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 is an IF instruction.  If the
  13  * expression matches the value, then the if will pass and the ip
  14  * should point to the follow instruction (which should be a SCOPE).
  15  * Otherwise the ip will be changed to point to the instruction
  16  * following the if block (one beyond the associated RSCOPE).
  17  * <p>
  18  * <pre>
  19  * ip (Instruction Pointer) Flow
  20  *
  21  *                      $e$ != value
  22  *       -------------------------------------------
  23  *       |                                         |
  24  *       |                                         V
  25  *     [IF] [SCOPE]..code block.. [RSCOPE] ... more code..
  26  *                   
  27  *
  28  * </pre>
  29  *
  30  *
  31  * @see autohit.vm.VMInstruction
  32  * @see autohit.vm.VMIScope
  33  *
  34  * @author Erich P. Gatejen
  35  * @version 1.0
  36  * <i>Version History</i>
  37  * <code>EPG - Initial - 14Jan99</code> 
  38  * 
  39  */
  40 public class VMIIf extends VMInstruction {
  41 	
  42 	// --- FINAL FIELDS ------------------------------------------------------	
  43 
  44 	// --- FIELDS ------------------------------------------------------------
  45 
  46     /**
  47      *  Expression.
  48      *  @serial
  49      */      	    
  50     public String           e;
  51     
  52     /**
  53      *  Value.
  54      *  @serial
  55      */      	    
  56     public String           value;
  57     
  58     /**
  59      *  False target.  Jump here is expression resolves as false
  60      *  @serial
  61      */      	    
  62     public int              target;      
  63 
  64 	// --- PUBLIC METHODS ----------------------------------------------------	
  65 
  66     /**
  67      *  Default constructor.
  68      */ 
  69     public VMIIf() {
  70         nToken = VMInstruction.IF;   
  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(" VMIIf ---------------------------- \n");
  81         d.append("    expression = " + e + "\n");
  82         d.append("    value = " + value + "\n");
  83         d.append("    target= " + target + "\n");
  84         return d.toString();                
  85     }
  86     
  87 	// --- PRIVATE METHODS ---------------------------------------------------
  88 
  89 }