1/* Subroutines for bison
2
3   Copyright (C) 1984, 1989, 2000-2002, 2007, 2009-2012 Free Software
4   Foundation, Inc.
5
6   This file is part of Bison, the GNU Compiler Compiler.
7
8   This program is free software: you can redistribute it and/or modify
9   it under the terms of the GNU General Public License as published by
10   the Free Software Foundation, either version 3 of the License, or
11   (at your option) any later version.
12
13   This program is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   You should have received a copy of the GNU General Public License
19   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
20
21#ifndef CLOSURE_H_
22# define CLOSURE_H_
23
24# include "gram.h"
25
26/* Allocates the itemset and ruleset vectors, and precomputes useful
27   data so that closure can be called.  n is the number of elements to
28   allocate for itemset.  */
29
30void new_closure (unsigned int n);
31
32
33/* Given the kernel (aka core) of a state (a sorted vector of item numbers
34   ITEMS, of length N), set up RULESET and ITEMSET to indicate what
35   rules could be run and which items could be accepted when those
36   items are the active ones.
37
38   RULESET contains a bit for each rule.  CLOSURE sets the bits for
39   all rules which could potentially describe the next input to be
40   read.
41
42   ITEMSET is a sorted vector of item numbers; NITEMSET is its size
43   (actually, points to just beyond the end of the part of it that is
44   significant).  CLOSURE places there the indices of all items which
45   represent units of input that could arrive next.  */
46
47void closure (item_number *items, size_t n);
48
49
50/* Frees ITEMSET, RULESET and internal data.  */
51
52void free_closure (void);
53
54extern item_number *itemset;
55extern size_t nitemset;
56
57#endif /* !CLOSURE_H_ */
58