src/closure.h

   1 /* Subroutines for bison
   2
   3    Copyright (C) 1984, 1989, 2000-2002, 2007, 2009-2013 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 const *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_ */