const char*
boyermoore_search(const char *haystack, const char *needle) {
/*
* Calc string sizes
*/
size_t needle_len, haystack_len;
needle_len = strlen(needle);
haystack_len = strlen(haystack);
/*
* Simple checks
*/
if(haystack_len == 0)
return NULL;
if(needle_len == 0)
return haystack;
/*
* Initialize heuristics
*/
int badcharacter[ALPHABET_SIZE];
int goodsuffix[needle_len+1];
prepare_badcharacter_heuristic(needle, needle_len, badcharacter);
prepare_goodsuffix_heuristic(needle, needle_len, goodsuffix);
/*
* Boyer-Moore search
*/
size_t s = 0;
while(s <= (haystack_len - needle_len))
{
size_t j = needle_len;
while(j > 0 && needle[j-1] == haystack[s+j-1])
j--;
if(j > 0)
{
int k = badcharacter[(size_t) haystack[s+j-1]];
int m;
if(k < (int)j && (m = j-k-1) > goodsuffix[j])
s+= m;
else
s+= goodsuffix[j];
}
else
{
return haystack + s;
}
}
/* not found */
return NULL;
}
/*
* Boyer-Moore search algorithm
*/
void boyermoore_search(c_array haystack_array, c_array needle_array)
{
/* Calc string sizes */
size_t needle_len, haystack_len;
needle_len = needle_array.len;
haystack_len = haystack_array.len;
byte* haystack = haystack_array.data;
byte* needle = needle_array.data;
printf("needle length = %lu\n", needle_len);
/** Simple checks */
if(haystack_len == 0)
return;
if(needle_len == 0)
return;
if(needle_len > haystack_len)
return;
printf("boyer_moore search\n");
/** Initialize heuristics */
int badcharacter[ALPHABET_SIZE];
int goodsuffix[needle_len+1];
prepare_badcharacter_heuristic(needle, needle_len, badcharacter);
prepare_goodsuffix_heuristic(needle, needle_len, goodsuffix);
/** Boyer-Moore search */
size_t s = 0, j = 0;
while(s <= (haystack_len - needle_len))
{
j = needle_len;
if (s > 6250 && s < 6260) {
while(j > 0 && needle[j-1] == haystack[s+j-1]) {
printf("%lu: %d %d\n",s+j-1, needle[j-1], haystack[s+j-1]);
j--;
}
printf("=%lu: %d %d\n", s+j-1, needle[j-1], haystack[s+j-1]);
} else {
while(j > 0 && needle[j-1] == haystack[s+j-1])
j--;
}
if(j > 0) {
int k = badcharacter[haystack[s+j-1]];
int m;
if(k < (int)j && (m = j-k-1) > goodsuffix[j]) {
s += m;
if (s > 6250 && s < 6260)
printf("adding m = %d\n", m);
} else {
s += goodsuffix[j];
if (s > 6250 && s < 6260)
printf("adding goodsuffix[%lu] = %d\n", j, goodsuffix[j]);
}
} else {
printf("Pattern found at %lu\n", s);
s += goodsuffix[0];
}
}
}