1 #if defined(PY_CALL_TRAMPOLINE)
2
3 #include <emscripten.h> // EM_JS
4 #include <Python.h>
5 #include "pycore_runtime.h" // _PyRuntime
6
7
8 /**
9 * This is the GoogleChromeLabs approved way to feature detect type-reflection:
10 * https://github.com/GoogleChromeLabs/wasm-feature-detect/blob/main/src/detectors/type-reflection/index.js
11 */
12 EM_JS(int, _PyEM_detect_type_reflection, (), {
13 if (!("Function" in WebAssembly)) {
14 return false;
15 }
16 if (WebAssembly.Function.type) {
17 // Node v20
18 Module.PyEM_CountArgs = (func) => WebAssembly.Function.type(wasmTable.get(func)).parameters.length;
19 } else {
20 // Node >= 22, v8-based browsers
21 Module.PyEM_CountArgs = (func) => wasmTable.get(func).type().parameters.length;
22 }
23 return true;
24 });
25
26 void
_Py_EmscriptenTrampoline_Init(_PyRuntimeState * runtime)27 _Py_EmscriptenTrampoline_Init(_PyRuntimeState *runtime)
28 {
29 runtime->wasm_type_reflection_available = _PyEM_detect_type_reflection();
30 }
31
32 /**
33 * Backwards compatible trampoline works with all JS runtimes
34 */
35 EM_JS(PyObject*,
36 _PyEM_TrampolineCall_JavaScript, (PyCFunctionWithKeywords func,
37 PyObject *arg1,
38 PyObject *arg2,
39 PyObject *arg3),
40 {
41 return wasmTable.get(func)(arg1, arg2, arg3);
42 }
43 );
44
45 /**
46 * In runtimes with WebAssembly type reflection, count the number of parameters
47 * and cast to the appropriate signature
48 */
49 EM_JS(int, _PyEM_CountFuncParams, (PyCFunctionWithKeywords func),
50 {
51 let n = _PyEM_CountFuncParams.cache.get(func);
52
53 if (n !== undefined) {
54 return n;
55 }
56 n = Module.PyEM_CountArgs(func);
57 _PyEM_CountFuncParams.cache.set(func, n);
58 return n;
59 }
60 _PyEM_CountFuncParams.cache = new Map();
61 )
62
63
64 typedef PyObject* (*zero_arg)(void);
65 typedef PyObject* (*one_arg)(PyObject*);
66 typedef PyObject* (*two_arg)(PyObject*, PyObject*);
67 typedef PyObject* (*three_arg)(PyObject*, PyObject*, PyObject*);
68
69
70 PyObject*
_PyEM_TrampolineCall_Reflection(PyCFunctionWithKeywords func,PyObject * self,PyObject * args,PyObject * kw)71 _PyEM_TrampolineCall_Reflection(PyCFunctionWithKeywords func,
72 PyObject* self,
73 PyObject* args,
74 PyObject* kw)
75 {
76 switch (_PyEM_CountFuncParams(func)) {
77 case 0:
78 return ((zero_arg)func)();
79 case 1:
80 return ((one_arg)func)(self);
81 case 2:
82 return ((two_arg)func)(self, args);
83 case 3:
84 return ((three_arg)func)(self, args, kw);
85 default:
86 PyErr_SetString(PyExc_SystemError,
87 "Handler takes too many arguments");
88 return NULL;
89 }
90 }
91
92 #endif
93