* src/LR0.c (new_state): Recognize the final state by the fact it

[bison.git] / src / LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index ef5624d434a63f8296d5c2ebf813d637cdf2e734..c1a0a8c1f2544bf0d22476166f2eb48b93803495 100644 (file)
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -30,18 +30,15 @@
 #include "complain.h"
 #include "closure.h"
 #include "LR0.h"
 #include "complain.h"
 #include "closure.h"
 #include "LR0.h"

-
+#include "lalr.h"
+#include "reduce.h"

 
 int nstates;
 int final_state;
 
 int nstates;
 int final_state;

-core *first_state = NULL;
-shifts *first_shift = NULL;
-reductions *first_reduction = NULL;
+static state_t *first_state = NULL;

 
 

-static core *this_state = NULL;
-static core *last_state = NULL;
-static shifts *last_shift = NULL;
-static reductions *last_reduction = NULL;
+static state_t *this_state = NULL;
+static state_t *last_state = NULL;

 
 static int nshifts;
 static short *shift_symbol = NULL;
 
 static int nshifts;
 static short *shift_symbol = NULL;


@@ -55,22 +52,24 @@ static short *kernel_items = NULL;
 
 /* hash table for states, to recognize equivalent ones.  */
 
 
 /* hash table for states, to recognize equivalent ones.  */
 

-#define        STATE_TABLE_SIZE        1009
-static core **state_table = NULL;
+#define        STATE_HASH_SIZE 1009
+static state_t **state_hash = NULL;

 
 \f
 static void
 allocate_itemsets (void)
 {
   int i;
 
 \f
 static void
 allocate_itemsets (void)
 {
   int i;

-  int count;
-  short *symbol_count = NULL;

 
 

-  count = 0;
-  symbol_count = XCALLOC (short, nsyms);
+  /* Count the number of occurrences of all the symbols in RITEMS.
+     Note that useless productions (hence useless nonterminals) are
+     browsed too, hence we need to allocate room for _all_ the
+     symbols.  */
+  int count = 0;
+  short *symbol_count = XCALLOC (short, nsyms + nuseless_nonterminals);

 
 

-  for (i = 0; ritem[i]; ++i)
-    if (ritem[i] > 0)
+  for (i = 0; i < nritems; ++i)
+    if (ritem[i] >= 0)

       {
        count++;
        symbol_count[ritem[i]]++;
       {
        count++;
        symbol_count[ritem[i]]++;


@@ -93,7 +92,7 @@ allocate_itemsets (void)
       count += symbol_count[i];
     }
 
       count += symbol_count[i];
     }
 

-  shift_symbol = symbol_count;
+  free (symbol_count);

   kernel_size = XCALLOC (int, nsyms);
 }
 
   kernel_size = XCALLOC (int, nsyms);
 }
 


@@ -105,20 +104,20 @@ allocate_storage (void)
 
   shiftset = XCALLOC (short, nsyms);
   redset = XCALLOC (short, nrules + 1);
 
   shiftset = XCALLOC (short, nsyms);
   redset = XCALLOC (short, nrules + 1);

-  state_table = XCALLOC (core *, STATE_TABLE_SIZE);
+  state_hash = XCALLOC (state_t *, STATE_HASH_SIZE);

 }
 
 
 static void
 free_storage (void)
 {
 }
 
 
 static void
 free_storage (void)
 {

-  XFREE (shift_symbol);
-  XFREE (redset);
-  XFREE (shiftset);
-  XFREE (kernel_base);
-  XFREE (kernel_size);
+  free (shift_symbol);
+  free (redset);
+  free (shiftset);
+  free (kernel_base);
+  free (kernel_size);

   XFREE (kernel_items);
   XFREE (kernel_items);

-  XFREE (state_table);
+  free (state_hash);

 }
 
 
 }
 
 


@@ -139,7 +138,6 @@ static void
 new_itemsets (void)
 {
   int i;
 new_itemsets (void)
 {
   int i;

-  int shiftcount;

 
   if (trace_flag)
     fprintf (stderr, "Entering new_itemsets, state = %d\n",
 
   if (trace_flag)
     fprintf (stderr, "Entering new_itemsets, state = %d\n",


@@ -148,25 +146,24 @@ new_itemsets (void)
   for (i = 0; i < nsyms; i++)
     kernel_size[i] = 0;
 
   for (i = 0; i < nsyms; i++)
     kernel_size[i] = 0;
 

-  shiftcount = 0;
+  shift_symbol = XCALLOC (short, nsyms);
+  nshifts = 0;

 
 

-  for (i = 0; i < itemsetsize; ++i)
+  for (i = 0; i < nitemset; ++i)

     {
       int symbol = ritem[itemset[i]];
     {
       int symbol = ritem[itemset[i]];

