Expansion


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22  
23  package org.javacc.parser;
24  
25  /**
26   * Describes expansions - entities that may occur on the
27   * right hand sides of productions.  This is the base class of
28   * a bunch of other more specific classes.
29   */
30  
31  public class Expansion {
32  
33    /**
34     * The line and column number of the construct that corresponds
35     * most closely to this node.
36     */
37    int line, column;
38  
39    /**
40     * A reimplementing of Object.hashCode() to be deterministic.  This uses
41     * the line and column fields to generate an arbitrary number - we assume
42     * that this method is called only after line and column are set to
43     * their actual values.
44     */
45    public int hashCode() {
46      return line + column;
47    }
48  
49    /**
50     * An internal name for this expansion.  This is used to generate parser
51     * routines.
52     */
53    String   internal_name = "";
54  
55    /**
56     * The parser routines are generated in three phases.  The generation
57     * of the second and third phase are on demand only, and the third phase
58     * can be recursive.  This variable is used to keep track of the
59     * expansions for which phase 3 generations have been already added to
60     * a list so that the recursion can be terminated.
61     */
62    boolean phase3done = false;
63  
64    /**
65     * The parent of this expansion node.  In case this is the top level
66     * expansion of the production it is a reference to the production node
67     * otherwise it is a reference to another Expansion node.  In case this
68     * is the top level of a lookahead expansion,then the parent is null.
69     */
70    public Object   parent;
71  
72    /**
73     * The ordinal of this node with respect to its parent.
74     */
75    int ordinal;
76  
77    /**
78     * To avoid right-recursive loops when calculating follow sets, we use
79     * a generation number which indicates if this expansion was visited
80     * by LookaheadWalk.genFollowSet in the same generation.  New generations
81     * are obtained by incrementing the static counter below, and the current
82     * generation is stored in the non-static variable below.
83     */
84    public static long nextGenerationIndex = 1;
85    public long myGeneration = 0;
86  
87    /**
88     * This flag is used for bookkeeping by the minimumSize method in class
89     * ParseEngine.
90     */
91    public boolean inMinimumSize = false;
92  
93     public static void reInit()
94     {
95        nextGenerationIndex = 1;
96     }
97  
98  }
99
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