[Draft] WASM support

README.md

@@ -15,6 +15,8 @@ The package has no library dependencies and provides pre-compiled wheels for all
 
 ```sh
 pip install tree-sitter
+# For wasm support
+pip install tree-sitter[wasm]
 ```
 
 ## Usage
@@ -39,6 +41,22 @@ from tree_sitter import Language, Parser
 PY_LANGUAGE = Language(tspython.language())
 ```
 
+#### Wasm support
+
+If you enable the `wasm` extra, then tree-sitter will be able to use wasmtime to load languages compiled to wasm and parse with them. Example:
+
+```python
+from pathlib import Path
+from wasmtime import Engine
+from tree_sitter import Language, Parser
+
+engine = Engine()
+wasm_bytes = Path("my_language.wasm").read_bytes()
+MY_LANGUAGE = Language.from_wasm("my_language", engine, wasm_bytes)
+```
+
+Languages loaded this way work identically to native-binary languages.
+
 ### Basic parsing
 
 Create a `Parser` and configure it to use a language:

pyproject.toml

@@ -38,6 +38,7 @@ tests = [
     "tree-sitter-python>=0.23.0",
     "tree-sitter-rust>=0.23.0",
 ]
+wasm = ["wasmtime>=25"]
 
 [tool.ruff]
 target-version = "py39"

setup.py

@@ -23,29 +23,33 @@
                 "tree_sitter/binding/range.c",
                 "tree_sitter/binding/tree.c",
                 "tree_sitter/binding/tree_cursor.c",
+                "tree_sitter/binding/wasmtime.c",
                 "tree_sitter/binding/module.c",
             ],
             include_dirs=[
                 "tree_sitter/binding",
                 "tree_sitter/core/lib/include",
                 "tree_sitter/core/lib/src",
+                "tree_sitter/core/lib/src/wasm",
             ],
             define_macros=[
                 ("PY_SSIZE_T_CLEAN", None),
                 ("TREE_SITTER_HIDE_SYMBOLS", None),
+                ("TREE_SITTER_FEATURE_WASM", None),
             ],
-            undef_macros=[
-                "TREE_SITTER_FEATURE_WASM",
-            ],
-            extra_compile_args=[
-                "-std=c11",
-                "-fvisibility=hidden",
-                "-Wno-cast-function-type",
-                "-Werror=implicit-function-declaration",
-            ] if system() != "Windows" else [
-                "/std:c11",
-                "/wd4244",
-            ],
+            extra_compile_args=(
+                [
+                    "-std=c11",
+                    "-fvisibility=hidden",
+                    "-Wno-cast-function-type",
+                    "-Werror=implicit-function-declaration",
+                ]
+                if system() != "Windows"
+                else [
+                    "/std:c11",
+                    "/wd4244",
+                ]
+            ),
         )
     ],
 )

tests/test_wasm.py

@@ -0,0 +1,36 @@
+import importlib.resources
+from unittest import TestCase
+
+from tree_sitter import Language, Parser, Tree
+
+try:
+    import wasmtime
+
+    class TestWasm(TestCase):
+        @classmethod
+        def setUpClass(cls):
+            javascript_wasm = (
+                importlib.resources.files("tests")
+                .joinpath("wasm/tree-sitter-javascript.wasm")
+                .read_bytes()
+            )
+            engine = wasmtime.Engine()
+            cls.javascript = Language.from_wasm("javascript", engine, javascript_wasm)
+
+        def test_parser(self):
+            parser = Parser(self.javascript)
+            self.assertIsInstance(parser.parse(b"test"), Tree)
+
+        def test_language_is_wasm(self):
+            self.assertEqual(self.javascript.is_wasm, True)
+
+except ImportError:
+
+    class TestWasmDisabled(TestCase):
+        def test_parser(self):
+            def runtest():
+                Language.from_wasm("javascript", None, b"")
+
+            self.assertRaisesRegex(
+                RuntimeError, "wasmtime module is not loaded", runtest
+            )

tree_sitter/__init__.py

@@ -17,7 +17,10 @@
     MIN_COMPATIBLE_LANGUAGE_VERSION,
 )
 
-Point.__doc__ = "A position in a multi-line text document, in terms of rows and columns."
+
+Point.__doc__ = (
+    "A position in a multi-line text document, in terms of rows and columns."
+)
 Point.row.__doc__ = "The zero-based row of the document."
 Point.column.__doc__ = "The zero-based column of the document."
