm,
                         .calc_vert_normal = use_vert_normal,
                     }));

  if (need_free) {
    BKE_id_free(NULL, me_eval);
  }

  Py_RETURN_NONE;
}

PyDoc_STRVAR(
    bpy_bmesh_from_mesh_doc,
    ".. method:: from_mesh(mesh, face_normals=True, vertex_normals=True, use_shape_key=False, "
    "shape_key_index=0)\n"
    "\n"
    "   Initialize this bmesh from existing mesh datablock.\n"
    "\n"
    "   :arg mesh: The mesh data to load.\n"
    "   :type mesh: :class:`Mesh`\n"
    "   :arg use_shape_key: Use the locations from a shape key.\n"
    "   :type use_shape_key: boolean\n"
    "   :arg shape_key_index: The shape key index to use.\n"
    "   :type shape_key_index: int\n"
    "\n"
    "   .. note::\n"
    "\n"
    "      Multiple calls can be used to join multiple meshes.\n"
    "\n"
    "      Custom-data layers are only copied from ``mesh`` on initialization.\n"
    "      Further calls will copy custom-data to matching layers, layers missing on the target "
    "mesh won't be added.\n");
static PyObject *bpy_bmesh_from_mesh(BPy_BMesh *self, PyObject *args, PyObject *kw)
{
  static const char *kwlist[] = {
      "mesh", "face_normals", "vertex_normals", "use_shape_key", "shape_key_index", NULL};
  BMesh *bm;
  PyObject *py_mesh;
  Mesh *me;
  bool use_fnorm = true;
  bool use_vert_normal = true;
  bool use_shape_key = false;
  int shape_key_index = 0;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTupleAndKeywords(args,
                                   kw,
                                   "O|$O&O&O&i:from_mesh",
                                   (char **)kwlist,
                                   &py_mesh,
                                   PyC_ParseBool,
                                   &use_fnorm,
                                   PyC_ParseBool,
                                   &use_vert_normal,
                                   PyC_ParseBool,
                                   &use_shape_key,
                                   &shape_key_index) ||
      !(me = PyC_RNA_AsPointer(py_mesh, "Mesh"))) {
    return NULL;
  }

  bm = self->bm;

  BM_mesh_bm_from_me(bm,
                     me,
                     (&(struct BMeshFromMeshParams){
                         .calc_face_normal = use_fnorm,
                         .calc_vert_normal = use_vert_normal,
                         .use_shapekey = use_shape_key,
                         .active_shapekey = shape_key_index + 1,
                     }));

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmesh_select_flush_mode_doc,
             ".. method:: select_flush_mode()\n"
             "\n"
             "   flush selection based on the current mode current :class:`BMesh.select_mode`.\n");
static PyObject *bpy_bmesh_select_flush_mode(BPy_BMesh *self)
{
  BPY_BM_CHECK_OBJ(self);

  BM_mesh_select_mode_flush(self->bm);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmesh_select_flush_doc,
             ".. method:: select_flush(select)\n"
             "\n"
             "   Flush selection, independent of the current selection mode.\n"
             "\n"
             "   :arg select: flush selection or de-selected elements.\n"
             "   :type select: boolean\n");
static PyObject *bpy_bmesh_select_flush(BPy_BMesh *self, PyObject *value)
{
  int param;

  BPY_BM_CHECK_OBJ(self);

  if ((param = PyC_Long_AsBool(value)) == -1) {
    return NULL;
  }

  if (param) {
    BM_mesh_select_flush(self->bm);
  }
  else {
    BM_mesh_deselect_flush(self->bm);
  }

  Py_RETURN_NONE;
}

PyDoc_STRVAR(
    bpy_bmesh_normal_update_doc,
    ".. method:: normal_update()\n"
    "\n"
    "   Update normals of mesh faces and verts.\n"
    "\n"
    "   .. note::\n"
    "\n"
    "      The normal of any vertex where :attr:`is_wire` is True will be a zero vector.\n");

static PyObject *bpy_bmesh_normal_update(BPy_BMesh *self)
{
  BPY_BM_CHECK_OBJ(self);

  BM_mesh_normals_update(self->bm);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmesh_transform_doc,
             ".. method:: transform(matrix, filter=None)\n"
             "\n"
             "   Transform the mesh (optionally filtering flagged data only).\n"
             "\n"
             "   :arg matrix: transform matrix.\n"
             "   :type matrix: 4x4 :class:`mathutils.Matrix`\n"
             "   :arg filter: set of values in " BPY_BM_HFLAG_ALL_STR
             ".\n"
             "   :type filter: set\n");
static PyObject *bpy_bmesh_transform(BPy_BMElem *self, PyObject *args, PyObject *kw)
{
  static const char *kwlist[] = {"matrix", "filter", NULL};

  MatrixObject *mat;
  PyObject *filter = NULL;
  int filter_flags = 0;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTupleAndKeywords(args,
                                   kw,
                                   "O!|$O!:transform",
                                   (char **)kwlist,
                                   &matrix_Type,
                                   &mat,
                                   &PySet_Type,
                                   &filter)) {
    return NULL;
  }

  BMVert *eve;
  BMIter iter;
  void *mat_ptr;

  if (BaseMath_ReadCallback(mat) == -1) {
    return NULL;
  }
  if (mat->col_num != 4 || mat->row_num != 4) {
    PyErr_SetString(PyExc_ValueError, "expected a 4x4 matrix");
    return NULL;
  }

  if (filter != NULL && PyC_FlagSet_ToBitfield(
                            bpy_bm_hflag_all_flags, filter, &filter_flags, "bm.transform") == -1) {
    return NULL;
  }

  mat_ptr = mat->matrix;

  if (!filter_flags) {
    BM_ITER_MESH (eve, &iter, self->bm, BM_VERTS_OF_MESH) {
      mul_m4_v3((float(*)[4])mat_ptr, eve->co);
    }
  }
  else {
    const char filter_flags_ch = (char)filter_flags;
    BM_ITER_MESH (eve, &iter, self->bm, BM_VERTS_OF_MESH) {
      if (BM_elem_flag_test(eve, filter_flags_ch)) {
        mul_m4_v3((float(*)[4])mat_ptr, eve->co);
      }
    }
  }

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmesh_calc_volume_doc,
             ".. method:: calc_volume(signed=False)\n"
             "\n"
             "   Calculate mesh volume based on face normals.\n"
             "\n"
             "   :arg signed: when signed is true, negative values may be returned.\n"
             "   :type signed: bool\n"
             "   :return: The volume of the mesh.\n"
             "   :rtype: float\n");
static PyObject *bpy_bmesh_calc_volume(BPy_BMElem *self, PyObject *args, PyObject *kw)
{
  static const char *kwlist[] = {"signed", NULL};
  PyObject *is_signed = Py_False;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTupleAndKeywords(
          args, kw, "|$O!:calc_volume", (char **)kwlist, &PyBool_Type, &is_signed)) {
    return NULL;
  }

  return PyFloat_FromDouble(BM_mesh_calc_volume(self->bm, is_signed != Py_False));
}

PyDoc_STRVAR(bpy_bmesh_calc_loop_triangles_doc,
             ".. method:: calc_loop_triangles()\n"
             "\n"
             "   Calculate triangle tessellation from quads/ngons.\n"
             "\n"
             "   :return: The triangulated faces.\n"
             "   :rtype: list of :class:`BMLoop` tuples\n");
static PyObject *bpy_bmesh_calc_loop_triangles(BPy_BMElem *self)
{
  BMesh *bm;

  int looptris_tot;
  BMLoop *(*looptris)[3];

  PyObject *ret;
  int i;

  BPY_BM_CHECK_OBJ(self);

  bm = self->bm;

  looptris_tot = poly_to_tri_count(bm->totface, bm->totloop);
  looptris = PyMem_MALLOC(sizeof(*looptris) * looptris_tot);

  BM_mesh_calc_tessellation(bm, looptris);

  ret = PyList_New(looptris_tot);
  for (i = 0; i < looptris_tot; i++) {
    PyList_SET_ITEM(ret, i, BPy_BMLoop_Array_As_Tuple(bm, looptris[i], 3));
  }

  PyMem_FREE(looptris);

  return ret;
}

/* Elem
 * ---- */

PyDoc_STRVAR(bpy_bm_elem_select_set_doc,
             ".. method:: select_set(select)\n"
             "\n"
             "   Set the selection.\n"
             "   This is different from the *select* attribute because it updates the selection "
             "state of associated geometry.\n"
             "\n"
             "   :arg select: Select or de-select.\n"
             "   :type select: boolean\n"
             "\n"
             "   .. note::\n"
             "\n"
             "      Currently this only flushes down, so selecting a face will select all its "
             "vertices but de-selecting a vertex "
             "      won't de-select all the faces that use it, before finishing with a mesh "
             "typically flushing is still needed.\n");
static PyObject *bpy_bm_elem_select_set(BPy_BMElem *self, PyObject *value)
{
  int param;

  BPY_BM_CHECK_OBJ(self);

  if ((param = PyC_Long_AsBool(value)) == -1) {
    return NULL;
  }

  BM_elem_select_set(self->bm, self->ele, param);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bm_elem_hide_set_doc,
             ".. method:: hide_set(hide)\n"
             "\n"
             "   Set the hide state.\n"
             "   This is different from the *hide* attribute because it updates the selection and "
             "hide state of associated geometry.\n"
             "\n"
             "   :arg hide: Hidden or visible.\n"
             "   :type hide: boolean\n");
static PyObject *bpy_bm_elem_hide_set(BPy_BMElem *self, PyObject *value)
{
  int param;

  BPY_BM_CHECK_OBJ(self);

  if ((param = PyC_Long_AsBool(value)) == -1) {
    return NULL;
  }

  BM_elem_hide_set(self->bm, self->ele, param);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bm_elem_copy_from_doc,
             ".. method:: copy_from(other)\n"
             "\n"
             "   Copy values from another element of matching type.\n");
static PyObject *bpy_bm_elem_copy_from(BPy_BMElem *self, BPy_BMElem *value)
{
  BPY_BM_CHECK_OBJ(self);

  if (Py_TYPE(self) != Py_TYPE(value)) {
    PyErr_Format(PyExc_TypeError,
                 "expected element of type '%.200s' not '%.200s'",
                 Py_TYPE(self)->tp_name,
                 Py_TYPE(value)->tp_name);
    return NULL;
  }

  if (value->ele != self->ele) {
    BM_elem_attrs_copy_ex(value->bm, self->bm, value->ele, self->ele, 0xff, CD_MASK_BM_ELEM_PYPTR);
  }

  Py_RETURN_NONE;
}

/* Vert
 * ---- */

PyDoc_STRVAR(bpy_bmvert_copy_from_vert_interp_doc,
             ".. method:: copy_from_vert_interp(vert_pair, fac)\n"
             "\n"
             "   Interpolate the customdata from a vert between 2 other verts.\n"
             "\n"
             "   :arg vert_pair: The vert to interpolate data from.\n"
             "   :type vert_pair: :class:`BMVert`\n");
static PyObject *bpy_bmvert_copy_from_vert_interp(BPy_BMVert *self, PyObject *args)
{
  PyObject *vert_seq;
  float fac;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "Of:BMVert.copy_from_vert_interp", &vert_seq, &fac)) {
    return NULL;
  }

  BMesh *bm = self->bm;
  BMVert **vert_array = NULL;
  Py_ssize_t vert_seq_len; /* always 2 */

  vert_array = BPy_BMElem_PySeq_As_Array(&bm,
                                         vert_seq,
                                         2,
                                         2,
                                         &vert_seq_len,
                                         BM_VERT,
                                         true,
                                         true,
                                         "BMVert.copy_from_vert_interp(...)");

  if (vert_array == NULL) {
    return NULL;
  }

  BM_data_interp_from_verts(bm, vert_array[0], vert_array[1], self->v, clamp_f(fac, 0.0f, 1.0f));

  PyMem_FREE(vert_array);
  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmvert_copy_from_face_interp_doc,
             ".. method:: copy_from_face_interp(face)\n"
             "\n"
             "   Interpolate the customdata from a face onto this loop (the loops vert should "
             "overlap the face).\n"
             "\n"
             "   :arg face: The face to interpolate data from.\n"
             "   :type face: :class:`BMFace`\n");
static PyObject *bpy_bmvert_copy_from_face_interp(BPy_BMVert *self, PyObject *args)
{
  BPy_BMFace *py_face = NULL;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "O!:BMVert.copy_from_face_interp", &BPy_BMFace_Type, &py_face)) {
    return NULL;
  }

  BMesh *bm = self->bm;

  BPY_BM_CHECK_SOURCE_OBJ(bm, "copy_from_face_interp()", py_face);

  BM_vert_interp_from_face(bm, self->v, py_face->f);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmvert_calc_edge_angle_doc,
             ".. method:: calc_edge_angle(fallback=None)\n"
             "\n"
             "   Return the angle between this vert's two connected edges.\n"
             "\n"
             "   :arg fallback: return this when the vert doesn't have 2 edges\n"
             "      (instead of raising a :exc:`ValueError`).\n"
             "   :type fallback: any\n"
             "   :return: Angle between edges in radians.\n"
             "   :rtype: float\n");
static PyObject *bpy_bmvert_calc_edge_angle(BPy_BMVert *self, PyObject *args)
{
  const float angle_invalid = -1.0f;
  float angle;
  PyObject *fallback = NULL;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "|O:calc_edge_angle", &fallback)) {
    return NULL;
  }

  angle = BM_vert_calc_edge_angle_ex(self->v, angle_invalid);

  if (angle == angle_invalid) {
    /* avoid exception */
    if (fallback) {
      Py_INCREF(fallback);
      return fallback;
    }

    PyErr_SetString(PyExc_ValueError,
                    "BMVert.calc_edge_angle(): "
                    "vert must connect to exactly 2 edges");
    return NULL;
  }

  return PyFloat_FromDouble(angle);
}

PyDoc_STRVAR(
    bpy_bmvert_calc_shell_factor_doc,
    ".. method:: calc_shell_factor()\n"
    "\n"
    "   Return a multiplier calculated based on the sharpness of the vertex.\n"
    "   Where a flat surface gives 1.0, and higher values sharper edges.\n"
    "   This is used to maintain shell thickness when offsetting verts along their normals.\n"
    "\n"
    "   :return: offset multiplier\n"
    "   :rtype: float\n");
static PyObject *bpy_bmvert_calc_shell_factor(BPy_BMVert *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyFloat_FromDouble(BM_vert_calc_shell_factor(self->v));
}

