[Python-checkins] bpo-44490: Add __parameters__ and __getitem__ to types.Union (GH-26980)
gvanrossum
webhook-mailer at python.org
Tue Jul 6 14:04:59 EDT 2021
https://github.com/python/cpython/commit/c45fa1a5d9b419cf13ad4b5a7cb453956495b83e
commit: c45fa1a5d9b419cf13ad4b5a7cb453956495b83e
branch: main
author: Yurii Karabas <1998uriyyo at gmail.com>
committer: gvanrossum <gvanrossum at gmail.com>
date: 2021-07-06T11:04:33-07:00
summary:
bpo-44490: Add __parameters__ and __getitem__ to types.Union (GH-26980)
Co-authored-by: Ken Jin <28750310+Fidget-Spinner at users.noreply.github.com>
Co-authored-by: Guido van Rossum <gvanrossum at gmail.com>
files:
A Misc/NEWS.d/next/Core and Builtins/2021-07-01-11-59-34.bpo-44490.xY80VR.rst
M Include/genericaliasobject.h
M Lib/test/test_types.py
M Objects/genericaliasobject.c
M Objects/unionobject.c
diff --git a/Include/genericaliasobject.h b/Include/genericaliasobject.h
index cf002976b27cd..4ce9244bb4ce7 100644
--- a/Include/genericaliasobject.h
+++ b/Include/genericaliasobject.h
@@ -5,6 +5,11 @@
extern "C" {
#endif
+#ifndef Py_LIMITED_API
+PyAPI_FUNC(PyObject *) _Py_subs_parameters(PyObject *, PyObject *, PyObject *, PyObject *);
+PyAPI_FUNC(PyObject *) _Py_make_parameters(PyObject *);
+#endif
+
PyAPI_FUNC(PyObject *) Py_GenericAlias(PyObject *, PyObject *);
PyAPI_DATA(PyTypeObject) Py_GenericAliasType;
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index ae7b17bd590e6..7f7ce86ff08ef 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -666,6 +666,16 @@ def test_or_type_operator_with_TypeVar(self):
assert TV | str == typing.Union[TV, str]
assert str | TV == typing.Union[str, TV]
+ def test_union_parameter_chaining(self):
+ T = typing.TypeVar("T")
+ S = typing.TypeVar("S")
+
+ self.assertEqual((float | list[T])[int], float | list[int])
+ self.assertEqual(list[int | list[T]].__parameters__, (T,))
+ self.assertEqual(list[int | list[T]][str], list[int | list[str]])
+ self.assertEqual((list[T] | list[S]).__parameters__, (T, S))
+ self.assertEqual((list[T] | list[S])[int, T], list[int] | list[T])
+
def test_or_type_operator_with_forward(self):
T = typing.TypeVar('T')
ForwardAfter = T | 'Forward'
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-07-01-11-59-34.bpo-44490.xY80VR.rst b/Misc/NEWS.d/next/Core and Builtins/2021-07-01-11-59-34.bpo-44490.xY80VR.rst
new file mode 100644
index 0000000000000..4912bca837bb1
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-07-01-11-59-34.bpo-44490.xY80VR.rst
@@ -0,0 +1,2 @@
+Add ``__parameters__`` attribute and ``__getitem__``
+operator to ``types.Union``. Patch provided by Yurii Karabas.
diff --git a/Objects/genericaliasobject.c b/Objects/genericaliasobject.c
index 803912b7a18a4..d3d387193d357 100644
--- a/Objects/genericaliasobject.c
+++ b/Objects/genericaliasobject.c
@@ -198,8 +198,8 @@ tuple_add(PyObject *self, Py_ssize_t len, PyObject *item)
return 0;
}
-static PyObject *
-make_parameters(PyObject *args)
+PyObject *
+_Py_make_parameters(PyObject *args)
{
Py_ssize_t nargs = PyTuple_GET_SIZE(args);
Py_ssize_t len = nargs;
@@ -294,18 +294,10 @@ subs_tvars(PyObject *obj, PyObject *params, PyObject **argitems)
return obj;
}
-static PyObject *
-ga_getitem(PyObject *self, PyObject *item)
+PyObject *
+_Py_subs_parameters(PyObject *self, PyObject *args, PyObject *parameters, PyObject *item)
{
- gaobject *alias = (gaobject *)self;
- // do a lookup for __parameters__ so it gets populated (if not already)
- if (alias->parameters == NULL) {
- alias->parameters = make_parameters(alias->args);
- if (alias->parameters == NULL) {
- return NULL;
- }
- }
- Py_ssize_t nparams = PyTuple_GET_SIZE(alias->parameters);
+ Py_ssize_t nparams = PyTuple_GET_SIZE(parameters);
if (nparams == 0) {
return PyErr_Format(PyExc_TypeError,
"There are no type variables left in %R",
@@ -320,32 +312,32 @@ ga_getitem(PyObject *self, PyObject *item)
nitems > nparams ? "many" : "few",
self);
}
- /* Replace all type variables (specified by alias->parameters)
+ /* Replace all type variables (specified by parameters)
with corresponding values specified by argitems.
