-- file: TimeExtras.mesa, last edit:
  -- Bruce, March 16, 1979  6:10 PM
  -- HGM, July 31, 1980  2:43 AM

-- Copyright  Xerox Corporation 1979, 1980

DIRECTORY
  String USING [
    InvalidNumber, StringBoundsFault,
    StringToNumber, AppendChar, EquivalentSubString, UpperCase, SubStringDescriptor],
  Time USING [Pack, Unpacked, Invalid],
  TimeExtraDefs;

TimeExtras: PROGRAM 
  IMPORTS String, Time
  EXPORTS TimeExtraDefs =
BEGIN

Empty: PROCEDURE [s: STRING] RETURNS [BOOLEAN] =
  BEGIN RETURN [s = NIL OR s.length = 0] END;

EquivalentChar: PUBLIC PROCEDURE [c1, c2: CHARACTER] RETURNS [BOOLEAN] =
  BEGIN RETURN [String.UpperCase[c1]=String.UpperCase[c2]] END;

GetToken: PROCEDURE [storage: STRING, s: STRING, c: CARDINAL]
    RETURNS [is: CARDINAL] =
  BEGIN
  ch: CHARACTER;
  FOR is _ c, is+1 UNTIL is >= s.length DO
    SELECT String.UpperCase[ch _ s[is]] FROM
      IN ['A..'Z], IN ['0..'9] =>
          String.AppendChar[storage, ch];
      ':, '- => EXIT;  -- terminator
      '  => IF ~Empty[storage] THEN EXIT;  --terminating blank
      ENDCASE;
    ENDLOOP;
    RETURN[is + 1];
  END;

PackedTimeFromString: PUBLIC PROCEDURE [s: STRING]
  RETURNS [t: LONG CARDINAL] =
  BEGIN
  --  string format must be: bDD-MMM-YYbbHH:MM:SSbbZZTb
  t _ DoIt[s !String.InvalidNumber, String.StringBoundsFault, Time.Invalid =>
    BEGIN t _ 0; CONTINUE END]
  END;

DoIt: PROCEDURE [s: STRING]
  RETURNS [t: LONG CARDINAL] =
  BEGIN

  Get: PROCEDURE = BEGIN s1.length _ 0; nextChar _ GetToken[s1, s, nextChar] END;

  GetNumber: PROCEDURE RETURNS [CARDINAL] = 
    BEGIN
    Get[];
    RETURN[String.StringToNumber[s1, 10]];
    END;

  m: String.SubStringDescriptor _ [
    base: "JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC"L, offset: NULL, length: 3];
  s1: STRING _ [3];
  month: String.SubStringDescriptor _ [base: s1, offset: 0, length: NULL];
  time: Time.Unpacked _ [0,0,0,0,0,0,0,8,FALSE];
  nextChar: CARDINAL _ 0;
  i: CARDINAL;
  packIt: BOOLEAN _ TRUE;

  IF Empty[s] THEN RETURN[0];
  time.day _ GetNumber[];
  Get[];
  month.length _ s1.length;
  FOR i IN [0..12) DO
    m.offset _ i*3;
    IF String.EquivalentSubString[@month, @m] THEN
      BEGIN time.month _ i; EXIT END;
    ENDLOOP;
  time.year _ GetNumber[]; time.year _ time.year + 1900;
  time.hour _ GetNumber[];
  time.minute _ GetNumber[];
  time.second _ GetNumber[];
  Get[];
  IF s1.length # 0 THEN
    BEGIN
    zones: PACKED ARRAY [5..8] OF CHARACTER = ['E,'C,'M,'P];
    FOR i IN [5..8] DO
      IF EquivalentChar[s1[0], zones[i]] THEN
        BEGIN time.zone _ i; EXIT END;
      REPEAT FINISHED => time.zone _ 0;  -- GMT
      ENDLOOP;
    time.dst _ EquivalentChar[s1[1],'D];
    packIt _ FALSE;
    END;
  t _ Time.Pack[time, packIt]
  END;

END.(1792)