1. package com.sun.java_cup.internal;

  2. 

  3. /** This class represents a part of a production which is a symbol (terminal

  4.  *  or non terminal).  This simply maintains a reference to the symbol in 

  5.  *  question.

  6.  *

  7.  * @see     com.sun.java_cup.internal.production

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

  9.  * @author  Scott Hudson

  10.  */

  11. public class symbol_part extends production_part {

  12. 

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

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

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

  16. 

  17.   /** Full constructor. 

  18.    * @param sym the symbol that this part is made up of.

  19.    * @param lab an optional label string for the part.

  20.    */

  21.   public symbol_part(symbol sym, String lab) throws internal_error

  22.     {

  23.       super(lab);

  24. 

  25.       if (sym == null)

  26. 	throw new internal_error(

  27. 	  "Attempt to construct a symbol_part with a null symbol");

  28.       _the_symbol = sym;

  29.     }

  30. 

  31.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  32. 

  33.   /** Constructor with no label. 

  34.    * @param sym the symbol that this part is made up of.

  35.    */

  36.   public symbol_part(symbol sym) throws internal_error

  37.     {

  38.       this(sym,null);

  39.     }

  40. 

  41.   /*-----------------------------------------------------------*/

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

  43.   /*-----------------------------------------------------------*/

  44. 

  45.   /** The symbol that this part is made up of. */

  46.   protected symbol _the_symbol;

  47. 

  48.   /** The symbol that this part is made up of. */

  49.   public symbol the_symbol() {return _the_symbol;}

  50. 

  51.   /*-----------------------------------------------------------*/

  52.   /*--- General Methods ---------------------------------------*/

  53.   /*-----------------------------------------------------------*/

  54. 

  55.   /** Respond that we are not an action part. */

  56.   public boolean is_action() { return false; }

  57. 

  58.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  59. 

  60.   /** Equality comparison. */

  61.   public boolean equals(symbol_part other)

  62.     {

  63.       return other != null && super.equals(other) && 

  64. 	     the_symbol().equals(other.the_symbol());

  65.     }

  66. 

  67.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  68. 

  69.   /** Generic equality comparison. */

  70.   public boolean equals(Object other)

  71.     {

  72.       if (!(other instanceof symbol_part))

  73. 	return false;

  74.       else

  75. 	return equals((symbol_part)other);

  76.     }

  77. 

  78.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  79. 

  80.   /** Produce a hash code. */

  81.   public int hashCode()

  82.     {

  83.       return super.hashCode() ^ 

  84. 	     (the_symbol()==null ? 0 : the_symbol().hashCode());

  85.     }

  86. 

  87.   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  88. 

  89.   /** Convert to a string. */

  90.   public String toString()

  91.     {

  92.       if (the_symbol() != null)

  93. 	return super.toString() + the_symbol();

  94.       else

  95. 	return super.toString() + "$$MISSING-SYMBOL$$";

  96.     }

  97. 

  98.   /*-----------------------------------------------------------*/

  99. 

  100. }