161 lines
4.8 KiB
C
161 lines
4.8 KiB
C
|
/* stringlib: fastsearch implementation */
|
||
|
|
|
||
|
|
#ifndef STRINGLIB_FASTSEARCH_H
|
||
|
|
#define STRINGLIB_FASTSEARCH_H
|
||
|
|
|
||
|
|
/* 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/zone/stringlib.htm */
|
||
|
|
|
||
|
|
/* 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 possible be a match in the target string, and 0 if
|
||
|
|
it has actually checked for matches, but didn't find any. callers
|
||
|
|
beware! */
|
||
|
|
|
||
|
|
#define FAST_COUNT 0
|
||
|
|
#define FAST_SEARCH 1
|
||
|
|
#define FAST_RSEARCH 2
|
||
|
|
|
||
|
|
#if LONG_BIT >= 128
|
||
|
|
#define STRINGLIB_BLOOM_WIDTH 128
|
||
|
|
#elif LONG_BIT >= 64
|
||
|
|
#define STRINGLIB_BLOOM_WIDTH 64
|
||
|
|
#elif LONG_BIT >= 32
|
||
|
|
#define STRINGLIB_BLOOM_WIDTH 32
|
||
|
|
#else
|
||
|
|
#error "LONG_BIT is smaller than 32"
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#define STRINGLIB_BLOOM_ADD(mask, ch) \
|
||
|
|
((mask |= (1UL << ((ch) & (STRINGLIB_BLOOM_WIDTH -1)))))
|
||
|
|
#define STRINGLIB_BLOOM(mask, ch) \
|
||
|
|
((mask & (1UL << ((ch) & (STRINGLIB_BLOOM_WIDTH -1)))))
|
||
|
|
|
||
|
|
Py_LOCAL_INLINE(Py_ssize_t)
|
||
|
|
fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
|
||
|
|
const STRINGLIB_CHAR* p, Py_ssize_t m,
|
||
|
|
Py_ssize_t maxcount, int mode)
|
||
|
|
{
|
||
|
|
unsigned long mask;
|
||
|
|
Py_ssize_t skip, count = 0;
|
||
|
|
Py_ssize_t i, j, mlast, w;
|
||
|
|
|
||
|
|
w = n - m;
|
||
|
|
|
||
|
|
if (w < 0 || (mode == FAST_COUNT && maxcount == 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++;
|
||
|
|
if (count == maxcount)
|
||
|
|
return maxcount;
|
||
|
|
}
|
||
|
|
return count;
|
||
|
|
} else if (mode == FAST_SEARCH) {
|
||
|
|
for (i = 0; i < n; i++)
|
||
|
|
if (s[i] == p[0])
|
||
|
|
return i;
|
||
|
|
} else { /* FAST_RSEARCH */
|
||
|
|
for (i = n - 1; i > -1; i--)
|
||
|
|
if (s[i] == p[0])
|
||
|
|
return i;
|
||
|
|
}
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
|
||
|
|
mlast = m - 1;
|
||
|
|
skip = mlast - 1;
|
||
|
|
mask = 0;
|
||
|
|
|
||
|
|
if (mode != FAST_RSEARCH) {
|
||
|
|
|
||
|
|
/* create compressed boyer-moore delta 1 table */
|
||
|
|
|
||
|
|
/* process pattern[:-1] */
|
||
|
|
for (i = 0; i < mlast; i++) {
|
||
|
|
STRINGLIB_BLOOM_ADD(mask, p[i]);
|
||
|
|
if (p[i] == p[mlast])
|
||
|
|
skip = mlast - i - 1;
|
||
|
|
}
|
||
|
|
/* process pattern[-1] outside the loop */
|
||
|
|
STRINGLIB_BLOOM_ADD(mask, p[mlast]);
|
||
|
|
|
||
|
|
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++;
|
||
|
|
if (count == maxcount)
|
||
|
|
return maxcount;
|
||
|
|
i = i + mlast;
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
/* miss: check if next character is part of pattern */
|
||
|
|
if (!STRINGLIB_BLOOM(mask, s[i+m]))
|
||
|
|
i = i + m;
|
||
|
|
else
|
||
|
|
i = i + skip;
|
||
|
|
} else {
|
||
|
|
/* skip: check if next character is part of pattern */
|
||
|
|
if (!STRINGLIB_BLOOM(mask, s[i+m]))
|
||
|
|
i = i + m;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
} else { /* FAST_RSEARCH */
|
||
|
|
|
||
|
|
/* create compressed boyer-moore delta 1 table */
|
||
|
|
|
||
|
|
/* process pattern[0] outside the loop */
|
||
|
|
STRINGLIB_BLOOM_ADD(mask, p[0]);
|
||
|
|
/* process pattern[:0:-1] */
|
||
|
|
for (i = mlast; i > 0; i--) {
|
||
|
|
STRINGLIB_BLOOM_ADD(mask, p[i]);
|
||
|
|
if (p[i] == p[0])
|
||
|
|
skip = i - 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
for (i = w; i >= 0; i--) {
|
||
|
|
if (s[i] == p[0]) {
|
||
|
|
/* candidate match */
|
||
|
|
for (j = mlast; j > 0; j--)
|
||
|
|
if (s[i+j] != p[j])
|
||
|
|
break;
|
||
|
|
if (j == 0)
|
||
|
|
/* got a match! */
|
||
|
|
return i;
|
||
|
|
/* miss: check if previous character is part of pattern */
|
||
|
|
if (i > 0 && !STRINGLIB_BLOOM(mask, s[i-1]))
|
||
|
|
i = i - m;
|
||
|
|
else
|
||
|
|
i = i - skip;
|
||
|
|
} else {
|
||
|
|
/* skip: check if previous character is part of pattern */
|
||
|
|
if (i > 0 && !STRINGLIB_BLOOM(mask, s[i-1]))
|
||
|
|
i = i - m;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (mode != FAST_COUNT)
|
||
|
|
return -1;
|
||
|
|
return count;
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif
|