* 使用Boyer-Moore-Horspool-Sunday 算法进行字符串匹配的系列函数
算法提出:BOYER, R., and S. MOORE. 1977. "A Fast String Searching Algorithm."
HORSPOOL, R. N. 1980. "Practical Fast Searching in Strings."
Software - Practice and Experience, 10, 501-06. Further improvements by HUME, A.,
and D. M. SUNDAY. 1991.
2002.08.20 周霖 KCN
*/
#include "system.h"
/* 字符串查找函数*/
char *bm_strstr(const char *string, const char *pattern)
{
size_t shift[256];
bool init = false;
return (char *) memfind(string, strlen(string), pattern, strlen(pattern), shift, &init);
}
/* 字符串多次匹配函数*/
char *bm_strstr_rp(const char *string, const char *pattern, size_t * shift, bool * init)
{
return (char *) memfind(string, strlen(string), pattern, strlen(pattern), shift, init);
}
/* 字符串大小写不敏感的匹配函数*/
char *bm_strcasestr(const char *string, const char *pattern)
{
size_t shift[256];
bool init = false;
return (char *) txtfind(string, strlen(string), pattern, strlen(pattern), shift, &init);
}
/* 字符串多次大小写不敏感匹配函数*/
char *bm_strcasestr_rp(const char *string, const char *pattern, size_t * shift, bool * init)
{
return (char *) txtfind(string, strlen(string), pattern, strlen(pattern), shift, init);
}
/* 内存匹配函数memfind
*/
void *memfind(const void *in_block, /* 数据块 */
const size_t block_size, /* 数据块长度 */
const void *in_pattern, /* 需要查找的数据 */
const size_t pattern_size, /* 查找数据的长度 */
size_t * shift, /* 移位表,应该是256*size_t的数组 */
bool * init)
{ /* 是否需要初始化移位表 */
size_t byte_nbr, /* Distance through block */
match_size, /* Size of matched part */
limit;
const unsigned char *match_ptr = NULL;
const unsigned char *block = (unsigned char *) in_block, /* Concrete pointer to block data */
*pattern = (unsigned char *) in_pattern; /* Concrete pointer to search value */
if (block == NULL || pattern == NULL || shift == NULL)
return (NULL);
/* 查找的串长应该小于 数据长度*/
if (block_size < pattern_size)
return (NULL);
if (pattern_size == 0) /* 空串匹配第一个 */
return ((void *) block);
/* 如果没有初始化,构造移位表*/
if (!init || !*init) {
for (byte_nbr = 0; byte_nbr < 256; byte_nbr++)
shift[byte_nbr] = pattern_size + 1;
for (byte_nbr = 0; byte_nbr < pattern_size; byte_nbr++)
shift[(unsigned char) pattern[byte_nbr]] = pattern_size - byte_nbr;
if (init)
*init = true;
}
/*开始搜索数据块,每次前进移位表中的数量*/
limit = block_size - pattern_size + 1;
for (byte_nbr = 0; byte_nbr < limit; byte_nbr += shift[block[byte_nbr + pattern_size]]) {
if (block[byte_nbr] == *pattern) {
/*
* 如果第一个字节匹配,那么继续匹配剩下的
*/
match_ptr = block + byte_nbr + 1;
match_size = 1;
do {
if (match_size == pattern_size)
return (void *) (block + byte_nbr);
} while (*match_ptr++ == pattern[match_size++]);
}
}
return NULL;
}
/* 大小写不敏感的匹配函数txtfind
*/
void *txtfind(const void *in_block, /* 数据块 */
const size_t block_size, /* 数据块长度 */
const void *in_pattern, /* 需要查找的数据 */
const size_t pattern_size, /* 查找数据的长度 */
size_t * shift, /* 移位表,应该是256*size_t的数组 */
bool * init)
{ /* 是否需要初始化移位表 */
size_t byte_nbr, /* Distance through block */
match_size, /* Size of matched part */
limit;
const unsigned char *match_ptr = NULL;
const unsigned char *block = (unsigned char *) in_block, /* Concrete pointer to block data */
*pattern = (unsigned char *) in_pattern; /* Concrete pointer to search value */
if (block == NULL || pattern == NULL || shift == NULL)
return (NULL);
/* 查找的串长应该小于 数据长度*/
if (block_size < pattern_size)
return (NULL);
if (pattern_size == 0) /* 空串匹配第一个 */
return ((void *) block);
/* 如果没有初始化,构造移位表*/
if (!init || !*init) {
for (byte_nbr = 0; byte_nbr < 256; byte_nbr++)
shift[byte_nbr] = pattern_size + 1;
for (byte_nbr = 0; byte_nbr < pattern_size; byte_nbr++)
shift[(unsigned char) tolower(pattern[byte_nbr])] = pattern_size - byte_nbr;
if (init)
*init = true;
}
/*开始搜索数据块,每次前进移位表中的数量*/
limit = block_size - pattern_size + 1;
for (byte_nbr = 0; byte_nbr < limit; byte_nbr += shift[tolower(block[byte_nbr + pattern_size])]) {
if (tolower(block[byte_nbr]) == tolower(*pattern)) {
/*
* 如果第一个字节匹配,那么继续匹配剩下的
*/
match_ptr = block + byte_nbr + 1;
match_size = 1;
do {
if (match_size == pattern_size)
return (void *) (block + byte_nbr);
} while (tolower(*match_ptr++) == tolower(pattern[match_size++]));
}
}
return NULL;
}