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Issue #16061: Speed up str.replace() for replacing 1-character strings.

This commit is contained in:
Serhiy Storchaka 2013-04-13 22:45:04 +03:00
parent a707f299cb
commit e2cef885a2
7 changed files with 102 additions and 26 deletions
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1
Makefile.pre.in
View File

@ -726,6 +726,7 @@ UNICODE_DEPS = \
$(srcdir)/Objects/stringlib/find_max_char.h \
$(srcdir)/Objects/stringlib/localeutil.h \
$(srcdir)/Objects/stringlib/partition.h \
$(srcdir)/Objects/stringlib/replace.h \
$(srcdir)/Objects/stringlib/split.h \
$(srcdir)/Objects/stringlib/ucs1lib.h \
$(srcdir)/Objects/stringlib/ucs2lib.h \

2
Misc/NEWS
View File

@ -10,6 +10,8 @@ What's New in Python 3.4.0 Alpha 1?
Core and Builtins
-----------------
- Issue #16061: Speed up str.replace() for replacing 1-character strings.
- Issue #17715: Fix segmentation fault from raising an exception in a __trunc__
method.

53
Objects/stringlib/replace.h Normal file
View File

@ -0,0 +1,53 @@
/* stringlib: replace implementation */
#ifndef STRINGLIB_FASTSEARCH_H
#error must include "stringlib/fastsearch.h" before including this module
#endif
Py_LOCAL_INLINE(void)
STRINGLIB(replace_1char_inplace)(STRINGLIB_CHAR* s, STRINGLIB_CHAR* end,
Py_UCS4 u1, Py_UCS4 u2, Py_ssize_t maxcount)
{
*s = u2;
while (--maxcount && ++s != end) {
/* Find the next character to be replaced.
If it occurs often, it is faster to scan for it using an inline
loop. If it occurs seldom, it is faster to scan for it using a
function call; the overhead of the function call is amortized
across the many characters that call covers. We start with an
inline loop and use a heuristic to determine whether to fall back
to a function call. */
if (*s != u1) {
int attempts = 10;
/* search u1 in a dummy loop */
while (1) {
if (++s == end)
return;
if (*s == u1)
break;
if (!--attempts) {
/* if u1 was not found for attempts iterations,
use FASTSEARCH() or memchr() */
#if STRINGLIB_SIZEOF_CHAR == 1
s++;
s = memchr(s, u1, end - s);
if (s == NULL)
return;
#else
Py_ssize_t i;
STRINGLIB_CHAR ch1 = (STRINGLIB_CHAR) u1;
s++;
i = FASTSEARCH(s, end - s, &ch1, 1, 0, FAST_SEARCH);
if (i < 0)
return;
s += i;
#endif
/* restart the dummy loop */
break;
}
}
}
*s = u2;
}
}

