* src/LR0.c: Attach shifts to states as soon as they are

[bison.git] / src / LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index cecc0eae33fa7d5c6913dfbbbb098ba481d20d52..a969abb456c65fc086d8a1506f5678ee3ecedf05 100644 (file)
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -30,18 +30,17 @@
 #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;
+state_t *first_state = NULL;

 shifts *first_shift = NULL;
 shifts *first_shift = NULL;

-reductions *first_reduction = NULL;

 
 

-static core *this_state = NULL;
-static core *last_state = NULL;
+static state_t *this_state = NULL;
+static state_t *last_state = NULL;

 static shifts *last_shift = NULL;
 static shifts *last_shift = NULL;

-static reductions *last_reduction = NULL;

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


@@ -50,24 +49,26 @@ static short *redset = NULL;
 static short *shiftset = NULL;
 
 static short **kernel_base = NULL;
 static short *shiftset = NULL;
 
 static short **kernel_base = NULL;

-static size_t *kernel_size = NULL;
+static int *kernel_size = NULL;

 static short *kernel_items = NULL;
 
 /* hash table for states, to recognize equivalent ones.  */
 
 static short *kernel_items = NULL;
 
 /* 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; ritem[i]; ++i)
     if (ritem[i] > 0)


@@ -93,8 +94,8 @@ allocate_itemsets (void)
       count += symbol_count[i];
     }
 
       count += symbol_count[i];
     }
 

-  shift_symbol = symbol_count;
-  kernel_size = XCALLOC (size_t, nsyms);
+  free (symbol_count);
+  kernel_size = XCALLOC (int, nsyms);

 }
 
 
 }
 
 


@@ -105,20 +106,20 @@ 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 +140,6 @@ 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 +148,24 @@ 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 < itemsetend - itemset; ++i)
+  for (i = 0; i < nitemset; ++i)

     {
       int symbol = ritem[itemset[i]];
       if (symbol > 0)
        {
          if (!kernel_size[symbol])
            {
     {
       int symbol = ritem[itemset[i]];
       if (symbol > 0)
        {
          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 +175,10 @@ 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 +187,7 @@ 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];


@@ -213,9 +212,8 @@ static int
 get_state (int symbol)
 {
   int key;
 get_state (int symbol)
 {
   int key;

-  short *isp2;

   int i;
   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",


@@ -226,8 +224,8 @@ 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)
     {


@@ -236,7 +234,6 @@ get_state (int symbol)
        {
          if (sp->nitems == kernel_size[symbol])
            {
        {
          if (sp->nitems == kernel_size[symbol])
            {

-             int i;

              found = 1;
              for (i = 0; i < kernel_size[symbol]; ++i)
                if (kernel_base[symbol][i] != sp->items[i])
              found = 1;
              for (i = 0; i < kernel_size[symbol]; ++i)
                if (kernel_base[symbol][i] != sp->items[i])


@@ -259,7 +256,7 @@ 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)


@@ -308,20 +305,23 @@ 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;
 }
 
 

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

 static void
 save_shifts (void)
 {
 static void
 save_shifts (void)
 {

-  shifts *p = SHIFTS_ALLOC (nshifts);
+  shifts *p = shifts_new (nshifts);

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

-  p->nshifts = nshifts;
-

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

+  this_state->shifts = p;

 
   if (last_shift)
     last_shift->next = p;
 
   if (last_shift)
     last_shift->next = p;


@@ -334,25 +334,67 @@ save_shifts (void)
 /*------------------------------------------------------------------.
 | Subroutine of augment_automaton.  Create the next-to-final state, |
 | to which a shift has already been made in the initial state.      |
 /*------------------------------------------------------------------.
 | Subroutine of augment_automaton.  Create the next-to-final state, |
 | to which a shift has already been made in the initial state.      |

+|                                                                   |
+| The task of this state consists in shifting (actually, it's a     |
+| goto, but shifts and gotos are both stored in SHIFTS) the start   |
+| symbols, hence the name.                                          |

 `------------------------------------------------------------------*/
 
 static void
 `------------------------------------------------------------------*/
 
 static void

-insert_start_shift (void)
+insert_start_shifting_state (void)

