302 lines
7.6 KiB
Python
302 lines
7.6 KiB
Python
doctests = """
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Test simple loop with conditional
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>>> sum(i*i for i in range(100) if i&1 == 1)
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166650
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Test simple nesting
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>>> list((i,j) for i in range(3) for j in range(4) )
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[(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)]
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Test nesting with the inner expression dependent on the outer
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>>> list((i,j) for i in range(4) for j in range(i) )
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[(1, 0), (2, 0), (2, 1), (3, 0), (3, 1), (3, 2)]
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Test the idiom for temporary variable assignment in comprehensions.
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>>> list((j*j for i in range(4) for j in [i+1]))
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[1, 4, 9, 16]
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>>> list((j*k for i in range(4) for j in [i+1] for k in [j+1]))
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[2, 6, 12, 20]
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>>> list((j*k for i in range(4) for j, k in [(i+1, i+2)]))
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[2, 6, 12, 20]
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Not assignment
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>>> list((i*i for i in [*range(4)]))
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[0, 1, 4, 9]
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>>> list((i*i for i in (*range(4),)))
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[0, 1, 4, 9]
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Make sure the induction variable is not exposed
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>>> i = 20
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>>> sum(i*i for i in range(100))
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328350
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>>> i
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20
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Test first class
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>>> g = (i*i for i in range(4))
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>>> type(g)
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<class 'generator'>
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>>> list(g)
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[0, 1, 4, 9]
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Test direct calls to next()
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>>> g = (i*i for i in range(3))
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>>> next(g)
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0
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>>> next(g)
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1
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>>> next(g)
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4
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>>> next(g)
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Traceback (most recent call last):
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File "<pyshell#21>", line 1, in -toplevel-
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next(g)
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StopIteration
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Does it stay stopped?
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>>> next(g)
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Traceback (most recent call last):
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File "<pyshell#21>", line 1, in -toplevel-
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next(g)
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StopIteration
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>>> list(g)
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[]
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Test running gen when defining function is out of scope
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>>> def f(n):
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... return (i*i for i in range(n))
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>>> list(f(10))
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[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
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>>> def f(n):
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... return ((i,j) for i in range(3) for j in range(n))
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>>> list(f(4))
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[(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)]
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>>> def f(n):
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... return ((i,j) for i in range(3) for j in range(4) if j in range(n))
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>>> list(f(4))
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[(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)]
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>>> list(f(2))
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[(0, 0), (0, 1), (1, 0), (1, 1), (2, 0), (2, 1)]
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Verify that parenthesis are required in a statement
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>>> def f(n):
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... return i*i for i in range(n)
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Traceback (most recent call last):
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...
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SyntaxError: invalid syntax
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Verify that parenthesis are required when used as a keyword argument value
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>>> dict(a = i for i in range(10))
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Traceback (most recent call last):
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...
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SyntaxError: invalid syntax
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Verify that parenthesis are required when used as a keyword argument value
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>>> dict(a = (i for i in range(10))) #doctest: +ELLIPSIS
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{'a': <generator object <genexpr> at ...>}
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Verify early binding for the outermost for-expression
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>>> x=10
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>>> g = (i*i for i in range(x))
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>>> x = 5
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>>> list(g)
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[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
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Verify that the outermost for-expression makes an immediate check
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for iterability
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>>> (i for i in 6)
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Traceback (most recent call last):
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File "<pyshell#4>", line 1, in -toplevel-
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(i for i in 6)
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TypeError: 'int' object is not iterable
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Verify late binding for the outermost if-expression
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>>> include = (2,4,6,8)
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>>> g = (i*i for i in range(10) if i in include)
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>>> include = (1,3,5,7,9)
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>>> list(g)
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[1, 9, 25, 49, 81]
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Verify late binding for the innermost for-expression
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>>> g = ((i,j) for i in range(3) for j in range(x))
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>>> x = 4
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>>> list(g)
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[(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)]
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Verify re-use of tuples (a side benefit of using genexps over listcomps)
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>>> tupleids = list(map(id, ((i,i) for i in range(10))))
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>>> int(max(tupleids) - min(tupleids))
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0
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Verify that syntax error's are raised for genexps used as lvalues
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>>> (y for y in (1,2)) = 10
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Traceback (most recent call last):
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...
