X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/13ca549a750537731955700f92ea2b9288eb3020..0fb1ffb1bfede38666fbc3a4b1e253b473bd6d7d:/src/lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 3851350b..87e91cd5 100644
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -24,8 +24,11 @@
    tokens they accept.  */
 
 #include "system.h"
+#include "bitset.h"
+#include "reader.h"
 #include "types.h"
 #include "LR0.h"
+#include "symtab.h"
 #include "gram.h"
 #include "complain.h"
 #include "lalr.h"
@@ -34,22 +37,21 @@
 #include "getargs.h"
 
 /* All the decorated states, indexed by the state number.  */
-state_t **state_table = NULL;
+state_t **states = NULL;
 
 int tokensetsize;
-short *LAruleno;
-unsigned *LA;
+short *LAruleno = NULL;
+bitset *LA = NULL;
 size_t nLA;
 
 static int ngotos;
-short *goto_map;
-short *from_state;
-short *to_state;
+short *goto_map = NULL;
+short *from_state = NULL;
+short *to_state = NULL;
 
 /* And for the famous F variable, which name is so descriptive that a
    comment is hardly needed.  <grin>.  */
-static unsigned *F = NULL;
-#define F(Rule)  (F + (Rule) * tokensetsize)
+static bitset *F = NULL;
 
 static short **includes;
 static shorts **lookback;
@@ -72,9 +74,7 @@ static void
 traverse (int i)
 {
   int j;
-  size_t k;
   int height;
-  size_t size = F (i + 1) - F(i);
 
   VERTICES[++top] = i;
   INDEX[i] = height = top;
@@ -88,8 +88,7 @@ traverse (int i)
 	if (INDEX[i] > INDEX[R[i][j]])
 	  INDEX[i] = INDEX[R[i][j]];
 
-	for (k = 0; k < size; ++k)
-	  F (i)[k] |= F (R[i][j])[k];
+	bitset_or (F[i], F[i], F[R[i][j]]);
       }
 
   if (INDEX[i] == height)
@@ -101,8 +100,7 @@ traverse (int i)
 	if (i == j)
 	  break;
 
-	for (k = 0; k < size; ++k)
-	  F (j)[k] = F (i)[k];
+	bitset_copy (F[j], F[i]);
       }
 }
 
@@ -134,32 +132,36 @@ digraph (short **relation)
 static void
 initialize_LA (void)
 {
-  int i;
+  size_t i;
   int j;
   short *np;
-  reductions *rp;
 
   /* Avoid having to special case 0.  */
   if (!nLA)
     nLA = 1;
 
-  LA = XCALLOC (unsigned, nLA * tokensetsize);
+  LA = XCALLOC (bitset, nLA);
+  for (i = 0; i < nLA; ++i)
+    {
+      LA[i] = bitset_create (ntokens, BITSET_FIXED);
+      bitset_zero (LA[i]);
+    }
   LAruleno = XCALLOC (short, nLA);
   lookback = XCALLOC (shorts *, nLA);
 
   np = LAruleno;
   for (i = 0; i < nstates; i++)
-    if (!state_table[i]->consistent)
-      if ((rp = state_table[i]->reductions))
-	for (j = 0; j < rp->nreds; j++)
-	  *np++ = rp->rules[j];
+    if (!states[i]->consistent)
+      for (j = 0; j < states[i]->reductions->nreds; j++)
+	*np++ = states[i]->reductions->rules[j];
 }
 
 
 static void
 set_goto_map (void)
 {
-  int state, i;
+  size_t state;
+  int i;
   short *temp_map;
 
   goto_map = XCALLOC (short, nvars + 1) - ntokens;
@@ -168,7 +170,7 @@ set_goto_map (void)
   ngotos = 0;
   for (state = 0; state < nstates; ++state)
     {
-      shifts *sp = state_table[state]->shifts;
+      shifts *sp = states[state]->shifts;
       for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
 	{
 	  if (ngotos == MAXSHORT)
@@ -199,7 +201,7 @@ set_goto_map (void)
 
   for (state = 0; state < nstates; ++state)
     {
-      shifts *sp = state_table[state]->shifts;
+      shifts *sp = states[state]->shifts;
       for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
 	{
 	  int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
@@ -255,16 +257,21 @@ initialize_F (void)
 
   int i;
 
-  F = XCALLOC (unsigned, ngotos * tokensetsize);
+  F = XCALLOC (bitset, ngotos);
+  for (i = 0; i < ngotos; ++i)
+    {
+      F[i] = bitset_create (ntokens, BITSET_FIXED);
+      bitset_zero (F[i]);
+    }
 
   for (i = 0; i < ngotos; i++)
     {
       int stateno = to_state[i];
-      shifts *sp = state_table[stateno]->shifts;
+      shifts *sp = states[stateno]->shifts;
 
       int j;
       for (j = 0; j < sp->nshifts && SHIFT_IS_SHIFT (sp, j); j++)
-	SETBIT (F (i), SHIFT_SYMBOL (sp, j));
+	bitset_set (F[i], SHIFT_SYMBOL (sp, j));
 
       for (; j < sp->nshifts; j++)
 	{
@@ -401,7 +408,7 @@ static void
 build_relations (void)
 {
   short *edge = XCALLOC (short, ngotos + 1);
-  short *states = XCALLOC (short, ritem_longest_rhs () + 1);
+  short *states1 = XCALLOC (short, ritem_longest_rhs () + 1);
   int i;
 