 {
 {

-  core *statep;
+  state_t *statep;

   shifts *sp;
 
   shifts *sp;
 

-  statep = CORE_ALLOC (0);
+  statep = STATE_ALLOC (0);

   statep->number = nstates;
   statep->number = nstates;

+
+  /* The distinctive feature of this state from the
+     eof_shifting_state, is that it is labeled as post-start-symbol
+     shifting.  I fail to understand why this state, and the
+     post-start-start can't be merged into one.  But it does fail if
+     you try. --akim */

   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.  */
   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_ALLOC (1);
+  sp = shifts_new (1);
+  statep->shifts = sp;
+  sp->number = nstates++;
+  sp->shifts[0] = nstates;
+
+  last_shift->next = sp;
+  last_shift = sp;
+}
+
+
+/*-----------------------------------------------------------------.
+| Subroutine of augment_automaton.  Create the final state, which  |
+| shifts `0', the end of file.  The initial state shifts the start |
+| symbol, and goes to here.                                        |
+`-----------------------------------------------------------------*/
+
+static void
+insert_eof_shifting_state (void)
+{
+  state_t *statep;
+  shifts *sp;
+
+  /* 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 = STATE_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);
+  statep->shifts = sp;

   sp->number = nstates++;
   sp->number = nstates++;

-  sp->nshifts = 1;

   sp->shifts[0] = nstates;
 
   last_shift->next = sp;
   sp->shifts[0] = nstates;
 
   last_shift->next = sp;


@@ -360,6 +402,30 @@ insert_start_shift (void)
 }
 
 
 }
 
 

+/*---------------------------------------------------------------.
+| Subroutine of augment_automaton.  Create the accepting state.  |
+`---------------------------------------------------------------*/
+
+static void
+insert_accepting_state (void)
+{
+  state_t *statep;
+
+   /* Note that the variable `final_state' refers to what we sometimes
+      call the termination state.  */
+  final_state = nstates;
+
+  /* Make the termination state.  */
+  statep = STATE_ALLOC (0);
+  statep->number = nstates++;
+  last_state->next = statep;
+  last_state = statep;
+}
+
+
+
+
+

 /*------------------------------------------------------------------.
 | 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 |
 /*------------------------------------------------------------------.
 | 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 |


@@ -371,167 +437,132 @@ insert_start_shift (void)
 static void
 augment_automaton (void)
 {
 static void
 augment_automaton (void)
 {

-  int i;
-  int k;
-  core *statep;
-  shifts *sp;
-  shifts *sp2;
-  shifts *sp1 = NULL;
+  if (!first_shift->nshifts)
+    {
+      /* There are no shifts for any state.  Make one shift, from the
+        initial state to the next-to-final state.  */

 
 

-  sp = first_shift;
+      shifts *sp = shifts_new (1);
+      first_state->shifts = sp;
+      sp->shifts[0] = nstates;

 
 

-  if (sp)
+      /* 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_shifting_state ();
+    }
+  else if (first_shift->number == 0)

     {
     {

-      if (sp->number == 0)
+      state_t *statep = first_state->next;
+      shifts *sp = first_shift;
+      shifts *sp1 = NULL;
+      /* The states reached by shifts from FIRST_STATE are numbered
+        1..(SP->NSHIFTS).  Look for one reached by START_SYMBOL.  */
+      while (statep->accessing_symbol != start_symbol
+            && statep->number < sp->nshifts)
+       statep = statep->next;
+
+      if (statep->accessing_symbol == start_symbol)

        {
        {

-         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.  */
+         while (sp && sp->number < statep->number)

            {
            {

-             /* 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_ALLOC (sp->nshifts + 1);
-                 sp2->number = k;
-                 sp2->nshifts = sp->nshifts + 1;
-                 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_ALLOC (1);
-                 sp2->number = k;
-                 sp2->nshifts = 1;
-                 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;
-               }
+             sp1 = sp;
+             sp = sp->next;

            }
            }

-         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_ALLOC (sp->nshifts + 1);
-             sp2->nshifts = 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.  */
+         if (sp && sp->number == statep->number)
+           {
+             int i;
+             shifts *sp2 = shifts_new (sp->nshifts + 1);
+             sp2->number = statep->number;
+             statep->shifts = sp2;
+             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;
              sp2->next = sp->next;