-      if (symbol > 0)
+      if (symbol >= 0)

        {
          if (!kernel_size[symbol])
            {
        {
          if (!kernel_size[symbol])
            {

-             shift_symbol[shiftcount] = symbol;
-             shiftcount++;
+             shift_symbol[nshifts] = symbol;
+             nshifts++;

            }
 
          kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1;
          kernel_size[symbol]++;
        }
     }
            }
 
          kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1;
          kernel_size[symbol]++;
        }
     }

-
-  nshifts = shiftcount;

 }
 
 
 }
 
 


@@ -176,10 +173,10 @@ new_itemsets (void)
 | necessary.                                                       |
 `-----------------------------------------------------------------*/
 
 | necessary.                                                       |
 `-----------------------------------------------------------------*/
 

-static core *
+static state_t *

 new_state (int symbol)
 {
 new_state (int symbol)
 {

-  core *p;
+  state_t *p;

 
   if (trace_flag)
     fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
 
   if (trace_flag)
     fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",


@@ -188,7 +185,7 @@ new_state (int symbol)
   if (nstates >= MAXSHORT)
     fatal (_("too many states (max %d)"), MAXSHORT);
 
   if (nstates >= MAXSHORT)
     fatal (_("too many states (max %d)"), MAXSHORT);
 

-  p = CORE_ALLOC (kernel_size[symbol]);
+  p = STATE_ALLOC (kernel_size[symbol]);

   p->accessing_symbol = symbol;
   p->number = nstates;
   p->nitems = kernel_size[symbol];
   p->accessing_symbol = symbol;
   p->number = nstates;
   p->nitems = kernel_size[symbol];


@@ -199,6 +196,10 @@ new_state (int symbol)
   last_state = p;
   nstates++;
 
   last_state = p;
   nstates++;
 

+  /* If this is the eoftoken, then this is the final state. */
+  if (symbol == 0)
+    final_state = p->number;
+

   return p;
 }
 
   return p;
 }
 


@@ -214,7 +215,7 @@ get_state (int symbol)
 {
   int key;
   int i;
 {
   int key;
   int i;

-  core *sp;
+  state_t *sp;

 
   if (trace_flag)
     fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
 
   if (trace_flag)
     fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",


@@ -225,8 +226,8 @@ get_state (int symbol)
   key = 0;
   for (i = 0; i < kernel_size[symbol]; ++i)
     key += kernel_base[symbol][i];
   key = 0;
   for (i = 0; i < kernel_size[symbol]; ++i)
     key += kernel_base[symbol][i];

-  key = key % STATE_TABLE_SIZE;
-  sp = state_table[key];
+  key = key % STATE_HASH_SIZE;
+  sp = state_hash[key];

 
   if (sp)
     {
 
   if (sp)
     {


@@ -257,7 +258,7 @@ get_state (int symbol)
     }
   else                         /* bucket is empty */
     {
     }
   else                         /* bucket is empty */
     {

-      state_table[key] = sp = new_state (symbol);
+      state_hash[key] = sp = new_state (symbol);

     }
 
   if (trace_flag)
     }
 
   if (trace_flag)


@@ -306,24 +307,11 @@ append_states (void)
 static void
 new_states (void)
 {
 static void
 new_states (void)
 {

-  first_state = last_state = this_state = CORE_ALLOC (0);
+  first_state = last_state = this_state = STATE_ALLOC (0);

   nstates = 1;
 }
 
 
   nstates = 1;
 }
 
 

-/*---------------------------------.
-| Create a new array of N shitfs.  |
-`---------------------------------*/
-
-static shifts *
-shifts_new (int n)
-{
-  shifts *res = SHIFTS_ALLOC (n);
-  res->nshifts = n;
-  return res;
-}
-
-

 /*------------------------------------------------------------.
 | Save the NSHIFTS of SHIFTSET into the current linked list.  |
 `------------------------------------------------------------*/
 /*------------------------------------------------------------.
 | Save the NSHIFTS of SHIFTSET into the current linked list.  |
 `------------------------------------------------------------*/


@@ -332,213 +320,8 @@ static void
 save_shifts (void)
 {
   shifts *p = shifts_new (nshifts);
 save_shifts (void)
 {
   shifts *p = shifts_new (nshifts);

-
-  p->number = this_state->number;
-

   shortcpy (p->shifts, shiftset, nshifts);
   shortcpy (p->shifts, shiftset, nshifts);

