4710c53dca
These files are a subset of the python-2.7.2.tgz distribution from python.org. Changed files from PyMod-2.7.2 have been copied into the corresponding directories of this tree, replacing the original files in the distribution. Signed-off-by: daryl.mcdaniel@intel.com git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13197 6f19259b-4bc3-4df7-8a09-765794883524
94 lines
3.1 KiB
Python
94 lines
3.1 KiB
Python
"""Example of a generator: re-implement the built-in range function
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without actually constructing the list of values.
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OldStyleRange is coded in the way required to work in a 'for' loop before
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iterators were introduced into the language; using __getitem__ and __len__ .
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"""
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def handleargs(arglist):
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"""Take list of arguments and extract/create proper start, stop, and step
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values and return in a tuple"""
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try:
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if len(arglist) == 1:
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return 0, int(arglist[0]), 1
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elif len(arglist) == 2:
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return int(arglist[0]), int(arglist[1]), 1
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elif len(arglist) == 3:
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if arglist[2] == 0:
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raise ValueError("step argument must not be zero")
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return tuple(int(x) for x in arglist)
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else:
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raise TypeError("range() accepts 1-3 arguments, given", len(arglist))
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except TypeError:
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raise TypeError("range() arguments must be numbers or strings "
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"representing numbers")
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def genrange(*a):
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"""Function to implement 'range' as a generator"""
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start, stop, step = handleargs(a)
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value = start
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while value < stop:
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yield value
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value += step
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class oldrange:
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"""Class implementing a range object.
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To the user the instances feel like immutable sequences
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(and you can't concatenate or slice them)
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Done using the old way (pre-iterators; __len__ and __getitem__) to have an
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object be used by a 'for' loop.
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"""
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def __init__(self, *a):
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""" Initialize start, stop, and step values along with calculating the
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nubmer of values (what __len__ will return) in the range"""
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self.start, self.stop, self.step = handleargs(a)
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self.len = max(0, (self.stop - self.start) // self.step)
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def __repr__(self):
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"""implement repr(x) which is also used by print"""
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return 'range(%r, %r, %r)' % (self.start, self.stop, self.step)
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def __len__(self):
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"""implement len(x)"""
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return self.len
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def __getitem__(self, i):
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"""implement x[i]"""
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if 0 <= i <= self.len:
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return self.start + self.step * i
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else:
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raise IndexError, 'range[i] index out of range'
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def test():
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import time, __builtin__
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#Just a quick sanity check
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correct_result = __builtin__.range(5, 100, 3)
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oldrange_result = list(oldrange(5, 100, 3))
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genrange_result = list(genrange(5, 100, 3))
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if genrange_result != correct_result or oldrange_result != correct_result:
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raise Exception("error in implementation:\ncorrect = %s"
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"\nold-style = %s\ngenerator = %s" %
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(correct_result, oldrange_result, genrange_result))
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print "Timings for range(1000):"
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t1 = time.time()
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for i in oldrange(1000):
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pass
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t2 = time.time()
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for i in genrange(1000):
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pass
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t3 = time.time()
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for i in __builtin__.range(1000):
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pass
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t4 = time.time()
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print t2-t1, 'sec (old-style class)'
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print t3-t2, 'sec (generator)'
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print t4-t3, 'sec (built-in)'
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if __name__ == '__main__':
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test()
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