Add JavaScript bindings and WASM support

Co-authored-by: Matija Kecman <matijak@google.com>
Co-authored-by: Sebastian Noreña Rendón <sebas.norena@creativa77.com.ar>
Co-authored-by: Kyle Bayes <kylebayes@google.com>
PiperOrigin-RevId: 826479070
Change-Id: I25acf36e6c20b091d8492e10798d028ae66f6733

wasm/codegen/generators/constants.py

@@ -0,0 +1,34 @@
+# Copyright 2025 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.
+
+"""Generator for the constants."""
+
+from wasm.codegen.helpers import common
+
+
+# TODO(manevi): Delete this file and use the genrule to handle the file copying
+class Generator:
+  """Generator for the constants."""
+
+  def run(self):
+    """Runs the generator."""
+    template_cc_file, output_cc_file = common.get_file_path(
+        "templates", "generated", "constants.cc"
+    )
+
+    with open(template_cc_file, "r") as f_template:
+      template_content = f_template.read()
+
+    with open(output_cc_file, "w") as f_output:
+      f_output.write(template_content)

wasm/codegen/generators/enums.py

@@ -0,0 +1,47 @@
+# Copyright 2025 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.
+
+"""Generates Embind bindings for MuJoCo enums."""
+
+from typing import Mapping
+
+from introspect import ast_nodes
+
+from wasm.codegen.helpers import code_builder
+
+
+class Generator:
+  """Generates Embind code for MuJoCo enums."""
+
+  def __init__(self, enums: Mapping[str, ast_nodes.EnumDecl]):
+    self.enums = enums
+
+  def _generate_enum_binding(self, enum: ast_nodes.EnumDecl) -> str:
+    """Generates the Embind code for a single enum."""
+
+    code = f'{code_builder.INDENT}enum_<{enum.name}>("{enum.name}")'
+
+    for value_name in enum.values:
+      code += f'\n{2*code_builder.INDENT}.value("{value_name}", {value_name})'
+
+    code += ";"
+    return code
+
+  def generate(self) -> str:
+    """Generates all Embind code for the provided enums."""
+
+    code = []
+    for enum in self.enums.values():
+      code.append(self._generate_enum_binding(enum))
+    return "\n\n".join(code) + "\n"

wasm/codegen/generators/enums_test.py

@@ -0,0 +1,62 @@
+# Copyright 2025 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.
+
+from absl.testing import absltest
+
+from introspect import ast_nodes
+
+from wasm.codegen.generators import enums
+
+
+class EnumsGeneratorTest(absltest.TestCase):
+
+  def test_generate_enum_bindings(self):
+
+    generator = enums.Generator({
+        "TestEnum": ast_nodes.EnumDecl(
+            name="TestEnum",
+            declname="enum TestEnum_",
+            values={"FIRST_VAL": 0, "SECOND_VAL": 1, "THIRD_VAL": 2},
+        ),
+        "AnotherEnum": ast_nodes.EnumDecl(
+            name="AnotherEnum",
+            declname="enum AnotherEnum_",
+            values={"ALPHA": 100, "BETA": 200},
+        ),
+        "EmptyEnum": ast_nodes.EnumDecl(
+            name="EmptyEnum",
+            declname="enum EmptyEnum_",
+            values={},
+        ),
+    })
+
+    expected_code = """  enum_<TestEnum>("TestEnum")
+    .value("FIRST_VAL", FIRST_VAL)
+    .value("SECOND_VAL", SECOND_VAL)
+    .value("THIRD_VAL", THIRD_VAL);
+
+  enum_<AnotherEnum>("AnotherEnum")
+    .value("ALPHA", ALPHA)
+    .value("BETA", BETA);
+
+  enum_<EmptyEnum>("EmptyEnum");
+"""
+
+    actual_code = generator.generate()
+
+    self.assertEqual(actual_code, expected_code)
+
+
+if __name__ == "__main__":
+  absltest.main()

wasm/codegen/generators/functions.py

@@ -0,0 +1,93 @@
+# Copyright 2025 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.
+
+"""Generates Embind bindings for MuJoCo functions."""
+
+import pathlib
+from typing import List, Mapping, TypeAlias
+
+from introspect import ast_nodes
+
+from wasm.codegen.helpers import code_builder
+from wasm.codegen.helpers import function_utils
+
+FunctionDecl: TypeAlias = ast_nodes.FunctionDecl
+FunctionParameterDecl: TypeAlias = ast_nodes.FunctionParameterDecl
+PointerType: TypeAlias = ast_nodes.PointerType
+ValueType: TypeAlias = ast_nodes.ValueType
+Path: TypeAlias = pathlib.Path
+
+
+class Generator:
+  """Generates Embind bindings for MuJoCo functions."""
+
+  def __init__(self, functions: Mapping[str, FunctionDecl]):
+    self.direct_bind_functions: List[FunctionDecl] = []
+    self.wrapper_bind_functions: List[FunctionDecl] = []
+
+    for func in functions.values():
+      if function_utils.should_be_wrapped(func):
+        self.wrapper_bind_functions.append(func)
+      else:
+        self.direct_bind_functions.append(func)
+
+  def _generate_wrappers(self) -> str:
+    """Generates Embind bindings for all functions that need wrappers."""
+
+    code = []
+    for func in self.wrapper_bind_functions:
+      wrapper_code = function_utils.generate_function_wrapper(func)
+      code.append(wrapper_code)
+
+    return "\n\n".join(code)
+
+  def _generate_direct_bindable_functions(self) -> str:
+    """Generates Embind bindings for all directly bindable functions."""
+
+    result = ""
+    for func in self.direct_bind_functions:
+      result += code_builder.INDENT
+      result += self._generate_function_binding(func)
+
+    return result
+
+  def _generate_function_binding(
+      self, func: FunctionDecl, is_wrapper=False
+  ) -> str:
+    """Generates the Embind code for a single function."""
+
+    js_name, cpp_func = func.name, func.name
+    if is_wrapper:
+      cpp_func += "_wrapper"
+
+    return f'function("{js_name}", &{cpp_func});\n'
+
+  def _generate_wrapper_bindable_functions(self) -> str:
+    """Generates Embind bindings for all functions that need wrappers."""
+
+    result = ""
+    for func in self.wrapper_bind_functions:
+      result += code_builder.INDENT
+      result += self._generate_function_binding(func, True)
+
+    return result
+
+  def generate(self) -> tuple[str, str]:
+    """Generates the bindings file for all functions."""
+
+    wrapper_functions = self._generate_wrappers()
+    function_bindings = self._generate_direct_bindable_functions()
+    function_bindings += self._generate_wrapper_bindable_functions()
+
+    return wrapper_functions, function_bindings

