made a copy of the string using PyString_FromStringAndSize(s, n) and modify
the copied string in-place. However, 1 (and 0) character strings are shared
from a cache. This cause "A".replace("A", "a") to change the cached version
of "A" -- used by everyone.
Now may the copy with NULL as the string and do the memcpy manually. I've
added regression tests to check if this happens in the future. Perhaps
there should be a PyString_Copy for this case?
both mystrtoul.c and longobject.c. Share the table instead. Also
cut its size by 64 entries (they had been used for an inscrutable
trick originally, but the code no longer tries to use that trick).
the Need For Speed sprint coding. Includes commented out overflow tests
which will be uncommented once the code is fixed.
This test will break the 8-bit string tests because
"".replace("", "A") == "" when it should == "A"
We have a fix for it, which should be added tomorrow.
results in a 2.5x speedup on the stringbench count tests, and a 20x (!)
speedup on the stringbench search/find/contains test, compared to 2.5a2.
for more on the algorithm, see:
http://effbot.org/zone/stringlib.htm
if you get weird results, you can disable the new algoritm by undefining
USE_FAST in Objects/unicodeobject.c.
enjoy /F
In rare cases of strings specifying true values near sys.maxint,
and oddball bases (not decimal or a power of 2), int(string, base)
could deliver insane answers. This repairs all such problems, and
also speeds string->int significantly. On my box, here are %
speedups for decimal strings of various lengths:
length speedup
------ -------
1 12.4%
2 15.7%
3 20.6%
4 28.1%
5 33.2%
6 37.5%
7 41.9%
8 46.3%
9 51.2%
10 19.5%
11 19.9%
12 23.9%
13 23.7%
14 23.3%
15 24.9%
16 25.3%
17 28.3%
18 27.9%
19 35.7%
Note that the difference between 9 and 10 is the difference between
short and long Python ints on a 32-bit box. The patch doesn't
actually do anything to speed conversion to long: the speedup is
due to detecting "unsigned long" overflow more quickly.
This is a bugfix candidate, but it's a non-trivial patch and it
would be painful to separate the "bug fix" from the "speed up" parts.
speed up splitlines and strip with charsets; etc. rsplit is now as
fast as split in all our tests (reverse takes no time at all), and
splitlines() is nearly as fast as a plain split("\n") in our tests.
and we're not done yet... ;-)
Andrew Dalke
Andrew M. Kuchling
Fredrik Lundh
Tim Peters
Kristján Valur Jónsson
Thomas Wouters
Walter Dörwald
Fred Drake
Bob Ippolito