Source code: java_cup/production_part.java
1 package java_cup;
2
3 /** This class represents one part (either a symbol or an action) of a
4 * production. In this base class it contains only an optional label
5 * string that the user can use to refer to the part within actions.<p>
6 *
7 * This is an abstract class.
8 *
9 * @see java_cup.production
10 * @version last updated: 11/25/95
11 * @author Scott Hudson
12 */
13 public abstract class production_part {
14
15 /*-----------------------------------------------------------*/
16 /*--- Constructor(s) ----------------------------------------*/
17 /*-----------------------------------------------------------*/
18
19 /** Simple constructor. */
20 public production_part(String lab)
21 {
22 _label = lab;
23 }
24
25 /*-----------------------------------------------------------*/
26 /*--- (Access to) Instance Variables ------------------------*/
27 /*-----------------------------------------------------------*/
28
29 /** Optional label for referring to the part within an action (null for
30 * no label).
31 */
32 protected String _label;
33
34 /** Optional label for referring to the part within an action (null for
35 * no label).
36 */
37 public String label() {return _label;}
38
39 /*-----------------------------------------------------------*/
40 /*--- General Methods ---------------------------------------*/
41 /*-----------------------------------------------------------*/
42
43 /** Indicate if this is an action (rather than a symbol). Here in the
44 * base class, we don't this know yet, so its an abstract method.
45 */
46 public abstract boolean is_action();
47
48 /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
49
50 /** Equality comparison. */
51 public boolean equals(production_part other)
52 {
53 if (other == null) return false;
54
55 /* compare the labels */
56 if (label() != null)
57 return label().equals(other.label());
58 else
59 return other.label() == null;
60 }
61
62 /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
63
64 /** Generic equality comparison. */
65 public boolean equals(Object other)
66 {
67 if (!(other instanceof production_part))
68 return false;
69 else
70 return equals((production_part)other);
71 }
72
73 /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
74
75 /** Produce a hash code. */
76 public int hashCode()
77 {
78 return label()==null ? 0 : label().hashCode();
79 }
80
81 /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
82
83 /** Convert to a string. */
84 public String toString()
85 {
86 if (label() != null)
87 return label() + ":";
88 else
89 return " ";
90 }
91
92 /*-----------------------------------------------------------*/
93
94 }