Recursive Decent Parsing:Functions to parse the Toy Grammar II

• Here are two more of the four functions needed to parse the Toy Grammar. Note the use of a while() loop to match possibly repeated elements in a grammar production, based on whether the look ahead token indicates that a repeated element is present:

• <> => <> ( (‘+’|‘-’) <> )*

expression(){

term(); /* non-terminal is function call */

while( tokentype == PLUS || tokentype == MINUS ){

scanner(); /* get next lookahead token */

term(); /* non-terminal is function call */

}

}

• <> => <> ( (‘*’|‘/’) <> )*

term(){

factor(); /* non-terminal is function call */

while( tokentype == MULT || tokentype == DIV ){

scanner(); /* get next lookahead token */

factor();/* non-terminal is function call */

}

}