X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/b408954b40e74d85ee90544ea7e296dbc99356c9..ccdc1577ef7fb32a5e30cb655337e7cd42b98987:/src/LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index efe9589a..a757f006 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,101 +1,121 @@
-/* Generate the nondeterministic finite state machine for bison,
-   Copyright 1984, 1986, 1989, 2000, 2001, 2002  Free Software Foundation, Inc.
+/* Generate the LR(0) parser states for Bison.
+
+   Copyright (C) 1984, 1986, 1989, 2000-2002, 2004-2012 Free Software
+   Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
-   Bison is free software; you can redistribute it and/or modify
+   This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
 
-   Bison is distributed in the hope that it will be useful,
+   This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    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.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 
 /* See comments in state.h for the data structures that represent it.
    The entry point is generate_states.  */
 
+#include <config.h>
 #include "system.h"
-#include "bitset.h"
-#include "quotearg.h"
-#include "symtab.h"
-#include "gram.h"
+
+#include <bitset.h>
+
+#include "LR0.h"
+#include "closure.h"
+#include "complain.h"
 #include "getargs.h"
-#include "reader.h"
 #include "gram.h"
-#include "state.h"
-#include "complain.h"
-#include "closure.h"
-#include "LR0.h"
 #include "lalr.h"
+#include "reader.h"
 #include "reduce.h"
+#include "state.h"
+#include "symtab.h"
 
-unsigned int nstates = 0;
-/* 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.
+typedef struct state_list
+{
+  struct state_list *next;
+  state *state;
+} state_list;
 
-   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 state_list *first_state = NULL;
+static state_list *last_state = NULL;
 
-static state_t *this_state = NULL;
-static state_t *last_state = NULL;
 
-static int nshifts;
-static symbol_number_t *shift_symbol = NULL;
+/*------------------------------------------------------------------.
+| A state was just discovered from another state.  Queue it for     |
+| later examination, in order to find its transitions.  Return it.  |
+`------------------------------------------------------------------*/
+
+static state *
+state_list_append (symbol_number sym, size_t core_size, item_number *core)
+{
+  state_list *node = xmalloc (sizeof *node);
+  state *s = state_new (sym, core_size, core);
+
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n",
+             nstates, sym, symbols[sym]->tag);
+
+  node->next = NULL;
+  node->state = s;
 
-static short *redset = NULL;
-static short *shiftset = NULL;
+  if (!first_state)
+    first_state = node;
+  if (last_state)
+    last_state->next = node;
+  last_state = node;
 
-static item_number_t **kernel_base = NULL;
-static int *kernel_size = NULL;
-static item_number_t *kernel_items = NULL;
+  return s;
+}
+
+static int nshifts;
+static symbol_number *shift_symbol;
 
-/* hash table for states, to recognize equivalent ones.  */
+static rule **redset;
+static state **shiftset;
 
-#define	STATE_HASH_SIZE	1009
-static state_t **state_hash = NULL;
+static item_number **kernel_base;
+static int *kernel_size;
+static item_number *kernel_items;
 
 
 static void
 allocate_itemsets (void)
 {
-  int i, r;
-  item_number_t *rhsp;
+  symbol_number i;
+  rule_number r;
+  item_number *rhsp;
 
   /* 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);
+  size_t count = 0;
+  size_t *symbol_count = xcalloc (nsyms + nuseless_nonterminals,
+                                  sizeof *symbol_count);
 
-  for (r = 1; r < nrules + 1; ++r)
+  for (r = 0; r < nrules; ++r)
     for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
       {
-	count++;
-	symbol_count[*rhsp]++;
+        count++;
+        symbol_count[*rhsp]++;
       }
 
   /* See comments before new_itemsets.  All the vectors of items
      live inside KERNEL_ITEMS.  The number of active items after
-     some symbol cannot be more than the number of times that symbol
-     appears as an item, which is symbol_count[symbol].
+     some symbol S cannot be more than the number of times that S
+     appears as an item, which is SYMBOL_COUNT[S].
      We allocate that much space for each symbol.  */
 
-  kernel_base = XCALLOC (item_number_t *, nsyms);
-  if (count)
-    kernel_items = XCALLOC (item_number_t, count);
+  kernel_base = xnmalloc (nsyms, sizeof *kernel_base);
+  kernel_items = xnmalloc (count, sizeof *kernel_items);
 
   count = 0;
   for (i = 0; i < nsyms; i++)
@@ -105,7 +125,7 @@ allocate_itemsets (void)
     }
 
   free (symbol_count);
-  kernel_size = XCALLOC (int, nsyms);
+  kernel_size = xnmalloc (nsyms, sizeof *kernel_size);
 }
 
