text: // Copyright 2022 DeepMind Technologies Limited
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  #ifndef MUJOCO_PYTHON_INDEXER_XMACRO_H_
  #define MUJOCO_PYTHON_INDEXER_XMACRO_H_
  
  #include <mjxmacro.h>
  
  #define MJMODEL_ACTUATOR                                          \
    X( int,     actuator_, trntype,      nu, 1                    ) \
    X( int,     actuator_, dyntype,      nu, 1                    ) \
    X( int,     actuator_, gaintype,     nu, 1                    ) \
    X( int,     actuator_, biastype,     nu, 1                    ) \
    X( int,     actuator_, trnid,        nu, 2                    ) \
    X( int,     actuator_, group,        nu, 1                    ) \
    X( mjtByte, actuator_, ctrllimited,  nu, 1                    ) \
    X( mjtByte, actuator_, forcelimited, nu, 1                    ) \
    X( mjtNum,  actuator_, dynprm,       nu, mjNDYN               ) \
    X( mjtNum,  actuator_, gainprm,      nu, mjNGAIN              ) \
    X( mjtNum,  actuator_, biasprm,      nu, mjNBIAS              ) \
    X( mjtNum,  actuator_, ctrlrange,    nu, 2                    ) \
    X( mjtNum,  actuator_, forcerange,   nu, 2                    ) \
    X( mjtNum,  actuator_, gear,         nu, 6                    ) \
    X( mjtNum,  actuator_, cranklength,  nu, 1                    ) \
    X( mjtNum,  actuator_, acc0,         nu, 1                    ) \
    X( mjtNum,  actuator_, length0,      nu, 1                    ) \
    X( mjtNum,  actuator_, lengthrange,  nu, 2                    ) \
    X( mjtNum,  actuator_, user,         nu, MJ_M(nuser_actuator) )
  
  #define MJMODEL_BODY                                        \
    X( int,     body_, parentid,    nbody, 1                ) \
    X( int,     body_, rootid,      nbody, 1                ) \
    X( int,     body_, weldid,      nbody, 1                ) \
    X( int,     body_, mocapid,     nbody, 1                ) \
    X( int,     body_, jntnum,      nbody, 1                ) \
    X( int,     body_, jntadr,      nbody, 1                ) \
    X( int,     body_, dofnum,      nbody, 1                ) \
    X( int,     body_, dofadr,      nbody, 1                ) \
    X( int,     body_, geomnum,     nbody, 1                ) \
    X( int,     body_, geomadr,     nbody, 1                ) \
    X( mjtByte, body_, simple,      nbody, 1                ) \
    X( mjtByte, body_, sameframe,   nbody, 1                ) \
    X( mjtNum,  body_, pos,         nbody, 3                ) \
    X( mjtNum,  body_, quat,        nbody, 4                ) \
    X( mjtNum,  body_, ipos,        nbody, 3                ) \
    X( mjtNum,  body_, iquat,       nbody, 4                ) \
    X( mjtNum,  body_, mass,        nbody, 1                ) \
    X( mjtNum,  body_, subtreemass, nbody, 1                ) \
    X( mjtNum,  body_, inertia,     nbody, 3                ) \
    X( mjtNum,  body_, invweight0,  nbody, 2                ) \
    X( mjtNum,  body_, user,        nbody, MJ_M(nuser_body) )
  
  #define MJMODEL_CAMERA                                   \
    X( int,    cam_, mode,         ncam, 1               ) \
    X( int,    cam_, bodyid,       ncam, 1               ) \
    X( int,    cam_, targetbodyid, ncam, 1               ) \
    X( mjtNum, cam_, pos,          ncam, 3               ) \
    X( mjtNum, cam_, quat,         ncam, 4               ) \
    X( mjtNum, cam_, poscom0,      ncam, 3               ) \
    X( mjtNum, cam_, pos0,         ncam, 3               ) \
    X( mjtNum, cam_, mat0,         ncam, 9               ) \
    X( mjtNum, cam_, fovy,         ncam, 1               ) \
    X( mjtNum, cam_, ipd,          ncam, 1               ) \
    X( mjtNum, cam_, user,         ncam, MJ_M(nuser_cam) )
  
