src/lalr.h

   1 /* Compute lookahead criteria for bison,
   2
   3    Copyright (C) 1984, 1986, 1989, 2000, 2002, 2004, 2006-2007,
   4    2009-2010 Free Software Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    This program 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 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef LALR_H_
  22 # define LALR_H_
  23
  24 # include <bitset.h>
  25 # include <bitsetv.h>
  26
  27 /* Import the definition of RULE_T. */
  28 # include "gram.h"
  29
  30 /* Import the definition of CORE, TRANSITIONS and REDUCTIONS. */
  31 # include "state.h"
  32
  33
  34 /** Build the LALR(1) automaton.
  35
  36    Compute how to make the finite state machine deterministic; find
  37    which rules need lookahead in each state, and which lookahead
  38    tokens they accept.
  39
  40    Builds:
  41    - #goto_map
  42    - #from_state
  43    - #to_state
  44 */
  45 void lalr (void);
  46
  47 /**
  48  * Update state numbers recorded in #goto_map, #from_state, and #to_state such
  49  * that:
  50  *   - \c nstates_old is the old number of states.
  51  *   - Where \c i is the old state number, <tt>old_to_new[i]</tt> is either:
  52  *     - \c nstates_old if state \c i is removed because it is unreachable.
  53  *       Thus, remove all goto entries involving this state.
  54  *     - The new state number.
  55  */
  56 void lalr_update_state_numbers (state_number old_to_new[],
  57                                 state_number nstates_old);
  58
  59
  60 /** Release the information related to lookahead tokens.
  61
  62    Can be performed once the action tables are computed.  */
  63 void lalr_free (void);
  64
  65
  66 typedef size_t goto_number;
  67 # define GOTO_NUMBER_MAXIMUM ((goto_number) -1)
  68
  69 /** Index into #from_state and #to_state.
  70
  71    All the transitions that accept a particular variable are grouped
  72    together and GOTO_MAP[I - NTOKENS] is the index in FROM_STATE and
  73    TO_STATE of the first of them.  */
  74 extern goto_number *goto_map;
  75
  76 /** State number which a transition leads from. */
  77 extern state_number *from_state;
  78
  79 /** State number it leads to.  */
  80 extern state_number *to_state;
  81
  82
  83 #endif /* !LALR_H_ */