X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/4a38e61393479c4c6006236205e42c9647a776ab..80e25d4d46e2f0745eea5658fa675a05a77dc68a:/src/LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index ef5624d4..a969abb4 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -30,18 +30,17 @@
 #include "complain.h"
 #include "closure.h"
 #include "LR0.h"
-
+#include "lalr.h"
+#include "reduce.h"
 
 int nstates;
 int final_state;
-core *first_state = NULL;
+state_t *first_state = 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 reductions *last_reduction = NULL;
 
 static int nshifts;
 static short *shift_symbol = NULL;
@@ -55,19 +54,21 @@ 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;
 
 
 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)
@@ -93,7 +94,7 @@ allocate_itemsets (void)
       count += symbol_count[i];
     }
 
-  shift_symbol = symbol_count;
+  free (symbol_count);
   kernel_size = XCALLOC (int, nsyms);
 }
 
@@ -105,20 +106,20 @@ allocate_storage (void)
 
   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)
 {
-  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 (state_table);
+  free (state_hash);
 }
 
 
@@ -139,7 +140,6 @@ static void
 new_itemsets (void)
 {
   int i;
-  int shiftcount;
 
   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;
 
-  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]];
       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]++;
 	}
     }
-
-  nshifts = shiftcount;
 }
 
 
@@ -176,10 +175,10 @@ new_itemsets (void)
 | necessary.                                                       |
 `-----------------------------------------------------------------*/
 
-static core *
+static state_t *
 new_state (int symbol)
 {
-  core *p;
+  state_t *p;
 
   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);
 
-  p = CORE_ALLOC (kernel_size[symbol]);
+  p = STATE_ALLOC (kernel_size[symbol]);
   p->accessing_symbol = symbol;
   p->number = nstates;
   p->nitems = kernel_size[symbol];
@@ -214,7 +213,7 @@ get_state (int symbol)
 {
   int key;
   int i;
-  core *sp;
+  state_t *sp;
 
   if (trace_flag)
     fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
@@ -225,8 +224,8 @@ get_state (int symbol)
   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)
     {
@@ -257,7 +256,7 @@ get_state (int symbol)
     }
   else				/* bucket is empty */
     {
-      state_table[key] = sp = new_state (symbol);
+      state_hash[key] = sp = new_state (symbol);
     }
 
   if (trace_flag)
@@ -306,24 +305,11 @@ append_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;
 }
 
 
-/*---------------------------------.
-| 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.  |
 `------------------------------------------------------------*/
@@ -334,8 +320,8 @@ save_shifts (void)
   shifts *p = shifts_new (nshifts);
 
   p->number = this_state->number;
-
   shortcpy (p->shifts, shiftset, nshifts);
+  this_state->shifts = p;
 
   if (last_shift)
     last_shift->next = p;
@@ -348,16 +334,26 @@ 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.      |
+|                                                                   |
+| 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
-insert_start_shift (void)
+insert_start_shifting_state (void)
 {
-  core *statep;
+  state_t *statep;
   shifts *sp;
 
-  statep = CORE_ALLOC (0);
+  statep = STATE_ALLOC (0);
   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;
@@ -365,6 +361,7 @@ insert_start_shift (void)
 
   /* Make a shift from this state to (what will be) the final state.  */
   sp = shifts_new (1);
+  statep->shifts = sp;
   sp->number = nstates++;
   sp->shifts[0] = nstates;
 
@@ -373,6 +370,62 @@ insert_start_shift (void)
 }
 
 
+/*-----------------------------------------------------------------.
+| 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->shifts[0] = nstates;
+
+  last_shift->next = sp;
+  last_shift = sp;
+}
+
+
+/*---------------------------------------------------------------.
+| 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 |
@@ -384,161 +437,132 @@ insert_start_shift (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_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;
-		}
+	      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_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.  */
+	  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;
-	      first_shift = sp2;
-	      if (last_shift == sp)
+	      sp1->next = sp2;
+	      if (sp == last_shift)
 		last_shift = sp2;
-
 	      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
 	{
-	  /* 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;
+	  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 sp into the chain of shifts at the beginning.  */
-	  sp->next = first_shift;
-	  first_shift = sp;
+	  /* 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 ();
+	  insert_start_shifting_state ();
 	}
     }
   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);
+      /* 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;
 
-      /* Initialize the chain of shifts with sp.  */
+      /* Patch sp into the chain of shifts at the beginning.  */
+      sp->next = first_shift;
       first_shift = sp;
-      last_shift = sp;
 
       /* 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_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;
+  insert_eof_shifting_state ();
+  insert_accepting_state ();
 }
 
 
@@ -557,7 +581,7 @@ save_reductions (void)
   /* Find and count the active items that represent ends of rules. */
 
   count = 0;
-  for (i = 0; i < itemsetsize; ++i)
+  for (i = 0; i < nitemset; ++i)
     {
       int item = ritem[itemset[i]];
       if (item < 0)
@@ -569,17 +593,10 @@ save_reductions (void)
   if (count)
     {
       reductions *p = REDUCTIONS_ALLOC (count);
-
-      p->number = this_state->number;
       p->nreds = count;
-
       shortcpy (p->rules, redset, count);
 
-      if (last_reduction)
-	last_reduction->next = p;
-      else
-	first_reduction = p;
-      last_reduction = p;
+      this_state->reductions = p;
     }
 }
 
@@ -598,6 +615,9 @@ generate_states (void)
 
   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
@@ -612,8 +632,7 @@ generate_states (void)
 
       /* create the shifts structures for the shifts to those states,
          now that the state numbers transitioning to are known */
-      if (nshifts > 0)
-	save_shifts ();
+      save_shifts ();
 
       /* states are queued when they are created; process them all */
       this_state = this_state->next;