 
@@ -114,10 +134,10 @@ allocate_storage (void)
 {
   allocate_itemsets ();
 
-  shiftset = XCALLOC (short, nsyms);
-  redset = XCALLOC (short, nrules + 1);
-  state_hash = XCALLOC (state_t *, STATE_HASH_SIZE);
-  shift_symbol = XCALLOC (symbol_number_t, nsyms);
+  shiftset = xnmalloc (nsyms, sizeof *shiftset);
+  redset = xnmalloc (nrules, sizeof *redset);
+  state_hash_new ();
+  shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol);
 }
 
 
@@ -129,227 +149,116 @@ free_storage (void)
   free (shiftset);
   free (kernel_base);
   free (kernel_size);
-  XFREE (kernel_items);
-  free (state_hash);
+  free (kernel_items);
+  state_hash_free ();
 }
 
 
 
 
-/*----------------------------------------------------------------.
-| Find which symbols can be shifted in the current state, and for |
-| each one record which items would be active after that shift.   |
-| Uses the contents of itemset.                                   |
-|                                                                 |
-| 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_size[symbol] is their numbers.              |
-`----------------------------------------------------------------*/
+/*---------------------------------------------------------------.
+| Find which symbols can be shifted in S, and for each one       |
+| record which items would be active after that shift.  Uses the |
+| contents of itemset.                                           |
+|                                                                |
+| 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_size[symbol] is their numbers.             |
+|                                                                |
+| itemset is sorted on item index in ritem, which is sorted on   |
+| rule number.  Compute each kernel_base[symbol] with the same   |
+| sort.                                                          |
+`---------------------------------------------------------------*/
 
 static void
-new_itemsets (void)
+new_itemsets (state *s)
 {
-  int i;
+  size_t i;
 
-  if (trace_flag)
-    fprintf (stderr, "Entering new_itemsets, state = %d\n",
-	     this_state->number);
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Entering new_itemsets, state = %d\n", s->number);
 
-  for (i = 0; i < nsyms; i++)
-    kernel_size[i] = 0;
+  memset (kernel_size, 0, nsyms * sizeof *kernel_size);
 
   nshifts = 0;
 
-  for (i = 0; i < nritemset; ++i)
-    if (ritem[itemset[i]] >= 0)
+  for (i = 0; i < nitemset; ++i)
+    if (item_number_is_symbol_number (ritem[itemset[i]]))
       {
-	symbol_number_t symbol
-	  = item_number_as_symbol_number (ritem[itemset[i]]);
-	if (!kernel_size[symbol])
-	  {
-	    shift_symbol[nshifts] = symbol;
-	    nshifts++;
-	  }
-
-	kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1;
-	kernel_size[symbol]++;
+        symbol_number sym = item_number_as_symbol_number (ritem[itemset[i]]);
+        if (!kernel_size[sym])
+          {
+            shift_symbol[nshifts] = sym;
+            nshifts++;
+          }
+
+        kernel_base[sym][kernel_size[sym]] = itemset[i] + 1;
+        kernel_size[sym]++;
       }
 }
 
 
 
-/*-----------------------------------------------------------------.
-| Subroutine of get_state.  Create a new state for those items, if |
-| necessary.                                                       |
-`-----------------------------------------------------------------*/
-
-static state_t *
-new_state (symbol_number_t symbol, size_t core_size, item_number_t *core)
-{
-  state_t *p;
-
-  if (trace_flag)
-    fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
-	     nstates, symbol, quotearg_style (escape_quoting_style,
-					      symbols[symbol]->tag));
-
-  if (nstates >= SHRT_MAX)
-    fatal (_("too many states (max %d)"), SHRT_MAX);
-
-  p = STATE_ALLOC (core_size);
-  p->accessing_symbol = symbol;
-  p->number = nstates;
-  p->solved_conflicts = NULL;
-
-  p->nitems = core_size;
-  memcpy (p->items, core, core_size * sizeof (core[0]));
-
-  /* If this is the eoftoken, and this is not the initial state, then
-     this is the final state.  */
-  if (symbol == 0 && first_state)
-    final_state = p->number;
-
-  if (!first_state)
-    first_state = p;
-  if (last_state)
-    last_state->next = p;
-  last_state = p;
-
-  nstates++;
-
-  return p;
-}
-
-
 /*--------------------------------------------------------------.
-| 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.        |
+| Find the state we would get to (from the current state) by    |
+| shifting SYM.  Create a new state if no equivalent one exists |
+| already.  Used by append_states.                              |
 `--------------------------------------------------------------*/
 
