CUP source - Formula parser

package szabivan.cup;

import java_cup.runtime.*;
import formula.data.*;

class FormulaParser;

terminal VEE, WEDGE, IMPLIES, IFF, LPAREN, RPAREN, UP, DOWN, NEGATION;
terminal String VARIABLE;

non terminal Formula formula;

precedence left IFF;
precedence right IMPLIES;
precedence left VEE;
precedence left WEDGE;
precedence left NEGATION;

formula ::= VARIABLE:v {: RESULT = new Variable(v); :} |
			LPAREN formula:f RPAREN {: RESULT = f; :} |
			formula:f VEE formula:g {: RESULT = new Disjunction(f,g); :} |
			formula:f WEDGE formula:g {: RESULT = new Conjunction(f,g); :} |
			formula:f IMPLIES formula:g {: RESULT = new Implication(f,g); :} |
			formula:f IFF formula:g {: RESULT = new Equivalence(f,g); :} |
			NEGATION formula:f {: RESULT = new Negation(f); :} |
			UP {: RESULT = True.getInstance(); :} |
			DOWN {: RESULT = False.getInstance(); :}
			;