/*
mymemcnt
Return the number of distinct times PAT is found in MEM.
meaning mem=1111 and pat==11 returns 2.
mem=11111 and pat==11 also return 2.
*/
static Py_ssize_t
mymemcnt(const char *mem, Py_ssize_t len, const char *pat, Py_ssize_t pat_len)
{
register Py_ssize_t offset = 0;
Py_ssize_t nfound = 0;
while (len >= 0) {
offset = mymemfind(mem, len, pat, pat_len);
if (offset == -1)
break;
mem += offset + pat_len;
len -= offset + pat_len;
nfound++;
}
return nfound;
}
int
mymemcnt(const char *mem, int len, const char *pat, int pat_len)
{
register int offset = 0;
int nfound = 0;
while (len >= 0) {
offset = mymemfind(mem, len, pat, pat_len);
if (offset == -1)
break;
mem += offset + pat_len;
len -= offset + pat_len;
nfound++;
}
return nfound;
}
/*
mymemreplace
Return a string in which all occurrences of PAT in memory STR are
replaced with SUB.
If length of PAT is less than length of STR or there are no occurrences
of PAT in STR, then the original string is returned. Otherwise, a new
string is allocated here and returned.
on return, out_len is:
the length of output string, or
-1 if the input string is returned, or
unchanged if an error occurs (no memory).
return value is:
the new string allocated locally, or
NULL if an error occurred.
*/
static char *
mymemreplace(const char *str, Py_ssize_t len, /* input string */
const char *pat, Py_ssize_t pat_len, /* pattern string to find */
const char *sub, Py_ssize_t sub_len, /* substitution string */
Py_ssize_t count, /* number of replacements */
Py_ssize_t *out_len)
{
char *out_s;
char *new_s;
Py_ssize_t nfound, offset, new_len;
if (len == 0 || pat_len > len)
goto return_same;
/* find length of output string */
nfound = mymemcnt(str, len, pat, pat_len);
if (count < 0)
count = PY_SSIZE_T_MAX;
else if (nfound > count)
nfound = count;
if (nfound == 0)
goto return_same;
new_len = len + nfound*(sub_len - pat_len);
if (new_len == 0) {
/* Have to allocate something for the caller to free(). */
out_s = (char *)PyMem_MALLOC(1);
if (out_s == NULL)
return NULL;
out_s[0] = '\0';
}
else {
assert(new_len > 0);
new_s = (char *)PyMem_MALLOC(new_len);
if (new_s == NULL)
return NULL;
out_s = new_s;
for (; count > 0 && len > 0; --count) {
/* find index of next instance of pattern */
offset = mymemfind(str, len, pat, pat_len);
if (offset == -1)
break;
/* copy non matching part of input string */
memcpy(new_s, str, offset);
str += offset + pat_len;
len -= offset + pat_len;
/* copy substitute into the output string */
new_s += offset;
memcpy(new_s, sub, sub_len);
new_s += sub_len;
}
/* copy any remaining values into output string */
if (len > 0)
memcpy(new_s, str, len);
}
*out_len = new_len;
return out_s;
return_same:
*out_len = -1;
return (char *)str; /* cast away const */
}
