use regex::{Captures, Regex};
pub fn replace_all_fallible<E>(
re: &Regex,
haystack: &str,
replacement: impl Fn(&Captures) -> Result<String, E>,
) -> Result<String, E> {
let mut new = String::with_capacity(haystack.len());
let mut last_match = 0;
for caps in re.captures_iter(haystack) {
let m = caps.get(0).unwrap();
new.push_str(&haystack[last_match..m.start()]);
new.push_str(&replacement(&caps)?);
last_match = m.end();
}
new.push_str(&haystack[last_match..]);
Ok(new)
}