| 1 | /* Subroutines for bison |
| 2 | |
| 3 | Copyright (C) 1984, 1989, 2000-2002, 2007, 2009-2010 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 | |
| 30 | void 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 | |
| 47 | void closure (item_number *items, size_t n); |
| 48 | |
| 49 | |
| 50 | /* Frees ITEMSET, RULESET and internal data. */ |
| 51 | |
| 52 | void free_closure (void); |
| 53 | |
| 54 | extern item_number *itemset; |
| 55 | extern size_t nitemset; |
| 56 | |
| 57 | #endif /* !CLOSURE_H_ */ |