Bitap algorithm in Java [closed]
- by davit-datuashvili
The following is the bitap algorithm according to Wikipedia. Can someone translate this to Java?
#include <string.h>
#include <limits.h>
const char *bitap_bitwise_search(const char *text, const char *pattern)
{
int m = strlen(pattern);
unsigned long R;
unsigned long pattern_mask[CHAR_MAX+1];
int i;
if (pattern[0] == '\0') return text;
if (m > 31) return "The pattern is too long!";
/* Initialize the bit array R */
R = ~1;
/* Initialize the pattern bitmasks */
for (i=0; i <= CHAR_MAX; ++i)
pattern_mask[i] = ~0;
for (i=0; i < m; ++i)
pattern_mask[pattern[i]] &= ~(1UL << i);
for (i=0; text[i] != '\0'; ++i) {
/* Update the bit array */
R |= pattern_mask[text[i]];
R <<= 1;
if (0 == (R & (1UL << m)))
return (text + i - m) + 1;
}
return NULL;
}
