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stdstring: Get rid of some strlen calls

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Now the function doesn't traverse strings more than necessary.
This commit is contained in:
Lioncash 2015-04-03 14:52:29 -04:00
parent 4f2547976c
commit 1f1cdae621
1 changed files with 14 additions and 9 deletions
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23
libretro-common/string/stdstring.c
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@ -27,21 +27,26 @@ char *string_replace_substring(const char *in, const char *pattern, const char *
char *needle = NULL; char *needle = NULL;
char *newstr = NULL; char *newstr = NULL;
char *head = NULL; char *head = NULL;
size_t pattern_len = 0;
size_t replacement_len = 0;
/* if either pattern or replacement is NULL, /* if either pattern or replacement is NULL,
* duplicate in and let caller handle it. */ * duplicate in and let caller handle it. */
if (!pattern || !replacement) if (!pattern || !replacement)
return strdup(in); return strdup(in);
pattern_len = strlen(pattern);
replacement_len = strlen(replacement);
newstr = strdup(in); newstr = strdup(in);
head = newstr; head = newstr;
while ((needle = strstr (head, pattern))) while ((needle = strstr(head, pattern)))
{ {
char* oldstr = newstr; char* oldstr = newstr;
newstr = (char*)malloc( size_t oldstr_len = strlen(oldstr);
strlen(oldstr) - strlen(pattern) + strlen(replacement) + 1);
newstr = (char*)malloc(oldstr_len - pattern_len + replacement_len + 1);
if (!newstr) if (!newstr)
{ {
/* Failed to allocate memory, /* Failed to allocate memory,
@ -51,14 +56,14 @@ char *string_replace_substring(const char *in, const char *pattern, const char *
} }
memcpy(newstr, oldstr, needle - oldstr); memcpy(newstr, oldstr, needle - oldstr);
memcpy(newstr + (needle - oldstr), replacement, strlen(replacement)); memcpy(newstr + (needle - oldstr), replacement, replacement_len);
memcpy(newstr + (needle - oldstr) + strlen(replacement), memcpy(newstr + (needle - oldstr) + replacement_len,
needle + strlen(pattern), needle + pattern_len,
strlen(oldstr) - strlen(pattern) - (needle - oldstr)); oldstr_len - pattern_len - (needle - oldstr));
newstr[strlen(oldstr) - strlen(pattern) + strlen(replacement)] = '\0'; newstr[oldstr_len - pattern_len + replacement_len] = '\0';
/* Move back head right after the last replacement. */ /* Move back head right after the last replacement. */
head = newstr + (needle - oldstr) + strlen(replacement); head = newstr + (needle - oldstr) + replacement_len;
free(oldstr); free(oldstr);
} }