production_part


1   package com.sun.java_cup.internal;
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     com.sun.java_cup.internal.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  }
95
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