X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/0e4d575330619dff7baab4fff77789773c7903b9..401aace63cef73a1f9ab6d217d5ece53bb816147:/src/lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 251878a0..65c55ab7 100644
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,6 +1,7 @@
-/* Compute look-ahead criteria for bison,
-   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002
-   Free Software Foundation, Inc.
+/* Compute look-ahead criteria for Bison.
+
+   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2003, 2004, 2005,
+   2006 Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -16,128 +17,121 @@
 
    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.  */
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
 
 
 /* Compute how to make the finite state machine deterministic; find
-   which rules need lookahead in each state, and which lookahead
+   which rules need look-ahead in each state, and which look-ahead
    tokens they accept.  */
 
+#include <config.h>
 #include "system.h"
-#include "bitset.h"
-#include "bitsetv.h"
-#include "relation.h"
-#include "quotearg.h"
-#include "symtab.h"
-#include "gram.h"
-#include "reader.h"
-#include "types.h"
+
+#include <bitset.h>
+#include <bitsetv.h>
+#include <quotearg.h>
+
 #include "LR0.h"
 #include "complain.h"
-#include "lalr.h"
-#include "nullable.h"
 #include "derives.h"
 #include "getargs.h"
+#include "gram.h"
+#include "lalr.h"
+#include "nullable.h"
+#include "reader.h"
+#include "relation.h"
+#include "symtab.h"
 
-rule_t **LArule = NULL;
-bitsetv LA = NULL;
-size_t nLA;
-
-static int ngotos;
-short *goto_map = NULL;
-state_number_t *from_state = NULL;
-state_number_t *to_state = NULL;
+goto_number *goto_map;
+static goto_number ngotos;
+state_number *from_state;
+state_number *to_state;
 
-/* And for the famous F variable, which name is so descriptive that a
-   comment is hardly needed.  <grin>.  */
-static bitsetv F = NULL;
+/* Linked list of goto numbers.  */
+typedef struct goto_list
+{
+  struct goto_list *next;
+  goto_number value;
+} goto_list;
 
-static short **includes;
-static shorts **lookback;
 
+/* LA is a LR by NTOKENS matrix of bits.  LA[l, i] is 1 if the rule
+   LArule[l] is applicable in the appropriate state when the next
+   token is symbol i.  If LA[l, i] and LA[l, j] are both 1 for i != j,
+   it is a conflict.  */
 
+static bitsetv LA = NULL;
+size_t nLA;
 
 
-static void
-initialize_LA (void)
-{
-  state_number_t i;
-  int j;
-  rule_t **np;
+/* And for the famous F variable, which name is so descriptive that a
+   comment is hardly needed.  <grin>.  */
+static bitsetv F = NULL;
 
-  /* Avoid having to special case 0.  */
-  if (!nLA)
-    nLA = 1;
+static goto_number **includes;
+static goto_list **lookback;
 
-  LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
-  LArule = XCALLOC (rule_t *, nLA);
-  lookback = XCALLOC (shorts *, nLA);
 
-  np = LArule;
-  for (i = 0; i < nstates; i++)
-    if (!states[i]->consistent)
-      for (j = 0; j < states[i]->reductions->nreds; j++)
-	*np++ = &rules[states[i]->reductions->rules[j]];
-}
 
 
 static void
 set_goto_map (void)
 {
-  state_number_t state;
-  short *temp_map;
+  state_number s;
+  goto_number *temp_map;
 
-  goto_map = XCALLOC (short, nvars + 1) - ntokens;
-  temp_map = XCALLOC (short, nvars + 1) - ntokens;
+  goto_map = xcalloc (nvars + 1, sizeof *goto_map);
+  temp_map = xnmalloc (nvars + 1, sizeof *temp_map);
 
   ngotos = 0;
-  for (state = 0; state < nstates; ++state)
+  for (s = 0; s < nstates; ++s)
     {
-      shifts_t *sp = states[state]->shifts;
+      transitions *sp = states[s]->transitions;
       int i;
-      for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
+      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
 	{
-	  if (ngotos == SHRT_MAX)
-	    fatal (_("too many gotos (max %d)"), SHRT_MAX);
-
 	  ngotos++;
-	  goto_map[SHIFT_SYMBOL (sp, i)]++;
+
+	  /* Abort if (ngotos + 1) would overflow.  */
+	  assert (ngotos != GOTO_NUMBER_MAXIMUM);
+
+	  goto_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;
 	}
     }
 
