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Java > Open Source Codes > com > sun > java_cup > internal > parse_action_table


1
2 package com.sun.java_cup.internal;
3
4 import java.util.Enumeration JavaDoc;
5
6 /** This class represents the complete "action" table of the parser.
7  * It has one row for each state in the parse machine, and a column for
8  * each terminal symbol. Each entry in the table represents a shift,
9  * reduce, or an error.
10  *
11  * @see com.sun.java_cup.internal.parse_action
12  * @see com.sun.java_cup.internal.parse_action_row
13  * @version last updated: 11/25/95
14  * @author Scott Hudson
15  */
16 public class parse_action_table {
17
18   /*-----------------------------------------------------------*/
19   /*--- Constructor(s) ----------------------------------------*/
20   /*-----------------------------------------------------------*/
21
22   /** Simple constructor. All terminals, non-terminals, and productions must
23    * already have been entered, and the viable prefix recognizer should
24    * have been constructed before this is called.
25    */
26   public parse_action_table()
27     {
28       /* determine how many states we are working with */
29       _num_states = lalr_state.number();
30
31       /* allocate the array and fill it in with empty rows */
32       under_state = new parse_action_row[_num_states];
33       for (int i=0; i<_num_states; i++)
34     under_state[i] = new parse_action_row();
35     }
36
37   /*-----------------------------------------------------------*/
38   /*--- (Access to) Instance Variables ------------------------*/
39   /*-----------------------------------------------------------*/
40
41   /** How many rows/states are in the machine/table. */
42   protected int _num_states;
43
44   /** How many rows/states are in the machine/table. */
45   public int num_states() {return _num_states;}
46
47   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
48
49   /** Actual array of rows, one per state. */
50   public parse_action_row[] under_state;
51
52   /*-----------------------------------------------------------*/
53   /*--- General Methods ---------------------------------------*/
54   /*-----------------------------------------------------------*/
55
56   /** Check the table to ensure that all productions have been reduced.
57    * Issue a warning message (to System.err) for each production that
58    * is never reduced.
59    */
60   public void check_reductions()
61     throws internal_error
62     {
63       parse_action act;
64       production prod;
65
66       /* tabulate reductions -- look at every table entry */
67       for (int row = 0; row < num_states(); row++)
68     {
69       for (int col = 0; col < under_state[row].size(); col++)
70         {
71           /* look at the action entry to see if its a reduce */
72           act = under_state[row].under_term[col];
73           if (act != null && act.kind() == parse_action.REDUCE)
74         {
75           /* tell production that we used it */
76           ((reduce_action)act).reduce_with().note_reduction_use();
77         }
78         }
79     }
80
81       /* now go across every production and make sure we hit it */
82       for (Enumeration JavaDoc p = production.all(); p.hasMoreElements(); )
83     {
84       prod = (production)p.nextElement();
85
86       /* if we didn't hit it give a warning */
87       if (prod.num_reductions() == 0)
88         {
89           /* count it *
90           emit.not_reduced++;
91
92           /* give a warning if they haven't been turned off */
93           if (!emit.nowarn)
94         {
95           System.err.println("*** Production \"" +
96                   prod.to_simple_string() + "\" never reduced");
97           lexer.warning_count++;
98         }
99         }
100     }
101     }
102
103   /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*
104
105   /** Convert to a string. */
106   public String JavaDoc toString()
107     {
108       String JavaDoc result;
109       int cnt;
110
111       result = "-------- ACTION_TABLE --------\n";
112       for (int row = 0; row < num_states(); row++)
113     {
114       result += "From state #" + row + "\n";
115       cnt = 0;
116       for (int col = 0; col < under_state[row].size(); col++)
117         {
118           /* if the action is not an error print it */
119           if (under_state[row].under_term[col].kind() != parse_action.ERROR)
120         {
121           result += " [term " + col + ":" + under_state[row].under_term[col] + "]";
122
123           /* end the line after the 2nd one */
124           cnt++;
125           if (cnt == 2)
126             {
127               result += "\n";
128               cnt = 0;
129             }
130         }
131         }
132           /* finish the line if we haven't just done that */
133       if (cnt != 0) result += "\n";
134     }
135       result += "------------------------------";
136
137       return result;
138     }
139
140   /*-----------------------------------------------------------*/
141
142 }
143
144
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