* NEWS (2.3a+): Mention yesterday's state-removal change.

[bison.git] / src / state.h

diff --git a/src/state.h b/src/state.h
index 6954d80335aca232b30a8718795c51c09e8414cf..e0aa6b75280fb14601e8c1102f240cec6c67e14b 100644 (file)
--- a/src/state.h
+++ b/src/state.h
@@ -1,6 +1,6 @@
 /* Type definitions for nondeterministic finite state machine for Bison.
 
-   Copyright (C) 1984, 1989, 2000, 2001, 2002, 2003, 2004 Free
+   Copyright (C) 1984, 1989, 2000, 2001, 2002, 2003, 2004, 2007 Free
    Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
@@ -17,8 +17,8 @@
 
    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.  */
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
 
 
 /* These type definitions are used to represent a nondeterministic
@@ -44,13 +44,13 @@
    ACCESSING_SYMBOL of the core.
 
    Each core contains a vector of NITEMS items which are the indices
-   in the RITEMS vector of the items that are selected in this state.
+   in the RITEM vector of the items that are selected in this state.
 
-   The two types of actions are shifts/gotos (push the look-ahead token
+   The two types of actions are shifts/gotos (push the lookahead token
    and read another/goto to the state designated by a nterm) and
    reductions (combine the last n things on the stack via a rule,
    replace them with the symbol that the rule derives, and leave the
-   look-ahead token alone).  When the states are generated, these
+   lookahead token alone).  When the states are generated, these
    actions are represented in two other lists.
 
    Each transition structure describes the possible transitions out
@@ -63,9 +63,8 @@
    deletes transitions by having them point to zero.
 
    Each reductions structure describes the possible reductions at the
-   state whose number is in the number field.  The data is a list of
-   nreds rules, represented by their rule numbers.  first_reduction
-   points to the list of these structures.
+   state whose number is in the number field.  rules is an array of
+   num rules.  lookahead_tokens is an array of bitsets, one per rule.
 
    Conflict resolution can decide that certain tokens in certain
    states should explicitly be errors (for implementing %nonassoc).
@@ -94,8 +93,8 @@
 | Numbering states.  |
 `-------------------*/
 
-typedef short int state_number;
-# define STATE_NUMBER_MAXIMUM SHRT_MAX
+typedef int state_number;
+# define STATE_NUMBER_MAXIMUM INT_MAX
 
 /* Be ready to map a state_number to an int.  */
 static inline int
@@ -113,7 +112,7 @@ typedef struct state state;
 
 typedef struct
 {
-  short int num;
+  int num;
   state *states[1];
 } transitions;
 
@@ -171,7 +170,7 @@ struct state *transitions_to (transitions *shifts, symbol_number sym);
 
 typedef struct
 {
-  short int num;
+  int num;
   symbol *symbols[1];
 } errs;
 
@@ -184,8 +183,8 @@ errs *errs_new (int num, symbol **tokens);
 
 typedef struct
 {
-  short int num;
-  bitset *look_ahead_tokens;
+  int num;
+  bitset *lookahead_tokens;
   rule *rules[1];
 } reductions;
 
@@ -203,16 +202,21 @@ struct state
   reductions *reductions;
   errs *errs;
 
-  /* Nonzero if no look-ahead is needed to decide what to do in state S.  */
+  /* Nonzero if no lookahead is needed to decide what to do in state S.  */
   char consistent;
 
   /* If some conflicts were solved thanks to precedence/associativity,
      a human readable description of the resolution.  */
   const char *solved_conflicts;
 
+  /* Conflict resolution sometimes makes states unreachable.  Initialized to 0
+     in state_new and then used by state_remove_unreachable_states after
+     conflicts_solve.  */
+  bool reachable;
+
   /* Its items.  Must be last, since ITEMS can be arbitrarily large.
      */
-  unsigned short int nitems;
+  size_t nitems;
   item_number items[1];
 };
 
@@ -234,9 +238,9 @@ int state_reduction_find (state *s, rule *r);
 /* Set the errs of STATE.  */
 void state_errs_set (state *s, int num, symbol **errors);
 
-/* Print on OUT all the look-ahead tokens such that this STATE wants to
+/* Print on OUT all the lookahead tokens such that this STATE wants to
    reduce R.  */
-void state_rule_look_ahead_tokens_print (state *s, rule *r, FILE *out);
+void state_rule_lookahead_tokens_print (state *s, rule *r, FILE *out);
 
 /* Create/destroy the states hash table.  */
 void state_hash_new (void);
@@ -249,9 +253,16 @@ state *state_hash_lookup (size_t core_size, item_number *core);
 /* Insert STATE in the state hash table.  */
 void state_hash_insert (state *s);
 
+/* Remove unreachable states, renumber remaining states, update NSTATES, and
+   write to OLD_TO_NEW a mapping of old state numbers to new state numbers such
+   that the old value of NSTATES is written as the new state number for removed
+   states.  The size of OLD_TO_NEW must be the old value of NSTATES.  */
+void state_remove_unreachable_states (state_number old_to_new[]);
+
 /* All the states, indexed by the state number.  */
 extern state **states;
 
 /* Free all the states.  */
 void states_free (void);
+
 #endif /* !STATE_H_ */