   {
-    int k = 0;
+    goto_number k = 0;
     int i;
     for (i = ntokens; i < nsyms; i++)
       {
-	temp_map[i] = k;
-	k += goto_map[i];
+	temp_map[i - ntokens] = k;
+	k += goto_map[i - ntokens];
       }
 
     for (i = ntokens; i < nsyms; i++)
-      goto_map[i] = temp_map[i];
+      goto_map[i - ntokens] = temp_map[i - ntokens];
 
-    goto_map[nsyms] = ngotos;
-    temp_map[nsyms] = ngotos;
+    goto_map[nsyms - ntokens] = ngotos;
+    temp_map[nsyms - ntokens] = ngotos;
   }
 
-  from_state = XCALLOC (state_number_t, ngotos);
-  to_state = XCALLOC (state_number_t, ngotos);
+  from_state = xcalloc (ngotos, sizeof *from_state);
+  to_state = xcalloc (ngotos, sizeof *to_state);
 
-  for (state = 0; state < nstates; ++state)
+  for (s = 0; s < nstates; ++s)
     {
-      shifts_t *sp = states[state]->shifts;
+      transitions *sp = states[s]->transitions;
       int i;
-      for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
+      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
 	{
-	  int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
-	  from_state[k] = state;
-	  to_state[k] = sp->shifts[i];
+	  goto_number k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;
+	  from_state[k] = s;
+	  to_state[k] = sp->states[i]->number;
 	}
     }
 
-  XFREE (temp_map + ntokens);
+  free (temp_map);
 }
 
 
@@ -146,67 +140,66 @@ set_goto_map (void)
 | Map a state/symbol pair into its numeric representation.  |
 `----------------------------------------------------------*/
 
-static int
-map_goto (state_number_t state, symbol_number_t symbol)
+static goto_number
+map_goto (state_number s0, symbol_number sym)
 {
-  int high;
-  int low;
-  int middle;
-  state_number_t s;
+  goto_number high;
+  goto_number low;
+  goto_number middle;
+  state_number s;
 
-  low = goto_map[symbol];
-  high = goto_map[symbol + 1] - 1;
+  low = goto_map[sym - ntokens];
+  high = goto_map[sym - ntokens + 1] - 1;
 
-  while (low <= high)
+  for (;;)
     {
+      assert (low <= high);
       middle = (low + high) / 2;
       s = from_state[middle];
-      if (s == state)
+      if (s == s0)
 	return middle;
-      else if (s < state)
+      else if (s < s0)
 	low = middle + 1;
       else
 	high = middle - 1;
     }
-
-  assert (0);
-  /* NOTREACHED */
-  return 0;
 }
 
 
 static void
 initialize_F (void)
 {
-  short **reads = XCALLOC (short *, ngotos);
-  short *edge = XCALLOC (short, ngotos + 1);
-  int nedges = 0;
+  goto_number **reads = xnmalloc (ngotos, sizeof *reads);
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  goto_number nedges = 0;
 
-  int i;
+  goto_number i;
 
   F = bitsetv_create (ngotos, ntokens, BITSET_FIXED);
 
   for (i = 0; i < ngotos; i++)
     {
-      state_number_t stateno = to_state[i];
-      shifts_t *sp = states[stateno]->shifts;
+      state_number stateno = to_state[i];
+      transitions *sp = states[stateno]->transitions;
 
       int j;
-      for (j = 0; j < sp->nshifts && SHIFT_IS_SHIFT (sp, j); j++)
-	bitset_set (F[i], SHIFT_SYMBOL (sp, j));
+      FOR_EACH_SHIFT (sp, j)
+	bitset_set (F[i], TRANSITION_SYMBOL (sp, j));
 
-      for (; j < sp->nshifts; j++)
+      for (; j < sp->num; j++)
 	{
-	  symbol_number_t symbol = SHIFT_SYMBOL (sp, j);
-	  if (nullable[symbol])
-	    edge[nedges++] = map_goto (stateno, symbol);
+	  symbol_number sym = TRANSITION_SYMBOL (sp, j);
+	  if (nullable[sym - ntokens])
+	    edge[nedges++] = map_goto (stateno, sym);
 	}
 