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SyntaxError: cannot assign to generator expression
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>>> (y for y in (1,2)) += 10
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Traceback (most recent call last):
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...
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SyntaxError: 'generator expression' is an illegal expression for augmented assignment
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########### Tests borrowed from or inspired by test_generators.py ############
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Make a generator that acts like range()
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>>> yrange = lambda n: (i for i in range(n))
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>>> list(yrange(10))
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[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
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Generators always return to the most recent caller:
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>>> def creator():
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... r = yrange(5)
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... print("creator", next(r))
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... return r
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>>> def caller():
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... r = creator()
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... for i in r:
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... print("caller", i)
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>>> caller()
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creator 0
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caller 1
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caller 2
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caller 3
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caller 4
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Generators can call other generators:
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>>> def zrange(n):
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... for i in yrange(n):
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... yield i
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>>> list(zrange(5))
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[0, 1, 2, 3, 4]
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Verify that a gen exp cannot be resumed while it is actively running:
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>>> g = (next(me) for i in range(10))
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>>> me = g
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>>> next(me)
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Traceback (most recent call last):
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File "<pyshell#30>", line 1, in -toplevel-
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next(me)
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File "<pyshell#28>", line 1, in <generator expression>
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g = (next(me) for i in range(10))
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ValueError: generator already executing
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Verify exception propagation
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>>> g = (10 // i for i in (5, 0, 2))
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>>> next(g)
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2
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>>> next(g)
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Traceback (most recent call last):
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File "<pyshell#37>", line 1, in -toplevel-
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next(g)
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File "<pyshell#35>", line 1, in <generator expression>
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g = (10 // i for i in (5, 0, 2))
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ZeroDivisionError: integer division or modulo by zero
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>>> next(g)
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Traceback (most recent call last):
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File "<pyshell#38>", line 1, in -toplevel-
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next(g)
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StopIteration
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Make sure that None is a valid return value
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>>> list(None for i in range(10))
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[None, None, None, None, None, None, None, None, None, None]
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Check that generator attributes are present
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>>> g = (i*i for i in range(3))
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>>> expected = set(['gi_frame', 'gi_running'])
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>>> set(attr for attr in dir(g) if not attr.startswith('__')) >= expected
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True
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>>> from test.support import HAVE_DOCSTRINGS
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>>> print(g.__next__.__doc__ if HAVE_DOCSTRINGS else 'Implement next(self).')
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Implement next(self).
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>>> import types
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>>> isinstance(g, types.GeneratorType)
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True
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Check the __iter__ slot is defined to return self
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>>> iter(g) is g
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True
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Verify that the running flag is set properly
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>>> g = (me.gi_running for i in (0,1))
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>>> me = g
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>>> me.gi_running
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0
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>>> next(me)
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1
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>>> me.gi_running
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0
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Verify that genexps are weakly referencable
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>>> import weakref
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>>> g = (i*i for i in range(4))
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>>> wr = weakref.ref(g)
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>>> wr() is g
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True
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>>> p = weakref.proxy(g)
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>>> list(p)
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[0, 1, 4, 9]
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"""
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import sys
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# Trace function can throw off the tuple reuse test.
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if hasattr(sys, 'gettrace') and sys.gettrace():
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__test__ = {}
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else:
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__test__ = {'doctests' : doctests}
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def test_main(verbose=None):
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from test import support
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from test import test_genexps
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support.run_doctest(test_genexps, verbose)
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# verify reference counting
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if verbose and hasattr(sys, "gettotalrefcount"):
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import gc
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counts = [None] * 5
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for i in range(len(counts)):
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support.run_doctest(test_genexps, verbose)
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gc.collect()
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counts[i] = sys.gettotalrefcount()
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print(counts)
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if __name__ == "__main__":
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test_main(verbose=True)
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