PyDoc_STRVAR(bpy_bmvert_normal_update_doc,
             ".. method:: normal_update()\n"
             "\n"
             "   Update vertex normal.\n"
             "   This does not update the normals of adjoining faces.\n"
             "\n"
             "   .. note::\n"
             "\n"
             "      The vertex normal will be a zero vector if vertex :attr:`is_wire` is True.\n");
static PyObject *bpy_bmvert_normal_update(BPy_BMVert *self)
{
  BPY_BM_CHECK_OBJ(self);

  BM_vert_normal_update(self->v);

  Py_RETURN_NONE;
}

/* Edge
 * ---- */

PyDoc_STRVAR(bpy_bmedge_calc_length_doc,
             ".. method:: calc_length()\n"
             "\n"
             "   :return: The length between both verts.\n"
             "   :rtype: float\n");
static PyObject *bpy_bmedge_calc_length(BPy_BMEdge *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyFloat_FromDouble(len_v3v3(self->e->v1->co, self->e->v2->co));
}

PyDoc_STRVAR(bpy_bmedge_calc_face_angle_doc,
             ".. method:: calc_face_angle(fallback=None)\n"
             "\n"
             "   :arg fallback: return this when the edge doesn't have 2 faces\n"
             "      (instead of raising a :exc:`ValueError`).\n"
             "   :type fallback: any\n"
             "   :return: The angle between 2 connected faces in radians.\n"
             "   :rtype: float\n");
static PyObject *bpy_bmedge_calc_face_angle(BPy_BMEdge *self, PyObject *args)
{
  const float angle_invalid = -1.0f;
  float angle;
  PyObject *fallback = NULL;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "|O:calc_face_angle", &fallback)) {
    return NULL;
  }

  angle = BM_edge_calc_face_angle_ex(self->e, angle_invalid);

  if (angle == angle_invalid) {
    /* avoid exception */
    if (fallback) {
      Py_INCREF(fallback);
      return fallback;
    }

    PyErr_SetString(PyExc_ValueError,
                    "BMEdge.calc_face_angle(): "
                    "edge doesn't use 2 faces");
    return NULL;
  }

  return PyFloat_FromDouble(angle);
}

PyDoc_STRVAR(
    bpy_bmedge_calc_face_angle_signed_doc,
    ".. method:: calc_face_angle_signed(fallback=None)\n"
    "\n"
    "   :arg fallback: return this when the edge doesn't have 2 faces\n"
    "      (instead of raising a :exc:`ValueError`).\n"
    "   :type fallback: any\n"
    "   :return: The angle between 2 connected faces in radians (negative for concave join).\n"
    "   :rtype: float\n");
static PyObject *bpy_bmedge_calc_face_angle_signed(BPy_BMEdge *self, PyObject *args)
{
  const float angle_invalid = -FLT_MAX;
  float angle;
  PyObject *fallback = NULL;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "|O:calc_face_angle_signed", &fallback)) {
    return NULL;
  }

  angle = BM_edge_calc_face_angle_signed_ex(self->e, angle_invalid);

  if (angle == angle_invalid) {
    /* avoid exception */
    if (fallback) {
      Py_INCREF(fallback);
      return fallback;
    }

    PyErr_SetString(PyExc_ValueError,
                    "BMEdge.calc_face_angle_signed(): "
                    "edge doesn't use 2 faces");
    return NULL;
  }

  return PyFloat_FromDouble(angle);
}

PyDoc_STRVAR(
    bpy_bmedge_calc_tangent_doc,
    ".. method:: calc_tangent(loop)\n"
    "\n"
    "   Return the tangent at this edge relative to a face (pointing inward into the face).\n"
    "   This uses the face normal for calculation.\n"
    "\n"
    "   :arg loop: The loop used for tangent calculation.\n"
    "   :type loop: :class:`BMLoop`\n"
    "   :return: a normalized vector.\n"
    "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmedge_calc_tangent(BPy_BMEdge *self, PyObject *args)
{
  BPy_BMLoop *py_loop;
  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "O!:BMEdge.calc_face_tangent", &BPy_BMLoop_Type, &py_loop)) {
    return NULL;
  }

  float vec[3];
  BPY_BM_CHECK_OBJ(py_loop);
  /* no need to check if they are from the same mesh or even connected */
  BM_edge_calc_face_tangent(self->e, py_loop->l, vec);
  return Vector_CreatePyObject(vec, 3, NULL);
}

PyDoc_STRVAR(
    bpy_bmedge_other_vert_doc,
    ".. method:: other_vert(vert)\n"
    "\n"
    "   Return the other vertex on this edge or None if the vertex is not used by this edge.\n"
    "\n"
    "   :arg vert: a vert in this edge.\n"
    "   :type vert: :class:`BMVert`\n"
    "   :return: The edges other vert.\n"
    "   :rtype: :class:`BMVert` or None\n");
static PyObject *bpy_bmedge_other_vert(BPy_BMEdge *self, BPy_BMVert *value)
{
  BMVert *other;
  BPY_BM_CHECK_OBJ(self);

  if (!BPy_BMVert_Check(value)) {
    PyErr_Format(PyExc_TypeError,
                 "BMEdge.other_vert(vert): BMVert expected, not '%.200s'",
                 Py_TYPE(value)->tp_name);
    return NULL;
  }

  BPY_BM_CHECK_SOURCE_OBJ(self->bm, "BMEdge.other_vert(vert)", value);

  other = BM_edge_other_vert(self->e, value->v);

  if (other) {
    return BPy_BMVert_CreatePyObject(self->bm, other);
  }

  /* could raise an exception here */
  Py_RETURN_NONE;
}

PyDoc_STRVAR(
    bpy_bmedge_normal_update_doc,
    ".. method:: normal_update()\n"
    "\n"
    "   Update normals of all connected faces and the edge verts.\n"
    "\n"
    "   .. note::\n"
    "\n"
    "      The normal of edge vertex will be a zero vector if vertex :attr:`is_wire` is True.\n");
static PyObject *bpy_bmedge_normal_update(BPy_BMEdge *self)
{
  BPY_BM_CHECK_OBJ(self);

  BM_edge_normals_update(self->e);

  Py_RETURN_NONE;
}

/* Face
 * ---- */

PyDoc_STRVAR(
    bpy_bmface_copy_from_face_interp_doc,
    ".. method:: copy_from_face_interp(face, vert=True)\n"
    "\n"
    "   Interpolate the customdata from another face onto this one (faces should overlap).\n"
    "\n"
    "   :arg face: The face to interpolate data from.\n"
    "   :type face: :class:`BMFace`\n"
    "   :arg vert: When True, also copy vertex data.\n"
    "   :type vert: boolean\n");
static PyObject *bpy_bmface_copy_from_face_interp(BPy_BMFace *self, PyObject *args)
{
  BPy_BMFace *py_face = NULL;
  bool do_vertex = true;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args,
                        "O!|O&:BMFace.copy_from_face_interp",
                        &BPy_BMFace_Type,
                        &py_face,
                        PyC_ParseBool,
                        &do_vertex)) {
    return NULL;
  }

  BMesh *bm = self->bm;

  BPY_BM_CHECK_SOURCE_OBJ(bm, "BMFace.copy_from_face_interp(face)", py_face);

  BM_face_interp_from_face(bm, self->f, py_face->f, do_vertex);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmface_copy_doc,
             ".. method:: copy(verts=True, edges=True)\n"
             "\n"
             "   Make a copy of this face.\n"
             "\n"
             "   :arg verts: When set, the faces verts will be duplicated too.\n"
             "   :type verts: boolean\n"
             "   :arg edges: When set, the faces edges will be duplicated too.\n"
             "   :type edges: boolean\n"
             "   :return: The newly created face.\n"
             "   :rtype: :class:`BMFace`\n");
static PyObject *bpy_bmface_copy(BPy_BMFace *self, PyObject *args, PyObject *kw)
{
  static const char *kwlist[] = {"verts", "edges", NULL};

  BMesh *bm = self->bm;
  bool do_verts = true;
  bool do_edges = true;

  BMFace *f_cpy;
  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTupleAndKeywords(args,
                                   kw,
                                   "|$O&O&:BMFace.copy",
                                   (char **)kwlist,
                                   PyC_ParseBool,
                                   &do_verts,
                                   PyC_ParseBool,
                                   &do_edges)) {
    return NULL;
  }

  f_cpy = BM_face_copy(bm, bm, self->f, do_verts, do_edges);

  if (f_cpy) {
    return BPy_BMFace_CreatePyObject(bm, f_cpy);
  }

  PyErr_SetString(PyExc_ValueError, "BMFace.copy(): couldn't create the new face, internal error");
  return NULL;
}

PyDoc_STRVAR(bpy_bmface_calc_area_doc,
             ".. method:: calc_area()\n"
             "\n"
             "   Return the area of the face.\n"
             "\n"
             "   :return: Return the area of the face.\n"
             "   :rtype: float\n");
static PyObject *bpy_bmface_calc_area(BPy_BMFace *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyFloat_FromDouble(BM_face_calc_area(self->f));
}

PyDoc_STRVAR(bpy_bmface_calc_perimeter_doc,
             ".. method:: calc_perimeter()\n"
             "\n"
             "   Return the perimeter of the face.\n"
             "\n"
             "   :return: Return the perimeter of the face.\n"
             "   :rtype: float\n");
static PyObject *bpy_bmface_calc_perimeter(BPy_BMFace *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyFloat_FromDouble(BM_face_calc_perimeter(self->f));
}

PyDoc_STRVAR(bpy_bmface_calc_tangent_edge_doc,
             ".. method:: calc_tangent_edge()\n"
             "\n"
             "   Return face tangent based on longest edge.\n"
             "\n"
             "   :return: a normalized vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmface_calc_tangent_edge(BPy_BMFace *self)
{
  float tangent[3];

  BPY_BM_CHECK_OBJ(self);
  BM_face_calc_tangent_edge(self->f, tangent);
  return Vector_CreatePyObject(tangent, 3, NULL);
}

PyDoc_STRVAR(bpy_bmface_calc_tangent_edge_pair_doc,
             ".. method:: calc_tangent_edge_pair()\n"
             "\n"
             "   Return face tangent based on the two longest disconnected edges.\n"
             "\n"
             "   - Tris: Use the edge pair with the most similar lengths.\n"
             "   - Quads: Use the longest edge pair.\n"
             "   - NGons: Use the two longest disconnected edges.\n"
             "\n"
             "   :return: a normalized vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmface_calc_tangent_edge_pair(BPy_BMFace *self)
{
  float tangent[3];

  BPY_BM_CHECK_OBJ(self);
  BM_face_calc_tangent_edge_pair(self->f, tangent);
  return Vector_CreatePyObject(tangent, 3, NULL);
}

PyDoc_STRVAR(bpy_bmface_calc_tangent_edge_diagonal_doc,
             ".. method:: calc_tangent_edge_diagonal()\n"
             "\n"
             "   Return face tangent based on the edge farthest from any vertex.\n"
             "\n"
             "   :return: a normalized vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmface_calc_tangent_edge_diagonal(BPy_BMFace *self)
{
  float tangent[3];

  BPY_BM_CHECK_OBJ(self);
  BM_face_calc_tangent_edge_diagonal(self->f, tangent);
  return Vector_CreatePyObject(tangent, 3, NULL);
}

PyDoc_STRVAR(bpy_bmface_calc_tangent_vert_diagonal_doc,
             ".. method:: calc_tangent_vert_diagonal()\n"
             "\n"
             "   Return face tangent based on the two most distant vertices.\n"
             "\n"
             "   :return: a normalized vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmface_calc_tangent_vert_diagonal(BPy_BMFace *self)
{
  float tangent[3];

  BPY_BM_CHECK_OBJ(self);
  BM_face_calc_tangent_vert_diagonal(self->f, tangent);
  return Vector_CreatePyObject(tangent, 3, NULL);
}

PyDoc_STRVAR(bpy_bmface_calc_center_median_doc,
             ".. method:: calc_center_median()\n"
             "\n"
             "   Return median center of the face.\n"
             "\n"
             "   :return: a 3D vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmface_calc_center_mean(BPy_BMFace *self)
{
  float cent[3];

  BPY_BM_CHECK_OBJ(self);
  BM_face_calc_center_median(self->f, cent);
  return Vector_CreatePyObject(cent, 3, NULL);
}

PyDoc_STRVAR(bpy_bmface_calc_center_median_weighted_doc,
             ".. method:: calc_center_median_weighted()\n"
             "\n"
             "   Return median center of the face weighted by edge lengths.\n"
             "\n"
             "   :return: a 3D vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmface_calc_center_median_weighted(BPy_BMFace *self)
{
  float cent[3];

  BPY_BM_CHECK_OBJ(self);
  BM_face_calc_center_median_weighted(self->f, cent);
  return Vector_CreatePyObject(cent, 3, NULL);
}

PyDoc_STRVAR(bpy_bmface_calc_center_bounds_doc,
             ".. method:: calc_center_bounds()\n"
             "\n"
             "   Return bounds center of the face.\n"
             "\n"
             "   :return: a 3D vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmface_calc_center_bounds(BPy_BMFace *self)
{
  float cent[3];

  BPY_BM_CHECK_OBJ(self);
  BM_face_calc_center_bounds(self->f, cent);
  return Vector_CreatePyObject(cent, 3, NULL);
}

PyDoc_STRVAR(bpy_bmface_normal_update_doc,
             ".. method:: normal_update()\n"
             "\n"
             "   Update face normal based on the positions of the face verts.\n"
             "   This does not update the normals of face verts.\n");
static PyObject *bpy_bmface_normal_update(BPy_BMFace *self)
{
  BPY_BM_CHECK_OBJ(self);

