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10 # the following conditions:
12 # The above copyright notice and this permission notice shall be included
13 # in all copies or substantial portions of the Software.
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24 __revision__ = "src/engine/SCons/compat/_scons_itertools.py 3842 2008/12/20 22:59:52 scons"
27 Implementations of itertools functions for Python versions that don't
30 These implement the functions by creating the entire list, not returning
31 it element-by-element as the real itertools functions do. This means
32 that early Python versions won't get the performance benefit of using
33 the itertools, but we can still use them so the later Python versions
34 do get the advantages of using iterators.
36 Because we return the entire list, we intentionally do not implement the
37 itertools functions that "return" infinitely-long lists: the count(),
38 cycle() and repeat() functions. Other functions below have remained
39 unimplemented simply because they aren't being used (yet) and it wasn't
40 obvious how to do it. Or, conversely, we only implemented those functions
41 that *were* easy to implement (mostly because the Python documentation
42 contained examples of equivalent code).
44 Note that these do not have independent unit tests, so it's possible
48 def chain(*iterables):
51 result.extend(list(x))
55 # returns infinite length, should not be supported
56 raise NotImplementedError
59 # returns infinite length, should not be supported
60 raise NotImplementedError
62 def dropwhile(predicate, iterable):
68 result.extend(iterable)
71 def groupby(iterable, *args):
72 raise NotImplementedError
74 def ifilter(predicate, iterable):
83 def ifilterfalse(predicate, iterable):
92 def imap(function, *iterables):
93 return apply(map, (function,) + tuple(iterables))
95 def islice(*args, **kw):
96 raise NotImplementedError
99 return apply(zip, iterables)
101 def repeat(*args, **kw):
102 # returns infinite length, should not be supported
103 raise NotImplementedError
105 def starmap(*args, **kw):
106 raise NotImplementedError
108 def takewhile(predicate, iterable):
117 def tee(*args, **kw):
118 raise NotImplementedError