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# Test iterators.
import unittest
from test_support import run_unittest, TESTFN, unlink
# Test result of triple loop (too big to inline)
TRIPLETS = [(0, 0, 0), (0, 0, 1), (0, 0, 2),
(0, 1, 0), (0, 1, 1), (0, 1, 2),
(0, 2, 0), (0, 2, 1), (0, 2, 2),
(1, 0, 0), (1, 0, 1), (1, 0, 2),
(1, 1, 0), (1, 1, 1), (1, 1, 2),
(1, 2, 0), (1, 2, 1), (1, 2, 2),
(2, 0, 0), (2, 0, 1), (2, 0, 2),
(2, 1, 0), (2, 1, 1), (2, 1, 2),
(2, 2, 0), (2, 2, 1), (2, 2, 2)]
# Helper classes
class BasicIterClass:
def __init__(self, n):
self.n = n
self.i = 0
def next(self):
res = self.i
if res >= self.n:
raise StopIteration
self.i = res + 1
return res
class IteratingSequenceClass:
def __init__(self, n):
self.n = n
def __iter__(self):
return BasicIterClass(self.n)
class SequenceClass:
def __init__(self, n):
self.n = n
def __getitem__(self, i):
if 0 <= i < self.n:
return i
else:
raise IndexError
# Main test suite
class TestCase(unittest.TestCase):
# Helper to check that an iterator returns a given sequence
def check_iterator(self, it, seq):
res = []
while 1:
try:
val = it.next()
except StopIteration:
break
res.append(val)
self.assertEqual(res, seq)
# Helper to check that a for loop generates a given sequence
def check_for_loop(self, expr, seq):
res = []
for val in expr:
res.append(val)
self.assertEqual(res, seq)
# Test basic use of iter() function
def test_iter_basic(self):
self.check_iterator(iter(range(10)), range(10))
# Test that iter(iter(x)) is the same as iter(x)
def test_iter_idempotency(self):
seq = range(10)
it = iter(seq)
it2 = iter(it)
self.assert_(it is it2)
# Test that for loops over iterators work
def test_iter_for_loop(self):
self.check_for_loop(iter(range(10)), range(10))
# Test several independent iterators over the same list
def test_iter_independence(self):
seq = range(3)
res = []
for i in iter(seq):
for j in iter(seq):
for k in iter(seq):
res.append((i, j, k))
self.assertEqual(res, TRIPLETS)
# Test triple list comprehension using iterators
def test_nested_comprehensions_iter(self):
seq = range(3)
res = [(i, j, k)
for i in iter(seq) for j in iter(seq) for k in iter(seq)]
self.assertEqual(res, TRIPLETS)
# Test triple list comprehension without iterators
def test_nested_comprehensions_for(self):
seq = range(3)
res = [(i, j, k) for i in seq for j in seq for k in seq]
self.assertEqual(res, TRIPLETS)
# Test a class with __iter__ in a for loop
def test_iter_class_for(self):
self.check_for_loop(IteratingSequenceClass(10), range(10))
# Test a class with __iter__ with explicit iter()
def test_iter_class_iter(self):
self.check_iterator(iter(IteratingSequenceClass(10)), range(10))
# Test for loop on a sequence class without __iter__
def test_seq_class_for(self):
self.check_for_loop(SequenceClass(10), range(10))
# Test iter() on a sequence class without __iter__
def test_seq_class_iter(self):
self.check_iterator(iter(SequenceClass(10)), range(10))
# Test two-argument iter() with callable instance
def test_iter_callable(self):
class C:
def __init__(self):
self.i = 0
def __call__(self):
i = self.i
self.i = i + 1
if i > 100:
raise IndexError # Emergency stop
return i
self.check_iterator(iter(C(), 10), range(10))
# Test two-argument iter() with function
def test_iter_function(self):
def spam(state=[0]):
i = state[0]
state[0] = i+1
return i
self.check_iterator(iter(spam, 10), range(10))
# Test two-argument iter() with function that raises StopIteration
def test_iter_function_stop(self):
def spam(state=[0]):
i = state[0]
if i == 10:
raise StopIteration
state[0] = i+1
return i
self.check_iterator(iter(spam, 20), range(10))
# Test exception propagation through function iterator
def test_exception_function(self):
def spam(state=[0]):
i = state[0]
state[0] = i+1
if i == 10:
raise RuntimeError
return i
res = []
try:
for x in iter(spam, 20):
res.append(x)
except RuntimeError:
self.assertEqual(res, range(10))
else:
self.fail("should have raised RuntimeError")
# Test exception propagation through sequence iterator
def test_exception_sequence(self):
class MySequenceClass(SequenceClass):
def __getitem__(self, i):
if i == 10:
raise RuntimeError
return SequenceClass.__getitem__(self, i)
res = []
try:
for x in MySequenceClass(20):
res.append(x)
except RuntimeError:
self.assertEqual(res, range(10))
else:
self.fail("should have raised RuntimeError")
# Test for StopIteration from __getitem__
def test_stop_sequence(self):
class MySequenceClass(SequenceClass):
def __getitem__(self, i):
if i == 10:
raise StopIteration
return SequenceClass.__getitem__(self, i)
self.check_for_loop(MySequenceClass(20), range(10))
# Test a big range
def test_iter_big_range(self):
self.check_for_loop(iter(range(10000)), range(10000))
# Test an empty list
def test_iter_empty(self):
self.check_for_loop(iter([]), [])
# Test a tuple
def test_iter_tuple(self):
self.check_for_loop(iter((0,1,2,3,4,5,6,7,8,9)), range(10))
# Test an xrange
def test_iter_xrange(self):
self.check_for_loop(iter(xrange(10)), range(10))
# Test a string
def test_iter_string(self):
self.check_for_loop(iter("abcde"), ["a", "b", "c", "d", "e"])
# Test a Unicode string
def test_iter_unicode(self):
self.check_for_loop(iter(u"abcde"), [u"a", u"b", u"c", u"d", u"e"])
# Test a directory
def test_iter_dict(self):
dict = {}
for i in range(10):
dict[i] = None
self.check_for_loop(dict, dict.keys())
# Test a file
def test_iter_file(self):
f = open(TESTFN, "w")
try:
for i in range(5):
f.write("%d\n" % i)
finally:
f.close()
f = open(TESTFN, "r")
try:
self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"])
self.check_for_loop(f, [])
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
run_unittest(TestCase)
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