  BM_face_normal_update(self->f);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmface_normal_flip_doc,
             ".. method:: normal_flip()\n"
             "\n"
             "   Reverses winding of a face, which flips its normal.\n");
static PyObject *bpy_bmface_normal_flip(BPy_BMFace *self)
{
  BPY_BM_CHECK_OBJ(self);

  BM_face_normal_flip(self->bm, self->f);

  Py_RETURN_NONE;
}

/* Loop
 * ---- */

PyDoc_STRVAR(bpy_bmloop_copy_from_face_interp_doc,
             ".. method:: copy_from_face_interp(face, vert=True, multires=True)\n"
             "\n"
             "   Interpolate the customdata from a face onto this loop (the loops vert should "
             "overlap the face).\n"
             "\n"
             "   :arg face: The face to interpolate data from.\n"
             "   :type face: :class:`BMFace`\n"
             "   :arg vert: When enabled, interpolate the loops vertex data (optional).\n"
             "   :type vert: boolean\n"
             "   :arg multires: When enabled, interpolate the loops multires data (optional).\n"
             "   :type multires: boolean\n");
static PyObject *bpy_bmloop_copy_from_face_interp(BPy_BMLoop *self, PyObject *args)
{
  BPy_BMFace *py_face = NULL;
  bool do_vertex = true;
  bool do_multires = true;

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args,
                        "O!|O&O&:BMLoop.copy_from_face_interp",
                        &BPy_BMFace_Type,
                        &py_face,
                        PyC_ParseBool,
                        &do_vertex,
                        PyC_ParseBool,
                        &do_multires)) {
    return NULL;
  }

  BMesh *bm = self->bm;

  BPY_BM_CHECK_SOURCE_OBJ(bm, "BMLoop.copy_from_face_interp(face)", py_face);

  BM_loop_interp_from_face(bm, self->l, py_face->f, do_vertex, do_multires);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmloop_calc_angle_doc,
             ".. method:: calc_angle()\n"
             "\n"
             "   Return the angle at this loops corner of the face.\n"
             "   This is calculated so sharper corners give lower angles.\n"
             "\n"
             "   :return: The angle in radians.\n"
             "   :rtype: float\n");
static PyObject *bpy_bmloop_calc_angle(BPy_BMLoop *self)
{
  BPY_BM_CHECK_OBJ(self);
  return PyFloat_FromDouble(BM_loop_calc_face_angle(self->l));
}

PyDoc_STRVAR(bpy_bmloop_calc_normal_doc,
             ".. method:: calc_normal()\n"
             "\n"
             "   Return normal at this loops corner of the face.\n"
             "   Falls back to the face normal for straight lines.\n"
             "\n"
             "   :return: a normalized vector.\n"
             "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmloop_calc_normal(BPy_BMLoop *self)
{
  float vec[3];
  BPY_BM_CHECK_OBJ(self);
  BM_loop_calc_face_normal(self->l, vec);
  return Vector_CreatePyObject(vec, 3, NULL);
}

PyDoc_STRVAR(
    bpy_bmloop_calc_tangent_doc,
    ".. method:: calc_tangent()\n"
    "\n"
    "   Return the tangent at this loops corner of the face (pointing inward into the face).\n"
    "   Falls back to the face normal for straight lines.\n"
    "\n"
    "   :return: a normalized vector.\n"
    "   :rtype: :class:`mathutils.Vector`\n");
static PyObject *bpy_bmloop_calc_tangent(BPy_BMLoop *self)
{
  float vec[3];
  BPY_BM_CHECK_OBJ(self);
  BM_loop_calc_face_tangent(self->l, vec);
  return Vector_CreatePyObject(vec, 3, NULL);
}

/* Vert Seq
 * -------- */
PyDoc_STRVAR(bpy_bmvertseq_new_doc,
             ".. method:: new(co=(0.0, 0.0, 0.0), example=None)\n"
             "\n"
             "   Create a new vertex.\n"
             "\n"
             "   :arg co: The initial location of the vertex (optional argument).\n"
             "   :type co: float triplet\n"
             "   :arg example: Existing vert to initialize settings.\n"
             "   :type example: :class:`BMVert`\n"
             "   :return: The newly created edge.\n"
             "   :rtype: :class:`BMVert`\n");
static PyObject *bpy_bmvertseq_new(BPy_BMElemSeq *self, PyObject *args)
{
  PyObject *py_co = NULL;
  BPy_BMVert *py_vert_example = NULL; /* optional */

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "|OO!:verts.new", &py_co, &BPy_BMVert_Type, &py_vert_example)) {
    return NULL;
  }

  BMesh *bm = self->bm;
  BMVert *v;
  float co[3] = {0.0f, 0.0f, 0.0f};

  if (py_vert_example) {
    BPY_BM_CHECK_OBJ(py_vert_example);
  }

  if (py_co && mathutils_array_parse(co, 3, 3, py_co, "verts.new(co)") == -1) {
    return NULL;
  }

  v = BM_vert_create(bm, co, NULL, BM_CREATE_NOP);

  if (v == NULL) {
    PyErr_SetString(PyExc_ValueError,
                    "faces.new(verts): couldn't create the new face, internal error");
    return NULL;
  }

  if (py_vert_example) {
    BM_elem_attrs_copy(py_vert_example->bm, bm, py_vert_example->v, v);
  }

  return BPy_BMVert_CreatePyObject(bm, v);
}

/* Edge Seq
 * -------- */
PyDoc_STRVAR(bpy_bmedgeseq_new_doc,
             ".. method:: new(verts, example=None)\n"
             "\n"
             "   Create a new edge from a given pair of verts.\n"
             "\n"
             "   :arg verts: Vertex pair.\n"
             "   :type verts: pair of :class:`BMVert`\n"
             "   :arg example: Existing edge to initialize settings (optional argument).\n"
             "   :type example: :class:`BMEdge`\n"
             "   :return: The newly created edge.\n"
             "   :rtype: :class:`BMEdge`\n");
static PyObject *bpy_bmedgeseq_new(BPy_BMElemSeq *self, PyObject *args)
{
  PyObject *vert_seq;
  BPy_BMEdge *py_edge_example = NULL; /* optional */

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "O|O!:edges.new", &vert_seq, &BPy_BMEdge_Type, &py_edge_example)) {
    return NULL;
  }

  BMesh *bm = self->bm;
  BMEdge *e;
  BMVert **vert_array = NULL;
  Py_ssize_t vert_seq_len; /* always 2 */
  PyObject *ret = NULL;

  if (py_edge_example) {
    BPY_BM_CHECK_OBJ(py_edge_example);
  }

  vert_array = BPy_BMElem_PySeq_As_Array(
      &bm, vert_seq, 2, 2, &vert_seq_len, BM_VERT, true, true, "edges.new(...)");

  if (vert_array == NULL) {
    return NULL;
  }

  if (BM_edge_exists(vert_array[0], vert_array[1])) {
    PyErr_SetString(PyExc_ValueError, "edges.new(): this edge exists");
    goto cleanup;
  }

  e = BM_edge_create(bm, vert_array[0], vert_array[1], NULL, BM_CREATE_NOP);

  if (e == NULL) {
    PyErr_SetString(PyExc_ValueError,
                    "faces.new(verts): couldn't create the new face, internal error");
    goto cleanup;
  }

  if (py_edge_example) {
    BM_elem_attrs_copy(py_edge_example->bm, bm, py_edge_example->e, e);
  }

  ret = BPy_BMEdge_CreatePyObject(bm, e);

cleanup:
  if (vert_array) {
    PyMem_FREE(vert_array);
  }
  return ret;
}

/* Face Seq
 * -------- */
PyDoc_STRVAR(bpy_bmfaceseq_new_doc,
             ".. method:: new(verts, example=None)\n"
             "\n"
             "   Create a new face from a given set of verts.\n"
             "\n"
             "   :arg verts: Sequence of 3 or more verts.\n"
             "   :type verts: :class:`BMVert`\n"
             "   :arg example: Existing face to initialize settings (optional argument).\n"
             "   :type example: :class:`BMFace`\n"
             "   :return: The newly created face.\n"
             "   :rtype: :class:`BMFace`\n");
static PyObject *bpy_bmfaceseq_new(BPy_BMElemSeq *self, PyObject *args)
{
  PyObject *vert_seq;
  BPy_BMFace *py_face_example = NULL; /* optional */

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "O|O!:faces.new", &vert_seq, &BPy_BMFace_Type, &py_face_example)) {
    return NULL;
  }

  BMesh *bm = self->bm;
  Py_ssize_t vert_seq_len;

  BMVert **vert_array = NULL;

  PyObject *ret = NULL;

  BMFace *f_new;

  if (py_face_example) {
    BPY_BM_CHECK_OBJ(py_face_example);
  }

  vert_array = BPy_BMElem_PySeq_As_Array(
      &bm, vert_seq, 3, PY_SSIZE_T_MAX, &vert_seq_len, BM_VERT, true, true, "faces.new(...)");

  if (vert_array == NULL) {
    return NULL;
  }

  /* check if the face exists */
  if (BM_face_exists(vert_array, vert_seq_len) != NULL) {
    PyErr_SetString(PyExc_ValueError, "faces.new(verts): face already exists");
    goto cleanup;
  }

  /* Go ahead and make the face!
   * --------------------------- */

  f_new = BM_face_create_verts(bm,
                               vert_array,
                               vert_seq_len,
                               py_face_example ? py_face_example->f : NULL,
                               BM_CREATE_NOP,
                               true);

  if (UNLIKELY(f_new == NULL)) {
    PyErr_SetString(PyExc_ValueError,
                    "faces.new(verts): couldn't create the new face, internal error");
    goto cleanup;
  }

  ret = BPy_BMFace_CreatePyObject(bm, f_new);

  /* pass through */
cleanup:
  if (vert_array) {
    PyMem_FREE(vert_array);
  }
  return ret;
}

/* Elem Seq
 * -------- */

PyDoc_STRVAR(bpy_bmvertseq_remove_doc,
             ".. method:: remove(vert)\n"
             "\n"
             "   Remove a vert.\n");
static PyObject *bpy_bmvertseq_remove(BPy_BMElemSeq *self, BPy_BMVert *value)
{
  BPY_BM_CHECK_OBJ(self);

  if (!BPy_BMVert_Check(value)) {
    return NULL;
  }

  BMesh *bm = self->bm;

  BPY_BM_CHECK_SOURCE_OBJ(bm, "verts.remove(vert)", value);

  BM_vert_kill(bm, value->v);
  bpy_bm_generic_invalidate((BPy_BMGeneric *)value);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmedgeseq_remove_doc,
             ".. method:: remove(edge)\n"
             "\n"
             "   Remove an edge.\n");
static PyObject *bpy_bmedgeseq_remove(BPy_BMElemSeq *self, BPy_BMEdge *value)
{
  BPY_BM_CHECK_OBJ(self);

  if (!BPy_BMEdge_Check(value)) {
    return NULL;
  }

  BMesh *bm = self->bm;

  BPY_BM_CHECK_SOURCE_OBJ(bm, "edges.remove(edges)", value);

  BM_edge_kill(bm, value->e);
  bpy_bm_generic_invalidate((BPy_BMGeneric *)value);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmfaceseq_remove_doc,
             ".. method:: remove(face)\n"
             "\n"
             "   Remove a face.\n");
static PyObject *bpy_bmfaceseq_remove(BPy_BMElemSeq *self, BPy_BMFace *value)
{
  BPY_BM_CHECK_OBJ(self);

  if (!BPy_BMFace_Check(value)) {
    return NULL;
  }

  BMesh *bm = self->bm;

  BPY_BM_CHECK_SOURCE_OBJ(bm, "faces.remove(face)", value);

  BM_face_kill(bm, value->f);
  bpy_bm_generic_invalidate((BPy_BMGeneric *)value);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmedgeseq_get__method_doc,
             ".. method:: get(verts, fallback=None)\n"
             "\n"
             "   Return an edge which uses the **verts** passed.\n"
             "\n"
             "   :arg verts: Sequence of verts.\n"
             "   :type verts: :class:`BMVert`\n"
             "   :arg fallback: Return this value if nothing is found.\n"
             "   :return: The edge found or None\n"
             "   :rtype: :class:`BMEdge`\n");
static PyObject *bpy_bmedgeseq_get__method(BPy_BMElemSeq *self, PyObject *args)
{
  PyObject *vert_seq;
  PyObject *fallback = Py_None; /* optional */

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "O|O:edges.get", &vert_seq, &fallback)) {
    return NULL;
  }

  BMesh *bm = self->bm;
  BMEdge *e;
  BMVert **vert_array = NULL;
  Py_ssize_t vert_seq_len; /* always 2 */
  PyObject *ret = NULL;

  vert_array = BPy_BMElem_PySeq_As_Array(
      &bm, vert_seq, 2, 2, &vert_seq_len, BM_VERT, true, true, "edges.get(...)");

  if (vert_array == NULL) {
    return NULL;
  }

  if ((e = BM_edge_exists(vert_array[0], vert_array[1]))) {
    ret = BPy_BMEdge_CreatePyObject(bm, e);
  }
  else {
    ret = fallback;
    Py_INCREF(ret);
  }

  PyMem_FREE(vert_array);
  return ret;
}

PyDoc_STRVAR(bpy_bmfaceseq_get__method_doc,
             ".. method:: get(verts, fallback=None)\n"
             "\n"
             "   Return a face which uses the **verts** passed.\n"
             "\n"
             "   :arg verts: Sequence of verts.\n"
             "   :type verts: :class:`BMVert`\n"
             "   :arg fallback: Return this value if nothing is found.\n"
             "   :return: The face found or None\n"
             "   :rtype: :class:`BMFace`\n");
static PyObject *bpy_bmfaceseq_get__method(BPy_BMElemSeq *self, PyObject *args)
{
  PyObject *vert_seq;
  PyObject *fallback = Py_None; /* optional */

  BPY_BM_CHECK_OBJ(self);

  if (!PyArg_ParseTuple(args, "O|O:faces.get", &vert_seq, &fallback)) {
    return NULL;
  }

