src/lalr.h

   1 /* Compute lookahead criteria for bison,
   2
   3    Copyright (C) 1984, 1986, 1989, 2000, 2002, 2004, 2006, 2007 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
   9    it 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,
  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 Bison; see the file COPYING.  If not, write to
  20    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21    Boston, MA 02110-1301, USA.  */
  22
  23 #ifndef LALR_H_
  24 # define LALR_H_
  25
  26 # include <bitset.h>
  27 # include <bitsetv.h>
  28
  29 /* Import the definition of RULE_T. */
  30 # include "gram.h"
  31
  32 /* Import the definition of CORE, TRANSITIONS and REDUCTIONS. */
  33 # include "state.h"
  34
  35
  36 /** Build the LALR(1) automaton.
  37
  38    Compute how to make the finite state machine deterministic; find
  39    which rules need lookahead in each state, and which lookahead
  40    tokens they accept.
  41
  42    Builds:
  43    - #goto_map
  44    - #from_state
  45    - #to_state
  46 */
  47 void lalr (void);
  48
  49 /**
  50  * Update state numbers recorded in #goto_map, #from_state, and #to_state such
  51  * that:
  52  *   - \c nstates_old is the old number of states.
  53  *   - Where \c i is the old state number, <tt>old_to_new[i]</tt> is either:
  54  *     - \c nstates_old if state \c i is removed because it is unreachable.
  55  *       Thus, remove all goto entries involving this state.
  56  *     - The new state number.
  57  */
  58 void lalr_update_state_numbers (state_number old_to_new[],
  59                                 state_number nstates_old);
  60
  61
  62 /** Release the information related to lookahead tokens.
  63
  64    Can be performed once the action tables are computed.  */
  65 void lalr_free (void);
  66
  67
  68 typedef size_t goto_number;
  69 # define GOTO_NUMBER_MAXIMUM ((goto_number) -1)
  70
  71 /** Index into #from_state and #to_state.
  72
  73    All the transitions that accept a particular variable are grouped
  74    together and GOTO_MAP[I - NTOKENS] is the index in FROM_STATE and
  75    TO_STATE of the first of them.  */
  76 extern goto_number *goto_map;
  77
  78 /** State number which a transition leads from. */
  79 extern state_number *from_state;
  80
  81 /** State number it leads to.  */
  82 extern state_number *to_state;
  83
  84
  85 #endif /* !LALR_H_ */