  #define MJMODEL_EQUALITY                    \
    X( int,     eq_, type,   neq, 1         ) \
    X( int,     eq_, obj1id, neq, 1         ) \
    X( int,     eq_, obj2id, neq, 1         ) \
    X( mjtByte, eq_, active, neq, 1         ) \
    X( mjtNum,  eq_, solref, neq, mjNREF    ) \
    X( mjtNum,  eq_, solimp, neq, mjNIMP    ) \
    X( mjtNum,  eq_, data,   neq, mjNEQDATA )
  
  #define MJMODEL_EXCLUDE                      \
    X( int, exclude_, signature, nexclude, 1 )
  
  #define MJMODEL_GEOM                                        \
    X( int,     geom_, type,        ngeom, 1                ) \
    X( int,     geom_, contype,     ngeom, 1                ) \
    X( int,     geom_, conaffinity, ngeom, 1                ) \
    X( int,     geom_, condim,      ngeom, 1                ) \
    X( int,     geom_, bodyid,      ngeom, 1                ) \
    X( int,     geom_, dataid,      ngeom, 1                ) \
    X( int,     geom_, matid,       ngeom, 1                ) \
    X( int,     geom_, group,       ngeom, 1                ) \
    X( int,     geom_, priority,    ngeom, 1                ) \
    X( mjtByte, geom_, sameframe,   ngeom, 1                ) \
    X( mjtNum,  geom_, solmix,      ngeom, 1                ) \
    X( mjtNum,  geom_, solref,      ngeom, mjNREF           ) \
    X( mjtNum,  geom_, solimp,      ngeom, mjNIMP           ) \
    X( mjtNum,  geom_, size,        ngeom, 3                ) \
    X( mjtNum,  geom_, rbound,      ngeom, 1                ) \
    X( mjtNum,  geom_, pos,         ngeom, 3                ) \
    X( mjtNum,  geom_, quat,        ngeom, 4                ) \
    X( mjtNum,  geom_, friction,    ngeom, 3                ) \
    X( mjtNum,  geom_, margin,      ngeom, 1                ) \
    X( mjtNum,  geom_, gap,         ngeom, 1                ) \
    X( mjtNum,  geom_, user,        ngeom, MJ_M(nuser_geom) ) \
    X( float,   geom_, rgba,        ngeom, 4                )
  
  #define MJMODEL_HFIELD                       \
    X( mjtNum, hfield_, size, nhfield,     4 ) \
    X( int,    hfield_, nrow, nhfield,     1 ) \
    X( int,    hfield_, ncol, nhfield,     1 ) \
    X( int,    hfield_, adr,  nhfield,     1 ) \
    X( float,  hfield_, data, nhfielddata, 1 )
  
  #define MJMODEL_JOINT                                     \
    X( mjtNum,  ,     qpos0,        nq,   1               ) \
    X( mjtNum,  ,     qpos_spring,  nq,   1               ) \
    X( int,     jnt_, type,         njnt, 1               ) \
    X( int,     jnt_, qposadr,      njnt, 1               ) \
    X( int,     jnt_, dofadr,       njnt, 1               ) \
    X( int,     jnt_, group,        njnt, 1               ) \
    X( mjtByte, jnt_, limited,      njnt, 1               ) \
    X( mjtNum,  jnt_, pos,          njnt, 3               ) \
    X( mjtNum,  jnt_, axis,         njnt, 3               ) \
    X( mjtNum,  jnt_, stiffness,    njnt, 1               ) \
    X( mjtNum,  jnt_, range,        njnt, 2               ) \
    X( mjtNum,  jnt_, margin,       njnt, 1               ) \
    X( mjtNum,  jnt_, user,         njnt, MJ_M(nuser_jnt) ) \
    X( int,     dof_, bodyid,       nv,   1               ) \
    X( int,     dof_, jntid,        nv,   1               ) \
    X( int,     dof_, parentid,     nv,   1               ) \
    X( int,     dof_, Madr,         nv,   1               ) \
    X( int,     dof_, simplenum,    nv,   1               ) \
    X( mjtNum,  dof_, solref,       nv,   mjNREF          ) \
    X( mjtNum,  dof_, solimp,       nv,   mjNIMP          ) \
    X( mjtNum,  dof_, frictionloss, nv,   1               ) \
    X( mjtNum,  dof_, armature,     nv,   1               ) \
    X( mjtNum,  dof_, damping,      nv,   1               ) \
    X( mjtNum,  dof_, invweight0,   nv,   1               ) \
    X( mjtNum,  dof_, M0,           nv,   1               )
  
