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Improve extended slicing support in builtin types and classes. Specifically:

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- Specialcase extended slices that amount to a shallow copy the same way as
   is done for simple slices, in the tuple, string and unicode case.

 - Specialcase step-1 extended slices to optimize the common case for all
   involved types.

 - For lists, allow extended slice assignment of differing lengths as long
   as the step is 1. (Previously, 'l[:2:1] = []' failed even though
   'l[:2] = []' and 'l[:2:None] = []' do not.)

 - Implement extended slicing for buffer, array, structseq, mmap and
   UserString.UserString.

 - Implement slice-object support (but not non-step-1 slice assignment) for
   UserString.MutableString.

 - Add tests for all new functionality.
This commit is contained in:
Thomas Wouters 2007-08-28 15:28:19 +00:00
parent 0f4a14b56f
commit 3ccec68a05
16 changed files with 730 additions and 120 deletions
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14
Lib/test/string_tests.py
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@ -912,7 +912,6 @@ class MixinStrUnicodeUserStringTest:
self.checkequal(u'abc', 'abc', '__getitem__', slice(0, 1000))
self.checkequal(u'a', 'abc', '__getitem__', slice(0, 1))
self.checkequal(u'', 'abc', '__getitem__', slice(0, 0))
# FIXME What about negative indices? This is handled differently by [] and __getitem__(slice)
self.checkraises(TypeError, 'abc', '__getitem__', 'def')
@ -926,10 +925,21 @@ class MixinStrUnicodeUserStringTest:
self.checkequal('', 'abc', '__getslice__', 1000, 1000)
self.checkequal('', 'abc', '__getslice__', 2000, 1000)
self.checkequal('', 'abc', '__getslice__', 2, 1)
# FIXME What about negative indizes? This is handled differently by [] and __getslice__
self.checkraises(TypeError, 'abc', '__getslice__', 'def')
def test_extended_getslice(self):
# Test extended slicing by comparing with list slicing.
s = string.ascii_letters + string.digits
indices = (0, None, 1, 3, 41, -1, -2, -37)
for start in indices:
for stop in indices:
# Skip step 0 (invalid)
for step in indices[1:]:
L = list(s)[start:stop:step]
self.checkequal(u"".join(L), s, '__getitem__',
slice(start, stop, step))
def test_mul(self):
self.checkequal('', 'abc', '__mul__', -1)
self.checkequal('', 'abc', '__mul__', 0)