1 package java_cup;
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     java_cup.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    */
symbol_part(symbol sym, String lab)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    */
symbol_part(symbol sym)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. */
the_symbol()49   public symbol the_symbol() {return _the_symbol;}
50 
51   /*-----------------------------------------------------------*/
52   /*--- General Methods ---------------------------------------*/
53   /*-----------------------------------------------------------*/
54 
55   /** Respond that we are not an action part. */
is_action()56   public boolean is_action() { return false; }
57 
58   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
59 
60   /** Equality comparison. */
equals(symbol_part other)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. */
equals(Object other)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. */
hashCode()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. */
toString()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 };
101