-
-  if (last_shift)
-    last_shift->next = p;
-  else
-    first_shift = p;
-  last_shift = p;
-}
-
-
-/*------------------------------------------------------------------.
-| Subroutine of augment_automaton.  Create the next-to-final state, |
-| to which a shift has already been made in the initial state.      |
-`------------------------------------------------------------------*/
-
-static void
-insert_start_shift (void)
-{
-  core *statep;
-  shifts *sp;
-
-  statep = CORE_ALLOC (0);
-  statep->number = nstates;
-  statep->accessing_symbol = start_symbol;
-
-  last_state->next = statep;
-  last_state = statep;
-
-  /* Make a shift from this state to (what will be) the final state.  */
-  sp = shifts_new (1);
-  sp->number = nstates++;
-  sp->shifts[0] = nstates;
-
-  last_shift->next = sp;
-  last_shift = sp;
-}
-
-
-/*------------------------------------------------------------------.
-| Make sure that the initial state has a shift that accepts the     |
-| grammar's start symbol and goes to the next-to-final state, which |
-| has a shift going to the final state, which has a shift to the    |
-| termination state.  Create such states and shifts if they don't   |
-| happen to exist already.                                          |
-`------------------------------------------------------------------*/
-
-static void
-augment_automaton (void)
-{
-  int i;
-  int k;
-  core *statep;
-  shifts *sp;
-  shifts *sp2;
-  shifts *sp1 = NULL;
-
-  sp = first_shift;
-
-  if (sp)
-    {
-      if (sp->number == 0)
-       {
-         k = sp->nshifts;
-         statep = first_state->next;
-
-         /* The states reached by shifts from first_state are numbered 1...K.
-            Look for one reached by start_symbol.  */
-         while (statep->accessing_symbol < start_symbol
-                && statep->number < k)
-           statep = statep->next;
-
-         if (statep->accessing_symbol == start_symbol)
-           {
-             /* We already have a next-to-final state.
-                Make sure it has a shift to what will be the final state.  */
-             k = statep->number;
-
-             while (sp && sp->number < k)
-               {
-                 sp1 = sp;
-                 sp = sp->next;
-               }
-
-             if (sp && sp->number == k)
-               {
-                 sp2 = shifts_new (sp->nshifts + 1);
-                 sp2->number = k;
-                 sp2->shifts[0] = nstates;
-                 for (i = sp->nshifts; i > 0; i--)
-                   sp2->shifts[i] = sp->shifts[i - 1];
-
-                 /* Patch sp2 into the chain of shifts in place of sp,
-                    following sp1.  */
-                 sp2->next = sp->next;
-                 sp1->next = sp2;
-                 if (sp == last_shift)
-                   last_shift = sp2;
-                 XFREE (sp);
-               }
-             else
-               {
-                 sp2 = shifts_new (1);
-                 sp2->number = k;
-                 sp2->shifts[0] = nstates;
-
-                 /* Patch sp2 into the chain of shifts between sp1 and sp.  */
-                 sp2->next = sp;
-                 sp1->next = sp2;
-                 if (sp == 0)
-                   last_shift = sp2;
-               }
-           }
-         else
-           {
-             /* There is no next-to-final state as yet.  */
-             /* Add one more shift in first_shift,
-                going to the next-to-final state (yet to be made).  */
-             sp = first_shift;
-
-             sp2 = shifts_new (sp->nshifts + 1);
-
-             /* Stick this shift into the vector at the proper place.  */
-             statep = first_state->next;
-             for (k = 0, i = 0; i < sp->nshifts; k++, i++)
-               {
-                 if (statep->accessing_symbol > start_symbol && i == k)
-                   sp2->shifts[k++] = nstates;
-                 sp2->shifts[k] = sp->shifts[i];
-                 statep = statep->next;
-               }
-             if (i == k)
-               sp2->shifts[k++] = nstates;
-
-             /* Patch sp2 into the chain of shifts
-                in place of sp, at the beginning.  */
-             sp2->next = sp->next;
-             first_shift = sp2;
-             if (last_shift == sp)
-               last_shift = sp2;
-
-             XFREE (sp);
-
-             /* Create the next-to-final state, with shift to
-                what will be the final state.  */
-             insert_start_shift ();
-           }
-       }
-      else
-       {
-         /* The initial state didn't even have any shifts.
-            Give it one shift, to the next-to-final state.  */
-         sp = shifts_new (1);
-         sp->shifts[0] = nstates;
-
-         /* Patch sp into the chain of shifts at the beginning.  */
-         sp->next = first_shift;
-         first_shift = sp;
-
-         /* Create the next-to-final state, with shift to
-            what will be the final state.  */
-         insert_start_shift ();
-       }
-    }
-  else
-    {
-      /* There are no shifts for any state.
-         Make one shift, from the initial state to the next-to-final state.  */
-
-      sp = shifts_new (1);
-      sp->shifts[0] = nstates;
-
-      /* Initialize the chain of shifts with sp.  */
-      first_shift = sp;
-      last_shift = sp;
-
-      /* Create the next-to-final state, with shift to
-         what will be the final state.  */
-      insert_start_shift ();
-    }
-
-  /* Make the final state--the one that follows a shift from the
-     next-to-final state.
-     The symbol for that shift is 0 (end-of-file).  */
-  statep = CORE_ALLOC (0);
-  statep->number = nstates;
-  last_state->next = statep;
-  last_state = statep;
-
-  /* Make the shift from the final state to the termination state.  */
-  sp = shifts_new (1);
-  sp->number = nstates++;
-  sp->shifts[0] = nstates;
-  last_shift->next = sp;
-  last_shift = sp;
-
-  /* Note that the variable `final_state' refers to what we sometimes call
-     the termination state.  */
-  final_state = nstates;
-
-  /* Make the termination state.  */
-  statep = CORE_ALLOC (0);
-  statep->number = nstates++;
-  last_state->next = statep;
-  last_state = statep;
+  this_state->shifts = p;