-static int
-get_state (symbol_number_t symbol, size_t core_size, item_number_t *core)
+static state *
+get_state (symbol_number sym, size_t core_size, item_number *core)
 {
-  int key;
-  size_t i;
-  state_t *sp;
-
-  if (trace_flag)
-    fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
-	     this_state->number, symbol, quotearg_style (escape_quoting_style,
-					      symbols[symbol]->tag));
-
-  /* Add up the target state's active item numbers to get a hash key.
-     */
-  key = 0;
-  for (i = 0; i < core_size; ++i)
-    key += core[i];
-  key = key % STATE_HASH_SIZE;
-  sp = state_hash[key];
-
-  if (sp)
-    {
-      int found = 0;
-      while (!found)
-	{
-	  if (sp->nitems == core_size)
-	    {
-	      found = 1;
-	      for (i = 0; i < core_size; ++i)
-		if (core[i] != sp->items[i])
-		  found = 0;
-	    }
-
-	  if (!found)
-	    {
-	      if (sp->link)
-		{
-		  sp = sp->link;
-		}
-	      else		/* bucket exhausted and no match */
-		{
-		  sp = sp->link = new_state (symbol, core_size, core);
-		  found = 1;
-		}
-	    }
-	}
-    }
-  else				/* bucket is empty */
-    {
-      state_hash[key] = sp = new_state (symbol, core_size, core);
-    }
+  state *s;
+
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Entering get_state, symbol = %d (%s)\n",
+             sym, symbols[sym]->tag);
+
+  s = state_hash_lookup (core_size, core);
+  if (!s)
+    s = state_list_append (sym, core_size, core);
 
-  if (trace_flag)
-    fprintf (stderr, "Exiting get_state => %d\n", sp->number);
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Exiting get_state => %d\n", s->number);
 
-  return sp->number;
+  return s;
 }
 
-/*------------------------------------------------------------------.
-| Use the information computed by new_itemsets to find the state    |
-| numbers reached by each shift transition from the current state.  |
-|                                                                   |
-| shiftset is set up as a vector of state numbers of those states.  |
-`------------------------------------------------------------------*/
+/*---------------------------------------------------------------.
+| Use the information computed by new_itemsets to find the state |
+| numbers reached by each shift transition from S.               |
+|                                                                |
+| SHIFTSET is set up as a vector of those states.                |
+`---------------------------------------------------------------*/
 
 static void
-append_states (void)
+append_states (state *s)
 {
   int i;
-  int j;
-  symbol_number_t symbol;
 
-  if (trace_flag)
-    fprintf (stderr, "Entering append_states, state = %d\n",
-	     this_state->number);
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Entering append_states, state = %d\n", s->number);
 
-  /* first sort shift_symbol into increasing order */
+  /* First sort shift_symbol into increasing order.  */
 
   for (i = 1; i < nshifts; i++)
     {
-      symbol = shift_symbol[i];
-      j = i;
-      while (j > 0 && shift_symbol[j - 1] > symbol)
-	{
-	  shift_symbol[j] = shift_symbol[j - 1];
-	  j--;
-	}
-      shift_symbol[j] = symbol;
+      symbol_number sym = shift_symbol[i];
+      int j;
+      for (j = i; 0 < j && sym < shift_symbol[j - 1]; j--)
+        shift_symbol[j] = shift_symbol[j - 1];
+      shift_symbol[j] = sym;
     }
 
   for (i = 0; i < nshifts; i++)
     {
-      symbol = shift_symbol[i];
-      shiftset[i] = get_state (symbol,
-			       kernel_size[symbol], kernel_base[symbol]);
+      symbol_number sym = shift_symbol[i];
+      shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]);
     }
 }
 
 
-static void
-new_states (void)
-{
-  /* The 0 at the lhs is the index of the item of this initial rule.  */
-  kernel_base[0][0] = 0;
-  kernel_size[0] = 1;
-  this_state = new_state (0, kernel_size[0], kernel_base[0]);
-}
-
-
-/*------------------------------------------------------------.
-| Save the NSHIFTS of SHIFTSET into the current linked list.  |
-`------------------------------------------------------------*/
-
-static void
-save_shifts (void)
-{
-  shifts *p = shifts_new (nshifts);
-  memcpy (p->shifts, shiftset, nshifts * sizeof (shiftset[0]));
-  this_state->shifts = p;
-}
-
-
 /*----------------------------------------------------------------.
 | Find which rules can be used for reduction transitions from the |
 | current state and make a reductions structure for the state to  |
@@ -357,27 +266,30 @@ save_shifts (void)
 `----------------------------------------------------------------*/
 
 static void
-save_reductions (void)
+save_reductions (state *s)
 {
   int count = 0;
-  int i;
-
-  /* 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;
+  size_t i;
 
