[utils] adding utf8_len function for strings, and utf8_is_digit

src/string_utils.c

@@ -293,6 +293,10 @@ inline bool utf8_is_letter(int cat) {
             || cat == UTF8PROC_CATEGORY_LM;
 }
 
+inline bool utf8_is_digit(int cat) {
+    return cat == UTF8PROC_CATEGORY_ND;
+}
+
 inline bool utf8_is_number(int cat) {
     return cat == UTF8PROC_CATEGORY_ND || cat == UTF8PROC_CATEGORY_NL || cat == UTF8PROC_CATEGORY_NO;
 }
@@ -336,6 +340,34 @@ inline bool utf8_is_whitespace(int32_t ch) {
            ;
 }
 
+
+ssize_t utf8_len(const char *str, size_t len) {
+    if (str == NULL) return -1;
+    if (len == 0) return 0;
+
+    int32_t ch = 0;
+    ssize_t num_utf8_chars = 0;
+    ssize_t char_len;
+
+    uint8_t *ptr = (uint8_t *)str;
+
+    size_t remaining = len;
+
+    while (1) {
+        char_len = utf8proc_iterate(ptr, -1, &ch);
+
+        if (ch == 0) break;
+        remaining -= char_len;
+        if (remaining == 0) break;
+
+        ptr += char_len;
+        num_utf8_chars += char_len;
+    }
+
+    return num_utf8_chars;
+}
+
+
 int utf8_compare_len(const char *str1, const char *str2, size_t len) {
     if (len == 0) return 0;
 

src/string_utils.h

@@ -83,6 +83,8 @@ size_t utf8_common_prefix_len(const char *str1, const char *str2, size_t len);
 size_t utf8_common_prefix_ignore_separators(const char *str1, const char *str2);
 size_t utf8_common_prefix_len_ignore_separators(const char *str1, const char *str2, size_t len);
 
+ssize_t utf8_len(const char *str, size_t len);
+
 bool utf8_is_hyphen(int32_t ch);
 bool utf8_is_letter(int cat);
 bool utf8_is_number(int cat);