src/closure.h

   1 /* Subroutines for bison
   2    Copyright (C) 1984, 1989, 2000, 2001, 2002  Free Software Foundation, Inc.
   3
   4    This file is part of Bison, the GNU Compiler Compiler.
   5
   6    Bison is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    Bison is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with Bison; see the file COPYING.  If not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  19    02111-1307, USA.  */
  20
  21 #ifndef CLOSURE_H_
  22 # define CLOSURE_H_
  23
  24 /* Allocates the itemset and ruleset vectors, and precomputes useful
  25    data so that closure can be called.  n is the number of elements to
  26    allocate for itemset.  */
  27
  28 void new_closure (int n);
  29
  30
  31 /* Given the kernel (aka core) of a state (a vector of item numbers
  32    ITEMS, of length N), set up RULESET and ITEMSET to indicate what
  33    rules could be run and which items could be accepted when those
  34    items are the active ones.
  35
  36    RULESET contains a bit for each rule.  CLOSURE sets the bits for
  37    all rules which could potentially describe the next input to be
  38    read.
  39
  40    ITEMSET is a vector of item numbers; NITEMSET is its size
  41    (actually, points to just beyond the end of the part of it that is
  42    significant).  CLOSURE places there the indices of all items which
  43    represent units of input that could arrive next.  */
  44
  45 void closure (item_number_t *items, int n);
  46
  47
  48 /* Frees ITEMSET, RULESET and internal data.  */
  49
  50 void free_closure (void);
  51
  52 extern item_number_t *itemset;
  53 extern int nritemset;
  54
  55 #endif /* !CLOSURE_H_ */