64
Objects/unicodeobject.c
View File

@ -605,6 +605,7 @@ make_bloom_mask(int kind, void* ptr, Py_ssize_t len)
#include "stringlib/split.h"
#include "stringlib/count.h"
#include "stringlib/find.h"
#include "stringlib/replace.h"
#include "stringlib/find_max_char.h"
#include "stringlib/localeutil.h"
#include "stringlib/undef.h"
@ -615,6 +616,7 @@ make_bloom_mask(int kind, void* ptr, Py_ssize_t len)
#include "stringlib/split.h"
#include "stringlib/count.h"
#include "stringlib/find.h"
#include "stringlib/replace.h"
#include "stringlib/find_max_char.h"
#include "stringlib/localeutil.h"
#include "stringlib/undef.h"
@ -625,6 +627,7 @@ make_bloom_mask(int kind, void* ptr, Py_ssize_t len)
#include "stringlib/split.h"
#include "stringlib/count.h"
#include "stringlib/find.h"
#include "stringlib/replace.h"
#include "stringlib/find_max_char.h"
#include "stringlib/localeutil.h"
#include "stringlib/undef.h"
@ -9927,6 +9930,31 @@ anylib_count(int kind, PyObject *sstr, void* sbuf, Py_ssize_t slen,
return 0;
}
static void
replace_1char_inplace(PyObject *u, Py_ssize_t pos,
Py_UCS4 u1, Py_UCS4 u2, Py_ssize_t maxcount)
{
int kind = PyUnicode_KIND(u);
void *data = PyUnicode_DATA(u);
Py_ssize_t len = PyUnicode_GET_LENGTH(u);
if (kind == PyUnicode_1BYTE_KIND) {
ucs1lib_replace_1char_inplace((Py_UCS1 *)data + pos,
(Py_UCS1 *)data + len,
u1, u2, maxcount);
}
else if (kind == PyUnicode_2BYTE_KIND) {
ucs2lib_replace_1char_inplace((Py_UCS2 *)data + pos,
(Py_UCS2 *)data + len,
u1, u2, maxcount);
}
else {
assert(kind == PyUnicode_4BYTE_KIND);
ucs4lib_replace_1char_inplace((Py_UCS4 *)data + pos,
(Py_UCS4 *)data + len,
u1, u2, maxcount);
}
}
static PyObject *
replace(PyObject *self, PyObject *str1,
PyObject *str2, Py_ssize_t maxcount)
@ -9943,7 +9971,7 @@ replace(PyObject *self, PyObject *str1,
Py_ssize_t len1 = PyUnicode_GET_LENGTH(str1);
Py_ssize_t len2 = PyUnicode_GET_LENGTH(str2);
int mayshrink;
Py_UCS4 maxchar, maxchar_str2;
Py_UCS4 maxchar, maxchar_str1, maxchar_str2;
if (maxcount < 0)
maxcount = PY_SSIZE_T_MAX;
@ -9952,15 +9980,16 @@ replace(PyObject *self, PyObject *str1,
if (str1 == str2)
goto nothing;
if (skind < kind1)
/* substring too wide to be present */
goto nothing;
maxchar = PyUnicode_MAX_CHAR_VALUE(self);
maxchar_str1 = PyUnicode_MAX_CHAR_VALUE(str1);
if (maxchar < maxchar_str1)
/* substring too wide to be present */
goto nothing;
maxchar_str2 = PyUnicode_MAX_CHAR_VALUE(str2);
/* Replacing str1 with str2 may cause a maxchar reduction in the
result string. */
mayshrink = (maxchar_str2 < maxchar);
mayshrink = (maxchar_str2 < maxchar_str1) && (maxchar == maxchar_str1);
maxchar = MAX_MAXCHAR(maxchar, maxchar_str2);
if (len1 == len2) {
@ -9970,36 +9999,19 @@ replace(PyObject *self, PyObject *str1,
if (len1 == 1) {
/* replace characters */
Py_UCS4 u1, u2;
int rkind;
Py_ssize_t index, pos;
char *src, *rbuf;
Py_ssize_t pos;
u1 = PyUnicode_READ(kind1, buf1, 0);
pos = findchar(sbuf, PyUnicode_KIND(self), slen, u1, 1);
pos = findchar(sbuf, skind, slen, u1, 1);
if (pos < 0)
goto nothing;
u2 = PyUnicode_READ(kind2, buf2, 0);
u = PyUnicode_New(slen, maxchar);
if (!u)
goto error;
_PyUnicode_FastCopyCharacters(u, 0, self, 0, slen);
rkind = PyUnicode_KIND(u);
rbuf = PyUnicode_DATA(u);
PyUnicode_WRITE(rkind, rbuf, pos, u2);
index = 0;
src = sbuf;
while (--maxcount)
{
pos++;
src += pos * PyUnicode_KIND(self);
slen -= pos;
index += pos;
pos = findchar(src, PyUnicode_KIND(self), slen, u1, 1);
if (pos < 0)
break;
PyUnicode_WRITE(rkind, rbuf, index + pos, u2);
}
_PyUnicode_FastCopyCharacters(u, 0, self, 0, slen);
replace_1char_inplace(u, pos, u1, u2, maxcount);
}
else {
int rkind = skind;

4
PC/VS9.0/pythoncore.vcproj
View File

@ -1586,6 +1586,10 @@
RelativePath="..\..\Objects\rangeobject.c"
>
</File>
<File
RelativePath="..\..\Objects\stringlib\replace.h"
>
</File>
<File
RelativePath="..\..\Objects\setobject.c"
>

1
PCbuild/pythoncore.vcxproj
View File

@ -475,6 +475,7 @@
<ClInclude Include="..\Objects\stringlib\fastsearch.h" />
<ClInclude Include="..\Objects\stringlib\find.h" />
<ClInclude Include="..\Objects\stringlib\partition.h" />
<ClInclude Include="..\Objects\stringlib\replace.h" />
<ClInclude Include="..\Objects\stringlib\split.h" />
<ClInclude Include="..\Objects\unicodetype_db.h" />
<ClInclude Include="..\Parser\parser.h" />

3
PCbuild/pythoncore.vcxproj.filters
View File

@ -378,6 +378,9 @@
<ClInclude Include="..\Objects\stringlib\partition.h">
<Filter>Objects</Filter>
</ClInclude>
<ClInclude Include="..\Objects\stringlib\replace.h">
<Filter>Objects</Filter>
</ClInclude>
<ClInclude Include="..\Objects\stringlib\split.h">
<Filter>Objects</Filter>
</ClInclude>