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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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6
Objects/unicodeobject.c
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@ -7385,6 +7385,12 @@ unicode_subscript(PyUnicodeObject* self, PyObject* item)
if (slicelength <= 0) {
return PyUnicode_FromUnicode(NULL, 0);
} else if (start == 0 && step == 1 && slicelength == self->length &&
PyUnicode_CheckExact(self)) {
Py_INCREF(self);
return (PyObject *)self;
} else if (step == 1) {
return PyUnicode_FromUnicode(self->str + start, slicelength);
} else {
source_buf = PyUnicode_AS_UNICODE((PyObject*)self);
result_buf = (Py_UNICODE *)PyMem_MALLOC(slicelength*