from testutils import assert_raises
a = []
assert a[:] == []
assert a[: 2 ** 100] == []
assert a[-2 ** 100 :] == []
assert a[:: 2 ** 100] == []
assert a[10:20] == []
assert a[-20:-10] == []
b = [1, 2]
assert b[:] == [1, 2]
assert b[slice(None)] == [1, 2]
assert b[: 2 ** 100] == [1, 2]
assert b[-2 ** 100 :] == [1, 2]
assert b[2 ** 100 :] == []
assert b[:: 2 ** 100] == [1]
assert b[-10:1] == [1]
assert b[0:0] == []
assert b[1:0] == []
assert_raises(ValueError, lambda: b[::0], "zero step slice")
assert b[::-1] == [2, 1]
assert b[1::-1] == [2, 1]
assert b[0::-1] == [1]
assert b[0:-5:-1] == [1]
assert b[:0:-1] == [2]
assert b[5:0:-1] == [2]
c = list(range(10))
assert c[9:6:-3] == [9]
assert c[9::-3] == [9, 6, 3, 0]
assert c[9::-4] == [9, 5, 1]
assert c[8 :: -2 ** 100] == [8]
assert c[7:7:-2] == []
assert c[7:8:-2] == []
d = "123456"
assert d[3::-1] == "4321"
assert d[4::-3] == "52"
assert [1, 2, 3, 5, 6][-1:-5:-1] == [6, 5, 3, 2]
slice_a = slice(5)
assert slice_a.start is None
assert slice_a.stop == 5
assert slice_a.step is None
slice_b = slice(1, 5)
assert slice_b.start == 1
assert slice_b.stop == 5
assert slice_b.step is None
slice_c = slice(1, 5, 2)
assert slice_c.start == 1
assert slice_c.stop == 5
assert slice_c.step == 2
a = object()
slice_d = slice(a, "v", 1.0)
assert slice_d.start is a
assert slice_d.stop == "v"
assert slice_d.step == 1.0
class SubScript(object):
def __getitem__(self, item):
assert type(item) == slice
def __setitem__(self, key, value):
assert type(key) == slice
ss = SubScript()
_ = ss[:]
ss[:1] = 1
class CustomIndex:
def __init__(self, x):
self.x = x
def __index__(self):
return self.x
assert c[CustomIndex(1):CustomIndex(3)] == [1, 2]
assert d[CustomIndex(1):CustomIndex(3)] == "23"
def test_all_slices():
mod = __import__('cpython_generated_slices')
ll = mod.LL
start = mod.START
end = mod.END
step = mod.STEP
slices_res = mod.SLICES_RES
count = 0
failures = []
for s in start:
for e in end:
for t in step:
lhs = ll[s:e:t]
try:
assert lhs == slices_res[count]
except AssertionError:
failures.append(
"start: {} ,stop: {}, step {}. Expected: {}, found: {}".format(
s, e, t, lhs, slices_res[count]
)
)
count += 1
if failures:
for f in failures:
print(f)
print(len(failures), "slices failed")
test_all_slices()