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4e9afdca39
NEEDS DOC CHANGES. Possibly contentious: The first time s.next() yields StopIteration (for a given map argument s) is the last time map() *tries* s.next(). That is, if other sequence args are longer, s will never again contribute anything but None values to the result, even if trying s.next() again could yield another result. This is the same behavior map() used to have wrt IndexError, so it's the only way to be wholly backward-compatible. I'm not a fan of letting StopIteration mean "try again later" anyway.
389 lines
12 KiB
Python
389 lines
12 KiB
Python
# Test iterators.
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import unittest
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from test_support import run_unittest, TESTFN, unlink
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# Test result of triple loop (too big to inline)
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TRIPLETS = [(0, 0, 0), (0, 0, 1), (0, 0, 2),
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(0, 1, 0), (0, 1, 1), (0, 1, 2),
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(0, 2, 0), (0, 2, 1), (0, 2, 2),
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(1, 0, 0), (1, 0, 1), (1, 0, 2),
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(1, 1, 0), (1, 1, 1), (1, 1, 2),
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(1, 2, 0), (1, 2, 1), (1, 2, 2),
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(2, 0, 0), (2, 0, 1), (2, 0, 2),
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(2, 1, 0), (2, 1, 1), (2, 1, 2),
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(2, 2, 0), (2, 2, 1), (2, 2, 2)]
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# Helper classes
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class BasicIterClass:
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def __init__(self, n):
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self.n = n
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self.i = 0
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def next(self):
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res = self.i
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if res >= self.n:
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raise StopIteration
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self.i = res + 1
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return res
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class IteratingSequenceClass:
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def __init__(self, n):
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self.n = n
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def __iter__(self):
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return BasicIterClass(self.n)
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class SequenceClass:
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def __init__(self, n):
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self.n = n
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def __getitem__(self, i):
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if 0 <= i < self.n:
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return i
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else:
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raise IndexError
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# Main test suite
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class TestCase(unittest.TestCase):
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# Helper to check that an iterator returns a given sequence
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def check_iterator(self, it, seq):
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res = []
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while 1:
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try:
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val = it.next()
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except StopIteration:
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break
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res.append(val)
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self.assertEqual(res, seq)
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# Helper to check that a for loop generates a given sequence
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def check_for_loop(self, expr, seq):
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res = []
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for val in expr:
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res.append(val)
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self.assertEqual(res, seq)
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# Test basic use of iter() function
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def test_iter_basic(self):
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self.check_iterator(iter(range(10)), range(10))
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# Test that iter(iter(x)) is the same as iter(x)
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def test_iter_idempotency(self):
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seq = range(10)
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it = iter(seq)
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it2 = iter(it)
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self.assert_(it is it2)
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# Test that for loops over iterators work
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def test_iter_for_loop(self):
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self.check_for_loop(iter(range(10)), range(10))
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# Test several independent iterators over the same list
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def test_iter_independence(self):
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seq = range(3)
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res = []
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for i in iter(seq):
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for j in iter(seq):
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for k in iter(seq):
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res.append((i, j, k))
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self.assertEqual(res, TRIPLETS)
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# Test triple list comprehension using iterators
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def test_nested_comprehensions_iter(self):
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seq = range(3)
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res = [(i, j, k)
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for i in iter(seq) for j in iter(seq) for k in iter(seq)]
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self.assertEqual(res, TRIPLETS)
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# Test triple list comprehension without iterators
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def test_nested_comprehensions_for(self):
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seq = range(3)
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res = [(i, j, k) for i in seq for j in seq for k in seq]
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self.assertEqual(res, TRIPLETS)
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# Test a class with __iter__ in a for loop
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def test_iter_class_for(self):
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self.check_for_loop(IteratingSequenceClass(10), range(10))
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# Test a class with __iter__ with explicit iter()
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def test_iter_class_iter(self):
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self.check_iterator(iter(IteratingSequenceClass(10)), range(10))
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# Test for loop on a sequence class without __iter__
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def test_seq_class_for(self):
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self.check_for_loop(SequenceClass(10), range(10))
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# Test iter() on a sequence class without __iter__
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def test_seq_class_iter(self):
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self.check_iterator(iter(SequenceClass(10)), range(10))
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# Test two-argument iter() with callable instance
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def test_iter_callable(self):
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class C:
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def __init__(self):
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self.i = 0
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def __call__(self):
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i = self.i
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self.i = i + 1
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if i > 100:
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raise IndexError # Emergency stop
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return i
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self.check_iterator(iter(C(), 10), range(10))
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# Test two-argument iter() with function
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def test_iter_function(self):