  BMesh *bm = self->bm;
  BMFace *f = NULL;
  BMVert **vert_array = NULL;
  Py_ssize_t vert_seq_len;
  PyObject *ret = NULL;

  vert_array = BPy_BMElem_PySeq_As_Array(
      &bm, vert_seq, 1, PY_SSIZE_T_MAX, &vert_seq_len, BM_VERT, true, true, "faces.get(...)");

  if (vert_array == NULL) {
    return NULL;
  }

  f = BM_face_exists(vert_array, vert_seq_len);
  if (f != NULL) {
    ret = BPy_BMFace_CreatePyObject(bm, f);
  }
  else {
    ret = fallback;
    Py_INCREF(ret);
  }

  PyMem_FREE(vert_array);
  return ret;
}

PyDoc_STRVAR(
    bpy_bmelemseq_index_update_doc,
    ".. method:: index_update()\n"
    "\n"
    "   Initialize the index values of this sequence.\n"
    "\n"
    "   This is the equivalent of looping over all elements and assigning the index values.\n"
    "\n"
    "   .. code-block:: python\n"
    "\n"
    "      for index, ele in enumerate(sequence):\n"
    "          ele.index = index\n"
    "\n"
    "   .. note::\n"
    "\n"
    "      Running this on sequences besides :class:`BMesh.verts`, :class:`BMesh.edges`, "
    ":class:`BMesh.faces`\n"
    "      works but won't result in each element having a valid index, instead its order in the "
    "sequence will be set.\n");
static PyObject *bpy_bmelemseq_index_update(BPy_BMElemSeq *self)
{
  BMesh *bm = self->bm;

  BPY_BM_CHECK_OBJ(self);

  switch ((BMIterType)self->itype) {
    case BM_VERTS_OF_MESH:
      BM_mesh_elem_index_ensure(self->bm, BM_VERT);
      break;
    case BM_EDGES_OF_MESH:
      BM_mesh_elem_index_ensure(self->bm, BM_EDGE);
      break;
    case BM_FACES_OF_MESH:
      BM_mesh_elem_index_ensure(self->bm, BM_FACE);
      break;
    default: {
      BMIter iter;
      BMElem *ele;
      int index = 0;
      const char htype = bm_iter_itype_htype_map[self->itype];

      BM_ITER_BPY_BM_SEQ (ele, &iter, self) {
        BM_elem_index_set(ele, index); /* set_dirty! */
        index++;
      }

      /* since this isn't the normal vert/edge/face loops,
       * we're setting dirty values here. so tag as dirty. */
      bm->elem_index_dirty |= htype;

      break;
    }
  }

  Py_RETURN_NONE;
}

PyDoc_STRVAR(bpy_bmelemseq_ensure_lookup_table_doc,
             ".. method:: ensure_lookup_table()\n"
             "\n"
             "   Ensure internal data needed for int subscription is initialized with "
             "verts/edges/faces, eg ``bm.verts[index]``.\n"
             "\n"
             "   This needs to be called again after adding/removing data in this sequence.");
static PyObject *bpy_bmelemseq_ensure_lookup_table(BPy_BMElemSeq *self)
{
  BPY_BM_CHECK_OBJ(self);

  BM_mesh_elem_table_ensure(self->bm, bm_iter_itype_htype_map[self->itype]);

  Py_RETURN_NONE;
}

PyDoc_STRVAR(
    bpy_bmelemseq_sort_doc,
    ".. method:: sort(key=None, reverse=False)\n"
    "\n"
    "   Sort the elements of this sequence, using an optional custom sort key.\n"
    "   Indices of elements are not changed, BMElemeSeq.index_update() can be used for that.\n"
    "\n"
    "   :arg key: The key that sets the ordering of the elements.\n"
    "   :type key: :function: returning a number\n"
    "   :arg reverse: Reverse the order of the elements\n"
    "   :type reverse: :boolean:\n"
    "\n"
    "   .. note::\n"
    "\n"
    "      When the 'key' argument is not provided, the elements are reordered following their "
    "current index value.\n"
    "      In particular this can be used by setting indices manually before calling this "
    "method.\n"
    "\n"
    "   .. warning::\n"
    "\n"
    "      Existing references to the N'th element, will continue to point the data at that "
    "index.\n");

/* Use a static variable here because there is the need to sort some array
 * doing comparisons on elements of another array, qsort_r would have been
 * wonderful to use here, but unfortunately it is not standard and it's not
 * portable across different platforms.
 *
 * If a portable alternative to qsort_r becomes available, remove this static
 * var hack!
 *
 * NOTE: the functions below assumes the keys array has been allocated and it
 * has enough elements to complete the task.
 */

static int bpy_bmelemseq_sort_cmp_by_keys_ascending(const void *index1_v,
                                                    const void *index2_v,
                                                    void *keys_v)
{
  const double *keys = keys_v;
  const int *index1 = (int *)index1_v;
  const int *index2 = (int *)index2_v;

  if (keys[*index1] < keys[*index2]) {
    return -1;
  }
  if (keys[*index1] > keys[*index2]) {
    return 1;
  }

  return 0;
}

static int bpy_bmelemseq_sort_cmp_by_keys_descending(const void *index1_v,
                                                     const void *index2_v,
                                                     void *keys_v)
{
  return -bpy_bmelemseq_sort_cmp_by_keys_ascending(index1_v, index2_v, keys_v);
}

static PyObject *bpy_bmelemseq_sort(BPy_BMElemSeq *self, PyObject *args, PyObject *kw)
{
  static const char *kwlist[] = {"key", "reverse", NULL};
  PyObject *keyfunc = NULL; /* optional */
  bool do_reverse = false;  /* optional */

  const char htype = bm_iter_itype_htype_map[self->itype];
  int n_elem;

  BMIter iter;
  BMElem *ele;

  double *keys;
  int *elem_idx;
  uint *elem_map_idx;
  int (*elem_idx_compare_by_keys)(const void *, const void *, void *);

  uint *vert_idx = NULL;
  uint *edge_idx = NULL;
  uint *face_idx = NULL;
  int i;

  BMesh *bm = self->bm;

  BPY_BM_CHECK_OBJ(self);

  if (args != NULL) {
    if (!PyArg_ParseTupleAndKeywords(args,
                                     kw,
                                     "|$OO&:BMElemSeq.sort",
                                     (char **)kwlist,
                                     &keyfunc,
                                     PyC_ParseBool,
                                     &do_reverse)) {
      return NULL;
    }
  }

  if (keyfunc != NULL && !PyCallable_Check(keyfunc)) {
    PyErr_SetString(PyExc_TypeError, "the 'key' argument is not a callable object");
    return NULL;
  }

  n_elem = BM_mesh_elem_count(bm, htype);
  if (n_elem <= 1) {
    /* 0 or 1 elements: sorted already */
    Py_RETURN_NONE;
  }

  keys = PyMem_MALLOC(sizeof(*keys) * n_elem);
  if (keys == NULL) {
    PyErr_NoMemory();
    return NULL;
  }

  i = 0;
  BM_ITER_BPY_BM_SEQ (ele, &iter, self) {
    if (keyfunc != NULL) {
      PyObject *py_elem;
      PyObject *index;

      py_elem = BPy_BMElem_CreatePyObject(self->bm, (BMHeader *)ele);
      index = PyObject_CallFunctionObjArgs(keyfunc, py_elem, NULL);
      Py_DECREF(py_elem);
      if (index == NULL) {
        /* No need to set the exception here,
         * PyObject_CallFunctionObjArgs() does that */
        PyMem_FREE(keys);
        return NULL;
      }

      if ((keys[i] = PyFloat_AsDouble(index)) == -1 && PyErr_Occurred()) {
        PyErr_SetString(PyExc_ValueError,
                        "the value returned by the 'key' function is not a number");
        Py_DECREF(index);
        PyMem_FREE(keys);
        return NULL;
      }

      Py_DECREF(index);
    }
    else {
      /* If the 'key' function is not provided we sort
       * according to the current index values */
      keys[i] = ele->head.index;
    }

    i++;
  }

  elem_idx = PyMem_MALLOC(sizeof(*elem_idx) * n_elem);
  if (elem_idx == NULL) {
    PyErr_NoMemory();
    PyMem_FREE(keys);
    return NULL;
  }

  /* Initialize the element index array */
  range_vn_i(elem_idx, n_elem, 0);

  /* Sort the index array according to the order of the 'keys' array */
  if (do_reverse) {
    elem_idx_compare_by_keys = bpy_bmelemseq_sort_cmp_by_keys_descending;
  }
  else {
    elem_idx_compare_by_keys = bpy_bmelemseq_sort_cmp_by_keys_ascending;
  }

  BLI_qsort_r(elem_idx, n_elem, sizeof(*elem_idx), elem_idx_compare_by_keys, keys);

  elem_map_idx = PyMem_MALLOC(sizeof(*elem_map_idx) * n_elem);
  if (elem_map_idx == NULL) {
    PyErr_NoMemory();
    PyMem_FREE(elem_idx);
    PyMem_FREE(keys);
    return NULL;
  }

  /* Initialize the map array
   *
   * We need to know the index such that if used as the new_index in
   * BM_mesh_remap() will give the order of the sorted keys like in
   * elem_idx */
  for (i = 0; i < n_elem; i++) {
    elem_map_idx[elem_idx[i]] = i;
  }

  switch ((BMIterType)self->itype) {
    case BM_VERTS_OF_MESH:
      vert_idx = elem_map_idx;
      break;
    case BM_EDGES_OF_MESH:
      edge_idx = elem_map_idx;
      break;
    case BM_FACES_OF_MESH:
      face_idx = elem_map_idx;
      break;
    default:
      PyErr_Format(PyExc_TypeError, "element type %d not supported", self->itype);
      PyMem_FREE(elem_map_idx);
      PyMem_FREE(elem_idx);
      PyMem_FREE(keys);
      return NULL;
  }

  BM_mesh_remap(bm, vert_idx, edge_idx, face_idx);

  PyMem_FREE(elem_map_idx);
  PyMem_FREE(elem_idx);
  PyMem_FREE(keys);

  Py_RETURN_NONE;
}

static struct PyMethodDef bpy_bmesh_methods[] = {
    /* utility */
    {"copy", (PyCFunction)bpy_bmesh_copy, METH_NOARGS, bpy_bmesh_copy_doc},
    {"clear", (PyCFunction)bpy_bmesh_clear, METH_NOARGS, bpy_bmesh_clear_doc},
    {"free", (PyCFunction)bpy_bmesh_free, METH_NOARGS, bpy_bmesh_free_doc},

    /* conversion */
    {"from_object",
     (PyCFunction)bpy_bmesh_from_object,
     METH_VARARGS | METH_KEYWORDS,
     bpy_bmesh_from_object_doc},
    {"from_mesh",
     (PyCFunction)bpy_bmesh_from_mesh,
     METH_VARARGS | METH_KEYWORDS,
     bpy_bmesh_from_mesh_doc},
    {"to_mesh", (PyCFunction)bpy_bmesh_to_mesh, METH_VARARGS, bpy_bmesh_to_mesh_doc},

    /* meshdata */
    {"select_flush_mode",
     (PyCFunction)bpy_bmesh_select_flush_mode,
     METH_NOARGS,
     bpy_bmesh_select_flush_mode_doc},
    {"select_flush", (PyCFunction)bpy_bmesh_select_flush, METH_O, bpy_bmesh_select_flush_doc},
    {"normal_update",
     (PyCFunction)bpy_bmesh_normal_update,
     METH_NOARGS,
     bpy_bmesh_normal_update_doc},
    {"transform",
     (PyCFunction)bpy_bmesh_transform,
     METH_VARARGS | METH_KEYWORDS,
     bpy_bmesh_transform_doc},

    /* calculations */
    {"calc_volume",
     (PyCFunction)bpy_bmesh_calc_volume,
     METH_VARARGS | METH_KEYWORDS,
     bpy_bmesh_calc_volume_doc},
    {"calc_loop_triangles",
     (PyCFunction)bpy_bmesh_calc_loop_triangles,
     METH_NOARGS,
     bpy_bmesh_calc_loop_triangles_doc},
    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmvert_methods[] = {
    {"select_set", (PyCFunction)bpy_bm_elem_select_set, METH_O, bpy_bm_elem_select_set_doc},
    {"hide_set", (PyCFunction)bpy_bm_elem_hide_set, METH_O, bpy_bm_elem_hide_set_doc},
    {"copy_from", (PyCFunction)bpy_bm_elem_copy_from, METH_O, bpy_bm_elem_copy_from_doc},
    {"copy_from_face_interp",
     (PyCFunction)bpy_bmvert_copy_from_face_interp,
     METH_VARARGS,
     bpy_bmvert_copy_from_face_interp_doc},
    {"copy_from_vert_interp",
     (PyCFunction)bpy_bmvert_copy_from_vert_interp,
     METH_VARARGS,
     bpy_bmvert_copy_from_vert_interp_doc},

    {"calc_edge_angle",
     (PyCFunction)bpy_bmvert_calc_edge_angle,
     METH_VARARGS,
     bpy_bmvert_calc_edge_angle_doc},
    {"calc_shell_factor",
     (PyCFunction)bpy_bmvert_calc_shell_factor,
     METH_NOARGS,
     bpy_bmvert_calc_shell_factor_doc},

    {"normal_update",
     (PyCFunction)bpy_bmvert_normal_update,
     METH_NOARGS,
     bpy_bmvert_normal_update_doc},

    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmedge_methods[] = {
    {"select_set", (PyCFunction)bpy_bm_elem_select_set, METH_O, bpy_bm_elem_select_set_doc},
    {"hide_set", (PyCFunction)bpy_bm_elem_hide_set, METH_O, bpy_bm_elem_hide_set_doc},
    {"copy_from", (PyCFunction)bpy_bm_elem_copy_from, METH_O, bpy_bm_elem_copy_from_doc},

    {"other_vert", (PyCFunction)bpy_bmedge_other_vert, METH_O, bpy_bmedge_other_vert_doc},

