1 /**
   2  * .
   3  * Copyright � 1999 Erich P G.
   4  *
   5  */
   6  
   7 package autohit.vm;
   8 
   9 import java.io.Serializable;
  10 
  11 /**
  12  * A Virtual Machine instruction.  This impliments the tail of a 
  13  * while loop.  If the expression matches the value, then the ip
  14  * will changed to point to the instruction following the 
  15  * block starting SCOPE.  Otherwise, the ip is incremented to point
  16  * to the following RSCOPE.
  17  * <p>
  18  * <pre>
  19  * ip (Instruction Pointer) Flow
  20  *
  21  *              expression == value
  22  *              ------------------
  23  *              |                |
  24  *              V                |
  25  *     [SCOPE] ..code block.. [WHILE][RSCOPE]
  26  *                               |      ^ 
  27  *                               -------|
  28  *                            expression != value
  29  *
  30  * </pre>
  31  * @see autohit.vm.VMInstruction
  32  *
  33  * @author Erich P. Gatejen
  34  * @version 1.0
  35  * <i>Version History</i>
  36  * <code>EPG - Initial - 19Jan99</code> 
  37  * 
  38  */
  39 public class VMIWhile extends VMInstruction {
  40 	
  41 	// --- FINAL FIELDS ------------------------------------------------------	
  42 
  43 	// --- FIELDS ------------------------------------------------------------
  44 
  45     /**
  46      * Expresion
  47      * @serial
  48      */ 
  49     public String   e;
  50     
  51     /**
  52      * Test value.
  53      * @serial
  54      */ 
  55     public String   value;
  56     
  57     /**
  58      * Target if expression true.
  59      * @serial
  60      */ 
  61     public int      target;        
  62 
  63 	// --- PUBLIC METHODS ----------------------------------------------------	
  64 
  65     /**
  66      *  Default constructor.
  67      */ 
  68     public VMIWhile() {
  69         nToken = VMInstruction.WHILE;   
  70     }
  71     
  72 
  73     /**
  74      *  Dump this Instruction.  Mostly for debugging.
  75      *
  76      *  @return a String containing the dump.
  77      */
  78     public String toString() {
  79         StringBuffer d = new StringBuffer();        
  80         d.append(" VMIWhile -------------------------- \n");
  81         d.append("    e = " + e + "\n");
  82         d.append("    value = " + value + "\n");
  83         d.append("    target = " + target + "\n");
  84         return d.toString();                
  85     }
  86 	// --- PRIVATE METHODS ---------------------------------------------------	
  87 
  88 
  89 }