@@ -1249,10 +1249,11 @@ def test_tee(self):
1249 1249
self.assertEqual(len(result), n)
1250 1250
self.assertEqual([list(x) for x in result], [list('abc')]*n)
1251 1251 1252 -
# tee pass-through to copyable iterator
1252 +
# tee objects are independent (see bug gh-123884)
1253 1253
a, b = tee('abc')
1254 1254
c, d = tee(a)
1255 -
self.assertTrue(a is c)
1255 +
e, f = tee(c)
1256 +
self.assertTrue(len({a, b, c, d, e, f}) == 6)
1256 1257 1257 1258
# test tee_new
1258 1259
t1, t2 = tee('abc')
@@ -1759,21 +1760,36 @@ def test_tee_recipe(self):
1759 1760 1760 1761
def tee(iterable, n=2):
1761 1762
if n < 0:
1762 -
raise ValueError('n must be >= 0')
1763 -
iterator = iter(iterable)
1764 -
shared_link = [None, None]
1765 -
return tuple(_tee(iterator, shared_link) for _ in range(n))
1763 +
raise ValueError
1764 +
if n == 0:
1765 +
return ()
1766 +
iterator = _tee(iterable)
1767 +
result = [iterator]
1768 +
for _ in range(n - 1):
1769 +
result.append(_tee(iterator))
1770 +
return tuple(result)
1771 + 1772 +
class _tee:
1773 + 1774 +
def __init__(self, iterable):
1775 +
it = iter(iterable)
1776 +
if isinstance(it, _tee):
1777 +
self.iterator = it.iterator
1778 +
self.link = it.link
1779 +
else:
1780 +
self.iterator = it
1781 +
self.link = [None, None]
1766 1782 1767 -
def _tee(iterator, link):
1768 -
try:
1769 -
while True:
1770 -
if link[1] is None:
1771 -
link[0] = next(iterator)
1772 -
link[1] = [None, None]
1773 -
value, link = link
1774 -
yield value
1775 -
except StopIteration:
1776 -
return
1783 +
def __iter__(self):
1784 +
return self
1785 + 1786 +
def __next__(self):
1787 +
link = self.link
1788 +
if link[1] is None:
1789 +
link[0] = next(self.iterator)
1790 +
link[1] = [None, None]
1791 +
value, self.link = link
1792 +
return value
1777 1793 1778 1794
# End tee() recipe #############################################
1779 1795
@@ -1819,12 +1835,10 @@ def _tee(iterator, link):
1819 1835
self.assertRaises(TypeError, tee, [1,2], 'x')
1820 1836
self.assertRaises(TypeError, tee, [1,2], 3, 'x')
1821 1837 1822 -
# Tests not applicable to the tee() recipe
1823 -
if False:
1824 -
# tee object should be instantiable
1825 -
a, b = tee('abc')
1826 -
c = type(a)('def')
1827 -
self.assertEqual(list(c), list('def'))
1838 +
# tee object should be instantiable
1839 +
a, b = tee('abc')
1840 +
c = type(a)('def')
1841 +
self.assertEqual(list(c), list('def'))
1828 1842 1829 1843
# test long-lagged and multi-way split
1830 1844
a, b, c = tee(range(2000), 3)
@@ -1845,21 +1859,19 @@ def _tee(iterator, link):
1845 1859
self.assertEqual(len(result), n)
1846 1860
self.assertEqual([list(x) for x in result], [list('abc')]*n)
1847 1861 1862 +
# tee objects are independent (see bug gh-123884)
1863 +
a, b = tee('abc')
1864 +
c, d = tee(a)
1865 +
e, f = tee(c)
1866 +
self.assertTrue(len({a, b, c, d, e, f}) == 6)
1848 1867 1849 -
# Tests not applicable to the tee() recipe
1850 -
if False:
1851 -
# tee pass-through to copyable iterator
1852 -
a, b = tee('abc')
1853 -
c, d = tee(a)
1854 -
self.assertTrue(a is c)
1855 - 1856 -
# test tee_new
1857 -
t1, t2 = tee('abc')
1858 -
tnew = type(t1)
1859 -
self.assertRaises(TypeError, tnew)
1860 -
self.assertRaises(TypeError, tnew, 10)
1861 -
t3 = tnew(t1)
1862 -
self.assertTrue(list(t1) == list(t2) == list(t3) == list('abc'))
1868 +
# test tee_new
1869 +
t1, t2 = tee('abc')
1870 +
tnew = type(t1)
1871 +
self.assertRaises(TypeError, tnew)
1872 +
self.assertRaises(TypeError, tnew, 10)
1873 +
t3 = tnew(t1)
1874 +
self.assertTrue(list(t1) == list(t2) == list(t3) == list('abc'))
1863 1875 1864 1876
# test that tee objects are weak referencable
1865 1877
a, b = tee(range(10))
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