  #define MJMODEL_LIGHT                             \
    X( int,     light_, mode,          nlight,  1 ) \
    X( int,     light_, bodyid,        nlight,  1 ) \
    X( int,     light_, targetbodyid,  nlight,  1 ) \
    X( mjtByte, light_, directional,   nlight,  1 ) \
    X( mjtByte, light_, castshadow,    nlight,  1 ) \
    X( mjtByte, light_, active,        nlight,  1 ) \
    X( mjtNum,  light_, pos,           nlight,  3 ) \
    X( mjtNum,  light_, dir,           nlight,  3 ) \
    X( mjtNum,  light_, poscom0,       nlight,  3 ) \
    X( mjtNum,  light_, pos0,          nlight,  3 ) \
    X( mjtNum,  light_, dir0,          nlight,  3 ) \
    X( float,   light_, attenuation,   nlight,  3 ) \
    X( float,   light_, cutoff,        nlight,  1 ) \
    X( float,   light_, exponent,      nlight,  1 ) \
    X( float,   light_, ambient,       nlight,  3 ) \
    X( float,   light_, diffuse,       nlight,  3 ) \
    X( float,   light_, specular,      nlight,  3 )
  
  #define MJMODEL_MATERIAL                   \
    X( int,     mat_, texid,       nmat, 1 ) \
    X( mjtByte, mat_, texuniform,  nmat, 1 ) \
    X( float,   mat_, texrepeat,   nmat, 2 ) \
    X( float,   mat_, emission,    nmat, 1 ) \
    X( float,   mat_, specular,    nmat, 1 ) \
    X( float,   mat_, shininess,   nmat, 1 ) \
    X( float,   mat_, reflectance, nmat, 1 ) \
    X( float,   mat_, rgba,        nmat, 4 )
  
  #define MJMODEL_MESH                   \
    X( int, mesh_, vertadr,     nmesh, 1 ) \
    X( int, mesh_, vertnum,     nmesh, 1 ) \
    X( int, mesh_, texcoordadr, nmesh, 1 ) \
    X( int, mesh_, faceadr,     nmesh, 1 ) \
    X( int, mesh_, facenum,     nmesh, 1 ) \
    X( int, mesh_, graphadr,    nmesh, 1 )
  
  #define MJMODEL_NUMERIC                        \
    X( int,    numeric_, adr,  nnumeric,     1 ) \
    X( int,    numeric_, size, nnumeric,     1 ) \
    X( mjtNum, numeric_, data, nnumericdata, 1 )
  
  #define MJMODEL_PAIR                            \
    X( int,     pair_, dim,       npair, 1      ) \
    X( int,     pair_, geom1,     npair, 1      ) \
    X( int,     pair_, geom2,     npair, 1      ) \
    X( int,     pair_, signature, npair, 1      ) \
    X( mjtNum,  pair_, solref,    npair, mjNREF ) \
    X( mjtNum,  pair_, solimp,    npair, mjNIMP ) \
    X( mjtNum,  pair_, margin,    npair, 1      ) \
    X( mjtNum,  pair_, gap,       npair, 1      ) \
    X( mjtNum,  pair_, friction,  npair, 5      )
  
  #define MJMODEL_SENSOR                                         \
    X( int,    sensor_, type,      nsensor, 1                  ) \
    X( int,    sensor_, datatype,  nsensor, 1                  ) \
    X( int,    sensor_, needstage, nsensor, 1                  ) \
    X( int,    sensor_, objtype,   nsensor, 1                  ) \
    X( int,    sensor_, objid,     nsensor, 1                  ) \
    X( int,    sensor_, reftype,   nsensor, 1                  ) \
    X( int,    sensor_, refid,     nsensor, 1                  ) \
    X( int,    sensor_, dim,       nsensor, 1                  ) \
    X( int,    sensor_, adr,       nsensor, 1                  ) \
    X( mjtNum, sensor_, cutoff,    nsensor, 1                  ) \
    X( mjtNum, sensor_, noise,     nsensor, 1                  ) \
    X( mjtNum, sensor_, user,      nsensor, MJ_M(nuser_sensor) )
  
