[numex] Concatenating a string of numeric expressions with no intervening tokens like Seventeen Eighty or Ten Oh Four

src/numex.c

@@ -984,8 +984,8 @@ char *replace_numeric_expressions(char *str, char *lang) {
     size_t len = strlen(str);
 
     char_array *replacement = char_array_new_size(len);
-    int start = 0;
-    int end = 0;
+    size_t start = 0;
+    size_t end = 0;
 
     for (int i = 0; i < results->n; i++) {
         numex_result_t result = results->a[i];
@@ -1001,7 +1001,10 @@ char *replace_numeric_expressions(char *str, char *lang) {
         char numeric_string[INT64_MAX_STRING_SIZE] = {0};
         sprintf(numeric_string, "%" PRId64, result.value);
 
-        char_array_append_len(replacement, str + start, end - start);
+        if (!string_is_ignorable(str + start, end - start)) {
+            char_array_append_len(replacement, str + start, end - start);
+        }
+        
         char_array_append(replacement, numeric_string);
 
         if (result.is_ordinal) {

src/string_utils.c

@@ -361,6 +361,31 @@ inline size_t utf8_common_prefix_ignore_separators(const char *str1, const char
     return utf8_common_prefix_len_ignore_separators(str1, str2, strlen(str2));
 }
 
+bool string_is_ignorable(char *str, size_t len) {
+    uint8_t *ptr = (uint8_t *)str;
+    size_t idx = 0;
+
+    bool ignorable = true;
+
+    while (idx < len) {
+        int32_t ch;
+        ssize_t char_len = utf8proc_iterate(ptr, len, &ch);
+
+        if (char_len <= 0) break;
+        if (ch == 0) break;
+        if (!(utf8proc_codepoint_valid(ch))) return false;
+
+        int cat = utf8proc_category(ch);
+        if (!utf8_is_separator(cat) && !utf8_is_hyphen(ch)) {
+            return false;
+        }
+
+        ptr += char_len;
+        idx += char_len;
+    }
+
+    return true;
+}
 
 bool string_contains_hyphen_len(char *str, size_t len) {
     uint8_t *ptr = (uint8_t *)str;

src/string_utils.h

@@ -84,6 +84,8 @@ bool utf8_is_punctuation(int cat);
 bool utf8_is_symbol(int cat);
 bool utf8_is_separator(int cat);
 
+bool string_is_ignorable(char *str, size_t len);
+
 bool string_contains_hyphen(char *str);
 bool string_contains_hyphen_len(char *str, size_t len);