Source code: java_cup/symbol_part.java
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 */
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 }