DATE
[
VLIB_DATE:z {<day_of_week $z.day_of_week>  <month $z.month> <day $z.day> <year $z.year> <modifier $z.modifier>}
]






VLIB_DATE [

  ; Special words and phrases
  VSUB_RELATIVE_DATE:r {return([<modifier $r>])}

  ; Sunday through Saturday
  ( ?( [ this the ] ?coming ) VSUB_DAY_OF_WEEK:d ) {return([<day_of_week $d>])}
  ( VSUB_LAST_THIS_NEXT_WEEK_FROM:t VSUB_DAY_OF_WEEK:d 
  ) {return([<day_of_week $d> <modifier $t>])}

  ; Days this month
  ( ?the VSUB_DAY_OF_MONTH_ORDINAL:d ?( ?day of [ the this ] month ) 
  ) {return([<day $d>])}
  ( VSUB_DAY_OF_WEEK:d the VSUB_DAY_OF_MONTH_ORDINAL:n 
  ) {return([<day_of_week $d> <day $n>])}
  ( VSUB_RELATIVE_DATE_SHORT:m the VSUB_DAY_OF_MONTH_ORDINAL:n
  ) {return([<modifier $m> <day $n>])}
  ( ?the VSUB_BEGINNING_END:m of [ the this ] month ) {return([<modifier $m>])}

  ; Days of an unnamed but specific month
  ( ?the VSUB_DAY_OF_MONTH_ORDINAL:d ?day ?of VSUB_LAST_THIS_NEXT:t month
  ) {return([<day $d> <modifier $t>])}

  ( ?the last ?day of VSUB_MONTH:m ) {return([<modifier "last"> <month $m>])}
  
  ; Month and day
  VSUB_DAY_AND_MONTH:v {return($v)}

  ; Month and day with relative day
  ( VSUB_RELATIVE_DATE_SHORT:m VSUB_DAY_AND_MONTH:v 
  ) {return([<modifier $m> <month $v.month> <day $v.day>])}

    ; Month and day with weekday
  ( VSUB_DAY_OF_WEEK:d VSUB_DAY_AND_MONTH:v 
  ) {return([<day_of_week $d> <month $v.month> <day $v.day>])}

  ; Month, day and year
  ( VSUB_DAY_AND_MONTH:v ?of VSUB_YEAR:y 
  ) {return([<month $v.month> <day $v.day> <year $y>])}

  ; Month, day, and year with weekday
  ( VSUB_DAY_OF_WEEK:d VSUB_DAY_AND_MONTH:v ?of VSUB_YEAR:y 
  ) {return([<day_of_week $d> <month $v.month> <day $v.day> <year $y>])}
]

VSUB_RELATIVE_DATE [
  VSUB_RELATIVE_DATE_SHORT:d {return($d)}
  ( ?the day after tomorrow ) {return("day_after_tomorrow")}
  ( ?the day before yesterday ) {return("day_before_yesterday")}
]

VSUB_RELATIVE_DATE_SHORT [
  today {return("today")}
  tomorrow {return("tomorrow")}
  yesterday {return("yesterday")}
]

VSUB_DAY_OF_WEEK [
  sunday {return("sunday")}
  monday {return("monday")}
  tuesday {return("tuesday")}
  wednesday {return("wednesday")}
  thursday {return("thursday")}
  friday {return("friday")}
  saturday {return("saturday")}
] 

VSUB_DAY_AND_MONTH [

  ; Month plus day
  ( VSUB_MONTH:m 
    [ ( ?the VSUB_DAY_OF_MONTH_ORDINAL:d ) ; "january the fifteenth"
      VSUB_DAY_OF_MONTH_CARDINAL:d ; "january fifteen"
    ]
  ) {return([<month $m> <day $d>])}
  
  ; Day plus month
  ( ?the VSUB_DAY_OF_MONTH_ORDINAL:d 
    of VSUB_MONTH:m
  ) {return([<month $m> <day $d>])}
]

