Return the position of matching characters
<boost/url/grammar/string_view_base.hpp>
constexpr
size_type
rfind(
    core::string_view str,
    size_type pos = core::string_view::npos) const noexcept;
See core::string_view::rfind
| Name | Description | 
|---|---|
| str | The characters to search for | 
| pos | The position to start searching from |