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needforspeed: stringlib refactoring (in progress)

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Fredrik Lundh 2006-05-26 17:04:58 +00:00
parent 877ab9bc23
commit a50d201bd9
4 changed files with 111 additions and 179 deletions
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99
Objects/stringobject.c
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@ -765,102 +765,17 @@ PyString_AsStringAndSize(register PyObject *obj,
}
/* -------------------------------------------------------------------- */
/* Helpers */
/* stringlib components */
#define USE_FAST /* experimental fast search implementation */
#define USE_FAST
/* XXX - this code is copied from unicodeobject.c. we really should
refactor the core implementations (see _sre.c for how this can be
done), but that'll have to wait -- fredrik */
#ifdef USE_FAST
/* fast search/count implementation, based on a mix between boyer-
moore and horspool, with a few more bells and whistles on the top.
for some more background, see: http://effbot.org/stringlib */
#define STRINGLIB_CHAR char
/* note: fastsearch may access s[n], which isn't a problem when using
Python's ordinary string types, but may cause problems if you're
using this code in other contexts. also, the count mode returns -1
if there cannot possibly be a match in the target string, and 0 if
it has actually checked for matches, but didn't find any. callers
beware! */
#include "stringlib/fastsearch.h"
#define FAST_COUNT 0
#define FAST_SEARCH 1
Py_LOCAL(Py_ssize_t)
fastsearch(const char* s, Py_ssize_t n, const char* p, Py_ssize_t m, int mode)
{
long mask;
Py_ssize_t skip, count = 0;
Py_ssize_t i, j, mlast, w;
w = n - m;
if (w < 0)
return -1;
/* look for special cases */
if (m <= 1) {
if (m <= 0)
return -1;
/* use special case for 1-character strings */
if (mode == FAST_COUNT) {
for (i = 0; i < n; i++)
if (s[i] == p[0])
count++;
return count;
} else {
for (i = 0; i < n; i++)
if (s[i] == p[0])
return i;
}
return -1;
}
mlast = m - 1;
/* create compressed boyer-moore delta 1 table */
skip = mlast - 1;
/* process pattern[:-1] */
for (mask = i = 0; i < mlast; i++) {
mask |= (1 << (p[i] & 0x1F));
if (p[i] == p[mlast])
skip = mlast - i - 1;
}
/* process pattern[-1] outside the loop */
mask |= (1 << (p[mlast] & 0x1F));
for (i = 0; i <= w; i++) {
/* note: using mlast in the skip path slows things down on x86 */
if (s[i+m-1] == p[m-1]) {
/* candidate match */
for (j = 0; j < mlast; j++)
if (s[i+j] != p[j])
break;
if (j == mlast) {
/* got a match! */
if (mode != FAST_COUNT)
return i;
count++;
i = i + mlast;
continue;
}
/* miss: check if next character is part of pattern */
if (!(mask & (1 << (s[i+m] & 0x1F))))
i = i + m;
else
i = i + skip;
} else {
/* skip: check if next character is part of pattern */
if (!(mask & (1 << (s[i+m] & 0x1F))))
i = i + m;
}
}
if (mode != FAST_COUNT)
return -1;
return count;
}
#endif
/* -------------------------------------------------------------------- */
/* Methods */
@ -2416,7 +2331,7 @@ string_count(PyStringObject *self, PyObject *args)
#else
r = 0;
while (i < m) {
const char *t
const char *t;
if (!memcmp(s+i, sub, n)) {
r++;
i += n;