Issue #28003: Implement PEP 525 -- Asynchronous Generators.

Include/ceval.h

@@ -25,6 +25,10 @@ PyAPI_FUNC(void) PyEval_SetProfile(Py_tracefunc, PyObject *);
 PyAPI_FUNC(void) PyEval_SetTrace(Py_tracefunc, PyObject *);
 PyAPI_FUNC(void) _PyEval_SetCoroutineWrapper(PyObject *);
 PyAPI_FUNC(PyObject *) _PyEval_GetCoroutineWrapper(void);
+PyAPI_FUNC(void) _PyEval_SetAsyncGenFirstiter(PyObject *);
+PyAPI_FUNC(PyObject *) _PyEval_GetAsyncGenFirstiter(void);
+PyAPI_FUNC(void) _PyEval_SetAsyncGenFinalizer(PyObject *);
+PyAPI_FUNC(PyObject *) _PyEval_GetAsyncGenFinalizer(void);
 #endif
 
 struct _frame; /* Avoid including frameobject.h */

Include/code.h

@@ -59,6 +59,7 @@ typedef struct {
    ``async def`` keywords) */
 #define CO_COROUTINE            0x0080
 #define CO_ITERABLE_COROUTINE   0x0100
+#define CO_ASYNC_GENERATOR      0x0200
 
 /* These are no longer used. */
 #if 0

Include/genobject.h

@@ -61,6 +61,37 @@ PyObject *_PyAIterWrapper_New(PyObject *aiter);
 PyObject *_PyCoro_GetAwaitableIter(PyObject *o);
 PyAPI_FUNC(PyObject *) PyCoro_New(struct _frame *,
     PyObject *name, PyObject *qualname);
+
+/* Asynchronous Generators */
+
+typedef struct {
+    _PyGenObject_HEAD(ag)
+    PyObject *ag_finalizer;
+
+    /* Flag is set to 1 when hooks set up by sys.set_asyncgen_hooks
+       were called on the generator, to avoid calling them more
+       than once. */
+    int ag_hooks_inited;
+
+    /* Flag is set to 1 when aclose() is called for the first time, or
+       when a StopAsyncIteration exception is raised. */
+    int ag_closed;
+} PyAsyncGenObject;
+
+PyAPI_DATA(PyTypeObject) PyAsyncGen_Type;
+PyAPI_DATA(PyTypeObject) _PyAsyncGenASend_Type;
+PyAPI_DATA(PyTypeObject) _PyAsyncGenWrappedValue_Type;
+PyAPI_DATA(PyTypeObject) _PyAsyncGenAThrow_Type;
+
+PyAPI_FUNC(PyObject *) PyAsyncGen_New(struct _frame *,
+    PyObject *name, PyObject *qualname);
+
+#define PyAsyncGen_CheckExact(op) (Py_TYPE(op) == &PyAsyncGen_Type)
+
+PyObject *_PyAsyncGenValueWrapperNew(PyObject *);
+
+int PyAsyncGen_ClearFreeLists(void);
+
 #endif
 
 #undef _PyGenObject_HEAD

Include/pylifecycle.h

@@ -107,6 +107,7 @@ PyAPI_FUNC(void) _PyGC_Fini(void);
 PyAPI_FUNC(void) PySlice_Fini(void);
 PyAPI_FUNC(void) _PyType_Fini(void);
 PyAPI_FUNC(void) _PyRandom_Fini(void);
+PyAPI_FUNC(void) PyAsyncGen_Fini(void);
 
 PyAPI_DATA(PyThreadState *) _Py_Finalizing;
 #endif

Include/pystate.h

@@ -148,6 +148,9 @@ typedef struct _ts {
     Py_ssize_t co_extra_user_count;
     freefunc co_extra_freefuncs[MAX_CO_EXTRA_USERS];
 
+    PyObject *async_gen_firstiter;
+    PyObject *async_gen_finalizer;
+
     /* XXX signal handlers should also be here */
 
 } PyThreadState;

Include/symtable.h

@@ -48,6 +48,7 @@ typedef struct _symtable_entry {
     unsigned ste_child_free : 1;  /* true if a child block has free vars,
                                      including free refs to globals */
     unsigned ste_generator : 1;   /* true if namespace is a generator */
+    unsigned ste_coroutine : 1;   /* true if namespace is a coroutine */
     unsigned ste_varargs : 1;     /* true if block has varargs */
     unsigned ste_varkeywords : 1; /* true if block has varkeywords */
     unsigned ste_returns_value : 1;  /* true if namespace uses return with