 }
 
 
 }
 
 


@@ -551,13 +334,16 @@ augment_automaton (void)
 static void
 save_reductions (void)
 {
 static void
 save_reductions (void)
 {

-  int count;
+  int count = 0;

   int i;
 
   int i;
 

-  /* Find and count the active items that represent ends of rules. */
+  /* If this is the final state, we want it to have no reductions at
+     all, although it has one for `START_SYMBOL EOF .'.  */
+  if (this_state->number == final_state)
+    return;

 
 

-  count = 0;
-  for (i = 0; i < itemsetsize; ++i)
+  /* Find and count the active items that represent ends of rules. */
+  for (i = 0; i < nitemset; ++i)

     {
       int item = ritem[itemset[i]];
       if (item < 0)
     {
       int item = ritem[itemset[i]];
       if (item < 0)


@@ -565,25 +351,37 @@ save_reductions (void)
     }
 
   /* Make a reductions structure and copy the data into it.  */
     }
 
   /* Make a reductions structure and copy the data into it.  */

+  this_state->reductions = reductions_new (count);
+  shortcpy (this_state->reductions->rules, redset, count);
+}

 
 

-  if (count)
-    {
-      reductions *p = REDUCTIONS_ALLOC (count);
-
-      p->number = this_state->number;
-      p->nreds = count;
+\f
+/*--------------------.
+| Build STATE_TABLE.  |
+`--------------------*/

 
 

-      shortcpy (p->rules, redset, count);
+static void
+set_state_table (void)
+{
+  state_t *sp;
+  state_table = XCALLOC (state_t *, nstates);

 
 

-      if (last_reduction)
-       last_reduction->next = p;
-      else
-       first_reduction = p;
-      last_reduction = p;
+  for (sp = first_state; sp; sp = sp->next)
+    {
+      /* Pessimization, but simplification of the code: make sure all
+        the states have a shifts, errs, and reductions, even if
+        reduced to 0.  */
+      if (!sp->shifts)
+       sp->shifts = shifts_new (0);
+      if (!sp->errs)
+       sp->errs = errs_new (0);
+      if (!sp->reductions)
+       sp->reductions = reductions_new (0);
+
+      state_table[sp->number] = sp;

     }
 }
 
     }
 }
 

-\f

 /*-------------------------------------------------------------------.
 | Compute the nondeterministic finite state machine (see state.h for |
 | details) from the grammar.                                         |
 /*-------------------------------------------------------------------.
 | Compute the nondeterministic finite state machine (see state.h for |
 | details) from the grammar.                                         |


@@ -598,6 +396,9 @@ generate_states (void)
 
   while (this_state)
     {
 
   while (this_state)
     {

+      if (trace_flag)
+       fprintf (stderr, "Processing state %d (reached by %s)\n",
+                this_state->number, tags[this_state->accessing_symbol]);

       /* Set up ruleset and itemset for the transitions out of this
          state.  ruleset gets a 1 bit for each rule that could reduce
          now.  itemset gets a vector of all the items that could be
       /* Set up ruleset and itemset for the transitions out of this
          state.  ruleset gets a 1 bit for each rule that could reduce
          now.  itemset gets a vector of all the items that could be


@@ -612,8 +413,7 @@ generate_states (void)
 
       /* create the shifts structures for the shifts to those states,
          now that the state numbers transitioning to are known */
 
       /* create the shifts structures for the shifts to those states,
          now that the state numbers transitioning to are known */

-      if (nshifts > 0)
-       save_shifts ();
+      save_shifts ();

 
       /* states are queued when they are created; process them all */
       this_state = this_state->next;
 
       /* states are queued when they are created; process them all */
       this_state = this_state->next;


@@ -623,6 +423,6 @@ generate_states (void)
   free_closure ();
   free_storage ();
 
   free_closure ();
   free_storage ();
 

-  /* set up initial and final states as parser wants them */
-  augment_automaton ();
+  /* Set up STATE_TABLE. */
+  set_state_table ();

 }
 }