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[bison.git] / src / lalr.h

diff --git a/src/lalr.h b/src/lalr.h
index b09db9b69372280a9c2e5fd108b69e3f76091a3a..c65c9b48803ad79d079d2c0cb8f11ffaabf0e8af 100644 (file)
--- a/src/lalr.h
+++ b/src/lalr.h
@@ -1,24 +1,22 @@
-/* Compute look-ahead criteria for bison,
+/* Compute lookahead criteria for bison,
 
-   Copyright (C) 1984, 1986, 1989, 2000, 2002, 2004 Free Software
+   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_
@@ -32,34 +30,53 @@
 /* Import the definition of CORE, TRANSITIONS and REDUCTIONS. */
 # include "state.h"
 
-/* Compute how to make the finite state machine deterministic; find
-   which rules need look-ahead in each state, and which look-ahead
-   tokens they accept.  */
 
+/** Build the LALR(1) automaton.
+
+   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);
 
-/* Release the information related to look-ahead tokens.  Can be performed
-   once the action tables are computed.  */
+/**
+ * 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);
 
-void lalr_free (void);
 
+/** Release the information related to lookahead tokens.
+
+   Can be performed once the action tables are computed.  */
+void lalr_free (void);
 
-/* lalr() builds these data structures. */
 
-/* GOTO_MAP, FROM_STATE and TO_STATE -- record each shift transition
-   which accepts a variable (a nonterminal).
+typedef size_t goto_number;
+# define GOTO_NUMBER_MAXIMUM ((goto_number) -1)
 
-   FROM_STATE[T] -- state number which a transition leads from.
-   TO_STATE[T] -- state number it leads to.
+/** Index into #from_state and #to_state.
 
    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.  */
-
-typedef size_t goto_number;
-
 extern goto_number *goto_map;
+
+/** State number which a transition leads from. */
 extern state_number *from_state;
+
+/** State number it leads to.  */
 extern state_number *to_state;