1. 

  2. package com.sun.java_cup.internal;

  3. 

  4. /** This class represents a shift action within the parse table. 

  5.  *  The action simply stores the state that it shifts to and responds 

  6.  *  to queries about its type.

  7.  *

  8.  * @version last updated: 11/25/95

  9.  * @author  Scott Hudson

  10.  */

  11. public class shift_action extends parse_action {

  12. 

  13.   /*-----------------------------------------------------------*/

  14.   /*--- Constructor(s) ----------------------------------------*/

  15.   /*-----------------------------------------------------------*/

  16. 

  17.   /** Simple constructor. 

  18.    * @param shft_to the state that this action shifts to.

  19.    */

  20.   public shift_action(lalr_state shft_to) throws internal_error

  21.     {

  22.       /* sanity check */

  23.       if (shft_to == null)

  24. 	throw new internal_error(

  25. 	  "Attempt to create a shift_action to a null state");

  26. 

  27.       _shift_to = shft_to;

  28.     }

  29. 

  30.   /*-----------------------------------------------------------*/

  31.   /*--- (Access to) Instance Variables ------------------------*/

  32.   /*-----------------------------------------------------------*/

  33. 

  34.   /** The state we shift to. */

  35.   protected lalr_state _shift_to;

  36. 

  37.   /** The state we shift to. */

  38.   public lalr_state shift_to() {return _shift_to;}

  39. 

  40.   /*-----------------------------------------------------------*/

  41.   /*--- General Methods ---------------------------------------*/

  42.   /*-----------------------------------------------------------*/

  43. 

  44.   /** Quick access to type of action. */

  45.   public int kind() {return SHIFT;}

  46. 

  47.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  48. 

  49.   /** Equality test. */

  50.   public boolean equals(shift_action other)

  51.     {

  52.       return other != null && other.shift_to() == shift_to();

  53.     }

  54. 

  55.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  56. 

  57.   /** Generic equality test. */

  58.   public boolean equals(Object other)

  59.     {

  60.       if (other instanceof shift_action)

  61. 	return equals((shift_action)other);

  62.       else

  63.        return false;

  64.     }

  65. 

  66.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  67. 

  68.   /** Compute a hash code. */

  69.   public int hashCode()

  70.     {

  71.       /* use the hash code of the state we are shifting to */

  72.       return shift_to().hashCode();

  73.     }

  74. 

  75.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  76. 

  77.   /** Convert to a string. */

  78.   public String toString() {return "SHIFT(to state " + shift_to().index() + ")";}

  79. 

  80.   /*-----------------------------------------------------------*/

  81. 

  82. }