Avoid empty-if warnings.

[bison.git] / src / lalr.h

diff --git a/src/lalr.h b/src/lalr.h
index 3bece77cc0a8f315458d3bf907c16db60c1858e6..c65c9b48803ad79d079d2c0cb8f11ffaabf0e8af 100644 (file)
--- a/src/lalr.h
+++ b/src/lalr.h
@@ -1,74 +1,83 @@
-/* Compute look-ahead criteria for bison,
-   Copyright (C) 1984, 1986, 1989, 2000, 2002 Free Software Foundation, Inc.
+/* Compute lookahead criteria for bison,
+
+   Copyright (C) 1984, 1986, 1989, 2000, 2002, 2004, 2006, 2007 Free Software
+   Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
-   Bison is free software; you can redistribute it and/or modify
+   This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
 
-   Bison is distributed in the hope that it will be useful,
+   This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with Bison; see the file COPYING.  If not, write to
-   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-   Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #ifndef LALR_H_
 # define LALR_H_
 
-#include "bitset.h"
-#include "bitsetv.h"
+# include <bitset.h>
+# include <bitsetv.h>
+
+/* Import the definition of RULE_T. */
+# include "gram.h"
 
 /* Import the definition of CORE, TRANSITIONS and REDUCTIONS. */
 # include "state.h"
 
-/* Import the definition of RULE_T. */
-# include "gram.h"
 
-/* Compute how to make the finite state machine deterministic; find
-   which rules need lookahead in each state, and which lookahead
-   tokens they accept.  */
+/** Build the LALR(1) automaton.
 
-void lalr PARAMS ((void));
+   Compute how to make the finite state machine deterministic; find
+   which rules need lookahead in each state, and which lookahead
+   tokens they accept.
 
+   Builds:
+   - #goto_map
+   - #from_state
+   - #to_state
+*/
+void lalr (void);
 
-/* lalr() builds these data structures. */
+/**
+ * Update state numbers recorded in #goto_map, #from_state, and #to_state such
+ * that:
+ *   - \c nstates_old is the old number of states.
+ *   - Where \c i is the old state number, <tt>old_to_new[i]</tt> is either:
+ *     - \c nstates_old if state \c i is removed because it is unreachable.
+ *       Thus, remove all goto entries involving this state.
+ *     - The new state number.
+ */
+void lalr_update_state_numbers (state_number old_to_new[],
+                                state_number nstates_old);
 
-/* GOTO_MAP, FROM_STATE and TO_STATE -- record each shift transition
-   which accepts a variable (a nonterminal).
 
-   FROM_STATE[T] -- state number which a transition leads from.
-   TO_STATE[T] -- state number it leads to.
+/** Release the information related to lookahead tokens.
 
-   All the transitions that accept a particular variable are grouped
-   together and GOTO_MAP[I - NTOKENS] is the index in FROM_STATE and
-   TO_STATE of the first of them.  */
+   Can be performed once the action tables are computed.  */
+void lalr_free (void);
 
-extern short *goto_map;
-extern state_number_t *from_state;
-extern state_number_t *to_state;
 
-/* LARULE is a vector which records the rules that need lookahead in
-   various states.  The elements of LARULE that apply to state S are
-   those from LOOKAHEADS[S] through LOOKAHEADS[S+1]-1.
+typedef size_t goto_number;
+# define GOTO_NUMBER_MAXIMUM ((goto_number) -1)
 
-   If LR is the length of LArule, then a number from 0 to LR-1 can
-   specify both a rule and a state where the rule might be applied.
-   */
+/** Index into #from_state and #to_state.
 
-extern rule_t **LArule;
+   All the transitions that accept a particular variable are grouped
+   together and GOTO_MAP[I - NTOKENS] is the index in FROM_STATE and
+   TO_STATE of the first of them.  */
+extern goto_number *goto_map;
 
-/* LA is a LR by NTOKENS matrix of bits.  LA[l, i] is 1 if the rule
-   LAruleno[l] is applicable in the appropriate state when the next
-   token is symbol i.  If LA[l, i] and LA[l, j] are both 1 for i != j,
-   it is a conflict.  */
+/** State number which a transition leads from. */
+extern state_number *from_state;
 
-extern bitsetv LA;
+/** State number it leads to.  */
+extern state_number *to_state;
 
 
 #endif /* !LALR_H_ */