import java_cup.runtime.*;

/* Terminals */
terminal SELECT,  FROM,  WHERE, COMMA, ID, AND, INT, EQ, NE, LT, LE, GT, GE;

/* Non terminals */
non terminal selectStatement, columnList, column, tableList, table, binop;
non terminal filterExpression, joinExpression, whereExpression, primaryExpression;

/* extremely simplified SQL grammar */
selectStatement ::= SELECT columnList FROM tableList WHERE whereExpression
                 ;

columnList ::= columnList COMMA column
            |  column
            ;

column ::= ID
        ;

tableList ::= tableList COMMA table
           | table
           ;

table ::= ID
       ;

whereExpression ::= primaryExpression
                 |  whereExpression AND primaryExpression
                 ;

primaryExpression ::= filterExpression
                   |  joinExpression
                   ;

filterExpression ::= INT binop column
                 |  column binop INT
                 ;

joinExpression ::= column EQ column
                ;

binop ::= EQ 
       |  NE
       |  LT
       |  LE
       |  GT
       |  GE
       ;