Function ruma::http_headers::quote_ascii_string_if_required

pub fn quote_ascii_string_if_required(value: &str) -> Cow<'_, str>

If the US-ASCII field value does not contain only token chars, convert it to a quoted string.

The string should be sanitized with sanitize_for_ascii_quoted_string() or should only contain characters that pass is_ascii_string_quotable().