   includes = XCALLOC (short *, ngotos);
@@ -409,7 +416,7 @@ build_relations (void)
   for (i = 0; i < ngotos; i++)
     {
       int nedges = 0;
-      int symbol1 = state_table[to_state[i]]->accessing_symbol;
+      int symbol1 = states[to_state[i]]->accessing_symbol;
       short *rulep;
 
       for (rulep = derives[symbol1]; *rulep > 0; rulep++)
@@ -417,21 +424,21 @@ build_relations (void)
 	  int done;
 	  int length = 1;
 	  short *rp;
-	  state_t *state = state_table[from_state[i]];
-	  states[0] = state->number;
+	  state_t *state = states[from_state[i]];
+	  states1[0] = state->number;
 
-	  for (rp = ritem + rule_table[*rulep].rhs; *rp > 0; rp++)
+	  for (rp = &ritem[rules[*rulep].rhs]; *rp >= 0; rp++)
 	    {
 	      shifts *sp = state->shifts;
 	      int j;
 	      for (j = 0; j < sp->nshifts; j++)
 		{
-		  state = state_table[sp->shifts[j]];
+		  state = states[sp->shifts[j]];
 		  if (state->accessing_symbol == *rp)
 		    break;
 		}
 
-	      states[length++] = state->number;
+	      states1[length++] = state->number;
 	    }
 
 	  if (!state->consistent)
@@ -446,7 +453,7 @@ build_relations (void)
 	      /* JF added rp>=ritem &&   I hope to god its right! */
 	      if (rp >= ritem && ISVAR (*rp))
 		{
-		  edge[nedges++] = map_goto (states[--length], *rp);
+		  edge[nedges++] = map_goto (states1[--length], *rp);
 		  if (nullable[*rp])
 		    done = 0;
 		}
@@ -464,7 +471,7 @@ build_relations (void)
     }
 
   XFREE (edge);
-  XFREE (states);
+  XFREE (states1);
 
   includes = transpose (includes, ngotos);
 }
@@ -493,18 +500,15 @@ compute_lookaheads (void)
 
   for (i = 0; i < nLA; i++)
     for (sp = lookback[i]; sp; sp = sp->next)
-      {
-	int size = LA (i + 1) - LA (i);
-	int j;
-	for (j = 0; j < size; ++j)
-	  LA (i)[j] |= F (sp->value)[j];
-      }
+      bitset_or (LA[i], LA[i], F[sp->value]);
 
   /* Free LOOKBACK. */
   for (i = 0; i < nLA; i++)
     LIST_FREE (shorts, lookback[i]);
 
   XFREE (lookback);
+  for (i = 0; i < (unsigned) ngotos; ++i)
+    bitset_free (F[i]);
   XFREE (F);
 }
 
@@ -516,34 +520,64 @@ compute_lookaheads (void)
 static void
 initialize_lookaheads (void)
 {
-  int i;
+  size_t i;
   nLA = 0;
   for (i = 0; i < nstates; i++)
     {
       int k;
       int nlookaheads = 0;
-      reductions *rp = state_table[i]->reductions;
-      shifts *sp = state_table[i]->shifts;
-
-      if (rp
-	  && (rp->nreds > 1 || (sp->nshifts && SHIFT_IS_SHIFT (sp, 0))))
+      reductions *rp = states[i]->reductions;
+      shifts *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
-	state_table[i]->consistent = 1;
+	states[i]->consistent = 1;
 
       for (k = 0; k < sp->nshifts; k++)
 	if (SHIFT_IS_ERROR (sp, k))
 	  {
-	    state_table[i]->consistent = 0;
+	    states[i]->consistent = 0;
 	    break;
 	  }
 
-      state_table[i]->nlookaheads = nlookaheads;
-      state_table[i]->lookaheadsp = nLA;
+      states[i]->nlookaheads = nlookaheads;
+      states[i]->lookaheadsp = nLA;
       nLA += nlookaheads;
     }
 }
 
+
+/*---------------------------------------.
+| Output the lookaheads for each state.  |
+`---------------------------------------*/
+
+static void
+lookaheads_print (FILE *out)
+{
+  size_t i;
+  int j, k;
+  fprintf (out, "Lookaheads: BEGIN\n");
+  for (i = 0; i < nstates; ++i)
+    {
+      fprintf (out, "State %d: %d lookaheads\n",
+	       i, states[i]->nlookaheads);
+
+      for (j = 0; j < states[i]->nlookaheads; ++j)
+	for (k = 0; k < ntokens; ++k)
+	  if (bitset_test (LA[states[i]->lookaheadsp + j], j))
+	    fprintf (out, "   on %d (%s) -> rule %d\n",
+		     k, symbols[k]->tag,
+		     -LAruleno[states[i]->lookaheadsp + j] - 1);
+    }
+  fprintf (out, "Lookaheads: END\n");
+}
+
 void
 lalr (void)
 {
@@ -556,4 +590,7 @@ lalr (void)
   build_relations ();
   compute_FOLLOWS ();
   compute_lookaheads ();
+
+  if (trace_flag)
+    lookaheads_print (stderr);
 }