-      if (nedges)
+      if (nedges == 0)
+	reads[i] = NULL;
+      else
 	{
-	  reads[i] = XCALLOC (short, nedges + 1);
-	  memcpy (reads[i], edge, nedges * sizeof (edge[0]));
-	  reads[i][nedges] = -1;
+	  reads[i] = xnmalloc (nedges + 1, sizeof reads[i][0]);
+	  memcpy (reads[i], edge, nedges * sizeof edge[0]);
+	  reads[i][nedges] = END_NODE;
 	  nedges = 0;
 	}
     }
@@ -214,29 +207,21 @@ initialize_F (void)
   relation_digraph (reads, ngotos, &F);
 
   for (i = 0; i < ngotos; i++)
-    XFREE (reads[i]);
+    free (reads[i]);
 
-  XFREE (reads);
-  XFREE (edge);
+  free (reads);
+  free (edge);
 }
 
 
 static void
-add_lookback_edge (state_t *state, rule_number_t ruleno, int gotono)
+add_lookback_edge (state *s, rule *r, goto_number gotono)
 {
-  int i;
-  shorts *sp;
-
-  for (i = 0; i < state->nlookaheads; ++i)
-    if (state->lookaheads_rule[i]->number == ruleno)
-      break;
-
-  assert (state->lookaheads_rule[i]->number == ruleno);
-
-  sp = XCALLOC (shorts, 1);
-  sp->next = lookback[(state->lookaheads - LA) + i];
+  int ri = state_reduction_find (s, r);
+  goto_list *sp = xmalloc (sizeof *sp);
+  sp->next = lookback[(s->reductions->look_ahead_tokens - LA) + ri];
   sp->value = gotono;
-  lookback[(state->lookaheads - LA) + i] = sp;
+  lookback[(s->reductions->look_ahead_tokens - LA) + ri] = sp;
 }
 
 
@@ -244,66 +229,70 @@ add_lookback_edge (state_t *state, rule_number_t ruleno, int gotono)
 static void
 build_relations (void)
 {
-  short *edge = XCALLOC (short, ngotos + 1);
-  state_number_t *states1 = XCALLOC (state_number_t, ritem_longest_rhs () + 1);
-  int i;
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  state_number *states1 = xnmalloc (ritem_longest_rhs () + 1, sizeof *states1);
+  goto_number i;
 
-  includes = XCALLOC (short *, ngotos);
+  includes = xnmalloc (ngotos, sizeof *includes);
 
   for (i = 0; i < ngotos; i++)
     {
       int nedges = 0;
-      symbol_number_t symbol1 = states[to_state[i]]->accessing_symbol;
-      rule_number_t *rulep;
+      symbol_number symbol1 = states[to_state[i]]->accessing_symbol;
+      rule **rulep;
 
-      for (rulep = derives[symbol1]; *rulep > 0; rulep++)
+      for (rulep = derives[symbol1 - ntokens]; *rulep; rulep++)
 	{
-	  int done;
+	  bool done;
 	  int length = 1;
-	  item_number_t *rp;
-	  state_t *state = states[from_state[i]];
-	  states1[0] = state->number;
+	  item_number const *rp;
+	  state *s = states[from_state[i]];
+	  states1[0] = s->number;
 
-	  for (rp = rules[*rulep].rhs; *rp >= 0; rp++)
+	  for (rp = (*rulep)->rhs; ! item_number_is_rule_number (*rp); rp++)
 	    {
-	      state = shifts_to (state->shifts,
-				 item_number_as_symbol_number (*rp));
-	      states1[length++] = state->number;
+	      s = transitions_to (s->transitions,
+				  item_number_as_symbol_number (*rp));
+	      states1[length++] = s->number;
 	    }
 
-	  if (!state->consistent)
-	    add_lookback_edge (state, *rulep, i);
+	  if (!s->consistent)
+	    add_lookback_edge (s, *rulep, i);
 
 	  length--;
-	  done = 0;
+	  done = false;
 	  while (!done)
 	    {
-	      done = 1;
+	      done = true;
+	      /* Each rhs ends in an item number, and there is a
+		 sentinel before the first rhs, so it is safe to
+		 decrement RP here.  */
 	      rp--;
-	      /* JF added rp>=ritem &&   I hope to god its right! */
-	      if (rp >= ritem && ISVAR (*rp))
+	      if (ISVAR (*rp))
 		{
-		  /* Downcasting from item_number_t to symbol_number_t. */
+		  /* Downcasting from item_number to symbol_number.  */
 		  edge[nedges++] = map_goto (states1[--length],
 					     item_number_as_symbol_number (*rp));
-		  if (nullable[*rp])
-		    done = 0;
+		  if (nullable[*rp - ntokens])
+		    done = false;
 		}
 	    }
 	}
 
