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
  25 /* Import the definition of CORE, SHIFTS and REDUCTIONS. */
  26 # include "state.h"
  27
  28
  29 /* Compute how to make the finite state machine deterministic; find
  30    which rules need lookahead in each state, and which lookahead
  31    tokens they accept.  */
  32
  33 void lalr PARAMS ((void));
  34
  35
  36 /* lalr() builds these data structures. */
  37
  38 /* goto_map, from_state and to_state --record each shift transition
  39    which accepts a variable (a nonterminal).
  40
  41    from_state[t] is the state number which a transition leads from and
  42    to_state[t] is the state number it leads to.  All the transitions
  43    that accept a particular variable are grouped together and
  44    goto_map[i - ntokens] is the index in from_state and to_state of
  45    the first of them.  */
  46
  47 extern short *goto_map;
  48 extern short *from_state;
  49 extern short *to_state;
  50
  51 /* CONSISTENT[S] is nonzero if no lookahead is needed to decide what
  52    to do in state S.  */
  53
  54 extern char *consistent;
  55
  56
  57 /* LARULENO is a vector which records the rules that need lookahead in
  58    various states.  The elements of LARULENO that apply to state S are
  59    those from LOOKAHEADS[S] through LOOKAHEADS[S+1]-1.  Each element
  60    of LARULENO is a rule number.
  61
  62    If LR is the length of LAruleno, then a number from 0 to LR-1 can
  63    specify both a rule and a state where the rule might be applied.
  64    */
  65
  66 extern short *LAruleno;
  67
  68 /* LA is a lr by ntokens matrix of bits.  LA[l, i] is 1 if the rule
  69    LAruleno[l] is applicable in the appropriate state when the next
  70    token is symbol i.  If LA[l, i] and LA[l, j] are both 1 for i != j,
  71    it is a conflict.  */
  72
  73 extern unsigned *LA;
  74
  75
  76 extern int tokensetsize;
  77 extern short *lookaheads;
  78 extern short *accessing_symbol;
  79 extern core **state_table;
  80 extern shifts **shift_table;
  81 extern reductions **reduction_table;
  82
  83
  84
  85 #endif /* !LALR_H_ */