 

tree_sitter/binding/language.c

@@ -1,5 +1,8 @@
 #include "types.h"
 
+extern void wasm_engine_delete(TSWasmEngine *engine);
+extern TSWasmEngine *wasmtime_engine_clone(TSWasmEngine *engine);
+
 int language_init(Language *self, PyObject *args, PyObject *Py_UNUSED(kwargs)) {
     PyObject *language;
     if (!PyArg_ParseTuple(args, "O:__init__", &language)) {
@@ -30,10 +33,119 @@ int language_init(Language *self, PyObject *args, PyObject *Py_UNUSED(kwargs)) {
 }
 
 void language_dealloc(Language *self) {
+    if (self->wasm_engine != NULL) {
+        wasm_engine_delete(self->wasm_engine);
+    }
     ts_language_delete(self->language);
     Py_TYPE(self)->tp_free(self);
 }
 
+// ctypes.cast(managed_pointer.ptr(), ctypes.c_void_p).value
+static void *get_managed_pointer(PyObject *cast, PyObject *c_void_p, PyObject *managed_pointer) {
+    void *ptr = NULL;
+    PyObject *ptr_method = NULL;
+    PyObject *ptr_result = NULL;
+    PyObject *cast_result = NULL;
+    PyObject *value_attr = NULL;
+
+    // Call .ptr() method on the managed pointer
+    ptr_method = PyObject_GetAttrString(managed_pointer, "ptr");
+    if (ptr_method == NULL) {
+        goto cleanup;
+    }
+    ptr_result = PyObject_CallObject(ptr_method, NULL);
+    if (ptr_result == NULL) {
+        goto cleanup;
+    }
+
+    // Call cast function
+    cast_result = PyObject_CallFunctionObjArgs(cast, ptr_result, c_void_p, NULL);
+    if (cast_result == NULL) {
+        goto cleanup;
+    }
+
+    // Get the 'value' attribute from the cast result
+    value_attr = PyObject_GetAttrString(cast_result, "value");
+    if (value_attr == NULL) {
+        goto cleanup;
+    }
+
+    // Convert the value attribute to a C void pointer
+    ptr = PyLong_AsVoidPtr(value_attr);
+
+cleanup:
+    Py_XDECREF(value_attr);
+    Py_XDECREF(cast_result);
+    Py_XDECREF(ptr_result);
+    Py_XDECREF(ptr_method);
+
+    if (PyErr_Occurred()) {
+        return NULL;
+    }
+
+    return ptr;
+}
+
+PyObject *language_from_wasm(PyTypeObject *cls, PyObject *args) {
+    ModuleState *state = (ModuleState *)PyType_GetModuleState(cls);
+    TSWasmError error;
+    TSWasmStore *wasm_store = NULL;
+    TSLanguage *language = NULL;
+    Language *self = NULL;
+    char *name;
+    PyObject *py_engine = NULL;
+    char *wasm;
+    Py_ssize_t wasm_length;
+    if (state->wasmtime_engine_type == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "wasmtime module is not loaded");
+        return NULL;
+    }
+    if (!PyArg_ParseTuple(args, "sO!y#:from_wasm", &name, state->wasmtime_engine_type, &py_engine, &wasm, &wasm_length)) {
+        return NULL;
+    }
+
+    TSWasmEngine *engine = (TSWasmEngine *)get_managed_pointer(state->ctypes_cast, state->c_void_p, py_engine);
+    if (engine == NULL) {
+        goto fail;
+    }
+    engine = wasmtime_engine_clone(engine);
+    if (engine == NULL) {
+        goto fail;
+    }
+
+    wasm_store = ts_wasm_store_new(engine, &error);
+    if (wasm_store == NULL) {
+        PyErr_Format(PyExc_RuntimeError, "Failed to create TSWasmStore: %s", error.message);
+        goto fail;
+    }
+
+    language = (TSLanguage *)ts_wasm_store_load_language(wasm_store, name, wasm, wasm_length, &error);
+    if (language == NULL) {
+        PyErr_Format(PyExc_RuntimeError, "Failed to load language: %s", error.message);
+        goto fail;
+    }
+
+    self = (Language *)cls->tp_alloc(cls, 0);
+    if (self == NULL) {
+        goto fail;
+    }
+
+    self->language = language;
+    self->wasm_engine = engine;
+    self->version = ts_language_version(self->language);
+#if HAS_LANGUAGE_NAMES
+    self->name = ts_language_name(self->language);
+#endif
+    return (PyObject *)self;
+
+fail:
+    if (engine != NULL) {
+        wasm_engine_delete(engine);
+    }
+    ts_language_delete(language);
+    return NULL;
+}
+
 PyObject *language_repr(Language *self) {
 #if HAS_LANGUAGE_NAMES
