Kaydet (Commit) 4879c907 authored tarafından Benjamin Peterson's avatar Benjamin Peterson

the Slice in x[::] has to have step as None to help the interpreter

üst a2514f4c
......@@ -150,7 +150,8 @@ class AST_Tests(unittest.TestCase):
slc = ast.parse("x[::]").body[0].value.slice
self.assertIsNone(slc.upper)
self.assertIsNone(slc.lower)
self.assertIsNone(slc.step)
self.assertTrue(isinstance(slc.step, ast.Name))
self.assertEqual(slc.step.id, "None")
def test_from_import(self):
im = ast.parse("from . import y").body[0]
......
......@@ -44,9 +44,6 @@ Core and Builtins
- Assignment to None using import statements now raises a SyntaxError.
- In the slice AST type, the step field will always be None if a step expression
is not specified.
- Issue #4547: When debugging a very large function, it was not always
possible to update the lineno attribute of the current frame.
......
......@@ -1471,7 +1471,21 @@ ast_for_slice(struct compiling *c, const node *n)
ch = CHILD(n, NCH(n) - 1);
if (TYPE(ch) == sliceop) {
if (NCH(ch) != 1) {
if (NCH(ch) == 1) {
/*
This is an extended slice (ie "x[::]") with no expression in the
step field. We set this literally to "None" in order to
disambiguate it from x[:]. (The interpreter might have to call
__getslice__ for x[:], but it must call __getitem__ for x[::].)
*/
identifier none = new_identifier("None", c->c_arena);
if (!none)
return NULL;
ch = CHILD(ch, 0);
step = Name(none, Load, LINENO(ch), ch->n_col_offset, c->c_arena);
if (!step)
return NULL;
} else {
ch = CHILD(ch, 1);
if (TYPE(ch) == test) {
step = ast_for_expr(c, ch);
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment