X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/2fa6973e6f491950d9b0345c1573888eed8e01d7..616429b50868bf9225d55143526442a024e32969:/src/LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index f0626fed..6a911f24 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,5 +1,5 @@
 /* Generate the nondeterministic finite state machine for bison,
-   Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc.
+   Copyright 1984, 1986, 1989, 2000, 2001  Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -23,69 +23,65 @@
    The entry point is generate_states.  */
 
 #include "system.h"
-#include "alloc.h"
+#include "symtab.h"
+#include "getargs.h"
+#include "reader.h"
 #include "gram.h"
 #include "state.h"
 #include "complain.h"
 #include "closure.h"
-
-extern char *nullable;
-extern short *itemset;
-extern short *itemsetend;
-
+#include "LR0.h"
+#include "lalr.h"
+#include "reduce.h"
 
 int nstates;
-int final_state;
-core *first_state;
-shifts *first_shift;
-reductions *first_reduction;
+/* Initialize the final state to -1, otherwise, it might be set to 0
+   by default, and since we don't compute the reductions of the final
+   state, we end up not computing the reductions of the initial state,
+   which is of course needed.
 
-extern void generate_states PARAMS ((void));
+   FINAL_STATE is properly set by new_state when it recognizes the
+   accessing symbol: EOF.  */
+int final_state = -1;
+static state_t *first_state = NULL;
 
-static core *this_state;
-static core *last_state;
-static shifts *last_shift;
-static reductions *last_reduction;
+static state_t *this_state = NULL;
+static state_t *last_state = NULL;
 
 static int nshifts;
-static short *shift_symbol;
+static short *shift_symbol = NULL;
 
-static short *redset;
-static short *shiftset;
+static short *redset = NULL;
+static short *shiftset = NULL;
 
-static short **kernel_base;
-static short **kernel_end;
-static short *kernel_items;
+static short **kernel_base = NULL;
+static int *kernel_size = NULL;
+static short *kernel_items = NULL;
 
 /* hash table for states, to recognize equivalent ones.  */
 
-#define	STATE_TABLE_SIZE	1009
-static core **state_table;
+#define	STATE_HASH_SIZE	1009
+static state_t **state_hash = NULL;
 
 
 static void
 allocate_itemsets (void)
 {
-  short *itemp;
-  int symbol;
   int i;
-  int count;
-  short *symbol_count;
 
-  count = 0;
-  symbol_count = NEW2 (nsyms, short);
+  /* 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);
 
-  itemp = ritem;
-  symbol = *itemp++;
-  while (symbol)
-    {
-      if (symbol > 0)
-	{
-	  count++;
-	  symbol_count[symbol]++;
-	}
-      symbol = *itemp++;
-    }
+  for (i = 0; i < nritems; ++i)
+    if (ritem[i] >= 0)
+      {
+	count++;
+	symbol_count[ritem[i]]++;
+      }
 
   /* See comments before new_itemsets.  All the vectors of items
      live inside KERNEL_ITEMS.  The number of active items after
@@ -93,8 +89,9 @@ allocate_itemsets (void)
      appears as an item, which is symbol_count[symbol].
      We allocate that much space for each symbol.  */
 
-  kernel_base = NEW2 (nsyms, short *);
-  kernel_items = NEW2 (count, short);
+  kernel_base = XCALLOC (short *, nsyms);
+  if (count)
+    kernel_items = XCALLOC (short, count);
 
   count = 0;
   for (i = 0; i < nsyms; i++)
@@ -103,8 +100,8 @@ allocate_itemsets (void)
       count += symbol_count[i];
     }
 
-  shift_symbol = symbol_count;
-  kernel_end = NEW2 (nsyms, short *);
+  free (symbol_count);
+  kernel_size = XCALLOC (int, nsyms);
 }
 
 
@@ -113,22 +110,23 @@ allocate_storage (void)
 {
   allocate_itemsets ();
 
-  shiftset = NEW2 (nsyms, short);
-  redset = NEW2 (nrules + 1, short);
-  state_table = NEW2 (STATE_TABLE_SIZE, core *);
+  shiftset = XCALLOC (short, nsyms);
+  redset = XCALLOC (short, nrules + 1);
+  state_hash = XCALLOC (state_t *, STATE_HASH_SIZE);
+  shift_symbol = XCALLOC (short, nsyms);
 }
 
 
 static void
 free_storage (void)
 {
-  FREE (shift_symbol);
-  FREE (redset);
-  FREE (shiftset);
-  FREE (kernel_base);
-  FREE (kernel_end);
-  FREE (kernel_items);
-  FREE (state_table);
+  free (shift_symbol);
+  free (redset);
+  free (shiftset);
+  free (kernel_base);
+  free (kernel_size);
+  XFREE (kernel_items);
+  free (state_hash);
 }
 
 
@@ -142,50 +140,38 @@ free_storage (void)
 | shift_symbol is set to a vector of the symbols that can be      |
 | shifted.  For each symbol in the grammar, kernel_base[symbol]   |
 | points to a vector of item numbers activated if that symbol is  |
-| shifted, and kernel_end[symbol] points after the end of that    |
-| vector.                                                         |
+| shifted, and kernel_size[symbol] is their numbers.              |
 `----------------------------------------------------------------*/
 
 static void
 new_itemsets (void)
 {
   int i;
-  int shiftcount;
-  short *isp;
-  short *ksp;
-  int symbol;
 
-#if TRACE
-  fprintf (stderr, "Entering new_itemsets\n");
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering new_itemsets, state = %d\n",
+	     this_state->number);
 
   for (i = 0; i < nsyms; i++)
-    kernel_end[i] = NULL;
-
-  shiftcount = 0;
+    kernel_size[i] = 0;
 
-  isp = itemset;
+  nshifts = 0;
 
-  while (isp < itemsetend)
+  for (i = 0; i < nitemset; ++i)
     {
-      i = *isp++;
-      symbol = ritem[i];
-      if (symbol > 0)
+      int symbol = ritem[itemset[i]];
+      if (symbol >= 0)
 	{
-	  ksp = kernel_end[symbol];
-
-	  if (!ksp)
+	  if (!kernel_size[symbol])
 	    {
-	      shift_symbol[shiftcount++] = symbol;
-	      ksp = kernel_base[symbol];
+	      shift_symbol[nshifts] = symbol;
+	      nshifts++;
 	    }
 
-	  *ksp++ = i + 1;
-	  kernel_end[symbol] = ksp;
+	  kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1;
+	  kernel_size[symbol]++;
 	}
     }
-
-  nshifts = shiftcount;
 }
 
 
@@ -195,41 +181,33 @@ new_itemsets (void)
 | necessary.                                                       |
 `-----------------------------------------------------------------*/
 
-static core *
+static state_t *
 new_state (int symbol)
 {
-  int n;
-  core *p;
-  short *isp1;
-  short *isp2;
-  short *iend;
+  state_t *p;
 
-#if TRACE
-  fprintf (stderr, "Entering new_state, symbol = %d\n", symbol);
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
+	     this_state->number, symbol, symbols[symbol]->tag);
 
   if (nstates >= MAXSHORT)
     fatal (_("too many states (max %d)"), MAXSHORT);
 
-  isp1 = kernel_base[symbol];
-  iend = kernel_end[symbol];
-  n = iend - isp1;
-
-  p =
-    (core *) xmalloc ((unsigned) (sizeof (core) + (n - 1) * sizeof (short)));
+  p = STATE_ALLOC (kernel_size[symbol]);
   p->accessing_symbol = symbol;
   p->number = nstates;
-  p->nitems = n;
+  p->nitems = kernel_size[symbol];
 
-  isp2 = p->items;
-  while (isp1 < iend)
-    *isp2++ = *isp1++;
+  shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]);
 
   last_state->next = p;
   last_state = p;
-
   nstates++;
 
