1package 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 */
11public 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};
101