    {"calc_length", (PyCFunction)bpy_bmedge_calc_length, METH_NOARGS, bpy_bmedge_calc_length_doc},
    {"calc_face_angle",
     (PyCFunction)bpy_bmedge_calc_face_angle,
     METH_VARARGS,
     bpy_bmedge_calc_face_angle_doc},
    {"calc_face_angle_signed",
     (PyCFunction)bpy_bmedge_calc_face_angle_signed,
     METH_VARARGS,
     bpy_bmedge_calc_face_angle_signed_doc},
    {"calc_tangent",
     (PyCFunction)bpy_bmedge_calc_tangent,
     METH_VARARGS,
     bpy_bmedge_calc_tangent_doc},

    {"normal_update",
     (PyCFunction)bpy_bmedge_normal_update,
     METH_NOARGS,
     bpy_bmedge_normal_update_doc},

    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmface_methods[] = {
    {"select_set", (PyCFunction)bpy_bm_elem_select_set, METH_O, bpy_bm_elem_select_set_doc},
    {"hide_set", (PyCFunction)bpy_bm_elem_hide_set, METH_O, bpy_bm_elem_hide_set_doc},

    {"copy_from", (PyCFunction)bpy_bm_elem_copy_from, METH_O, bpy_bm_elem_copy_from_doc},
    {"copy_from_face_interp",
     (PyCFunction)bpy_bmface_copy_from_face_interp,
     METH_O,
     bpy_bmface_copy_from_face_interp_doc},

    {"copy", (PyCFunction)bpy_bmface_copy, METH_VARARGS | METH_KEYWORDS, bpy_bmface_copy_doc},

    {"calc_area", (PyCFunction)bpy_bmface_calc_area, METH_NOARGS, bpy_bmface_calc_area_doc},
    {"calc_perimeter",
     (PyCFunction)bpy_bmface_calc_perimeter,
     METH_NOARGS,
     bpy_bmface_calc_perimeter_doc},
    {"calc_tangent_edge",
     (PyCFunction)bpy_bmface_calc_tangent_edge,
     METH_NOARGS,
     bpy_bmface_calc_tangent_edge_doc},
    {"calc_tangent_edge_pair",
     (PyCFunction)bpy_bmface_calc_tangent_edge_pair,
     METH_NOARGS,
     bpy_bmface_calc_tangent_edge_pair_doc},
    {"calc_tangent_edge_diagonal",
     (PyCFunction)bpy_bmface_calc_tangent_edge_diagonal,
     METH_NOARGS,
     bpy_bmface_calc_tangent_edge_diagonal_doc},
    {"calc_tangent_vert_diagonal",
     (PyCFunction)bpy_bmface_calc_tangent_vert_diagonal,
     METH_NOARGS,
     bpy_bmface_calc_tangent_vert_diagonal_doc},
    {"calc_center_median",
     (PyCFunction)bpy_bmface_calc_center_mean,
     METH_NOARGS,
     bpy_bmface_calc_center_median_doc},
    {"calc_center_median_weighted",
     (PyCFunction)bpy_bmface_calc_center_median_weighted,
     METH_NOARGS,
     bpy_bmface_calc_center_median_weighted_doc},
    {"calc_center_bounds",
     (PyCFunction)bpy_bmface_calc_center_bounds,
     METH_NOARGS,
     bpy_bmface_calc_center_bounds_doc},

    {"normal_update",
     (PyCFunction)bpy_bmface_normal_update,
     METH_NOARGS,
     bpy_bmface_normal_update_doc},
    {"normal_flip", (PyCFunction)bpy_bmface_normal_flip, METH_NOARGS, bpy_bmface_normal_flip_doc},

    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmloop_methods[] = {
    {"copy_from", (PyCFunction)bpy_bm_elem_copy_from, METH_O, bpy_bm_elem_copy_from_doc},
    {"copy_from_face_interp",
     (PyCFunction)bpy_bmloop_copy_from_face_interp,
     METH_O,
     bpy_bmloop_copy_from_face_interp_doc},

    {"calc_angle", (PyCFunction)bpy_bmloop_calc_angle, METH_NOARGS, bpy_bmloop_calc_angle_doc},
    {"calc_normal", (PyCFunction)bpy_bmloop_calc_normal, METH_NOARGS, bpy_bmloop_calc_normal_doc},
    {"calc_tangent",
     (PyCFunction)bpy_bmloop_calc_tangent,
     METH_NOARGS,
     bpy_bmloop_calc_tangent_doc},
    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmelemseq_methods[] = {
    /* odd function, initializes index values */
    {"index_update",
     (PyCFunction)bpy_bmelemseq_index_update,
     METH_NOARGS,
     bpy_bmelemseq_index_update_doc},
    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmvertseq_methods[] = {
    {"new", (PyCFunction)bpy_bmvertseq_new, METH_VARARGS, bpy_bmvertseq_new_doc},
    {"remove", (PyCFunction)bpy_bmvertseq_remove, METH_O, bpy_bmvertseq_remove_doc},

    /* odd function, initializes index values */
    {"index_update",
     (PyCFunction)bpy_bmelemseq_index_update,
     METH_NOARGS,
     bpy_bmelemseq_index_update_doc},
    {"ensure_lookup_table",
     (PyCFunction)bpy_bmelemseq_ensure_lookup_table,
     METH_NOARGS,
     bpy_bmelemseq_ensure_lookup_table_doc},
    {"sort",
     (PyCFunction)bpy_bmelemseq_sort,
     METH_VARARGS | METH_KEYWORDS,
     bpy_bmelemseq_sort_doc},
    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmedgeseq_methods[] = {
    {"new", (PyCFunction)bpy_bmedgeseq_new, METH_VARARGS, bpy_bmedgeseq_new_doc},
    {"remove", (PyCFunction)bpy_bmedgeseq_remove, METH_O, bpy_bmedgeseq_remove_doc},
    /* 'bpy_bmelemseq_get' for different purpose */
    {"get", (PyCFunction)bpy_bmedgeseq_get__method, METH_VARARGS, bpy_bmedgeseq_get__method_doc},

    /* odd function, initializes index values */
    {"index_update",
     (PyCFunction)bpy_bmelemseq_index_update,
     METH_NOARGS,
     bpy_bmelemseq_index_update_doc},
    {"ensure_lookup_table",
     (PyCFunction)bpy_bmelemseq_ensure_lookup_table,
     METH_NOARGS,
     bpy_bmelemseq_ensure_lookup_table_doc},
    {"sort",
     (PyCFunction)bpy_bmelemseq_sort,
     METH_VARARGS | METH_KEYWORDS,
     bpy_bmelemseq_sort_doc},
    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmfaceseq_methods[] = {
    {"new", (PyCFunction)bpy_bmfaceseq_new, METH_VARARGS, bpy_bmfaceseq_new_doc},
    {"remove", (PyCFunction)bpy_bmfaceseq_remove, METH_O, bpy_bmfaceseq_remove_doc},
    /* 'bpy_bmelemseq_get' for different purpose */
    {"get", (PyCFunction)bpy_bmfaceseq_get__method, METH_VARARGS, bpy_bmfaceseq_get__method_doc},

    /* odd function, initializes index values */
    {"index_update",
     (PyCFunction)bpy_bmelemseq_index_update,
     METH_NOARGS,
     bpy_bmelemseq_index_update_doc},
    {"ensure_lookup_table",
     (PyCFunction)bpy_bmelemseq_ensure_lookup_table,
     METH_NOARGS,
     bpy_bmelemseq_ensure_lookup_table_doc},
    {"sort",
     (PyCFunction)bpy_bmelemseq_sort,
     METH_VARARGS | METH_KEYWORDS,
     bpy_bmelemseq_sort_doc},
    {NULL, NULL, 0, NULL},
};

static struct PyMethodDef bpy_bmloopseq_methods[] = {
    /* odd function, initializes index values */
    /* no: index_update() function since we can't iterate over loops */
    /* no: sort() function since we can't iterate over loops */
    {NULL, NULL, 0, NULL},
};

/* Sequences
 * ========= */

/* BMElemSeq / Iter
 * ---------------- */

static PyTypeObject *bpy_bm_itype_as_pytype(const char itype)
{
  /* should cover all types */
  switch ((BMIterType)itype) {
    case BM_VERTS_OF_MESH:
    case BM_VERTS_OF_FACE:
    case BM_VERTS_OF_EDGE:
      return &BPy_BMVert_Type;

    case BM_EDGES_OF_MESH:
    case BM_EDGES_OF_FACE:
    case BM_EDGES_OF_VERT:
      return &BPy_BMEdge_Type;

    case BM_FACES_OF_MESH:
    case BM_FACES_OF_EDGE:
    case BM_FACES_OF_VERT:
      return &BPy_BMFace_Type;

    // case BM_ALL_LOOPS_OF_FACE:
    case BM_LOOPS_OF_FACE:
    case BM_LOOPS_OF_EDGE:
    case BM_LOOPS_OF_VERT:
    case BM_LOOPS_OF_LOOP:
      return &BPy_BMLoop_Type;
  }

  return NULL;
}

static Py_ssize_t bpy_bmelemseq_length(BPy_BMElemSeq *self)
{
  BPY_BM_CHECK_INT(self);

  /* first check if the size is known */
  switch ((BMIterType)self->itype) {
    /* main-types */
    case BM_VERTS_OF_MESH:
      return self->bm->totvert;
    case BM_EDGES_OF_MESH:
      return self->bm->totedge;
    case BM_FACES_OF_MESH:
      return self->bm->totface;

      /* sub-types */
    case BM_VERTS_OF_FACE:
    case BM_EDGES_OF_FACE:
    case BM_LOOPS_OF_FACE:
      BPY_BM_CHECK_INT(self->py_ele);
      return ((BMFace *)self->py_ele->ele)->len;

    case BM_VERTS_OF_EDGE:
      return 2;

    default:
      /* quiet compiler */
      break;
  }

  /* loop over all items, avoid this if we can */
  {
    BMIter iter;
    BMHeader *ele;
    Py_ssize_t tot = 0;

    BM_ITER_BPY_BM_SEQ (ele, &iter, self) {
      tot++;
    }
    return tot;
  }
}

static PyObject *bpy_bmelemseq_subscript_int(BPy_BMElemSeq *self, int keynum)
{
  BPY_BM_CHECK_OBJ(self);

  if (keynum < 0) {
    /* only get length on negative value, may loop entire seq */
    keynum += bpy_bmelemseq_length(self);
  }
  if (keynum >= 0) {
    if (self->itype <= BM_FACES_OF_MESH) {
      if ((self->bm->elem_table_dirty & bm_iter_itype_htype_map[self->itype]) == 0) {
        BMHeader *ele = NULL;
        switch (self->itype) {
          case BM_VERTS_OF_MESH:
            if (keynum < self->bm->totvert) {
              ele = (BMHeader *)self->bm->vtable[keynum];
            }
            break;
          case BM_EDGES_OF_MESH:
            if (keynum < self->bm->totedge) {
              ele = (BMHeader *)self->bm->etable[keynum];
            }
            break;
          case BM_FACES_OF_MESH:
            if (keynum < self->bm->totface) {
              ele = (BMHeader *)self->bm->ftable[keynum];
            }
            break;
        }
        if (ele) {
          return BPy_BMElem_CreatePyObject(self->bm, ele);
        }
        /* fall through to index error below */
      }
      else {
        PyErr_SetString(PyExc_IndexError,
                        "BMElemSeq[index]: outdated internal index table, "
                        "run ensure_lookup_table() first");
        return NULL;
      }
    }
    else {
      BMHeader *ele = BM_iter_at_index(
          self->bm, self->itype, self->py_ele ? self->py_ele->ele : NULL, keynum);
      if (ele) {
        return BPy_BMElem_CreatePyObject(self->bm, ele);
      }
    }
  }

  PyErr_Format(PyExc_IndexError, "BMElemSeq[index]: index %d out of range", keynum);
  return NULL;
}

static PyObject *bpy_bmelemseq_subscript_slice(BPy_BMElemSeq *self,
                                               Py_ssize_t start,
                                               Py_ssize_t stop)
{
  BMIter iter;
  int count = 0;
  bool ok;

  PyObject *list;
  BMHeader *ele;

  BPY_BM_CHECK_OBJ(self);

  list = PyList_New(0);

  ok = BM_iter_init(&iter, self->bm, self->itype, self->py_ele ? self->py_ele->ele : NULL);

  BLI_assert(ok == true);

  if (UNLIKELY(ok == false)) {
    return list;
  }

  /* first loop up-until the start */
  for (ok = true; ok; ok = (BM_iter_step(&iter) != NULL)) {
    if (count == start) {
      break;
    }
    count++;
  }

  /* add items until stop */
  while ((ele = BM_iter_step(&iter))) {
    PyList_APPEND(list, BPy_BMElem_CreatePyObject(self->bm, ele));

    count++;
    if (count == stop) {
      break;
    }
  }

  return list;
}

static PyObject *bpy_bmelemseq_subscript(BPy_BMElemSeq *self, PyObject *key)
{
  /* don't need error check here */
  if (PyIndex_Check(key)) {
    const Py_ssize_t i = PyNumber_AsSsize_t(key, PyExc_IndexError);
    if (i == -1 && PyErr_Occurred()) {
      return NULL;
    }
    return bpy_bmelemseq_subscript_int(self, i);
  }
  if (PySlice_Check(key)) {
    PySliceObject *key_slice = (PySliceObject *)key;
    Py_ssize_t step = 1;

    if (key_slice->step != Py_None && !_PyEval_SliceIndex(key, &step)) {
      return NULL;
    }
    if (step != 1) {
      PyErr_SetString(PyExc_TypeError, "BMElemSeq[slice]: slice steps not supported");
      return NULL;
    }
    if (key_slice->start == Py_None && key_slice->stop == Py_None) {
      return bpy_bmelemseq_subscript_slice(self, 0, PY_SSIZE_T_MAX);
    }

    Py_ssize_t start = 0, stop = PY_SSIZE_T_MAX;