+  /* If this is the eoftoken, then this is the final state. */
+  if (symbol == 0)
+    final_state = p->number;
+
   return p;
 }
 
@@ -237,54 +215,39 @@ new_state (int symbol)
 /*--------------------------------------------------------------.
 | Find the state number for the state we would get to (from the |
 | current state) by shifting symbol.  Create a new state if no  |
-| equivalent one exists already.  Used by append_states.         |
+| equivalent one exists already.  Used by append_states.        |
 `--------------------------------------------------------------*/
 
 static int
 get_state (int symbol)
 {
   int key;
-  short *isp1;
-  short *isp2;
-  short *iend;
-  core *sp;
-  int found;
-
-  int n;
-
-#if TRACE
-  fprintf (stderr, "Entering get_state, symbol = %d\n", symbol);
-#endif
+  int i;
+  state_t *sp;
 
-  isp1 = kernel_base[symbol];
-  iend = kernel_end[symbol];
-  n = iend - isp1;
+  if (trace_flag)
+    fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
+	     this_state->number, symbol, symbols[symbol]->tag);
 
-  /* add up the target state's active item numbers to get a hash key */
+  /* Add up the target state's active item numbers to get a hash key.
+     */
   key = 0;
-  while (isp1 < iend)
-    key += *isp1++;
-
-  key = key % STATE_TABLE_SIZE;
-
-  sp = state_table[key];
+  for (i = 0; i < kernel_size[symbol]; ++i)
+    key += kernel_base[symbol][i];
+  key = key % STATE_HASH_SIZE;
+  sp = state_hash[key];
 
   if (sp)
     {
-      found = 0;
+      int found = 0;
       while (!found)
 	{
-	  if (sp->nitems == n)
+	  if (sp->nitems == kernel_size[symbol])
 	    {
 	      found = 1;
-	      isp1 = kernel_base[symbol];
-	      isp2 = sp->items;
-
-	      while (found && isp1 < iend)
-		{
-		  if (*isp1++ != *isp2++)
-		    found = 0;
-		}
+	      for (i = 0; i < kernel_size[symbol]; ++i)
+		if (kernel_base[symbol][i] != sp->items[i])
+		  found = 0;
 	    }
 
 	  if (!found)
@@ -303,9 +266,12 @@ 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)
+    fprintf (stderr, "Exiting get_state => %d\n", sp->number);
+
   return sp->number;
 }
 
@@ -323,9 +289,9 @@ append_states (void)
   int j;
   int symbol;
 
-#if TRACE
-  fprintf (stderr, "Entering append_states\n");
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering append_states, state = %d\n",
+	     this_state->number);
 
   /* first sort shift_symbol into increasing order */
 
@@ -342,263 +308,28 @@ append_states (void)
     }
 
   for (i = 0; i < nshifts; i++)
-    {
-      symbol = shift_symbol[i];
-      shiftset[i] = get_state (symbol);
-    }
+    shiftset[i] = get_state (shift_symbol[i]);
 }
 
 
 static void
 new_states (void)
 {
-  core *p;
-
-  p = (core *) xmalloc ((unsigned) (sizeof (core) - sizeof (short)));
-  first_state = last_state = this_state = p;
+  first_state = last_state = this_state = STATE_ALLOC (0);
   nstates = 1;
 }
 
