millenniumbug.js

%{
    Date.prototype.get_floor = function() {
        return this.low_resolution
          ? new Date(this.getYear() + 1900, this.getMonth(), this.getDate())
          : this;
    }
    Date.prototype.get_ceiling = function() {
        return this.low_resolution
          ? new Date(this.getYear() + 1900, this.getMonth(), this.getDate(), 23, 59, 59, 999)
          : this;
    }
    Date.prototype.set_low_resolution = function(en) {
        this.low_resolution = en;
    }
    function safeparse(k) {
      var parts = /(\d+)\/(\d+)\/?(\d*)(\s+)?(\d+)?\:?(\d+)?\:?(\d+)?\.?(\d+)?/.exec(k);

      var dd = parseInt(parts[1]),
          mm = parseInt(parts[2]),
          yy = parseInt(parts[3]),
          h = parseInt(parts[5]),
          m = parseInt(parts[6]),
          s = parseInt(parts[7]),
          ms = parseInt(parts[8]);
      /* caution: deliberate millennium bug */
      yy = yy < 100 ? 2000 + yy : yy;
      var date = new Date(yy || new Date().getYear() + 1900, mm - 1, dd, h || 0, m || 0, s || 0, ms || 0);
      if (isNaN(h))
        date.set_low_resolution(true);
      return date;
    }
%}

/* lexical grammar */
%lex
%%

\s+                   /* skip whitespace */
[0-9]+                return 'INTEGER'
[0-9]+("."[0-9]+)?\b  return 'REAL'
'to'                  return 'TO'
'from'                return 'FROM'
':'                   return ':'
'/'                   return '/'
'>='                  return 'GTE'
'<='                  return 'LTE'
'>'                   return 'GT'
'<'                   return 'LT'
','                   return 'COMMA'
<<EOF>>               return 'EOF'
.                     return 'INVALID'

/lex

/* operator associations and precedence */
%left '>' '<' '>=' '<='

%start query

%% /* language grammar */

query
    : statements EOF
        { var statements = Array.prototype.concat($statements);
          var program = function(k) {
            var result = false;
            while(result == false && statements.length > 0)
              result = result | statements.shift()(k);
            return result;
          }
          return program;
        }
    ;

time
    : INTEGER ':' INTEGER ':' REAL
        {$$ = $1 + ':' + $3 + ':' + $5;}
    | INTEGER ':' INTEGER
        {$$ = $1 + ':' + $3 + ':00';}
    ;
date
    : INTEGER '/' INTEGER '/' INTEGER
        {$$ = $3 + '/' + $1 + '/' + $5;}
    | INTEGER '/' INTEGER
        {$$ = $3 + '/' + $1 + '/' + (1900 + (new Date().getYear())).toString();}
    ;

op
    : GT
    | LT
    | GTE
    | LTE
    | TO
    | FROM
    ;

datetime
    : date time
        {$$ = new Date($date + ' ' + $time);}
    | date
        {$$ = new Date($date); $$.set_low_resolution(true);}
    | time
        {$$ = new Date(new Date().date() + $time);}
    ;

statements
    : statement
    | statement COMMA statements
        {$$ = Array.prototype.concat($statement, $statements);}
    ;

statement
    : datetime
        {$$ = function(k) {
            k = safeparse(k);
            if ($datetime.low_resolution) {
              k.set_low_resolution(true);
            }
            return k.get_floor().toString() == $datetime.get_floor().toString();
          }
        }
    | op datetime
        {$$ = function(k) {
            k = safeparse(k);
            var result =
                $op == '<'    ? k.get_floor() <  $datetime.get_ceiling()
              : $op == '>'    ? k.get_ceiling() >  $datetime.get_floor()
              : $op == '>='   ? k.get_ceiling() >= $datetime.get_floor()
              : $op == '<='   ? k.get_floor() <= $datetime.get_ceiling()
              : $op == 'to'   ? k.get_floor() <= $datetime.get_ceiling()
              : $op == 'from' ? k.get_ceiling() >= $datetime.get_floor()
              : false;
            return result;
        }}
    | datetime op datetime
          {$$ = function(k) {
              k = safeparse(k);
              var result =
                  $op == 'to' ? k.get_ceiling() >= $1.get_floor() && k.get_floor() <= $3.get_ceiling()
                : false;
              return result;
        }}
    ;