    /* avoid PySlice_GetIndicesEx because it needs to know the length ahead of time. */
    if (key_slice->start != Py_None && !_PyEval_SliceIndex(key_slice->start, &start)) {
      return NULL;
    }
    if (key_slice->stop != Py_None && !_PyEval_SliceIndex(key_slice->stop, &stop)) {
      return NULL;
    }

    if (start < 0 || stop < 0) {
      /* only get the length for negative values */
      const Py_ssize_t len = bpy_bmelemseq_length(self);
      if (start < 0) {
        start += len;
        CLAMP_MIN(start, 0);
      }
      if (stop < 0) {
        stop += len;
        CLAMP_MIN(stop, 0);
      }
    }

    if (stop - start <= 0) {
      return PyList_New(0);
    }

    return bpy_bmelemseq_subscript_slice(self, start, stop);
  }

  PyErr_SetString(PyExc_AttributeError, "BMElemSeq[key]: invalid key, key must be an int");
  return NULL;
}

static int bpy_bmelemseq_contains(BPy_BMElemSeq *self, PyObject *value)
{
  BPY_BM_CHECK_INT(self);

  if (Py_TYPE(value) == bpy_bm_itype_as_pytype(self->itype)) {
    BPy_BMElem *value_bm_ele = (BPy_BMElem *)value;
    if (value_bm_ele->bm == self->bm) {
      BMElem *ele, *ele_test = value_bm_ele->ele;
      BMIter iter;
      BM_ITER_BPY_BM_SEQ (ele, &iter, self) {
        if (ele == ele_test) {
          return 1;
        }
      }
    }
  }

  return 0;
}

/* BMElem (customdata)
 * ------------------- */

static PyObject *bpy_bmelem_subscript(BPy_BMElem *self, BPy_BMLayerItem *key)
{
  BPY_BM_CHECK_OBJ(self);

  return BPy_BMLayerItem_GetItem(self, key);
}

static int bpy_bmelem_ass_subscript(BPy_BMElem *self, BPy_BMLayerItem *key, PyObject *value)
{
  BPY_BM_CHECK_INT(self);

  return BPy_BMLayerItem_SetItem(self, key, value);
}

static PySequenceMethods bpy_bmelemseq_as_sequence = {
    (lenfunc)bpy_bmelemseq_length, /* sq_length */
    NULL,                          /* sq_concat */
    NULL,                          /* sq_repeat */
    (ssizeargfunc)bpy_bmelemseq_subscript_int,
    /* sq_item */                       /* Only set this so PySequence_Check() returns True */
    NULL,                               /* sq_slice */
    (ssizeobjargproc)NULL,              /* sq_ass_item */
    NULL,                               /* *was* sq_ass_slice */
    (objobjproc)bpy_bmelemseq_contains, /* sq_contains */
    (binaryfunc)NULL,                   /* sq_inplace_concat */
    (ssizeargfunc)NULL,                 /* sq_inplace_repeat */
};

static PyMappingMethods bpy_bmelemseq_as_mapping = {
    (lenfunc)bpy_bmelemseq_length,       /* mp_length */
    (binaryfunc)bpy_bmelemseq_subscript, /* mp_subscript */
    (objobjargproc)NULL,                 /* mp_ass_subscript */
};

/* for customdata access */
static PyMappingMethods bpy_bm_elem_as_mapping = {
    (lenfunc)NULL,
    /* mp_length */                          /* keep this empty, messes up 'if elem: ...' test */
    (binaryfunc)bpy_bmelem_subscript,        /* mp_subscript */
    (objobjargproc)bpy_bmelem_ass_subscript, /* mp_ass_subscript */
};

/* Iterator
 * -------- */

static PyObject *bpy_bmelemseq_iter(BPy_BMElemSeq *self)
{
  BPy_BMIter *py_iter;

  BPY_BM_CHECK_OBJ(self);
  py_iter = (BPy_BMIter *)BPy_BMIter_CreatePyObject(self->bm);
  BM_iter_init(&(py_iter->iter), self->bm, self->itype, self->py_ele ? self->py_ele->ele : NULL);
  return (PyObject *)py_iter;
}

static PyObject *bpy_bmiter_next(BPy_BMIter *self)
{
  BMHeader *ele = BM_iter_step(&self->iter);
  if (ele == NULL) {
    PyErr_SetNone(PyExc_StopIteration);
    return NULL;
  }

  return (PyObject *)BPy_BMElem_CreatePyObject(self->bm, ele);
}

/* Deallocate Functions
 * ==================== */

static void bpy_bmesh_dealloc(BPy_BMesh *self)
{
  BMesh *bm = self->bm;

  /* The mesh has not been freed by #BMesh. */
  if (bm) {
    bm_dealloc_editmode_warn(self);

    if (CustomData_has_layer(&bm->vdata, CD_BM_ELEM_PYPTR)) {
      BM_data_layer_free(bm, &bm->vdata, CD_BM_ELEM_PYPTR);
    }
    if (CustomData_has_layer(&bm->edata, CD_BM_ELEM_PYPTR)) {
      BM_data_layer_free(bm, &bm->edata, CD_BM_ELEM_PYPTR);
    }
    if (CustomData_has_layer(&bm->pdata, CD_BM_ELEM_PYPTR)) {
      BM_data_layer_free(bm, &bm->pdata, CD_BM_ELEM_PYPTR);
    }
    if (CustomData_has_layer(&bm->ldata, CD_BM_ELEM_PYPTR)) {
      BM_data_layer_free(bm, &bm->ldata, CD_BM_ELEM_PYPTR);
    }

    bm->py_handle = NULL;

    if ((self->flag & BPY_BMFLAG_IS_WRAPPED) == 0) {
      BM_mesh_free(bm);
    }
  }

  PyObject_DEL(self);
}

static void bpy_bmvert_dealloc(BPy_BMElem *self)
{
  BMesh *bm = self->bm;
  if (bm) {
    void **ptr = CustomData_bmesh_get(&bm->vdata, self->ele->head.data, CD_BM_ELEM_PYPTR);
    if (ptr) {
      *ptr = NULL;
    }
  }
  PyObject_DEL(self);
}

static void bpy_bmedge_dealloc(BPy_BMElem *self)
{
  BMesh *bm = self->bm;
  if (bm) {
    void **ptr = CustomData_bmesh_get(&bm->edata, self->ele->head.data, CD_BM_ELEM_PYPTR);
    if (ptr) {
      *ptr = NULL;
    }
  }
  PyObject_DEL(self);
}

static void bpy_bmface_dealloc(BPy_BMElem *self)
{
  BMesh *bm = self->bm;
  if (bm) {
    void **ptr = CustomData_bmesh_get(&bm->pdata, self->ele->head.data, CD_BM_ELEM_PYPTR);
    if (ptr) {
      *ptr = NULL;
    }
  }
  PyObject_DEL(self);
}

static void bpy_bmloop_dealloc(BPy_BMElem *self)
{
  BMesh *bm = self->bm;
  if (bm) {
    void **ptr = CustomData_bmesh_get(&bm->ldata, self->ele->head.data, CD_BM_ELEM_PYPTR);
    if (ptr) {
      *ptr = NULL;
    }
  }
  PyObject_DEL(self);
}

static void bpy_bmelemseq_dealloc(BPy_BMElemSeq *self)
{
  Py_XDECREF(self->py_ele);

  PyObject_DEL(self);
}

/* not sure where this should go */
static Py_hash_t bpy_bm_elem_hash(PyObject *self)
{
  return _Py_HashPointer(((BPy_BMElem *)self)->ele);
}

static Py_hash_t bpy_bm_hash(PyObject *self)
{
  return _Py_HashPointer(((BPy_BMesh *)self)->bm);
}

/* Type Docstrings
 * =============== */

PyDoc_STRVAR(bpy_bmesh_doc, "The BMesh data structure\n");
PyDoc_STRVAR(bpy_bmvert_doc, "The BMesh vertex type\n");
PyDoc_STRVAR(bpy_bmedge_doc, "The BMesh edge connecting 2 verts\n");
PyDoc_STRVAR(bpy_bmface_doc, "The BMesh face with 3 or more sides\n");
PyDoc_STRVAR(bpy_bmloop_doc,
             "This is normally accessed from :class:`BMFace.loops` where each face loop "
             "represents a corner of the face.\n");
PyDoc_STRVAR(bpy_bmelemseq_doc,
             "General sequence type used for accessing any sequence of\n"
             ":class:`BMVert`, :class:`BMEdge`, :class:`BMFace`, :class:`BMLoop`.\n"
             "\n"
             "When accessed via :class:`BMesh.verts`, :class:`BMesh.edges`, :class:`BMesh.faces`\n"
             "there are also functions to create/remove items.\n");
PyDoc_STRVAR(bpy_bmiter_doc,
             "Internal BMesh type for looping over verts/faces/edges,\n"
             "used for iterating over :class:`BMElemSeq` types.\n");

static PyObject *bpy_bmesh_repr(BPy_BMesh *self)
{
  BMesh *bm = self->bm;

  if (bm) {
    return PyUnicode_FromFormat("<BMesh(%p), totvert=%d, totedge=%d, totface=%d, totloop=%d>",
                                bm,
                                bm->totvert,
                                bm->totedge,
                                bm->totface,
                                bm->totloop);
  }

  return PyUnicode_FromFormat("<BMesh dead at %p>", self);
}

static PyObject *bpy_bmvert_repr(BPy_BMVert *self)
{
  BMesh *bm = self->bm;

  if (bm) {
    BMVert *v = self->v;
    return PyUnicode_FromFormat("<BMVert(%p), index=%d>", v, BM_elem_index_get(v));
  }

  return PyUnicode_FromFormat("<BMVert dead at %p>", self);
}

static PyObject *bpy_bmedge_repr(BPy_BMEdge *self)
{
  BMesh *bm = self->bm;

  if (bm) {
    BMEdge *e = self->e;
    return PyUnicode_FromFormat("<BMEdge(%p), index=%d, verts=(%p/%d, %p/%d)>",
                                e,
                                BM_elem_index_get(e),
                                e->v1,
                                BM_elem_index_get(e->v1),
                                e->v2,
                                BM_elem_index_get(e->v2));
  }

  return PyUnicode_FromFormat("<BMEdge dead at %p>", self);
}

static PyObject *bpy_bmface_repr(BPy_BMFace *self)
{
  BMesh *bm = self->bm;

  if (bm) {
    BMFace *f = self->f;
    return PyUnicode_FromFormat(
        "<BMFace(%p), index=%d, totverts=%d>", f, BM_elem_index_get(f), f->len);
  }

  return PyUnicode_FromFormat("<BMFace dead at %p>", self);
}

static PyObject *bpy_bmloop_repr(BPy_BMLoop *self)
{
  BMesh *bm = self->bm;

  if (bm) {
    BMLoop *l = self->l;
    return PyUnicode_FromFormat("<BMLoop(%p), index=%d, vert=%p/%d, edge=%p/%d, face=%p/%d>",
                                l,
                                BM_elem_index_get(l),
                                l->v,
                                BM_elem_index_get(l->v),
                                l->e,
                                BM_elem_index_get(l->e),
                                l->f,
                                BM_elem_index_get(l->f));
  }

  return PyUnicode_FromFormat("<BMLoop dead at %p>", self);
}

/* Types
 * ===== */

PyTypeObject BPy_BMesh_Type;
PyTypeObject BPy_BMVert_Type;
PyTypeObject BPy_BMEdge_Type;
PyTypeObject BPy_BMFace_Type;
PyTypeObject BPy_BMLoop_Type;
PyTypeObject BPy_BMElemSeq_Type;
PyTypeObject BPy_BMVertSeq_Type;
PyTypeObject BPy_BMEdgeSeq_Type;
PyTypeObject BPy_BMFaceSeq_Type;
PyTypeObject BPy_BMLoopSeq_Type;
PyTypeObject BPy_BMIter_Type;

void BPy_BM_init_types(void)
{
  BPy_BMesh_Type.tp_basicsize = sizeof(BPy_BMesh);
  BPy_BMVert_Type.tp_basicsize = sizeof(BPy_BMVert);
  BPy_BMEdge_Type.tp_basicsize = sizeof(BPy_BMEdge);
  BPy_BMFace_Type.tp_basicsize = sizeof(BPy_BMFace);
  BPy_BMLoop_Type.tp_basicsize = sizeof(BPy_BMLoop);
  BPy_BMElemSeq_Type.tp_basicsize = sizeof(BPy_BMElemSeq);
  BPy_BMVertSeq_Type.tp_basicsize = sizeof(BPy_BMElemSeq);
  BPy_BMEdgeSeq_Type.tp_basicsize = sizeof(BPy_BMElemSeq);
  BPy_BMFaceSeq_Type.tp_basicsize = sizeof(BPy_BMElemSeq);
  BPy_BMLoopSeq_Type.tp_basicsize = sizeof(BPy_BMElemSeq);
  BPy_BMIter_Type.tp_basicsize = sizeof(BPy_BMIter);

  BPy_BMesh_Type.tp_name = "BMesh";
  BPy_BMVert_Type.tp_name = "BMVert";
  BPy_BMEdge_Type.tp_name = "BMEdge";
  BPy_BMFace_Type.tp_name = "BMFace";
  BPy_BMLoop_Type.tp_name = "BMLoop";
  BPy_BMElemSeq_Type.tp_name = "BMElemSeq";
  BPy_BMVertSeq_Type.tp_name = "BMVertSeq";
  BPy_BMEdgeSeq_Type.tp_name = "BMEdgeSeq";
  BPy_BMFaceSeq_Type.tp_name = "BMFaceSeq";
  BPy_BMLoopSeq_Type.tp_name = "BMLoopSeq";
  BPy_BMIter_Type.tp_name = "BMIter";

  BPy_BMesh_Type.tp_doc = bpy_bmesh_doc;
  BPy_BMVert_Type.tp_doc = bpy_bmvert_doc;
  BPy_BMEdge_Type.tp_doc = bpy_bmedge_doc;
  BPy_BMFace_Type.tp_doc = bpy_bmface_doc;
  BPy_BMLoop_Type.tp_doc = bpy_bmloop_doc;
  BPy_BMElemSeq_Type.tp_doc = bpy_bmelemseq_doc;
  BPy_BMVertSeq_Type.tp_doc = NULL;
  BPy_BMEdgeSeq_Type.tp_doc = NULL;
  BPy_BMFaceSeq_Type.tp_doc = NULL;
  BPy_BMLoopSeq_Type.tp_doc = NULL;
  BPy_BMIter_Type.tp_doc = bpy_bmiter_doc;