 
-static void
-save_shifts (void)
-{
-  shifts *p;
-  short *sp1;
-  short *sp2;
-  short *send;
-
-  p = (shifts *) xmalloc ((unsigned) (sizeof (shifts) +
-				      (nshifts - 1) * sizeof (short)));
-
-  p->number = this_state->number;
-  p->nshifts = nshifts;
-
-  sp1 = shiftset;
-  sp2 = p->shifts;
-  send = shiftset + nshifts;
-
-  while (sp1 < send)
-    *sp2++ = *sp1++;
-
-  if (last_shift)
-    {
-      last_shift->next = p;
-      last_shift = 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.      |
-`------------------------------------------------------------------*/
+/*------------------------------------------------------------.
+| Save the NSHIFTS of SHIFTSET into the current linked list.  |
+`------------------------------------------------------------*/
 
 static void
-insert_start_shift (void)
-{
-  core *statep;
-  shifts *sp;
-
-  statep = (core *) xmalloc ((unsigned) (sizeof (core) - sizeof (short)));
-  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 = NEW (shifts);
-  sp->number = nstates++;
-  sp->nshifts = 1;
-  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)
+save_shifts (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 *) xmalloc ((unsigned) (sizeof (shifts)
-							+
-							sp->nshifts *
-							sizeof (short)));
-		  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;
-		  FREE (sp);
-		}
-	      else
-		{
-		  sp2 = NEW (shifts);
-		  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;
-		}
-	    }
-	  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 *) xmalloc (sizeof (shifts)
-					+ sp->nshifts * sizeof (short));
-	      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.  */
-	      sp2->next = sp->next;
-	      first_shift = sp2;
-	      if (last_shift == sp)
-		last_shift = sp2;
-
-	      FREE (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 = NEW (shifts);
-	  sp->nshifts = 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 = NEW (shifts);
-      sp->nshifts = 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 *) xmalloc ((unsigned) (sizeof (core) - sizeof (short)));
-  statep->number = nstates;
-  last_state->next = statep;
-  last_state = statep;
-
-  /* Make the shift from the final state to the termination state.  */
-  sp = NEW (shifts);
-  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 *) xmalloc ((unsigned) (sizeof (core) - sizeof (short)));
-  statep->number = nstates++;
-  last_state->next = statep;
-  last_state = statep;
+  shifts *p = shifts_new (nshifts);
+  shortcpy (p->shifts, shiftset, nshifts);
+  this_state->shifts = p;
 }
 
 
@@ -611,56 +342,54 @@ augment_automaton (void)
 static void
 save_reductions (void)
 {
-  short *isp;
-  short *rp1;
-  short *rp2;
-  int item;
-  int count;
-  reductions *p;
+  int count = 0;
+  int i;
 
-  short *rend;
+  /* 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;
 
   /* 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;
     }
 
   /* 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)
-    {
-      p = (reductions *) xmalloc ((unsigned) (sizeof (reductions) +
-					      (count - 1) * sizeof (short)));
-
-      p->number = this_state->number;
-      p->nreds = count;
-
-      rp1 = redset;
-      rp2 = p->rules;
-      rend = rp1 + count;
+
+/*---------------.
+| Build STATES.  |
+`---------------*/
 
-      for (/* nothing */; rp1 < rend; ++rp1, ++rp2)
-	*rp2 = *rp1;
+static void
+set_states (void)
+{
+  state_t *sp;
+  states = XCALLOC (state_t *, nstates);
 
-      if (last_reduction)
-	{
-	  last_reduction->next = p;
-	  last_reduction = 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);
+
+      states[sp->number] = sp;
     }
 }
 
-
 /*-------------------------------------------------------------------.
 | Compute the nondeterministic finite state machine (see state.h for |
 | details) from the grammar.                                         |
@@ -670,11 +399,15 @@ void
 generate_states (void)
 {
   allocate_storage ();
-  new_closure (nitems);
+  new_closure (nritems);
   new_states ();
 
   while (this_state)
     {
+      if (trace_flag)
+	fprintf (stderr, "Processing state %d (reached by %s)\n",
+		 this_state->number,
+		 symbols[this_state->accessing_symbol]->tag);
       /* 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
@@ -689,8 +422,7 @@ 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;
@@ -700,6 +432,6 @@ generate_states (void)
   free_closure ();
   free_storage ();
 
-  /* set up initial and final states as parser wants them */
-  augment_automaton ();
+  /* Set up STATES. */
+  set_states ();
 }