VSUB_MONTH [
  january {return("january")}
  february {return("february")}
  march {return("march")}
  april {return("april")}
  may {return("may")}
  june {return("june")}
  july {return("july")}
  august {return("august")}
  september {return("september")}
  october {return("october")}
  november {return("november")}
  december {return("december")}
]

VSUB_DAY_OF_MONTH_CARDINAL [
  VSUB_DIGIT_ONE_THRU_NINE:n {return($n)}
  ten {return(10)}
  VSUB_TEEN:n {return($n)}
  twenty {return(20)}
  ( twenty VSUB_DIGIT_ONE_THRU_NINE:n ) {return(add(20 $n))}
  thirty {return(30)}
  ( thirty one ) {return(31)}
]

VSUB_DAY_OF_MONTH_ORDINAL [
  VSUB_FIRST_THRU_NINTH_DATE:n {return($n)}
  tenth {return(10)}
  eleventh {return(11)}
  twelfth {return(12)}
  thirteenth {return(13)}
  fourteenth {return(14)}
  fifteenth {return(15)}
  sixteenth {return(16)}
  seventeenth {return(17)}
  eighteenth {return(18)}
  nineteenth {return(19)}
  twentieth {return(20)}
  ( twenty VSUB_FIRST_THRU_NINTH_DATE:n ) {return(add(20 $n))}
  thirtieth {return(30)}
  ( thirty first ) {return(31)}
]

VSUB_FIRST_THRU_NINTH_DATE [
  first {return(1)}
  second {return(2)}
  third {return(3)}
  fourth {return(4)}
  fifth {return(5)}
  sixth {return(6)}
  seventh {return(7)}
  eighth {return(8)}
  ninth {return(9)}
]

VSUB_YEAR [

  ; 1900
  ( nineteen hundred ) {return(1900)}

  ; 1901-1909
  ( nineteen [ ( hundred ?and ) oh ] VSUB_DIGIT_ONE_THRU_NINE:n ) {return(add(1900 $n))}

  ; 1910
  ( nineteen ?( hundred ?and ) ten ) {return(1910)}

  ; 1911-1919
  ( nineteen ?( hundred ?and ) VSUB_TEEN:t ) {return(add(1900 $t))}

  ; 1920-1990, even 10's only
  ( nineteen ?( hundred ?and ) VSUB_DECADE:t ) {return(add(1900 $t))}

  ; 1921-1999, except even 10's
  ( nineteen ?( hundred ?and ) VSUB_DECADE:t VSUB_DIGIT_ONE_THRU_NINE:u
  ) {return(add(1900 add($t $u)))}

  ; 2000
  ( ?( the year ) two thousand ) {return(2000)}

  ; 2001-2009
  ( [ ( twenty oh ) ( two thousand ?and ) ] VSUB_DIGIT_ONE_THRU_NINE:n 
  ) {return(add(2000 $n))}

  ; 2010
  ( [ twenty ( two thousand ?and ) ] ten ) {return(2010)}

  ; 2011-2019
  ( [ twenty ( two thousand ?and ) ] VSUB_TEEN:t ) {return(add(2000 $t))}

  ; 2020-2090, even 10's only
  ( [ twenty ( two thousand ?and ) ] VSUB_DECADE:t ) {return(add(2000 $t))}

  ; 2021-2099, except even 10's
  ( [ twenty ( two thousand ?and ) ] VSUB_DECADE:t VSUB_DIGIT_ONE_THRU_NINE:u
  ) {return(add(2000 add($t $u)))}

  ; 00
  ( double zero ) {return(2000)}

  ; 01-09
  ( [ oh zero ] VSUB_DIGIT:n ) {return(add(2000 $n))}

  ; 10
  ten {return(2010)}

  ; 11-19
  VSUB_TEEN:n {return(add(2000 $n))}

  ; 20 and 30
  VSUB_DATE_DECADE_TWENTY_THRU_THIRTY:n {return(add(2000 $n))}

  ; 21-39, except even 10's
  ( VSUB_DATE_DECADE_TWENTY_THRU_THIRTY:t VSUB_DIGIT_ONE_THRU_NINE:u 
  ) {return(add(2000 add($t $u)))}

