src/lalr.h

   1 /* Compute look-ahead criteria for bison,
   2    Copyright (C) 1984, 1986, 1989 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
   7    it 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,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU 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
  18    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #ifndef LALR_H_
  22 # define LALR_H_
  23
  24 /* Compute how to make the finite state machine deterministic; find
  25    which rules need lookahead in each state, and which lookahead
  26    tokens they accept.  */
  27
  28 void lalr PARAMS ((void));
  29
  30
  31 /* lalr() builds these data structures. */
  32
  33 /* goto_map, from_state and to_state --record each shift transition
  34    which accepts a variable (a nonterminal).
  35
  36    from_state[t] is the state number which a transition leads from and
  37    to_state[t] is the state number it leads to.  All the transitions
  38    that accept a particular variable are grouped together and
  39    goto_map[i - ntokens] is the index in from_state and to_state of
  40    the first of them.  */
  41
  42 extern short *goto_map;
  43 extern short *from_state;
  44 extern short *to_state;
  45
  46 /* CONSISTENT[S] is nonzero if no lookahead is needed to decide what
  47    to do in state S.  */
  48
  49 extern char *consistent;
  50
  51
  52 /* LARULENO is a vector which records the rules that need lookahead in
  53    various states.  The elements of LARULENO that apply to state S are
  54    those from LOOKAHEADS[S] through LOOKAHEADS[S+1]-1.  Each element
  55    of LARULENO is a rule number.
  56
  57    If LR is the length of LAruleno, then a number from 0 to LR-1 can
  58    specify both a rule and a state where the rule might be applied.
  59    */
  60
  61 extern short *LAruleno;
  62
  63 /* LA is a lr by ntokens matrix of bits.  LA[l, i] is 1 if the rule
  64    LAruleno[l] is applicable in the appropriate state when the next
  65    token is symbol i.  If LA[l, i] and LA[l, j] are both 1 for i != j,
  66    it is a conflict.  */
  67
  68 extern unsigned *LA;
  69
  70
  71 extern int tokensetsize;
  72 extern short *lookaheads;
  73 extern short *accessing_symbol;
  74 extern core **state_table;
  75 extern shifts **shift_table;
  76 extern reductions **reduction_table;
  77
  78
  79
  80 #endif /* !LALR_H_ */