-             first_shift = sp2;
-             if (last_shift == sp)
+             sp1->next = sp2;
+             if (sp == last_shift)

                last_shift = sp2;
                last_shift = sp2;

-

              XFREE (sp);
              XFREE (sp);

-
-             /* Create the next-to-final state, with shift to
-                what will be the final state.  */
-             insert_start_shift ();
+           }
+         else
+           {
+             shifts *sp2 = shifts_new (1);
+             sp2->number = statep->number;
+             statep->shifts = sp2;
+             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
        {
            }
        }
       else
        {

-         /* The initial state didn't even have any shifts.
-            Give it one shift, to the next-to-final state.  */
-         sp = SHIFTS_ALLOC (1);
-         sp->nshifts = 1;
-         sp->shifts[0] = nstates;
+         int i, k;
+         shifts *sp2;
+         sp = first_shift;
+
+         /* 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).  */
+         sp2 = shifts_new (sp->nshifts + 1);
+         first_state->shifts = sp2;
+         /* 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;

 
 

-         /* Patch sp into the chain of shifts at the beginning.  */
-         sp->next = first_shift;
-         first_shift = sp;
+         XFREE (sp);

 
          /* Create the next-to-final state, with shift to
             what will be the final state.  */
 
          /* Create the next-to-final state, with shift to
             what will be the final state.  */

-         insert_start_shift ();
+         insert_start_shifting_state ();

        }
     }
   else
     {
        }
     }
   else
     {

-      /* There are no shifts for any state.
-         Make one shift, from the initial state to the next-to-final state.  */
-
-      sp = SHIFTS_ALLOC (1);
-      sp->nshifts = 1;
+      /* The initial state didn't even have any shifts.
+        Give it one shift, to the next-to-final state.  */
+      shifts *sp = shifts_new (1);
+      first_state->shifts = sp;

       sp->shifts[0] = nstates;
 
       sp->shifts[0] = nstates;
 

-      /* Initialize the chain of shifts with sp.  */
+      /* Patch sp into the chain of shifts at the beginning.  */
+      sp->next = first_shift;

       first_shift = sp;
       first_shift = sp;

-      last_shift = sp;

 
       /* Create the next-to-final state, with shift to
 
       /* Create the next-to-final state, with shift to

-         what will be the final state.  */
-      insert_start_shift ();
+        what will be the final state.  */
+      insert_start_shifting_state ();

     }
 
     }
 

-  /* 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_ALLOC (1);
-  sp->number = nstates++;
-  sp->nshifts = 1;
-  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;
+  insert_eof_shifting_state ();
+  insert_accepting_state ();

 }
 
 
 }
 
 


@@ -544,19 +575,15 @@ augment_automaton (void)
 static void
 save_reductions (void)
 {
 static void
 save_reductions (void)
 {

-  short *isp;
-  int item;

   int count;
   int count;

-  reductions *p;
-
-  short *rend;
+  int i;

 
   /* Find and count the active items that represent ends of rules. */
 
   count = 0;
 
   /* Find and count the active items that represent ends of rules. */
 
   count = 0;

-  for (isp = itemset; isp < itemsetend; isp++)
+  for (i = 0; i < nitemset; ++i)

     {
     {

-      item = ritem[*isp];
+      int item = ritem[itemset[i]];

       if (item < 0)
        redset[count++] = -item;
     }
       if (item < 0)
        redset[count++] = -item;
     }


@@ -565,18 +592,11 @@ save_reductions (void)
 
   if (count)
     {
 
   if (count)
     {

-      p = REDUCTIONS_ALLOC (count);
-
-      p->number = this_state->number;
+      reductions *p = REDUCTIONS_ALLOC (count);

       p->nreds = count;
       p->nreds = count;

-

       shortcpy (p->rules, redset, count);
 
       shortcpy (p->rules, redset, count);
 

-      if (last_reduction)
-       last_reduction->next = p;
-      else
-       first_reduction = p;
-      last_reduction = p;
+      this_state->reductions = p;

     }
 }
 
     }
 }
 


@@ -595,6 +615,9 @@ 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


@@ -609,8 +632,7 @@ 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;