  #define MJMODEL_SITE                                      \
    X( int,     site_, type,      nsite, 1                ) \
    X( int,     site_, bodyid,    nsite, 1                ) \
    X( int,     site_, matid,     nsite, 1                ) \
    X( int,     site_, group,     nsite, 1                ) \
    X( mjtByte, site_, sameframe, nsite, 1                ) \
    X( mjtNum,  site_, size,      nsite, 3                ) \
    X( mjtNum,  site_, pos,       nsite, 3                ) \
    X( mjtNum,  site_, quat,      nsite, 4                ) \
    X( mjtNum,  site_, user,      nsite, MJ_M(nuser_site) ) \
    X( float,   site_, rgba,      nsite, 4                )
  
  #define MJMODEL_SKIN                       \
    X( int,   skin_, matid,       nskin, 1 ) \
    X( float, skin_, rgba,        nskin, 4 ) \
    X( float, skin_, inflate,     nskin, 1 ) \
    X( int,   skin_, vertadr,     nskin, 1 ) \
    X( int,   skin_, vertnum,     nskin, 1 ) \
    X( int,   skin_, texcoordadr, nskin, 1 ) \
    X( int,   skin_, faceadr,     nskin, 1 ) \
    X( int,   skin_, facenum,     nskin, 1 ) \
    X( int,   skin_, boneadr,     nskin, 1 ) \
    X( int,   skin_, bonenum,     nskin, 1 )
  
  #define MJMODEL_TENDON                                             \
    X( int,     tendon, _adr,          ntendon, 1                  ) \
    X( int,     tendon, _num,          ntendon, 1                  ) \
    X( int,     tendon, _matid,        ntendon, 1                  ) \
    X( int,     tendon, _group,        ntendon, 1                  ) \
    X( mjtByte, tendon, _limited,      ntendon, 1                  ) \
    X( mjtNum,  tendon, _width,        ntendon, 1                  ) \
    X( mjtNum,  tendon, _solref_lim,   ntendon, mjNREF             ) \
    X( mjtNum,  tendon, _solimp_lim,   ntendon, mjNIMP             ) \
    X( mjtNum,  tendon, _solref_fri,   ntendon, mjNREF             ) \
    X( mjtNum,  tendon, _solimp_fri,   ntendon, mjNIMP             ) \
    X( mjtNum,  tendon, _range,        ntendon, 2                  ) \
    X( mjtNum,  tendon, _margin,       ntendon, 1                  ) \
    X( mjtNum,  tendon, _stiffness,    ntendon, 1                  ) \
    X( mjtNum,  tendon, _damping,      ntendon, 1                  ) \
    X( mjtNum,  tendon, _frictionloss, ntendon, 1                  ) \
    X( mjtNum,  tendon, _lengthspring, ntendon, 1                  ) \
    X( mjtNum,  tendon, _length0,      ntendon, 1                  ) \
    X( mjtNum,  tendon, _invweight0,   ntendon, 1                  ) \
    X( mjtNum,  tendon, _user,         ntendon, MJ_M(nuser_tendon) ) \
    X( float,   tendon, _rgba,         ntendon, 4                  )
  
  #define MJMODEL_TEXTURE                   \
    X( int,     tex_, type,   ntex,     1 ) \
    X( int,     tex_, height, ntex,     1 ) \
    X( int,     tex_, width,  ntex,     1 ) \
    X( int,     tex_, adr,    ntex,     1 ) \
    X( mjtByte, tex_, rgb,    ntexdata, 1 )
  
  #define MJMODEL_TUPLE                         \
    X( int,    tuple_, adr,     ntuple,     1 ) \
    X( int,    tuple_, size,    ntuple,     1 ) \
    X( int,    tuple_, objtype, ntupledata, 1 ) \
    X( int,    tuple_, objid,   ntupledata, 1 ) \
    X( mjtNum, tuple_, objprm,  ntupledata, 1 )
  
  #define MJMODEL_KEYFRAME                         \
    X( mjtNum, key_, time,  nkey, 1              ) \
    X( mjtNum, key_, qpos,  nkey, MJ_M(nq)       ) \
    X( mjtNum, key_, qvel,  nkey, MJ_M(nv)       ) \
    X( mjtNum, key_, act,   nkey, MJ_M(na)       ) \
    X( mjtNum, key_, mpos,  nkey, MJ_M(nmocap)*3 ) \
    X( mjtNum, key_, mquat, nkey, MJ_M(nmocap)*4 )
  
