Function der_parser::der::parse_der_explicit_optional

pub fn parse_der_explicit_optional<F>(
    i: &[u8], 
    tag: DerTag, 
    f: F
) -> DerResult<'_> where
    F: Fn(&[u8]) -> DerResult<'_>, 

Parse an optional tagged object, applying function to get content

This function returns a DerObject, trying to read content as generic DER objects. If parsing failed, return an optional object containing None.

To support other return or error types, use parse_der_tagged_explicit_g

This function will never fail: if parsing content failed, the BER value Optional(None) is returned.