-      if (nedges)
+      if (nedges == 0)
+	includes[i] = NULL;
+      else
 	{
 	  int j;
-	  includes[i] = XCALLOC (short, nedges + 1);
+	  includes[i] = xnmalloc (nedges + 1, sizeof includes[i][0]);
 	  for (j = 0; j < nedges; j++)
 	    includes[i][j] = edge[j];
-	  includes[i][nedges] = -1;
+	  includes[i][nedges] = END_NODE;
 	}
     }
 
-  XFREE (edge);
-  XFREE (states1);
+  free (edge);
+  free (states1);
 
   relation_transpose (&includes, ngotos);
 }
@@ -313,22 +302,22 @@ build_relations (void)
 static void
 compute_FOLLOWS (void)
 {
-  int i;
+  goto_number i;
 
   relation_digraph (includes, ngotos, &F);
 
   for (i = 0; i < ngotos; i++)
-    XFREE (includes[i]);
+    free (includes[i]);
 
-  XFREE (includes);
+  free (includes);
 }
 
 
 static void
-compute_lookaheads (void)
+compute_look_ahead_tokens (void)
 {
   size_t i;
-  shorts *sp;
+  goto_list *sp;
 
   for (i = 0; i < nLA; i++)
     for (sp = lookback[i]; sp; sp = sp->next)
@@ -336,115 +325,139 @@ compute_lookaheads (void)
 
   /* Free LOOKBACK. */
   for (i = 0; i < nLA; i++)
-    LIST_FREE (shorts, lookback[i]);
+    LIST_FREE (goto_list, lookback[i]);
 
-  XFREE (lookback);
+  free (lookback);
   bitsetv_free (F);
 }
 
 
-/*-------------------------------------------------------------.
-| Count the number of lookaheads required for each state       |
-| (NLOOKAHEADS member).  Compute the total number of LA, NLA.  |
-`-------------------------------------------------------------*/
+/*-----------------------------------------------------.
+| Count the number of look-ahead tokens required for S |
+| (N_LOOK_AHEAD_TOKENS member).                        |
+`-----------------------------------------------------*/
 
-static void
-states_lookaheads_count (void)
+static int
+state_look_ahead_tokens_count (state *s)
 {
-  state_number_t i;
-  nLA = 0;
-
-  /* Count   */
-  for (i = 0; i < nstates; i++)
-    {
-      int k;
-      int nlookaheads = 0;
-      reductions_t *rp = states[i]->reductions;
-      shifts_t *sp = states[i]->shifts;
-
-      /* We need a lookahead either to distinguish different
-	 reductions (i.e., there are two or more), or to distinguish a
-	 reduction from a shift.  Otherwise, it is straightforward,
-	 and the state is `consistent'.  */
-      if (rp->nreds > 1
-	  || (rp->nreds == 1 && sp->nshifts && SHIFT_IS_SHIFT (sp, 0)))
-	nlookaheads += rp->nreds;
-      else
-	states[i]->consistent = 1;
-
-      for (k = 0; k < sp->nshifts; k++)
-	if (SHIFT_IS_ERROR (sp, k))
-	  {
-	    states[i]->consistent = 0;
-	    break;
-	  }
+  int k;
+  int n_look_ahead_tokens = 0;
+  reductions *rp = s->reductions;
+  transitions *sp = s->transitions;
+
+  /* We need a look-ahead either to distinguish different
+     reductions (i.e., there are two or more), or to distinguish a
+     reduction from a shift.  Otherwise, it is straightforward,
+     and the state is `consistent'.  */
+  if (rp->num > 1
+      || (rp->num == 1 && sp->num &&
+	  !TRANSITION_IS_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0)))
+    n_look_ahead_tokens += rp->num;
+  else
+    s->consistent = 1;
+
+  for (k = 0; k < sp->num; k++)
+    if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k))
+      {
+	s->consistent = 0;
+	break;
+      }
 
-      states[i]->nlookaheads = nlookaheads;
-      nLA += nlookaheads;
-    }
+  return n_look_ahead_tokens;
 }
 