  #define MJMODEL_VIEW_GROUPS                                            \
    XGROUP( MjModelActuatorViews, actuator, nu,       MJMODEL_ACTUATOR ) \
    XGROUP( MjModelBodyViews,     body,     nbody,    MJMODEL_BODY     ) \
    XGROUP( MjModelCameraViews,   cam,      ncam,     MJMODEL_CAMERA   ) \
    XGROUP( MjModelEqualityViews, eq,       neq,      MJMODEL_EQUALITY ) \
    XGROUP( MjModelExcludeViews,  exclude,  nexclude, MJMODEL_EXCLUDE  ) \
    XGROUP( MjModelGeomViews,     geom,     ngeom,    MJMODEL_GEOM     ) \
    XGROUP( MjModelHfieldViews,   hfield,   nhfield,  MJMODEL_HFIELD   ) \
    XGROUP( MjModelJointViews,    jnt,      njnt,     MJMODEL_JOINT    ) \
    XGROUP( MjModelLightViews,    light,    nlight,   MJMODEL_LIGHT    ) \
    XGROUP( MjModelMaterialViews, mat,      nmat,     MJMODEL_MATERIAL ) \
    XGROUP( MjModelMeshViews,     mesh,     nmesh,    MJMODEL_MESH     ) \
    XGROUP( MjModelNumericViews,  numeric,  nnumeric, MJMODEL_NUMERIC  ) \
    XGROUP( MjModelPairViews,     pair,     npair,    MJMODEL_PAIR     ) \
    XGROUP( MjModelSensorViews,   sensor,   nsensor,  MJMODEL_SENSOR   ) \
    XGROUP( MjModelSiteViews,     site,     nsite,    MJMODEL_SITE     ) \
    XGROUP( MjModelSkinViews,     skin,     nskin,    MJMODEL_SKIN     ) \
    XGROUP( MjModelTendonViews,   tendon,   ntendon,  MJMODEL_TENDON   ) \
    XGROUP( MjModelTextureViews,  tex,      ntex,     MJMODEL_TEXTURE  ) \
    XGROUP( MjModelTupleViews,    tuple,    ntuple,   MJMODEL_TUPLE    ) \
    XGROUP( MjModelKeyframeViews, key,      nkey,     MJMODEL_KEYFRAME )
  
  #define MJMODEL_VIEW_GROUPS_ALTNAMES        \
    XGROUP( cam, camera,   MJMODEL_CAMERA   ) \
    XGROUP( eq,  equality, MJMODEL_EQUALITY ) \
    XGROUP( jnt, joint,    MJMODEL_JOINT    ) \
    XGROUP( mat, material, MJMODEL_MATERIAL ) \
    XGROUP( tex, texture,  MJMODEL_TEXTURE  ) \
    XGROUP( key, keyframe, MJMODEL_KEYFRAME )
  
  #define MJDATA_ACTUATOR                          \
    X( mjtNum, ,          ctrl,     nu, 1        ) \
    X( mjtNum, actuator_, length,   nu, 1        ) \
    X( mjtNum, actuator_, moment,   nu, MJ_M(nv) ) \
    X( mjtNum, actuator_, velocity, nu, 1        ) \
    X( mjtNum, actuator_, force,    nu, 1        )
  
  #define MJDATA_BODY                        \
    X( mjtNum, , xfrc_applied,   nbody, 6  ) \
    X( mjtNum, , xpos,           nbody, 3  ) \
    X( mjtNum, , xquat,          nbody, 4  ) \
    X( mjtNum, , xmat,           nbody, 9  ) \
    X( mjtNum, , xipos,          nbody, 3  ) \
    X( mjtNum, , ximat,          nbody, 9  ) \
    X( mjtNum, , subtree_com,    nbody, 3  ) \
    X( mjtNum, , cinert,         nbody, 10 ) \
    X( mjtNum, , crb,            nbody, 10 ) \
    X( mjtNum, , cvel,           nbody, 6  ) \
    X( mjtNum, , subtree_linvel, nbody, 3  ) \
    X( mjtNum, , subtree_angmom, nbody, 3  ) \
    X( mjtNum, , cacc,           nbody, 6  ) \
    X( mjtNum, , cfrc_int,       nbody, 6  ) \
    X( mjtNum, , cfrc_ext,       nbody, 6  )
  
  #define MJDATA_CAMERA              \
    X( mjtNum, cam_, xpos, ncam, 3 ) \
    X( mjtNum, cam_, xmat, ncam, 9 )
  