  BPy_BMesh_Type.tp_repr = (reprfunc)bpy_bmesh_repr;
  BPy_BMVert_Type.tp_repr = (reprfunc)bpy_bmvert_repr;
  BPy_BMEdge_Type.tp_repr = (reprfunc)bpy_bmedge_repr;
  BPy_BMFace_Type.tp_repr = (reprfunc)bpy_bmface_repr;
  BPy_BMLoop_Type.tp_repr = (reprfunc)bpy_bmloop_repr;
  BPy_BMElemSeq_Type.tp_repr = NULL;
  BPy_BMVertSeq_Type.tp_repr = NULL;
  BPy_BMEdgeSeq_Type.tp_repr = NULL;
  BPy_BMFaceSeq_Type.tp_repr = NULL;
  BPy_BMLoopSeq_Type.tp_repr = NULL;
  BPy_BMIter_Type.tp_repr = NULL;

  BPy_BMesh_Type.tp_getset = bpy_bmesh_getseters;
  BPy_BMVert_Type.tp_getset = bpy_bmvert_getseters;
  BPy_BMEdge_Type.tp_getset = bpy_bmedge_getseters;
  BPy_BMFace_Type.tp_getset = bpy_bmface_getseters;
  BPy_BMLoop_Type.tp_getset = bpy_bmloop_getseters;
  BPy_BMElemSeq_Type.tp_getset = NULL;
  BPy_BMVertSeq_Type.tp_getset = bpy_bmvertseq_getseters;
  BPy_BMEdgeSeq_Type.tp_getset = bpy_bmedgeseq_getseters;
  BPy_BMFaceSeq_Type.tp_getset = bpy_bmfaceseq_getseters;
  BPy_BMLoopSeq_Type.tp_getset = bpy_bmloopseq_getseters;
  BPy_BMIter_Type.tp_getset = NULL;

  BPy_BMesh_Type.tp_methods = bpy_bmesh_methods;
  BPy_BMVert_Type.tp_methods = bpy_bmvert_methods;
  BPy_BMEdge_Type.tp_methods = bpy_bmedge_methods;
  BPy_BMFace_Type.tp_methods = bpy_bmface_methods;
  BPy_BMLoop_Type.tp_methods = bpy_bmloop_methods;
  BPy_BMElemSeq_Type.tp_methods = bpy_bmelemseq_methods;
  BPy_BMVertSeq_Type.tp_methods = bpy_bmvertseq_methods;
  BPy_BMEdgeSeq_Type.tp_methods = bpy_bmedgeseq_methods;
  BPy_BMFaceSeq_Type.tp_methods = bpy_bmfaceseq_methods;
  BPy_BMLoopSeq_Type.tp_methods = bpy_bmloopseq_methods;
  BPy_BMIter_Type.tp_methods = NULL;

  /* #BPy_BMElem_Check() uses #bpy_bm_elem_hash() to check types.
   * if this changes update the macro. */
  BPy_BMesh_Type.tp_hash = bpy_bm_hash;
  BPy_BMVert_Type.tp_hash = bpy_bm_elem_hash;
  BPy_BMEdge_Type.tp_hash = bpy_bm_elem_hash;
  BPy_BMFace_Type.tp_hash = bpy_bm_elem_hash;
  BPy_BMLoop_Type.tp_hash = bpy_bm_elem_hash;
  BPy_BMElemSeq_Type.tp_hash = NULL;
  BPy_BMVertSeq_Type.tp_hash = NULL;
  BPy_BMEdgeSeq_Type.tp_hash = NULL;
  BPy_BMFaceSeq_Type.tp_hash = NULL;
  BPy_BMLoopSeq_Type.tp_hash = NULL;
  BPy_BMIter_Type.tp_hash = NULL;

  BPy_BMElemSeq_Type.tp_as_sequence = &bpy_bmelemseq_as_sequence;
  BPy_BMVertSeq_Type.tp_as_sequence = &bpy_bmelemseq_as_sequence;
  BPy_BMEdgeSeq_Type.tp_as_sequence = &bpy_bmelemseq_as_sequence;
  BPy_BMFaceSeq_Type.tp_as_sequence = &bpy_bmelemseq_as_sequence;
  BPy_BMLoopSeq_Type.tp_as_sequence = NULL; /* this is not a seq really, only for layer access */

  BPy_BMElemSeq_Type.tp_as_mapping = &bpy_bmelemseq_as_mapping;
  BPy_BMVertSeq_Type.tp_as_mapping = &bpy_bmelemseq_as_mapping;
  BPy_BMEdgeSeq_Type.tp_as_mapping = &bpy_bmelemseq_as_mapping;
  BPy_BMFaceSeq_Type.tp_as_mapping = &bpy_bmelemseq_as_mapping;
  BPy_BMLoopSeq_Type.tp_as_mapping = NULL; /* this is not a seq really, only for layer access */

  /* layer access */
  BPy_BMVert_Type.tp_as_mapping = &bpy_bm_elem_as_mapping;
  BPy_BMEdge_Type.tp_as_mapping = &bpy_bm_elem_as_mapping;
  BPy_BMFace_Type.tp_as_mapping = &bpy_bm_elem_as_mapping;
  BPy_BMLoop_Type.tp_as_mapping = &bpy_bm_elem_as_mapping;

  BPy_BMElemSeq_Type.tp_iter = (getiterfunc)bpy_bmelemseq_iter;
  BPy_BMVertSeq_Type.tp_iter = (getiterfunc)bpy_bmelemseq_iter;
  BPy_BMEdgeSeq_Type.tp_iter = (getiterfunc)bpy_bmelemseq_iter;
  BPy_BMFaceSeq_Type.tp_iter = (getiterfunc)bpy_bmelemseq_iter;
  BPy_BMLoopSeq_Type.tp_iter = NULL; /* no mapping */

  /* only 1 iteratir so far */
  BPy_BMIter_Type.tp_iternext = (iternextfunc)bpy_bmiter_next;
  BPy_BMIter_Type.tp_iter = PyObject_SelfIter;

  BPy_BMesh_Type.tp_dealloc = (destructor)bpy_bmesh_dealloc;
  BPy_BMVert_Type.tp_dealloc = (destructor)bpy_bmvert_dealloc;
  BPy_BMEdge_Type.tp_dealloc = (destructor)bpy_bmedge_dealloc;
  BPy_BMFace_Type.tp_dealloc = (destructor)bpy_bmface_dealloc;
  BPy_BMLoop_Type.tp_dealloc = (destructor)bpy_bmloop_dealloc;
  BPy_BMElemSeq_Type.tp_dealloc = (destructor)bpy_bmelemseq_dealloc;
  BPy_BMVertSeq_Type.tp_dealloc = (destructor)bpy_bmelemseq_dealloc;
  BPy_BMEdgeSeq_Type.tp_dealloc = (destructor)bpy_bmelemseq_dealloc;
  BPy_BMFaceSeq_Type.tp_dealloc = (destructor)bpy_bmelemseq_dealloc;
  BPy_BMLoopSeq_Type.tp_dealloc = (destructor)bpy_bmelemseq_dealloc;
  BPy_BMIter_Type.tp_dealloc = NULL;

  BPy_BMesh_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMVert_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMEdge_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMFace_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMLoop_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMElemSeq_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMVertSeq_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMEdgeSeq_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMFaceSeq_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMLoopSeq_Type.tp_flags = Py_TPFLAGS_DEFAULT;
  BPy_BMIter_Type.tp_flags = Py_TPFLAGS_DEFAULT;

  PyType_Ready(&BPy_BMesh_Type);
  PyType_Ready(&BPy_BMVert_Type);
  PyType_Ready(&BPy_BMEdge_Type);
  PyType_Ready(&BPy_BMFace_Type);
  PyType_Ready(&BPy_BMLoop_Type);
  PyType_Ready(&BPy_BMElemSeq_Type);
  PyType_Ready(&BPy_BMVertSeq_Type);
  PyType_Ready(&BPy_BMEdgeSeq_Type);
  PyType_Ready(&BPy_BMFaceSeq_Type);
  PyType_Ready(&BPy_BMLoopSeq_Type);
  PyType_Ready(&BPy_BMIter_Type);
}

/* bmesh.types submodule
 * ********************* */

static struct PyModuleDef BPy_BM_types_module_def = {
    PyModuleDef_HEAD_INIT,
    "bmesh.types", /* m_name */
    NULL,          /* m_doc */
    0,             /* m_size */
    NULL,          /* m_methods */
    NULL,          /* m_slots */
    NULL,          /* m_traverse */
    NULL,          /* m_clear */
    NULL,          /* m_free */
};

PyObject *BPyInit_bmesh_types(void)
{
  PyObject *submodule;

  submodule = PyModule_Create(&BPy_BM_types_module_def);

  /* bmesh_py_types.c */
  PyModule_AddType(submodule, &BPy_BMesh_Type);
  PyModule_AddType(submodule, &BPy_BMVert_Type);
  PyModule_AddType(submodule, &BPy_BMEdge_Type);
  PyModule_AddType(submodule, &BPy_BMFace_Type);
  PyModule_AddType(submodule, &BPy_BMLoop_Type);
  PyModule_AddType(submodule, &BPy_BMElemSeq_Type);
  PyModule_AddType(submodule, &BPy_BMVertSeq_Type);
  PyModule_AddType(submodule, &BPy_BMEdgeSeq_Type);
  PyModule_AddType(submodule, &BPy_BMFaceSeq_Type);
  PyModule_AddType(submodule, &BPy_BMLoopSeq_Type);
  PyModule_AddType(submodule, &BPy_BMIter_Type);
  /* bmesh_py_types_select.c */
  PyModule_AddType(submodule, &BPy_BMEditSelSeq_Type);
  PyModule_AddType(submodule, &BPy_BMEditSelIter_Type);
  /* bmesh_py_types_customdata.c */
  PyModule_AddType(submodule, &BPy_BMLayerAccessVert_Type);
  PyModule_AddType(submodule, &BPy_BMLayerAccessEdge_Type);
  PyModule_AddType(submodule, &BPy_BMLayerAccessFace_Type);
  PyModule_AddType(submodule, &BPy_BMLayerAccessLoop_Type);
  PyModule_AddType(submodule, &BPy_BMLayerCollection_Type);
  PyModule_AddType(submodule, &BPy_BMLayerItem_Type);
  /* bmesh_py_types_meshdata.c */
  PyModule_AddType(submodule, &BPy_BMLoopUV_Type);
  PyModule_AddType(submodule, &BPy_BMDeformVert_Type);

  return submodule;
}

/* Utility Functions
 * ***************** */

PyObject *BPy_BMesh_CreatePyObject(BMesh *bm, int flag)
{
  BPy_BMesh *self;

  if (bm->py_handle) {
    self = bm->py_handle;
    Py_INCREF(self);
  }
  else {
    self = PyObject_New(BPy_BMesh, &BPy_BMesh_Type);
    self->bm = bm;
    self->flag = flag;

    bm->py_handle = self; /* point back */

    /* avoid allocating layers when we don't have to */
#if 0
    BM_data_layer_add(bm, &bm->vdata, CD_BM_ELEM_PYPTR);
    BM_data_layer_add(bm, &bm->edata, CD_BM_ELEM_PYPTR);
    BM_data_layer_add(bm, &bm->pdata, CD_BM_ELEM_PYPTR);
    BM_data_layer_add(bm, &bm->ldata, CD_BM_ELEM_PYPTR);
#endif
  }

  return (PyObject *)self;
}

PyObject *BPy_BMVert_CreatePyObject(BMesh *bm, BMVert *v)
{
  BPy_BMVert *self;

  void **ptr = CustomData_bmesh_get(&bm->vdata, v->head.data, CD_BM_ELEM_PYPTR);

  /* bmesh may free layers, ensure we have one to store ourself */
  if (UNLIKELY(ptr == NULL)) {
    BM_data_layer_add(bm, &bm->vdata, CD_BM_ELEM_PYPTR);
    ptr = CustomData_bmesh_get(&bm->vdata, v->head.data, CD_BM_ELEM_PYPTR);
  }

  if (*ptr != NULL) {
    self = *ptr;
    Py_INCREF(self);
  }
  else {
    self = PyObject_New(BPy_BMVert, &BPy_BMVert_Type);
    BLI_assert(v != NULL);
    self->bm = bm;
    self->v = v;
    *ptr = self;
  }
  return (PyObject *)self;
}

PyObject *BPy_BMEdge_CreatePyObject(BMesh *bm, BMEdge *e)
{
  BPy_BMEdge *self;

  void **ptr = CustomData_bmesh_get(&bm->edata, e->head.data, CD_BM_ELEM_PYPTR);

  /* bmesh may free layers, ensure we have one to store ourself */
  if (UNLIKELY(ptr == NULL)) {
    BM_data_layer_add(bm, &bm->edata, CD_BM_ELEM_PYPTR);
    ptr = CustomData_bmesh_get(&bm->edata, e->head.data, CD_BM_ELEM_PYPTR);
  }

  if (*ptr != NULL) {
    self = *ptr;
    Py_INCREF(self);
  }
  else {
    self = PyObject_New(BPy_BMEdge, &BPy_BMEdge_Type);
    BLI_assert(e != NULL);
    self->bm = bm;
    self->e = e;
    *ptr = self;
  }
  return (PyObject *)self;
}

PyObject *BPy_BMFace_CreatePyObject(BMesh *bm, BMFace *f)
{
  BPy_BMFace *self;

  void **ptr = CustomData_bmesh_get(&bm->pdata, f->head.data, CD_BM_ELEM_PYPTR);

  /* bmesh may free layers, ensure we have one to store ourself */
  if (UNLIKELY(ptr == NULL)) {
    BM_data_layer_add(bm, &bm->pdata, CD_BM_ELEM_PYPTR);
    ptr = CustomData_bmesh_get(&bm->pdata, f->head.data, CD_BM_ELEM_PYPTR);
  }

  if (*ptr != NULL) {
    self = *ptr;
    Py_INCREF(self);
  }
  else {
    self = PyObject_New(BPy_BMFace, &BPy_BMFace_Type);
    BLI_assert(f != NULL);
    self->bm = bm;
    self->f = f;
    *ptr = self;
  }
  return (PyObject *)self;
}

