reduce_action


1   
2   package com.sun.java_cup.internal;
3   
4   /** This class represents a reduce action within the parse table. 
5    *  The action simply stores the production that it reduces with and 
6    *  responds to queries about its type.
7    *
8    * @version last updated: 11/25/95
9    * @author  Scott Hudson
10   */
11  public class reduce_action extends parse_action {
12   
13    /*-----------------------------------------------------------*/
14    /*--- Constructor(s) ----------------------------------------*/
15    /*-----------------------------------------------------------*/
16  
17    /** Simple constructor. 
18     * @param prod the production this action reduces with.
19     */
20    public reduce_action(production prod ) throws internal_error
21      {
22        /* sanity check */
23        if (prod == null)
24      throw new internal_error(
25        "Attempt to create a reduce_action with a null production");
26  
27        _reduce_with = prod;
28      }
29  
30    /*-----------------------------------------------------------*/
31    /*--- (Access to) Instance Variables ------------------------*/
32    /*-----------------------------------------------------------*/
33    
34    /** The production we reduce with. */
35    protected production _reduce_with;
36  
37    /** The production we reduce with. */
38    public production reduce_with() {return _reduce_with;}
39  
40    /*-----------------------------------------------------------*/
41    /*--- General Methods ---------------------------------------*/
42    /*-----------------------------------------------------------*/
43  
44    /** Quick access to type of action. */
45    public int kind() {return REDUCE;}
46  
47    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
48  
49    /** Equality test. */
50    public boolean equals(reduce_action other)
51      {
52        return other != null && other.reduce_with() == reduce_with();
53      }
54  
55    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
56  
57    /** Generic equality test. */
58    public boolean equals(Object   other)
59      {
60        if (other instanceof reduce_action)
61      return equals((reduce_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 production we are reducing with */
72        return reduce_with().hashCode();
73      }
74  
75  
76    /** Convert to string. */
77    public String   toString() 
78      {
79        return "REDUCE(with prod " + reduce_with().index() + ")";
80      }
81  
82    /*-----------------------------------------------------------*/
83  
84  }
85
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