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def spam(state=[0]):
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i = state[0]
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state[0] = i+1
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return i
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self.check_iterator(iter(spam, 10), range(10))
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# Test two-argument iter() with function that raises StopIteration
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def test_iter_function_stop(self):
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def spam(state=[0]):
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i = state[0]
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if i == 10:
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raise StopIteration
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state[0] = i+1
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return i
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self.check_iterator(iter(spam, 20), range(10))
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# Test exception propagation through function iterator
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def test_exception_function(self):
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def spam(state=[0]):
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i = state[0]
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state[0] = i+1
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if i == 10:
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raise RuntimeError
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return i
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res = []
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try:
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for x in iter(spam, 20):
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res.append(x)
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except RuntimeError:
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self.assertEqual(res, range(10))
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else:
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self.fail("should have raised RuntimeError")
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# Test exception propagation through sequence iterator
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def test_exception_sequence(self):
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class MySequenceClass(SequenceClass):
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def __getitem__(self, i):
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if i == 10:
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raise RuntimeError
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return SequenceClass.__getitem__(self, i)
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res = []
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try:
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for x in MySequenceClass(20):
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res.append(x)
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except RuntimeError:
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self.assertEqual(res, range(10))
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else:
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self.fail("should have raised RuntimeError")
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# Test for StopIteration from __getitem__
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def test_stop_sequence(self):
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class MySequenceClass(SequenceClass):
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def __getitem__(self, i):
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if i == 10:
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raise StopIteration
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return SequenceClass.__getitem__(self, i)
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self.check_for_loop(MySequenceClass(20), range(10))
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# Test a big range
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def test_iter_big_range(self):
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self.check_for_loop(iter(range(10000)), range(10000))
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# Test an empty list
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def test_iter_empty(self):
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self.check_for_loop(iter([]), [])
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# Test a tuple
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def test_iter_tuple(self):
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self.check_for_loop(iter((0,1,2,3,4,5,6,7,8,9)), range(10))
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# Test an xrange
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def test_iter_xrange(self):
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self.check_for_loop(iter(xrange(10)), range(10))
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# Test a string
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def test_iter_string(self):
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self.check_for_loop(iter("abcde"), ["a", "b", "c", "d", "e"])
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# Test a Unicode string
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def test_iter_unicode(self):
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self.check_for_loop(iter(u"abcde"), [u"a", u"b", u"c", u"d", u"e"])
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# Test a directory
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def test_iter_dict(self):
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dict = {}
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for i in range(10):
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dict[i] = None
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self.check_for_loop(dict, dict.keys())
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# Test a file
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def test_iter_file(self):
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f = open(TESTFN, "w")
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try:
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for i in range(5):
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f.write("%d\n" % i)
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finally:
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f.close()
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f = open(TESTFN, "r")
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try:
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self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"])
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self.check_for_loop(f, [])
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finally:
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f.close()
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try:
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unlink(TESTFN)
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except OSError:
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pass
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# Test list()'s use of iterators.
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def test_builtin_list(self):
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self.assertEqual(list(SequenceClass(5)), range(5))
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self.assertEqual(list(SequenceClass(0)), [])
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self.assertEqual(list(()), [])
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self.assertEqual(list(range(10, -1, -1)), range(10, -1, -1))
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d = {"one": 1, "two": 2, "three": 3}
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self.assertEqual(list(d), d.keys())
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self.assertRaises(TypeError, list, list)
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self.assertRaises(TypeError, list, 42)
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f = open(TESTFN, "w")
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try:
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for i in range(5):
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f.write("%d\n" % i)
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finally:
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f.close()
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f = open(TESTFN, "r")
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try:
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self.assertEqual(list(f), ["0\n", "1\n", "2\n", "3\n", "4\n"])
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f.seek(0, 0)
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self.assertEqual(list(f.xreadlines()),
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["0\n", "1\n", "2\n", "3\n", "4\n"])
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finally:
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f.close()
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try:
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unlink(TESTFN)
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except OSError:
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pass
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# Test filter()'s use of iterators.
