Jison version of PragProg's (the book) timerparser from chapt 2 exercise 7

timeparser.jison

/* lexical grammar */
%lex
%%

\s+                   /* skip whitespace */
([0-9])              return 'DIGIT'
"am"                  return 'AM'
"pm"                  return 'PM'
":"                   return ':'
<<EOF>>               return 'EOF'

/lex


%start time

%% /* language grammar */

time      : spec EOF
              { if ($1 >= 24*60) console.log("Time is too large");
                console.log("%d minutes past midnight", $1);
                return;
              }
          ;

spec      : hour ':' minute
              { $$ = $1 + $3; }
          | hour ':' minute ampm
              { if ($1 > 11*60) console.log("Hour out of range");
                $$ = $1 + $3 + $4;
              }
          | hour ampm
              { if ($1 > 11*60) console.log("Hour out of range");
                $$ = $1 + $2;
              }
          ;

hour      : hour_num
              { if ($1 > 23) console.log("Hour out of range");
                $$ = $1 * 60;
              }
          ;

minute    : DIGIT DIGIT
              { $$ = $1 * 10 + Number($2);
                if ($$ > 59) console.log("Minute out of range");
              }
          ;

ampm      : AM
              { $$ = 0; }
          | PM
              { $$ = 12 * 60; }
          ;

hour_num  : DIGIT
              { $$ = $1; }
          | DIGIT DIGIT
              { $$ = $1 * 10 + Number($2); }
          ;