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// UTF-32 string
typedef struct {
size_t len;
char32_t *str;
} String32;
void str32_free(String32 *s) {
free(s->str);
s->str = NULL;
s->len = 0;
}
// the string returned should be str32_free'd.
// this will return an empty string if the allocation failed or the string is invalid UTF-8
String32 str32_from_utf8(char const *utf8) {
String32 string = {0, NULL};
size_t len = strlen(utf8);
if (len) {
// the wide string uses at most as many "characters" (elements?) as the UTF-8 string
char32_t *widestr = calloc(len, sizeof *widestr);
if (widestr) {
char32_t *wide_p = widestr;
char const *utf8_p = utf8;
char const *utf8_end = utf8_p + len;
mbstate_t mbstate = {0};
while (utf8_p < utf8_end) {
char32_t c = 0;
size_t n = mbrtoc32(&c, utf8_p, (size_t)(utf8_end - utf8_p), &mbstate);
if (n == 0// null character. this shouldn't happen.
|| n == (size_t)(-2) // incomplete character
|| n == (size_t)(-1) // invalid UTF-8
) {
free(widestr);
widestr = wide_p = NULL;
break;
} else if (n == (size_t)(-3)) { // no bytes consumed, but a character was produced
*wide_p++ = c;
} else {
// n bytes consumed
*wide_p++ = c;
utf8_p += n;
}
}
string.str = widestr;
string.len = (size_t)(wide_p - widestr);
}
}
return string;
}
// returns a null-terminated UTF-8 string
// the string returned should be free'd
// this will return NULL on failure
static char *str32_to_utf8_cstr(String32 s) {
char *utf8 = calloc(4 * s.len + 1, 1); // each codepoint takes up at most 4 bytes in UTF-8, + we need a terminating null byte
if (utf8) {
char *p = utf8;
mbstate_t mbstate; memset(&mbstate, 0, sizeof mbstate);
for (size_t i = 0; i < s.len; ++i) {
size_t bytes = c32rtomb(p, s.str[i], &mbstate);
if (bytes == (size_t)-1) {
// invalid UTF-32 character
free(utf8);
return NULL;
} else {
p += bytes;
}
}
*p = '\0';
}
return utf8;
}
// returns the index of the given character in the string, or the length of the string if it's not found.
size_t str32chr(String32 s, char32_t c) {
for (size_t i = 0; i < s.len; ++i) {
if (s.str[i] == c)
return i;
}
return s.len;
}
// returns number of instances of c in s
size_t str32_count_char(String32 s, char32_t c) {
size_t total = 0;
for (size_t i = 0; i < s.len; ++i) {
total += s.str[i] == c;
}
return total;
}
// returns number of characters deleted from s
size_t str32_remove_all_instances_of_char(String32 *s, char32_t c) {
bool increment = true;
char32_t *str = s->str;
size_t ndeleted = 0;
for (size_t i = 0; i < s->len; i += increment, increment = true) {
if (str[i] == c) {
--s->len;
if (i < s->len) {
str[i] = str[i+1];
}
++ndeleted;
increment = false;
}
}
return ndeleted;
}
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