  ; 40-90, even 10's only
  VSUB_DATE_DECADE_FORTY_THRU_NINETY:n {return(add(1900 $n))}

  ; 41-99, except even 10's
  ( VSUB_DATE_DECADE_FORTY_THRU_NINETY:t VSUB_DIGIT_ONE_THRU_NINE:u 
  ) {return(add(1900 add($t $u)))}
]

VSUB_DATE_DECADE_TWENTY_THRU_THIRTY [
  twenty {return(20)}
  thirty {return(30)}
]

VSUB_DATE_DECADE_FORTY_THRU_NINETY [
  forty {return(40)}
  fifty {return(50)}
  sixty {return(60)}
  seventy {return(70)}
  eighty {return(80)}
  ninety {return(90)}
]

VSUB_LAST_THIS_NEXT_WEEK_FROM [
  VSUB_LAST_THIS_NEXT:r {return($r)}
  ( [ one a ] week from ) {return("a_week_from")}
]

VSUB_LAST_THIS_NEXT [
  last {return("last")}
  this
  next {return("next")}
]

VSUB_BEGINNING_END [
  beginning {return("beginning_of_month")}
  [ end ( last ?day ) ] {return("end_of_month")}
]


VSUB_DIGIT_TWO_THRU_NINE [
  two {return(2)}
  three {return(3)}
  four {return(4)}
  five {return(5)}
  six {return(6)}
  seven {return(7)}
  eight {return(8)}
  nine {return(9)}
]

VSUB_DIGIT_ONE_THRU_NINE [
  one {return(1)}
  VSUB_DIGIT_TWO_THRU_NINE:n {return($n)}
]

VSUB_DIGIT [
  [ zero oh ] {return(0)}
  VSUB_DIGIT_ONE_THRU_NINE:n {return($n)}
]

; Single-digit grammars that return string values

VSUB_DIGIT_TWO_THRU_NINE_STRING [
  two {return("2")}
  three {return("3")}
  four {return("4")}
  five {return("5")}
  six {return("6")}
  seven {return("7")}
  eight {return("8")}
  nine {return("9")}
]

VSUB_DIGIT_ONE_THRU_NINE_STRING [
  one {return("1")}
  VSUB_DIGIT_TWO_THRU_NINE_STRING:n {return($n)}
]

VSUB_DIGIT_STRING [
  [ zero oh ] {return("0")}
  VSUB_DIGIT_ONE_THRU_NINE_STRING:n {return($n)}
]

VSUB_TEEN_STRING [
  eleven {return("11")}
  twelve {return("12")}
  thirteen {return("13")}
  fourteen {return("14")}
  fifteen {return("15")}
  sixteen {return("16")}
  seventeen {return("17")}
  eighteen {return("18")}
  nineteen {return("19")}
]

VSUB_DECADE_STRING [
  twenty {return("2")}
  thirty {return("3")}
  forty {return("4")}
  fifty {return("5")}
  sixty {return("6")}
  seventy {return("7")}
  eighty {return("8")}
  ninety {return("9")}
]

VSUB_TEEN [
  eleven {return(11)}
  twelve {return(12)}
  thirteen {return(13)}
  fourteen {return(14)}
  fifteen {return(15)}
  sixteen {return(16)}
  seventeen {return(17)}
  eighteen {return(18)}
  nineteen {return(19)}
]

VSUB_DECADE [
  twenty {return(20)}
  thirty {return(30)}
  forty {return(40)}
  fifty {return(50)}
  sixty {return(60)}
  seventy {return(70)}
  eighty {return(80)}
  ninety {return(90)}
]