Type Alias MappedLocalTime

The result of mapping a local time to a concrete instant in a given time zone.

The calculation to go from a local time (wall clock time) to an instant in UTC can end up in three cases:

• A single, simple result.
• An ambiguous result when the clock is turned backwards during a transition due to for example DST.
• No result when the clock is turned forwards during a transition due to for example DST.

When the clock is turned backwards it creates a fold in local time, during which the local time is ambiguous. When the clock is turned forwards it creates a gap in local time, during which the local time is missing, or does not exist.

Chrono does not return a default choice or invalid data during time zone transitions, but has the MappedLocalTime type to help deal with the result correctly.

The type of T is usually a DateTime but may also be only an offset.