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def test_builtin_filter(self):
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self.assertEqual(filter(None, SequenceClass(5)), range(1, 5))
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self.assertEqual(filter(None, SequenceClass(0)), [])
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self.assertEqual(filter(None, ()), ())
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self.assertEqual(filter(None, "abc"), "abc")
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d = {"one": 1, "two": 2, "three": 3}
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self.assertEqual(filter(None, d), d.keys())
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self.assertRaises(TypeError, filter, None, list)
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self.assertRaises(TypeError, filter, None, 42)
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class Boolean:
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def __init__(self, truth):
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self.truth = truth
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def __nonzero__(self):
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return self.truth
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True = Boolean(1)
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False = Boolean(0)
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class Seq:
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def __init__(self, *args):
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self.vals = args
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def __iter__(self):
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class SeqIter:
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def __init__(self, vals):
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self.vals = vals
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self.i = 0
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def __iter__(self):
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return self
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def next(self):
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i = self.i
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self.i = i + 1
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if i < len(self.vals):
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return self.vals[i]
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else:
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raise StopIteration
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return SeqIter(self.vals)
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seq = Seq(*([True, False] * 25))
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self.assertEqual(filter(lambda x: not x, seq), [False]*25)
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self.assertEqual(filter(lambda x: not x, iter(seq)), [False]*25)
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# Test max() and min()'s use of iterators.
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def test_builtin_max_min(self):
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self.assertEqual(max(SequenceClass(5)), 4)
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self.assertEqual(min(SequenceClass(5)), 0)
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self.assertEqual(max(8, -1), 8)
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self.assertEqual(min(8, -1), -1)
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d = {"one": 1, "two": 2, "three": 3}
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self.assertEqual(max(d), "two")
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self.assertEqual(min(d), "one")
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self.assertEqual(max(d.itervalues()), 3)
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self.assertEqual(min(iter(d.itervalues())), 1)
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f = open(TESTFN, "w")
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try:
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f.write("medium line\n")
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f.write("xtra large line\n")
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f.write("itty-bitty line\n")
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finally:
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f.close()
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f = open(TESTFN, "r")
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try:
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self.assertEqual(min(f), "itty-bitty line\n")
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f.seek(0, 0)
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self.assertEqual(max(f), "xtra large line\n")
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finally:
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f.close()
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try:
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unlink(TESTFN)
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except OSError:
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pass
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# Test map()'s use of iterators.
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def test_builtin_map(self):
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self.assertEqual(map(None, SequenceClass(5)), range(5))
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self.assertEqual(map(lambda x: x+1, SequenceClass(5)), range(1, 6))
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d = {"one": 1, "two": 2, "three": 3}
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self.assertEqual(map(None, d), d.keys())
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self.assertEqual(map(lambda k, d=d: (k, d[k]), d), d.items())
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dkeys = d.keys()
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expected = [(i < len(d) and dkeys[i] or None,
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i,
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i < len(d) and dkeys[i] or None)
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for i in range(5)]
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self.assertEqual(map(None, d,
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SequenceClass(5),
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iter(d.iterkeys())),
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expected)
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f = open(TESTFN, "w")
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try:
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for i in range(10):
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f.write("xy" * i + "\n") # line i has len 2*i+1
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finally:
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f.close()
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f = open(TESTFN, "r")
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try:
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self.assertEqual(map(len, f), range(1, 21, 2))
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f.seek(0, 0)
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finally:
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f.close()
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try:
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unlink(TESTFN)
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except OSError:
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pass
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run_unittest(TestCase)
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