Replace the Studio parser module with a pure Python implementation

PiperOrigin-RevId: 953181335
Change-Id: I1d2ce6f27f50aa4c30cce6d43caed80186ddef42

python/mujoco/experimental/studio/CMakeLists.txt

@@ -23,9 +23,6 @@ set(STUDIO_COMMON_LIBS
   structs_wrappers
 )
 
-mujoco_pybind11_module(parser parser.cc)
-target_link_libraries(parser PRIVATE ${STUDIO_COMMON_LIBS})
-
 mujoco_pybind11_module(native_viewer_cc native_viewer.cc)
 target_link_libraries(native_viewer_cc PRIVATE ${STUDIO_COMMON_LIBS})
 
@@ -39,7 +36,6 @@ mujoco_pybind11_module(sim sim.cc)
 target_link_libraries(sim PRIVATE ${STUDIO_COMMON_LIBS})
 
 set(MUJOCO_STUDIO_TARGETS
-    parser
     native_viewer_cc
     renderer
     ux
@@ -73,7 +69,6 @@ set_target_properties(implot PROPERTIES
 # when linking both GLFW (via Filament) and SDL2 statically on Linux.
 if(UNIX AND NOT APPLE)
   set(STUDIO_PY_MODULES
-      parser
       native_viewer_cc
       renderer
       ux
@@ -86,7 +81,6 @@ endif()
 
 if(APPLE)
   set(STUDIO_PY_MODULES
-      parser
       native_viewer_cc
       renderer
       ux

python/mujoco/experimental/studio/parser.cc

@@ -1,52 +0,0 @@
-// Copyright 2026 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
-//
-//     https://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.
-
-#include <memory>
-#include <string_view>
-
-#include <mujoco/mujoco.h>
-#include <mujoco/experimental/platform/sim/model_holder.h>
-#include "structs.h"
-#include <pybind11/pybind11.h>
-
-namespace mujoco::python {
-
-// Loads, parses, and compiles a MuJoCo model from the given file. Returns the
-// python mjData object (which also contains the compiled mjModel).
-py::object Parse(std::string_view filepath) {
-  std::unique_ptr<platform::ModelHolder> holder;
-  {
-    py::gil_scoped_release no_gil;
-    holder = platform::ModelHolder::FromFile(filepath);
-  }
-  if (!holder->ok()) {
-    throw py::value_error(
-        std::string("Failed to load model from '") +
-        std::string(filepath) + "': " + std::string(holder->error()));
-  }
-  mjModel* model = holder->ReleaseModel();
-  mjData* data = holder->ReleaseData();
-  py::object py_model = py::cast(MjModelWrapper(model));
-  py::object py_data =
-      py::cast(MjDataWrapper(py::cast<MjModelWrapper*>(py_model), data));
-  return py_data;
-}
-
-}  // namespace mujoco::python
-
-PYBIND11_MODULE(parser, m, pybind11::mod_gil_not_used()) {
-  pybind11::module_::import("mujoco._structs");
-  m.def("parse", &mujoco::python::Parse,
-        pybind11::return_value_policy::take_ownership);
-}

python/mujoco/experimental/studio/parser.py

@@ -0,0 +1,24 @@
+# Copyright 2026 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
+#
+#     https://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.
+"""Loads and compiles MuJoCo models for the studio viewer."""
+
+import mujoco
+
+
+def parse(filepath: str) -> mujoco.MjData:
+  if filepath.endswith('.mjb'):
+    model = mujoco.MjModel.from_binary_path(filepath)
+  else:
+    model = mujoco.MjSpec.from_file(filepath).compile()
+  return mujoco.MjData(model)