     if (self->name == NULL) {
@@ -82,6 +194,10 @@ PyObject *language_get_field_count(Language *self, void *Py_UNUSED(payload)) {
     return PyLong_FromUnsignedLong(ts_language_field_count(self->language));
 }
 
+PyObject *language_is_wasm(Language *self, void *Py_UNUSED(payload)) {
+    return PyBool_FromLong(ts_language_is_wasm(self->language));
+}
+
 PyObject *language_node_kind_for_id(Language *self, PyObject *args) {
     TSSymbol symbol;
     if (!PyArg_ParseTuple(args, "H:node_kind_for_id", &symbol)) {
@@ -190,6 +306,9 @@ PyObject *language_query(Language *self, PyObject *args) {
     return PyObject_CallFunction((PyObject *)state->query_type, "Os#", self, source, length);
 }
 
+PyDoc_STRVAR(language_from_wasm_doc,
+             "from_wasm(self, name, engine, wasm, /)\n--\n\n"
+             "Load a language compiled as wasm.");
 PyDoc_STRVAR(language_node_kind_for_id_doc,
              "node_kind_for_id(self, id, /)\n--\n\n"
              "Get the name of the node kind for the given numerical id.");
@@ -220,6 +339,12 @@ PyDoc_STRVAR(
     "Create a new :class:`Query` from a string containing one or more S-expression patterns.");
 
 static PyMethodDef language_methods[] = {
+    {
+        .ml_name = "from_wasm",
+        .ml_meth = (PyCFunction)language_from_wasm,
+        .ml_flags = METH_CLASS | METH_VARARGS,
+        .ml_doc = language_from_wasm_doc,
+    },
     {
         .ml_name = "node_kind_for_id",
         .ml_meth = (PyCFunction)language_node_kind_for_id,
@@ -291,6 +416,8 @@ static PyGetSetDef language_accessors[] = {
      PyDoc_STR("The number of valid states in this language."), NULL},
     {"field_count", (getter)language_get_field_count, NULL,
      PyDoc_STR("The number of distinct field names in this language."), NULL},
+    {"is_wasm", (getter)language_is_wasm, NULL,
+     PyDoc_STR("Check if the language came from a wasm module."), NULL},
     {NULL},
 };
 

tree_sitter/binding/module.c

@@ -1,3 +1,4 @@
+#include <wasm.h>
 #include "types.h"
 
 extern PyType_Spec language_type_spec;
@@ -15,6 +16,8 @@ extern PyType_Spec range_type_spec;
 extern PyType_Spec tree_cursor_type_spec;
 extern PyType_Spec tree_type_spec;
 
+void tsp_load_wasmtime_symbols();
+
 // TODO(0.24): drop Python 3.9 support
 #if PY_MINOR_VERSION > 9
 #define AddObjectRef PyModule_AddObjectRef
@@ -62,6 +65,9 @@ static void module_free(void *self) {
     Py_XDECREF(state->tree_type);
     Py_XDECREF(state->query_error);
     Py_XDECREF(state->re_compile);
+    Py_XDECREF(state->wasmtime_engine_type);
+    Py_XDECREF(state->ctypes_cast);
+    Py_XDECREF(state->c_void_p);
 }
 
 static struct PyModuleDef module_definition = {
@@ -147,6 +153,35 @@ PyMODINIT_FUNC PyInit__binding(void) {
     if (namedtuple == NULL) {
         goto cleanup;
     }
+
+    PyObject *wasmtime_engine = import_attribute("wasmtime", "Engine");
+    if (wasmtime_engine == NULL) {
+        // No worries, disable functionality.
+        PyErr_Clear();
+    } else {
+        // Ensure wasmtime_engine is a PyTypeObject
+        if (!PyType_Check(wasmtime_engine)) {
+            PyErr_SetString(PyExc_TypeError, "wasmtime.Engine is not a type");
+            goto cleanup;
+        }
+        state->wasmtime_engine_type = (PyTypeObject *)wasmtime_engine;
+
+        tsp_load_wasmtime_symbols();
+        if (PyErr_Occurred()) {
+            goto cleanup;
+        }
+
+        state->ctypes_cast = import_attribute("ctypes", "cast");
+        if (state->ctypes_cast == NULL) {
+            goto cleanup;
+        }
+
+        state->c_void_p = import_attribute("ctypes", "c_void_p");
+        if (state->c_void_p == NULL) {
+            goto cleanup;
+        }
+    }
+
     PyObject *point_args = Py_BuildValue("s[ss]", "Point", "row", "column");
     PyObject *point_kwargs = PyDict_New();
     PyDict_SetItemString(point_kwargs, "module", PyUnicode_FromString("tree_sitter"));