Source code: java_cup/shift_action.java
1
2 package java_cup;
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 }