Else parser

[sebastienros]

Create an Else parser that is invoked when the previous one is not matched. Identical to Then but with the opposite trigger.

Can be used to return an object as a fallback (or default value).

Example:

var p = a.Or(b).Else(() => new DefaultValue()); // if neither a or b were parsed

Note this might be doable with ZeroOrOne and then check if the results is set

[sebastienros]

ZeroOrOne(a.Or(b)).Then(x => x ?? new DefaultValue());