[Gedcom-parse-devel] DATE is not LR (I think)

[prapp <pr...@er...>]

I think that GEDCOM dates are not LR for two reasons:

  1) date_phrase matches, for example, "1 SEP 1993 or 1994"
       but you don't know that is a date_phrase til you get past the 1993
       (and find out it is not a valid date)

  2) "25" looks like the start of a day month year, but is actually
     just a year


If I am correct, it will be more difficult to parse dates with
a bison grammar, yes ?


In fact, I decided to do a custom date parse, because I don't know enough
  to handle the phrase backtracking.
(Also because I'm revising an existing date parser in LifeLines which is
custom, and is a freeform, non-LR parser).

(I think I'll use some context-sensitivity in calendars eventually -- if I
add support for the Islam calendar eventually, I can recognize it by the 
month name,
and then can expect AH or BH as an optional trailer instead of AD or BC).

I'm not planning to worry about a BC-equivalent for the Hebrew or Roman
calendars :)
(both go back pretty far, and probably have no standard trailer for such)