wasm/codegen/generators/functions_test.py

@@ -0,0 +1,67 @@
+# Copyright 2025 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.
+
+from absl.testing import absltest
+
+from introspect import ast_nodes
+
+from wasm.codegen.generators import functions
+
+
+class FunctionsGeneratorTest(absltest.TestCase):
+
+  def setUp(self):
+    super().setUp()
+    self.generator = functions.Generator({})
+    self.int_type = ast_nodes.ValueType(name="int")
+
+  def test_generate_function_binding_simple_case(self):
+    func_simple_void = ast_nodes.FunctionDecl(
+        name="do_nothing",
+        return_type=ast_nodes.ValueType(name="void"),
+        parameters=tuple(),
+        doc="doc",
+    )
+    self.assertEqual(
+        self.generator._generate_function_binding(func_simple_void),
+        'function("do_nothing", &do_nothing);\n',
+    )
+
+  def test_generate_direct_bindable_functions_simple_filter(self):
+    direct_bind = ast_nodes.FunctionDecl(
+        name="direct_bind",
+        return_type=self.int_type,
+        parameters=(
+            ast_nodes.FunctionParameterDecl(name="val", type=self.int_type),
+        ),
+        doc="doc",
+    )
+    needs_wrap = ast_nodes.FunctionDecl(
+        name="needs_wrap",
+        return_type=ast_nodes.PointerType(inner_type=self.int_type),
+        parameters=tuple(),
+        doc="doc",
+    )
+    self.generator = functions.Generator({
+        "direct1": direct_bind,
+        "wrapped1": needs_wrap,
+    })
+
+    generated_code = self.generator._generate_direct_bindable_functions()
+    self.assertIn('function("direct_bind", &direct_bind);\n', generated_code)
+    self.assertNotIn('function("needs_wrap", &needs_wrap);\n', generated_code)
+
+
+if __name__ == "__main__":
+  absltest.main()

wasm/codegen/generators/structs.py

@@ -0,0 +1,88 @@
+# Copyright 2025 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.
+
+"""Generates Embind bindings for MuJoCo structs."""
+
+from typing import Optional
+
+from wasm.codegen.helpers import constants
+from wasm.codegen.helpers import structs_parser
+from wasm.codegen.helpers import structs_wrappers_data
+
+
+class Generator:
+  """Generates C++ code for binding and wrapping MuJoCo structs."""
+
+  def __init__(self):
+    # Set up the correct input dict based on the structs we want to bind
+    # and already have a wrapper manually created in the template/bindings.cc
+    wrapped_structs = structs_wrappers_data.create_wrapped_structs_set_up_data(
+        constants.STRUCTS_TO_BIND
+    )
+
+    # Traverse the introspect dictionary to get the field
+    # wrapper/bindings statements set up for each struct
+    self.structs_to_bind_data = structs_parser.generate_wasm_bindings(
+        wrapped_structs
+    )
+
+  def generate_header(
+      self
+  ) -> list[tuple[str, list[Optional[str]]]]:
+    """Generates C++ header file for binding and wrapping MuJoCo structs."""
+    autogenned_struct_definitions = []
+    markers_and_content = []
+
+    # Sort by struct name by dependency to ensure deterministic output order
+    sorted_struct_names = structs_parser.sort_structs_by_dependency(
+        constants.STRUCTS_TO_BIND
+    )
+
+    for struct_name in sorted_struct_names:
+      struct_data = self.structs_to_bind_data[struct_name]
+      if struct_data.wrapped_header:
+        autogenned_struct_definitions.append(
+            struct_data.wrapped_header + "\n"
+        )
+      else:
+        markers_and_content.append((
+            f"// INSERT-GENERATED-{struct_data.wrap_name}-DEFINITIONS",
+            [
+                l.definition if l.definition else ""
+                for l in struct_data.wrapped_fields
+            ],
+        ))
+    markers_and_content.append((
+        "// {{ AUTOGENNED_STRUCT_DEFINITIONS }}",
+        autogenned_struct_definitions,
+    ))
+    return markers_and_content
+
+  def generate_source(self) -> list[tuple[str, list[str]]]:
+    """Generates C++ source file for binding and wrapping MuJoCo structs."""
+    constructors = [
+        (
+            f"// INSERT-GENERATED-{struct_data.wrap_name}-CONSTRUCTOR",
+            [struct_data.wrapped_source],
+        )
+        for _, struct_data in self.structs_to_bind_data.items()
+    ]
+    properties = [
+        (
+            f"// INSERT-GENERATED-{struct_data.wrap_name}-BINDINGS",
+            [l.binding for l in struct_data.wrapped_fields],
+        )
+        for _, struct_data in self.structs_to_bind_data.items()
+    ]
+    return constructors + properties