 
-/*--------------------------------------.
-| Initializing the lookaheads members.  |
-`--------------------------------------*/
+/*-----------------------------------------------------.
+| Compute LA, NLA, and the look_ahead_tokens members.  |
+`-----------------------------------------------------*/
 
 static void
-states_lookaheads_initialize (void)
+initialize_LA (void)
 {
-  state_number_t i;
-  bitsetv pLA = LA;
-  rule_t **pLArule = LArule;
+  state_number i;
+  bitsetv pLA;
 
-  /* Initialize the members LOOKAHEADS and LOOKAHEADS_RULE for each
-     state.  */
+  /* Compute the total number of reductions requiring a look-ahead.  */
+  nLA = 0;
+  for (i = 0; i < nstates; i++)
+    nLA += state_look_ahead_tokens_count (states[i]);
+  /* Avoid having to special case 0.  */
+  if (!nLA)
+    nLA = 1;
+
+  pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
+  lookback = xcalloc (nLA, sizeof *lookback);
+
+  /* Initialize the members LOOK_AHEAD_TOKENS for each state whose reductions
+     require look-ahead tokens.  */
   for (i = 0; i < nstates; i++)
     {
-      states[i]->lookaheads = pLA;
-      states[i]->lookaheads_rule = pLArule;
-      pLA += states[i]->nlookaheads;
-      pLArule += states[i]->nlookaheads;
+      int count = state_look_ahead_tokens_count (states[i]);
+      if (count)
+	{
+	  states[i]->reductions->look_ahead_tokens = pLA;
+	  pLA += count;
+	}
     }
 }
 
 
-/*---------------------------------------.
-| Output the lookaheads for each state.  |
-`---------------------------------------*/
+/*----------------------------------------------.
+| Output the look-ahead tokens for each state.  |
+`----------------------------------------------*/
 
 static void
-lookaheads_print (FILE *out)
+look_ahead_tokens_print (FILE *out)
 {
-  state_number_t i;
+  state_number i;
   int j, k;
-  fprintf (out, "Lookaheads: BEGIN\n");
+  fprintf (out, "Look-ahead tokens: BEGIN\n");
   for (i = 0; i < nstates; ++i)
     {
-      fprintf (out, "State %d: %d lookaheads\n",
-	       i, states[i]->nlookaheads);
+      reductions *reds = states[i]->reductions;
+      bitset_iterator iter;
+      int n_look_ahead_tokens = 0;
+
+      if (reds->look_ahead_tokens)
+	for (k = 0; k < reds->num; ++k)
+	  if (reds->look_ahead_tokens[k])
+	    ++n_look_ahead_tokens;
+
+      fprintf (out, "State %d: %d look-ahead tokens\n",
+	       i, n_look_ahead_tokens);
 
-      for (j = 0; j < states[i]->nlookaheads; ++j)
-	for (k = 0; k < ntokens; ++k)
-	  if (bitset_test (states[i]->lookaheads[j], k))
+      if (reds->look_ahead_tokens)
+	for (j = 0; j < reds->num; ++j)
+	  BITSET_FOR_EACH (iter, reds->look_ahead_tokens[j], k, 0)
+	  {
 	    fprintf (out, "   on %d (%s) -> rule %d\n",
-		     k, symbol_tag_get (symbols[k]),
-		     states[i]->lookaheads_rule[j]->number - 1);
+		     k, symbols[k]->tag,
+		     reds->rules[j]->number);
+	  };
     }
-  fprintf (out, "Lookaheads: END\n");
+  fprintf (out, "Look-ahead tokens: END\n");
 }
 
 void
 lalr (void)
 {
-  states_lookaheads_count ();
   initialize_LA ();
-  states_lookaheads_initialize ();
   set_goto_map ();
   initialize_F ();
   build_relations ();
   compute_FOLLOWS ();
-  compute_lookaheads ();
+  compute_look_ahead_tokens ();
 
-  if (trace_flag)
-    lookaheads_print (stderr);
+  if (trace_flag & trace_sets)
+    look_ahead_tokens_print (stderr);
+}
+
+
+void
+lalr_free (void)
+{
+  state_number s;
+  for (s = 0; s < nstates; ++s)
+    states[s]->reductions->look_ahead_tokens = NULL;
+  bitsetv_free (LA);
 }