t = list[T]; t[int] -> newargs = [int]
t = dict[str, T]; t[int] -> newargs = [str, int]
t = dict[T, list[S]]; t[str, int] -> newargs = [str, list[int]]
*/
- Py_ssize_t nargs = PyTuple_GET_SIZE(alias->args);
+ Py_ssize_t nargs = PyTuple_GET_SIZE(args);
PyObject *newargs = PyTuple_New(nargs);
if (newargs == NULL) {
return NULL;
}
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
- PyObject *arg = PyTuple_GET_ITEM(alias->args, iarg);
+ PyObject *arg = PyTuple_GET_ITEM(args, iarg);
int typevar = is_typevar(arg);
if (typevar < 0) {
Py_DECREF(newargs);
return NULL;
}
if (typevar) {
- Py_ssize_t iparam = tuple_index(alias->parameters, nparams, arg);
+ Py_ssize_t iparam = tuple_index(parameters, nparams, arg);
assert(iparam >= 0);
arg = argitems[iparam];
Py_INCREF(arg);
}
else {
- arg = subs_tvars(arg, alias->parameters, argitems);
+ arg = subs_tvars(arg, parameters, argitems);
if (arg == NULL) {
Py_DECREF(newargs);
return NULL;
@@ -354,6 +346,26 @@ ga_getitem(PyObject *self, PyObject *item)
PyTuple_SET_ITEM(newargs, iarg, arg);
}
+ return newargs;
+}
+
+static PyObject *
+ga_getitem(PyObject *self, PyObject *item)
+{
+ gaobject *alias = (gaobject *)self;
+ // Populate __parameters__ if needed.
+ if (alias->parameters == NULL) {
+ alias->parameters = _Py_make_parameters(alias->args);
+ if (alias->parameters == NULL) {
+ return NULL;
+ }
+ }
+
+ PyObject *newargs = _Py_subs_parameters(self, alias->args, alias->parameters, item);
+ if (newargs == NULL) {
+ return NULL;
+ }
+
PyObject *res = Py_GenericAlias(alias->origin, newargs);
Py_DECREF(newargs);
@@ -550,7 +562,7 @@ ga_parameters(PyObject *self, void *unused)
{
gaobject *alias = (gaobject *)self;
if (alias->parameters == NULL) {
- alias->parameters = make_parameters(alias->args);
+ alias->parameters = _Py_make_parameters(alias->args);
if (alias->parameters == NULL) {
return NULL;
}
diff --git a/Objects/unionobject.c b/Objects/unionobject.c
index 8435763b5ea7c..d2a10dfec858e 100644
--- a/Objects/unionobject.c
+++ b/Objects/unionobject.c
@@ -8,6 +8,7 @@
typedef struct {
PyObject_HEAD
PyObject *args;
+ PyObject *parameters;
} unionobject;
static void
@@ -18,6 +19,7 @@ unionobject_dealloc(PyObject *self)
_PyObject_GC_UNTRACK(self);
Py_XDECREF(alias->args);
+ Py_XDECREF(alias->parameters);
Py_TYPE(self)->tp_free(self);
}
@@ -26,6 +28,7 @@ union_traverse(PyObject *self, visitproc visit, void *arg)
{
unionobject *alias = (unionobject *)self;
Py_VISIT(alias->args);
+ Py_VISIT(alias->parameters);
return 0;
}
@@ -435,6 +438,53 @@ static PyMethodDef union_methods[] = {
{"__subclasscheck__", union_subclasscheck, METH_O},
{0}};
+
+static PyObject *
+union_getitem(PyObject *self, PyObject *item)
+{
+ unionobject *alias = (unionobject *)self;
+ // Populate __parameters__ if needed.
+ if (alias->parameters == NULL) {
+ alias->parameters = _Py_make_parameters(alias->args);
+ if (alias->parameters == NULL) {
+ return NULL;
+ }
+ }
+
+ PyObject *newargs = _Py_subs_parameters(self, alias->args, alias->parameters, item);
+ if (newargs == NULL) {
+ return NULL;
+ }
+
+ PyObject *res = _Py_Union(newargs);
+
+ Py_DECREF(newargs);
+ return res;
+}
+
+static PyMappingMethods union_as_mapping = {
+ .mp_subscript = union_getitem,
+};
+
+static PyObject *
+union_parameters(PyObject *self, void *Py_UNUSED(unused))
+{
+ unionobject *alias = (unionobject *)self;
+ if (alias->parameters == NULL) {
+ alias->parameters = _Py_make_parameters(alias->args);
+ if (alias->parameters == NULL) {
+ return NULL;
+ }
+ }
+ Py_INCREF(alias->parameters);
+ return alias->parameters;
+}
+
+static PyGetSetDef union_properties[] = {
+ {"__parameters__", union_parameters, (setter)NULL, "Type variables in the types.Union.", NULL},
+ {0}
+};
+
static PyNumberMethods union_as_number = {
.nb_or = _Py_union_type_or, // Add __or__ function
};
@@ -456,8 +506,10 @@ PyTypeObject _Py_UnionType = {
.tp_members = union_members,
.tp_methods = union_methods,
.tp_richcompare = union_richcompare,
+ .tp_as_mapping = &union_as_mapping,
.tp_as_number = &union_as_number,
.tp_repr = union_repr,
+ .tp_getset = union_properties,
};
PyObject *
@@ -489,6 +541,7 @@ _Py_Union(PyObject *args)
return NULL;
}
+ result->parameters = NULL;
result->args = dedup_and_flatten_args(args);
_PyObject_GC_TRACK(result);
if (result->args == NULL) {
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