jimjjewett at gmail
Aug 23, 2006, 6:01 AM
Post #2 of 3
(166 views)
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Re: r51494 - python/branches/p3yk-noslice/Objects/stringobject.c python/branches/p3yk-noslice/Objects/tupleobject.c python/branches/p3yk-noslice/Objects/unicodeobject.c
[In reply to]
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(1) I would personally prefer
if (step == 1) {
if (start == 0 && ...) {}
else {}
}
I realize that the compiler can do this, but I like flagging "this is
an odd special case"
(2) Why the CheckExact? Is there a promise (even in py3K) that
constructors won't return a subclass? I had thought that the question
was only when/if to *guarantee* that the subclass would be used. If
the intent is to guard against subclasses with a different internal
layout, then it should come before the GET_SIZE macros.
-jJ
On 8/22/06, thomas.wouters <python-checkins [at] python> wrote:
> Author: thomas.wouters
> Date: Wed Aug 23 00:37:35 2006
> New Revision: 51494
>
> Modified:
> python/branches/p3yk-noslice/Objects/stringobject.c
> python/branches/p3yk-noslice/Objects/tupleobject.c
> python/branches/p3yk-noslice/Objects/unicodeobject.c
> Log:
>
> Copy some of the special cases from normal slicing to extended slicing, for
> general speedup.
>
>
>
> Modified: python/branches/p3yk-noslice/Objects/stringobject.c
> ==============================================================================
> --- python/branches/p3yk-noslice/Objects/stringobject.c (original)
> +++ python/branches/p3yk-noslice/Objects/stringobject.c Wed Aug 23 00:37:35 2006
> @@ -1210,6 +1210,17 @@
> if (slicelength <= 0) {
> return PyString_FromStringAndSize("", 0);
> }
> + else if (start == 0 && step == 1 &&
> + slicelength == PyString_GET_SIZE(self) &&
> + PyString_CheckExact(self)) {
> + Py_INCREF(self);
> + return (PyObject *)self;
> + }
> + else if (step == 1) {
> + return PyString_FromStringAndSize(
> + PyString_AS_STRING(self) + start,
> + slicelength);
> + }
> else {
> source_buf = PyString_AsString((PyObject*)self);
> result_buf = (char *)PyMem_Malloc(slicelength);
>
> Modified: python/branches/p3yk-noslice/Objects/tupleobject.c
> ==============================================================================
> --- python/branches/p3yk-noslice/Objects/tupleobject.c (original)
> +++ python/branches/p3yk-noslice/Objects/tupleobject.c Wed Aug 23 00:37:35 2006
> @@ -603,6 +603,12 @@
> if (slicelength <= 0) {
> return PyTuple_New(0);
> }
> + else if (start == 0 && step == 1 &&
> + slicelength == PyTuple_GET_SIZE(self) &&
> + PyTuple_CheckExact(self)) {
> + Py_INCREF(self);
> + return (PyObject *)self;
> + }
> else {
> result = PyTuple_New(slicelength);
> if (!result) return NULL;
>
> Modified: python/branches/p3yk-noslice/Objects/unicodeobject.c
> ==============================================================================
> --- python/branches/p3yk-noslice/Objects/unicodeobject.c (original)
> +++ python/branches/p3yk-noslice/Objects/unicodeobject.c Wed Aug 23 00:37:35 2006
> @@ -7083,6 +7083,12 @@
>
> 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*
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