parse-timestamp

Parse a string containing an RFC3339-like like timestamp.

The function new-instant is called with the following arguments.

                min  max           default
                ---  ------------  -------
  years          0           9999      N/A (s must provide years)
  months         1             12        1
  days           1             31        1 (actual max days depends
  hours          0             23        0  on month and year)
  minutes        0             59        0
  seconds        0             60        0 (though 60 is only valid
  nanoseconds    0      999999999        0  when minutes is 59)
  offset-sign   -1              1        0
  offset-hours   0             23        0
  offset-minutes 0             59        0

These are all integers and will be non-nil. (The listed defaults
will be passed if the corresponding field is not present in s.)

Grammar (of s):

  date-fullyear   = 4DIGIT
  date-month      = 2DIGIT  ; 01-12
  date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on
                            ; month/year
  time-hour       = 2DIGIT  ; 00-23
  time-minute     = 2DIGIT  ; 00-59
  time-second     = 2DIGIT  ; 00-58, 00-59, 00-60 based on leap second
                            ; rules
  time-secfrac    = '.' 1*DIGIT
  time-numoffset  = ('+' / '-') time-hour ':' time-minute
  time-offset     = 'Z' / time-numoffset

  time-part       = time-hour [ ':' time-minute [ ':' time-second
                    [time-secfrac] [time-offset] ] ]

  timestamp       = date-year [ '-' date-month [ '-' date-mday
                    [ 'T' time-part ] ] ]

Unlike RFC3339:

  - we only parse the timestamp format
  - timestamp can elide trailing components
  - time-offset is optional (defaults to +00:00)

Though time-offset is syntactically optional, a missing time-offset
will be treated as if the time-offset zero (+00:00) had been
specified.

read-instant-calendar

To read an instant as a java.util.Calendar, bind *data-readers* to a map with
this var as the value for the 'inst key.  Calendar preserves the timezone
offset.

read-instant-date

To read an instant as a java.util.Date, bind *data-readers* to a map with
this var as the value for the 'inst key. The timezone offset will be used
to convert into UTC.

read-instant-timestamp

To read an instant as a java.sql.Timestamp, bind *data-readers* to a
map with this var as the value for the 'inst key. Timestamp preserves
fractional seconds with nanosecond precision. The timezone offset will
be used to convert into UTC.

validated

Usage: (validated new-instance)

Return a function which constructs and instant by calling constructor
after first validting that those arguments are in range and otherwise
plausible. The resulting function will throw an exception if called
with invalid arguments.