src/closure.h

   1 /* Subroutines for bison
   2
   3    Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software
   4    Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    Bison is free software; you can redistribute it and/or modify it
   9    under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2, or (at your option)
  11    any later version.
  12
  13    Bison is distributed in the hope that it will be useful, but
  14    WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Bison; see the file COPYING.  If not, write to the Free
  20    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  21    02111-1307, USA.  */
  22
  23 #ifndef CLOSURE_H_
  24 # define CLOSURE_H_
  25
  26 # include "gram.h"
  27
  28 /* Allocates the itemset and ruleset vectors, and precomputes useful
  29    data so that closure can be called.  n is the number of elements to
  30    allocate for itemset.  */
  31
  32 void new_closure (int n);
  33
  34
  35 /* Given the kernel (aka core) of a state (a vector of item numbers
  36    ITEMS, of length N), set up RULESET and ITEMSET to indicate what
  37    rules could be run and which items could be accepted when those
  38    items are the active ones.
  39
  40    RULESET contains a bit for each rule.  CLOSURE sets the bits for
  41    all rules which could potentially describe the next input to be
  42    read.
  43
  44    ITEMSET is a vector of item numbers; NITEMSET is its size
  45    (actually, points to just beyond the end of the part of it that is
  46    significant).  CLOSURE places there the indices of all items which
  47    represent units of input that could arrive next.  */
  48
  49 void closure (item_number *items, int n);
  50
  51
  52 /* Frees ITEMSET, RULESET and internal data.  */
  53
  54 void free_closure (void);
  55
  56 extern item_number *itemset;
  57 extern int nritemset;
  58
  59 #endif /* !CLOSURE_H_ */