  #define MJDATA_GEOM                  \
    X( mjtNum, geom_, xpos, ngeom, 3 ) \
    X( mjtNum, geom_, xmat, ngeom, 9 )
  
  #define MJDATA_JOINT                                \
    X( mjtNum, , qpos,            nq,   1           ) \
    X( mjtNum, , qvel,            nv,   1           ) \
    X( mjtNum, , qacc_warmstart,  nv,   1           ) \
    X( mjtNum, , qfrc_applied,    nv,   1           ) \
    X( mjtNum, , qacc,            nv,   1           ) \
    X( mjtNum, , xanchor,         njnt, 3           ) \
    X( mjtNum, , xaxis,           njnt, 3           ) \
    X( mjtNum, , cdof,            nv,   6           ) \
    X( mjtNum, , qLDiagInv,       nv,   1           ) \
    X( mjtNum, , qLDiagSqrtInv,   nv,   1           ) \
    X( int,    , efc_JT_rownnz,   nv,   1           ) \
    X( int,    , efc_JT_rowadr,   nv,   1           ) \
    X( int,    , efc_JT_rowsuper, nv,   1           ) \
    X( int,    , efc_JT_colind,   nv,   MJ_M(njmax) ) \
    X( mjtNum, , efc_JT,          nv,   MJ_M(njmax) ) \
    X( mjtNum, , cdof_dot,        nv,   6           ) \
    X( mjtNum, , qfrc_bias,       nv,   1           ) \
    X( mjtNum, , qfrc_passive,    nv,   1           ) \
    X( mjtNum, , qfrc_actuator,   nv,   1           ) \
    X( mjtNum, , qfrc_unc,        nv,   1           ) \
    X( mjtNum, , qacc_unc,        nv,   1           ) \
    X( mjtNum, , qfrc_constraint, nv,   1           ) \
    X( mjtNum, , qfrc_inverse,    nv,   1           )
  
  #define MJDATA_LIGHT                   \
    X( mjtNum, light_, xpos, nlight, 3 ) \
    X( mjtNum, light_, xdir, nlight, 3 )
  
  #define MJDATA_SENSOR                       \
    X( mjtNum, sensor, data, nsensordata, 1 )
  
  #define MJDATA_SITE                  \
    X( mjtNum, site_, xpos, nsite, 3 ) \
    X( mjtNum, site_, xmat, nsite, 9 )
  
  #define MJDATA_TENDON                            \
    X( int, ten_,    wrapadr , ntendon, 1        ) \
    X( int, ten_,    wrapnum , ntendon, 1        ) \
    X( int, ten_,    J_rownnz, ntendon, 1        ) \
    X( int, ten_,    J_rowadr, ntendon, 1        ) \
    X( int, ten_,    J_colind, ntendon, MJ_M(nv) ) \
    X( mjtNum, ten_, length  , ntendon, 1        ) \
    X( mjtNum, ten_, J       , ntendon, MJ_M(nv) ) \
    X( mjtNum, ten_, velocity, ntendon, 1        )
  
  #define MJDATA_VIEW_GROUPS                                           \
    XGROUP( MjDataActuatorViews, actuator, nu,       MJDATA_ACTUATOR ) \
    XGROUP( MjDataBodyViews,     body,     nbody,    MJDATA_BODY     ) \
    XGROUP( MjDataCameraViews,   cam,      ncam,     MJDATA_CAMERA   ) \
    XGROUP( MjDataGeomViews,     geom,     ngeom,    MJDATA_GEOM     ) \
    XGROUP( MjDataJointViews,    jnt,      njnt,     MJDATA_JOINT    ) \
    XGROUP( MjDataLightViews,    light,    nlight,   MJDATA_LIGHT    ) \
    XGROUP( MjDataSensorViews,   sensor,   nsensor,  MJDATA_SENSOR   ) \
    XGROUP( MjDataSiteViews,     site,     nsite,    MJDATA_SITE     ) \
    XGROUP( MjDataTendonViews,   tendon,   ntendon,  MJDATA_TENDON   )
  
  #define MJDATA_VIEW_GROUPS_ALTNAMES       \
    XGROUP( cam,    camera, MJDATA_CAMERA ) \
    XGROUP( jnt,    joint,  MJDATA_JOINT  ) \
    XGROUP( tendon, ten,    MJDATA_TENDON )
  
  #endif  // MUJOCO_PYTHON_INDEXER_XMACRO_H_
  