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bpo-32925: Optimized iterating and containing test for literal lists (GH-5842)

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consisting of non-constants: `x in [a, b]` and `for x in [a, b]`.
The case of all constant elements already was optimized.
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Serhiy Storchaka 2018-03-11 10:54:47 +02:00 • committed by GitHub
parent 4e2442505c
commit 3f7e9aa2ef
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3 changed files with 44 additions and 2 deletions
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19
Python/ast_opt.c
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@ -369,7 +369,8 @@ fold_subscr(expr_ty node, PyArena *arena, int optimize)
}
/* Change literal list or set of constants into constant
tuple or frozenset respectively.
tuple or frozenset respectively. Change literal list of
non-constants into tuple.
Used for right operand of "in" and "not in" tests and for iterable
in "for" loop and comprehensions.
*/
@ -378,7 +379,21 @@ fold_iter(expr_ty arg, PyArena *arena, int optimize)
{
PyObject *newval;
if (arg->kind == List_kind) {
newval = make_const_tuple(arg->v.List.elts);
/* First change a list into tuple. */
asdl_seq *elts = arg->v.List.elts;
Py_ssize_t n = asdl_seq_LEN(elts);
for (Py_ssize_t i = 0; i < n; i++) {
expr_ty e = (expr_ty)asdl_seq_GET(elts, i);
if (e->kind == Starred_kind) {
return 1;
}
}
expr_context_ty ctx = arg->v.List.ctx;
arg->kind = Tuple_kind;
arg->v.Tuple.elts = elts;
arg->v.Tuple.ctx = ctx;
/* Try to create a constant tuple. */
newval = make_const_tuple(elts);
}
else if (arg->kind == Set_kind) {
newval = make_const_tuple(arg->v.Set.elts);