PyObject *BPy_BMLoop_CreatePyObject(BMesh *bm, BMLoop *l)
{
  BPy_BMLoop *self;

  void **ptr = CustomData_bmesh_get(&bm->ldata, l->head.data, CD_BM_ELEM_PYPTR);

  /* bmesh may free layers, ensure we have one to store ourself */
  if (UNLIKELY(ptr == NULL)) {
    BM_data_layer_add(bm, &bm->ldata, CD_BM_ELEM_PYPTR);
    ptr = CustomData_bmesh_get(&bm->ldata, l->head.data, CD_BM_ELEM_PYPTR);
  }

  if (*ptr != NULL) {
    self = *ptr;
    Py_INCREF(self);
  }
  else {
    self = PyObject_New(BPy_BMLoop, &BPy_BMLoop_Type);
    BLI_assert(l != NULL);
    self->bm = bm;
    self->l = l;
    *ptr = self;
  }
  return (PyObject *)self;
}

PyObject *BPy_BMElemSeq_CreatePyObject(BMesh *bm, BPy_BMElem *py_ele, const char itype)
{
  BPy_BMElemSeq *self = PyObject_New(BPy_BMElemSeq, &BPy_BMElemSeq_Type);
  self->bm = bm;
  self->py_ele = py_ele; /* can be NULL */
  self->itype = itype;
  Py_XINCREF(py_ele);
  return (PyObject *)self;
}

PyObject *BPy_BMVertSeq_CreatePyObject(BMesh *bm)
{
  BPy_BMElemSeq *self = PyObject_New(BPy_BMElemSeq, &BPy_BMVertSeq_Type);
  self->bm = bm;
  self->py_ele = NULL; /* unused */
  self->itype = BM_VERTS_OF_MESH;
  return (PyObject *)self;
}

PyObject *BPy_BMEdgeSeq_CreatePyObject(BMesh *bm)
{
  BPy_BMElemSeq *self = PyObject_New(BPy_BMElemSeq, &BPy_BMEdgeSeq_Type);
  self->bm = bm;
  self->py_ele = NULL; /* unused */
  self->itype = BM_EDGES_OF_MESH;
  return (PyObject *)self;
}

PyObject *BPy_BMFaceSeq_CreatePyObject(BMesh *bm)
{
  BPy_BMElemSeq *self = PyObject_New(BPy_BMElemSeq, &BPy_BMFaceSeq_Type);
  self->bm = bm;
  self->py_ele = NULL; /* unused */
  self->itype = BM_FACES_OF_MESH;
  return (PyObject *)self;
}

PyObject *BPy_BMLoopSeq_CreatePyObject(BMesh *bm)
{
  BPy_BMElemSeq *self = PyObject_New(BPy_BMElemSeq, &BPy_BMLoopSeq_Type);
  self->bm = bm;
  self->py_ele = NULL; /* unused */
  self->itype = 0;     /* should never be passed to the iterator function */
  return (PyObject *)self;
}

PyObject *BPy_BMIter_CreatePyObject(BMesh *bm)
{
  BPy_BMIter *self = PyObject_New(BPy_BMIter, &BPy_BMIter_Type);
  self->bm = bm;
  /* caller must initialize 'iter' member */
  return (PyObject *)self;
}

PyObject *BPy_BMElem_CreatePyObject(BMesh *bm, BMHeader *ele)
{
  switch (ele->htype) {
    case BM_VERT:
      return BPy_BMVert_CreatePyObject(bm, (BMVert *)ele);
    case BM_EDGE:
      return BPy_BMEdge_CreatePyObject(bm, (BMEdge *)ele);
    case BM_FACE:
      return BPy_BMFace_CreatePyObject(bm, (BMFace *)ele);
    case BM_LOOP:
      return BPy_BMLoop_CreatePyObject(bm, (BMLoop *)ele);
    default:
      BLI_assert_unreachable();
      PyErr_SetString(PyExc_SystemError, "internal error");
      return NULL;
  }
}

int bpy_bm_generic_valid_check(BPy_BMGeneric *self)
{
  if (LIKELY(self->bm)) {

    /* far too slow to enable by default but handy
     * to uncomment for debugging tricky errors,
     * note that this will throw error on entering a
     * function where the actual error will be caused by
     * the previous action. */
#if 0
    if (BM_mesh_validate(self->bm) == false) {
      PyErr_Format(
          PyExc_ReferenceError, "BMesh used by %.200s has become invalid", Py_TYPE(self)->tp_name);
      return -1;
    }
#endif

    return 0;
  }

  PyErr_Format(
      PyExc_ReferenceError, "BMesh data of type %.200s has been removed", Py_TYPE(self)->tp_name);
  return -1;
}

int bpy_bm_generic_valid_check_source(BMesh *bm_source,
                                      const char *error_prefix,
                                      void **args,
                                      uint args_tot)
{
  int ret = 0;

  while (args_tot--) {
    BPy_BMGeneric *py_bm_elem = args[args_tot];
    if (py_bm_elem) {

      BLI_assert(BPy_BMesh_Check(py_bm_elem) || BPy_BMElem_Check(py_bm_elem));

      ret = bpy_bm_generic_valid_check(py_bm_elem);
      if (UNLIKELY(ret == -1)) {
        break;
      }

      if (UNLIKELY(py_bm_elem->bm != bm_source)) {
        /* could give more info here */
        PyErr_Format(PyExc_ValueError,
                     "%.200s: BMesh data of type %.200s is from another mesh",
                     error_prefix,
                     Py_TYPE(py_bm_elem)->tp_name);
        ret = -1;
        break;
      }
    }
  }

  return ret;
}

void bpy_bm_generic_invalidate(BPy_BMGeneric *self)
{
  self->bm = NULL;
}

void *BPy_BMElem_PySeq_As_Array_FAST(BMesh **r_bm,
                                     PyObject *seq_fast,
                                     Py_ssize_t min,
                                     Py_ssize_t max,
                                     Py_ssize_t *r_size,
                                     const char htype,
                                     const bool do_unique_check,
                                     const bool do_bm_check,
                                     const char *error_prefix)
{
  BMesh *bm = (r_bm && *r_bm) ? *r_bm : NULL;
  PyObject **seq_fast_items = PySequence_Fast_ITEMS(seq_fast);
  const Py_ssize_t seq_len = PySequence_Fast_GET_SIZE(seq_fast);
  Py_ssize_t i, i_last_dirty = PY_SSIZE_T_MAX;

  BPy_BMElem *item;
  BMElem **alloc;

  *r_size = 0;

  if (seq_len < min || seq_len > max) {
    PyErr_Format(PyExc_TypeError,
                 "%s: sequence incorrect size, expected [%d - %d], given %d",
                 error_prefix,
                 min,
                 max,
                 seq_len);
    return NULL;
  }

  /* from now on, use goto */
  alloc = PyMem_MALLOC(seq_len * sizeof(BPy_BMElem **));

  for (i = 0; i < seq_len; i++) {
    item = (BPy_BMElem *)seq_fast_items[i];

    if (!BPy_BMElem_CheckHType(Py_TYPE(item), htype)) {
      PyErr_Format(PyExc_TypeError,
                   "%s: expected %.200s, not '%.200s'",
                   error_prefix,
                   BPy_BMElem_StringFromHType(htype),
                   Py_TYPE(item)->tp_name);
      goto err_cleanup;
    }
    else if (!BPY_BM_IS_VALID(item)) {
      PyErr_Format(
          PyExc_TypeError, "%s: %d %s has been removed", error_prefix, i, Py_TYPE(item)->tp_name);
      goto err_cleanup;
    }
    /* trick so we can ensure all items have the same mesh,
     * and allows us to pass the 'bm' as NULL. */
    else if (do_bm_check && (bm && bm != item->bm)) {
      PyErr_Format(PyExc_ValueError,
                   "%s: %d %s is from another mesh",
                   error_prefix,
                   i,
                   BPy_BMElem_StringFromHType(htype));
      goto err_cleanup;
    }

    if (bm == NULL) {
      bm = item->bm;
    }

    alloc[i] = item->ele;

    if (do_unique_check) {
      BM_elem_flag_enable(item->ele, BM_ELEM_INTERNAL_TAG);
      i_last_dirty = i;
    }
  }

  if (do_unique_check) {
    /* check for double verts! */
    bool ok = true;
    for (i = 0; i < seq_len; i++) {
      if (UNLIKELY(BM_elem_flag_test(alloc[i], BM_ELEM_INTERNAL_TAG) == false)) {
        ok = false;
      }

      /* ensure we don't leave this enabled */
      BM_elem_flag_disable(alloc[i], BM_ELEM_INTERNAL_TAG);
    }

    if (ok == false) {
      /* Cleared above. */
      i_last_dirty = PY_SSIZE_T_MAX;
      PyErr_Format(PyExc_ValueError,
                   "%s: found the same %.200s used multiple times",
                   error_prefix,
                   BPy_BMElem_StringFromHType(htype));
      goto err_cleanup;
    }
  }

  *r_size = seq_len;
  if (r_bm) {
    *r_bm = bm;
  }
  return alloc;

err_cleanup:
  if (do_unique_check && (i_last_dirty != PY_SSIZE_T_MAX)) {
    for (i = 0; i <= i_last_dirty; i++) {
      BM_elem_flag_disable(alloc[i], BM_ELEM_INTERNAL_TAG);
    }
  }
  PyMem_FREE(alloc);
  return NULL;
}

void *BPy_BMElem_PySeq_As_Array(BMesh **r_bm,
                                PyObject *seq,
                                Py_ssize_t min,
                                Py_ssize_t max,
                                Py_ssize_t *r_size,
                                const char htype,
                                const bool do_unique_check,
                                const bool do_bm_check,
                                const char *error_prefix)
{
  PyObject *seq_fast;
  PyObject *ret;

  if (!(seq_fast = PySequence_Fast(seq, error_prefix))) {
    return NULL;
  }

  ret = BPy_BMElem_PySeq_As_Array_FAST(
      r_bm, seq_fast, min, max, r_size, htype, do_unique_check, do_bm_check, error_prefix);

  Py_DECREF(seq_fast);
  return ret;
}

PyObject *BPy_BMElem_Array_As_Tuple(BMesh *bm, BMHeader **elem, Py_ssize_t elem_len)
{
  Py_ssize_t i;
  PyObject *ret = PyTuple_New(elem_len);
  for (i = 0; i < elem_len; i++) {
    PyTuple_SET_ITEM(ret, i, BPy_BMElem_CreatePyObject(bm, elem[i]));
  }
  return ret;
}
PyObject *BPy_BMVert_Array_As_Tuple(BMesh *bm, BMVert **elem, Py_ssize_t elem_len)
{
  Py_ssize_t i;
  PyObject *ret = PyTuple_New(elem_len);
  for (i = 0; i < elem_len; i++) {
    PyTuple_SET_ITEM(ret, i, BPy_BMVert_CreatePyObject(bm, elem[i]));
  }
  return ret;
}
PyObject *BPy_BMEdge_Array_As_Tuple(BMesh *bm, BMEdge **elem, Py_ssize_t elem_len)
{
  Py_ssize_t i;
  PyObject *ret = PyTuple_New(elem_len);
  for (i = 0; i < elem_len; i++) {
    PyTuple_SET_ITEM(ret, i, BPy_BMEdge_CreatePyObject(bm, elem[i]));
  }

  return ret;
}
PyObject *BPy_BMFace_Array_As_Tuple(BMesh *bm, BMFace **elem, Py_ssize_t elem_len)
{
  Py_ssize_t i;
  PyObject *ret = PyTuple_New(elem_len);
  for (i = 0; i < elem_len; i++) {
    PyTuple_SET_ITEM(ret, i, BPy_BMFace_CreatePyObject(bm, elem[i]));
  }

  return ret;
}
PyObject *BPy_BMLoop_Array_As_Tuple(BMesh *bm, BMLoop **elem, Py_ssize_t elem_len)
{
  Py_ssize_t i;
  PyObject *ret = PyTuple_New(elem_len);
  for (i = 0; i < elem_len; i++) {
    PyTuple_SET_ITEM(ret, i, BPy_BMLoop_CreatePyObject(bm, elem[i]));
  }

  return ret;
}

int BPy_BMElem_CheckHType(PyTypeObject *type, const char htype)
{
  return (((htype & BM_VERT) && (type == &BPy_BMVert_Type)) ||
          ((htype & BM_EDGE) && (type == &BPy_BMEdge_Type)) ||
          ((htype & BM_FACE) && (type == &BPy_BMFace_Type)) ||
          ((htype & BM_LOOP) && (type == &BPy_BMLoop_Type)));
}

char *BPy_BMElem_StringFromHType_ex(const char htype, char ret[32])
{
  /* zero to ensure string is always NULL terminated */
  char *ret_ptr = ret;
  if (htype & BM_VERT) {
    ret_ptr += sprintf(ret_ptr, "/%s", BPy_BMVert_Type.tp_name);
  }
  if (htype & BM_EDGE) {
    ret_ptr += sprintf(ret_ptr, "/%s", BPy_BMEdge_Type.tp_name);
  }
  if (htype & BM_FACE) {
    ret_ptr += sprintf(ret_ptr, "/%s", BPy_BMFace_Type.tp_name);
  }
  if (htype & BM_LOOP) {
    ret_ptr += sprintf(ret_ptr, "/%s", BPy_BMLoop_Type.tp_name);
  }
  ret[0] = '(';
  *ret_ptr++ = ')';
  *ret_ptr = '\0';
  return ret;
}
char *BPy_BMElem_StringFromHType(const char htype)
{
  /* zero to ensure string is always NULL terminated */
  static char ret[32];
  return BPy_BMElem_StringFromHType_ex(htype, ret);
}

/* -------------------------------------------------------------------- */
/* keep at bottom */

/* This function is called on free, it should stay quite fast */
static void bm_dealloc_editmode_warn(BPy_BMesh *self)
{
  if (self->flag & BPY_BMFLAG_IS_WRAPPED) {
    /* Currently NOP - this works without warnings now. */
  }
}