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bpo-41979: Accept star-unpacking on with-item targets (GH-22611) 

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
This commit is contained in:
Batuhan Taskaya 2020-10-09 12:56:48 +03:00 committed by GitHub
parent 666f583e9e
commit 48f305fd12
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 18 additions and 8 deletions
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2
Grammar/python.gram
View File

@ -182,7 +182,7 @@ with_stmt[stmt_ty]:
| ASYNC 'with' a[asdl_withitem_seq*]=','.with_item+ ':' tc=[TYPE_COMMENT] b=block {
CHECK_VERSION(5, "Async with statements are", _Py_AsyncWith(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA)) }
with_item[withitem_ty]:
| e=expression 'as' t=target &(',' | ')' | ':') { _Py_withitem(e, t, p->arena) }
| e=expression 'as' t=star_target &(',' | ')' | ':') { _Py_withitem(e, t, p->arena) }
| invalid_with_item
| e=expression { _Py_withitem(e, NULL, p->arena) }

8
Lib/test/test_with.py
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@ -7,7 +7,7 @@ __email__ = "mbland at acm dot org"
import sys
import unittest
from collections import deque
from contextlib import _GeneratorContextManager, contextmanager
from contextlib import _GeneratorContextManager, contextmanager, nullcontext
class MockContextManager(_GeneratorContextManager):
@ -641,6 +641,12 @@ class AssignmentTargetTestCase(unittest.TestCase):
self.assertEqual(blah.two, 2)
self.assertEqual(blah.three, 3)
def testWithExtendedTargets(self):
with nullcontext(range(1, 5)) as (a, *b, c):
self.assertEqual(a, 1)
self.assertEqual(b, [2, 3])
self.assertEqual(c, 4)
class ExitSwallowsExceptionTestCase(unittest.TestCase):

1
Misc/NEWS.d/next/Core and Builtins/2020-10-09-10-55-50.bpo-41979.ImXIk2.rst Normal file
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@ -0,0 +1 @@
Star-unpacking is now allowed for with item's targets in the PEG parser.

15
Parser/parser.c
View File

@ -4290,7 +4290,10 @@ with_stmt_rule(Parser *p)
return _res;
}
// with_item: expression 'as' target &(',' | ')' | ':') | invalid_with_item | expression
// with_item:
// | expression 'as' star_target &(',' | ')' | ':')
// | invalid_with_item
// | expression
static withitem_ty
with_item_rule(Parser *p)
{
@ -4301,12 +4304,12 @@ with_item_rule(Parser *p)
}
withitem_ty _res = NULL;
int _mark = p->mark;
{ // expression 'as' target &(',' | ')' | ':')
{ // expression 'as' star_target &(',' | ')' | ':')
if (p->error_indicator) {
D(p->level--);
return NULL;
}
D(fprintf(stderr, "%*c> with_item[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "expression 'as' target &(',' | ')' | ':')"));
D(fprintf(stderr, "%*c> with_item[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "expression 'as' star_target &(',' | ')' | ':')"));
Token * _keyword;
expr_ty e;
expr_ty t;
@ -4315,12 +4318,12 @@ with_item_rule(Parser *p)
&&
(_keyword = _PyPegen_expect_token(p, 520)) // token='as'
&&
(t = target_rule(p)) // target
(t = star_target_rule(p)) // star_target
&&
_PyPegen_lookahead(1, _tmp_47_rule, p)
)
{
D(fprintf(stderr, "%*c+ with_item[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "expression 'as' target &(',' | ')' | ':')"));
D(fprintf(stderr, "%*c+ with_item[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "expression 'as' star_target &(',' | ')' | ':')"));
_res = _Py_withitem ( e , t , p -> arena );
if (_res == NULL && PyErr_Occurred()) {
p->error_indicator = 1;
@ -4331,7 +4334,7 @@ with_item_rule(Parser *p)
}
p->mark = _mark;
D(fprintf(stderr, "%*c%s with_item[%d-%d]: %s failed!\n", p->level, ' ',
p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "expression 'as' target &(',' | ')' | ':')"));
p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "expression 'as' star_target &(',' | ')' | ':')"));
}
{ // invalid_with_item
if (p->error_indicator) {