   /* Find and count the active items that represent ends of rules. */
-  for (i = 0; i < nritemset; ++i)
+  for (i = 0; i < nitemset; ++i)
     {
-      int item = ritem[itemset[i]];
-      if (item < 0)
-	redset[count++] = -item;
+      item_number item = ritem[itemset[i]];
+      if (item_number_is_rule_number (item))
+        {
+          rule_number r = item_number_as_rule_number (item);
+          redset[count++] = &rules[r];
+          if (r == 0)
+            {
+              /* This is "reduce 0", i.e., accept. */
+              aver (!final_state);
+              final_state = s;
+            }
+        }
     }
 
   /* Make a reductions structure and copy the data into it.  */
-  this_state->reductions = reductions_new (count);
-  memcpy (this_state->reductions->rules, redset, count * sizeof (redset[0]));
+  state_reductions_set (s, count, redset);
 }
 
 
@@ -388,62 +300,70 @@ save_reductions (void)
 static void
 set_states (void)
 {
-  state_t *sp;
-  states = XCALLOC (state_t *, nstates);
+  states = xcalloc (nstates, sizeof *states);
 
-  for (sp = first_state; sp; sp = sp->next)
+  while (first_state)
     {
+      state_list *this = first_state;
+
       /* 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;
+         the states have valid transitions and reductions members,
+         even if reduced to 0.  It is too soon for errs, which are
+         computed later, but set_conflicts.  */
+      state *s = this->state;
+      if (!s->transitions)
+        state_transitions_set (s, 0, 0);
+      if (!s->reductions)
+        state_reductions_set (s, 0, 0);
+
+      states[s->number] = s;
+
+      first_state = this->next;
+      free (this);
     }
+  first_state = NULL;
+  last_state = NULL;
 }
 
+
 /*-------------------------------------------------------------------.
-| Compute the nondeterministic finite state machine (see state.h for |
-| details) from the grammar.                                         |
+| Compute the LR(0) parser states (see state.h for details) from the |
+| grammar.                                                           |
 `-------------------------------------------------------------------*/
 
 void
 generate_states (void)
 {
+  item_number initial_core = 0;
+  state_list *list = NULL;
   allocate_storage ();
   new_closure (nritems);
-  new_states ();
 
-  while (this_state)
+  /* Create the initial state.  The 0 at the lhs is the index of the
+     item of this initial rule.  */
+  state_list_append (0, 1, &initial_core);
+
+  /* States are queued when they are created; process them all.  */
+  for (list = first_state; list; list = list->next)
     {
-      if (trace_flag)
-	fprintf (stderr, "Processing state %d (reached by %s)\n",
-		 this_state->number,
-		 quotearg_style (escape_quoting_style,
-				 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
-         accepted next.  */
-      closure (this_state->items, this_state->nitems);
-      /* record the reductions allowed out of this state */
-      save_reductions ();
-      /* find the itemsets of the states that shifts can reach */
-      new_itemsets ();
-      /* find or create the core structures for those states */
-      append_states ();
-
-      /* create the shifts structures for the shifts to those states,
-         now that the state numbers transitioning to are known */
-      save_shifts ();
-
-      /* states are queued when they are created; process them all */
-      this_state = this_state->next;
+      state *s = list->state;
+      if (trace_flag & trace_automaton)
+        fprintf (stderr, "Processing state %d (reached by %s)\n",
+                 s->number,
+                 symbols[s->accessing_symbol]->tag);
+      /* Set up itemset for the transitions out of this state.  itemset gets a
+         vector of all the items that could be accepted next.  */
+      closure (s->items, s->nitems);
+      /* Record the reductions allowed out of this state.  */
+      save_reductions (s);
+      /* Find the itemsets of the states that shifts can reach.  */
+      new_itemsets (s);
+      /* Find or create the core structures for those states.  */
+      append_states (s);
+
+      /* Create the shifts structures for the shifts to those states,
+         now that the state numbers transitioning to are known.  */
+      state_transitions_set (s, nshifts, shiftset);
     }
 
   /* discard various storage */