fn parse_iso_or_friendly(bytes: &[u8]) -> Result<SignedDuration, Error>Expand description
A common parsing function that works in bytes.
Specifically, this parses either an ISO 8601 duration into a
SignedDuration or a “friendly” duration into a SignedDuration. It also
tries to give decent error messages.
This works because the friendly and ISO 8601 formats have non-overlapping
prefixes. Both can start with a + or -, but aside from that, an ISO
8601 duration always has to start with a P or p. We can utilize this
property to very quickly determine how to parse the input. We just need to
handle the possibly ambiguous case with a leading sign a little carefully
in order to ensure good error messages.
(We do the same thing for Span.)