1 package G4ip;

     2 

     3 import java.util.Vector;

     4 import G4ip.Form.*;

     5 

     6 /** Context acts as a multiset.<p>

     7   * Typical contexts in logical rules are Gamma, Delta, etc.

     8   * @author      Christian Urban

     9   */

    10 public class Context extends Vector {

    11   

    12   public Context() { super(); }

    13 

    14   public Context(Context init_context) {

    15     super();

    16     for (int i=0;i<init_context.size();i++) {

    17       addElement(init_context.elementAt(i));

    18     }

    19   }

    20 

    21   /** should be toString, but this is a "final" method in Vector 

    22     */

    23   public String makeString() {

    24     String s = new String();

    25     int i;                      // size()-1 because the last formula

    26     for (i=0;i<size()-1;i++) {  // should be printed without a comma

    27       s=s.concat(elementAt(i).toString());

    28       s=s.concat(", ");

    29     }

    30     if (size() > 0) {           // add last formula 

    31       s=s.concat(elementAt(i).toString()); 

    32     }

    33     return s;

    34   }

    35 

    36   /** returns a context with one additional formula at the beginning 

    37     * @param   new_formula    a formula

    38     */

    39   public Context add(Form new_formula) {

    40     Context new_c = new Context(this);

    41     new_c.insertElementAt(new_formula,0);

    42     return new_c;

    43   }

    44 

    45   /** returns a context with two additional formulae at the beginning 

    46     * @param new_formula1,new_formula2    two formulae

    47     */

    48   public Context add(Form new_formula1, Form new_formula2) {

    49     Context new_c = new Context(this);

    50     new_c.insertElementAt(new_formula1,0);

    51     new_c.insertElementAt(new_formula2,0);

    52     return new_c;

    53   }

    54 

    55   /** tests whether a context contains a specific atom 

    56     * @param a a formula

    57     */

    58   public boolean includes(Form a) {

    59     if (a instanceof Atm) {

    60       for (int i=0;i<size();i++) {

    61         switch((Form)elementAt(i)) {

    62         case Atm(String c):

    63           if (c.compareTo(((Atm)a).c) == 0) return true; break;

    64         }

    65       }

    66     }

    67     return false;

    68   }

    69 

    70 }