1 

     2 package G4ip;

     3 

     4 /** Class for propositional formulae.<p>

     5   * @author      Christian Urban

     6   */

     7 public class Form {

     8 

     9   public case False();         

    10   public case And(Form c1,Form c2);

    11   public case Or(Form c1,Form c2);

    12   public case Imp(Form c1,Form c2);

    13   //public case Equ(Form c1,Form c2);

    14   public case Atm(String c);

    15 

    16   public String toString() {

    17     switch(this) {

    18     case False(): 

    19       return "false"; 

    20     case And(Form c1,Form c2): 

    21       return "(" + c1.toString() + " & "   + c2.toString() + ")"; 

    22     case Or(Form c1,Form c2):  

    23       return "(" + c1.toString() + " v "   + c2.toString() + ")"; 

    24     case Imp(Form c1,Form c2): 

    25       return "(" + c1.toString() + " -> "  + c2.toString() + ")"; 

    26     case Atm(String c): 

    27       return c; 

    28     }

    29   }

    30 

    31   // for testing

    32   public String internalString() {

    33     switch(this) {

    34     case False(): 

    35       return "false"; 

    36     case And(Form c1,Form c2): 

    37       return "And(" + c1.internalString() + ","   + c2.internalString() + ")"; 

    38     case Or(Form c1,Form c2):  

    39       return "Or(" + c1.internalString() + ","   + c2.internalString() + ")"; 

    40     case Imp(Form c1,Form c2): 

    41       return "Imp(" + c1.internalString() + ","  + c2.internalString() + ")"; 

    42     case Atm(String c): 

    43       return "Atm(\"p"+ c + "\")"; 

    44     }

    45   }

    46 

    47 }

    48