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bpo-45045: Optimize mapping patterns of structural pattern matching #28043

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Merged
merged 4 commits into from
Aug 30, 2021
Merged

bpo-45045: Optimize mapping patterns of structural pattern matching #28043

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696d0bd
bpo-45045: Optimize mapping patterns of structural pattern matching
corona10 Aug 29, 2021
c95a7ea
bpo-45045: Address code review
corona10 Aug 29, 2021
7a30496
bpo-45045 Add unbound method test case
corona10 Aug 29, 2021
71fe76d
bpo-45045: nit
corona10 Aug 30, 2021
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13 changes: 13 additions & 0 deletions Lib/test/test_patma.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2641,6 +2641,19 @@ def f(x):
self.assertEqual(f((False, range(-1, -11, -1), True)), alts[3])
self.assertEqual(f((False, range(10, 20), True)), alts[4])

def test_patma_248(self):
class C(dict):
@staticmethod
def get(key, default=None):
return 'bar'

x = C({'foo': 'bar'})
match x:
case {'foo': bar}:
y = bar

self.assertEqual(y, 'bar')


class TestSyntaxErrors(unittest.TestCase):

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23 changes: 17 additions & 6 deletions Python/ceval.c
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Original file line number Diff line number Diff line change
Expand Up @@ -841,12 +841,18 @@ match_keys(PyThreadState *tstate, PyObject *map, PyObject *keys)
PyObject *seen = NULL;
PyObject *dummy = NULL;
PyObject *values = NULL;
PyObject *get_name = NULL;
PyObject *get = NULL;
// We use the two argument form of map.get(key, default) for two reasons:
// - Atomically check for a key and get its value without error handling.
// - Don't cause key creation or resizing in dict subclasses like
// collections.defaultdict that define __missing__ (or similar).
_Py_IDENTIFIER(get);
PyObject *get = _PyObject_GetAttrId(map, &PyId_get);
get_name = _PyUnicode_FromId(&PyId_get); // borrowed
if (get_name == NULL) {
return NULL;
}
int meth_found = _PyObject_GetMethod(map, get_name, &get);
if (get == NULL) {
goto fail;
}
Expand All @@ -859,7 +865,7 @@ match_keys(PyThreadState *tstate, PyObject *map, PyObject *keys)
if (dummy == NULL) {
goto fail;
}
values = PyList_New(0);
values = PyTuple_New(nkeys);
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The size of the tuple is predictable.

if (values == NULL) {
goto fail;
}
Expand All @@ -873,7 +879,14 @@ match_keys(PyThreadState *tstate, PyObject *map, PyObject *keys)
}
goto fail;
}
PyObject *value = PyObject_CallFunctionObjArgs(get, key, dummy, NULL);
PyObject *args[] = { map, key, dummy };
PyObject *value = NULL;
if (meth_found) {
value = PyObject_Vectorcall(get, args, 3, NULL);
}
else {
value = PyObject_Vectorcall(get, &args[1], 2, NULL);
}
if (value == NULL) {
goto fail;
}
Expand All @@ -886,10 +899,8 @@ match_keys(PyThreadState *tstate, PyObject *map, PyObject *keys)
values = Py_None;
goto done;
}
PyList_Append(values, value);
Py_DECREF(value);
PyTuple_SET_ITEM(values, i, value);
}
Py_SETREF(values, PyList_AsTuple(values));
// Success:
done:
Py_DECREF(get);
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