program.java

myassembler（大学作业）

import java.util.*;

public class Program {
   public static Hashtable state = new Hashtable();

   public static void main(String args[]) {
     try {
        Declare d0 = new Declare("a");
        Declare d1 = new Declare("b");
        ReadVariable ra = new ReadVariable("a");
        ReadVariable rb = new ReadVariable("b");
        Constant zero = new Constant(0);
        Constant seven = new Constant(7);
        Assign a0 = new Assign("a", seven);
        Assign a1 = new Assign("b", new Constant(-1));
        
        PrintString msg1 = new PrintString("a must be greater than zero.");
        PrintString msg2 = new PrintString("b must be greater than zero.");

        Loop l1 = new Loop(
                     new Or(
                       new Equal(rb, zero),
                       new GreaterThan(rb, zero)
                     ), a1);
                
        Statement sts[] = new Statement[4];
        sts[0] = d0; sts[1] = d1; sts[2] = a0;
        
        Sequence ss0 = new Sequence(new Statement[]{msg2, new Assign("b", seven)});
        Selection s1 = new Selection(new GreaterThan(rb, zero), l1, ss0);

        Declare d2 = new Declare("ab");
        a1 = new Assign("ab", ra);
        Assign a3 = new Assign("ab", new Add(new ReadVariable("ab"), ra));
        Assign a2 = new Assign("b", new Subtract(rb, new Constant(1)));
        l1 = new Loop(
                new GreaterThan(rb, zero), 
                new Sequence(new Statement[]{a3, a2})
                );
        Sequence ss1 = 
             new Sequence(
                new Statement[]{
                   new Assign("b", new Constant(-1)),
                   s1,
                   d2,
                   a1,
                   l1,
                   new PrintExpression(new ReadVariable("ab"))
                }
             );
        sts[3] = new Selection(new Not(new GreaterThan(ra, zero)), msg1, ss1);
        ss1 = new Sequence(sts);
        System.out.println(ss1);
        ss1.run();
     } catch(ExecutionException e) {e.printStackTrace();}
  }
}