X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/d0b0fefa03737d162ca8341c979881c70bebb868..e9f87b5b7df2e328d2e4196d276c0d96594c906b:/src/lalr.c?ds=sidebyside

diff --git a/src/lalr.c b/src/lalr.c
index 1dfb293d..c16c6f52 100644
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -24,8 +24,10 @@
    tokens they accept.  */
 
 #include "system.h"
+#include "reader.h"
 #include "types.h"
 #include "LR0.h"
+#include "symtab.h"
 #include "gram.h"
 #include "complain.h"
 #include "lalr.h"
@@ -34,7 +36,7 @@
 #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;
@@ -137,7 +139,6 @@ initialize_LA (void)
   int i;
   int j;
   short *np;
-  reductions *rp;
 
   /* Avoid having to special case 0.  */
   if (!nLA)
@@ -149,10 +150,9 @@ initialize_LA (void)
 
   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];
 }
 
 
@@ -168,16 +168,14 @@ 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)
 	{
-	  int symbol = state_table[sp->shifts[i]]->accessing_symbol;
-
 	  if (ngotos == MAXSHORT)
 	    fatal (_("too many gotos (max %d)"), MAXSHORT);
 
 	  ngotos++;
-	  goto_map[symbol]++;
+	  goto_map[SHIFT_SYMBOL (sp, i)]++;
 	}
     }
 
@@ -201,15 +199,12 @@ 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 state2 = sp->shifts[i];
-	  int symbol = state_table[state2]->accessing_symbol;
-
-	  int k = temp_map[symbol]++;
+	  int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
 	  from_state[k] = state;
-	  to_state[k] = state2;
+	  to_state[k] = sp->shifts[i];
 	}
     }
 
@@ -265,18 +260,15 @@ initialize_F (void)
   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++)
-	{
-	  int symbol = state_table[sp->shifts[j]]->accessing_symbol;
-	  SETBIT (F (i), symbol);
-	}
+	SETBIT (F (i), SHIFT_SYMBOL (sp, j));
 
       for (; j < sp->nshifts; j++)
 	{
-	  int symbol = state_table[sp->shifts[j]]->accessing_symbol;
+	  int symbol = SHIFT_SYMBOL (sp, j);
 	  if (nullable[symbol])
 	    edge[nedges++] = map_goto (stateno, symbol);
 	}
@@ -301,21 +293,21 @@ initialize_F (void)
 
 
 static void
-add_lookback_edge (int stateno, int ruleno, int gotono)
+add_lookback_edge (state_t *state, int ruleno, int gotono)
 {
   int i;
   shorts *sp;
 
-  for (i = 0; i < state_table[stateno]->nlookaheads; ++i)
-    if (LAruleno[state_table[stateno]->lookaheadsp + i] == ruleno)
+  for (i = 0; i < state->nlookaheads; ++i)
+    if (LAruleno[state->lookaheadsp + i] == ruleno)
       break;
 
-  assert (LAruleno[state_table[stateno]->lookaheadsp + i] == ruleno);
+  assert (LAruleno[state->lookaheadsp + i] == ruleno);
 
   sp = XCALLOC (shorts, 1);
-  sp->next = lookback[state_table[stateno]->lookaheadsp + i];
+  sp->next = lookback[state->lookaheadsp + i];
   sp->value = gotono;
-  lookback[state_table[stateno]->lookaheadsp + i] = sp;
+  lookback[state->lookaheadsp + i] = sp;
 }
 
 
@@ -409,7 +401,7 @@ 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);
@@ -417,34 +409,33 @@ build_relations (void)
   for (i = 0; i < ngotos; i++)
     {
       int nedges = 0;
-      int state1 = from_state[i];
-      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++)
 	{
 	  int done;
 	  int length = 1;
-	  int stateno = state1;
 	  short *rp;
-	  states[0] = state1;
+	  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_table[stateno]->shifts;
+	      shifts *sp = state->shifts;
 	      int j;
 	      for (j = 0; j < sp->nshifts; j++)
 		{
-		  stateno = sp->shifts[j];
-		  if (state_table[stateno]->accessing_symbol == *rp)
+		  state = states[sp->shifts[j]];
+		  if (state->accessing_symbol == *rp)
 		    break;
 		}
 
-	      states[length++] = stateno;
+	      states1[length++] = state->number;
 	    }
 
-	  if (!state_table[stateno]->consistent)
-	    add_lookback_edge (stateno, *rulep, i);
+	  if (!state->consistent)
+	    add_lookback_edge (state, *rulep, i);
 
 	  length--;
 	  done = 0;
@@ -455,8 +446,7 @@ build_relations (void)
 	      /* JF added rp>=ritem &&   I hope to god its right! */
 	      if (rp >= ritem && ISVAR (*rp))
 		{
-		  stateno = states[--length];
-		  edge[nedges++] = map_goto (stateno, *rp);
+		  edge[nedges++] = map_goto (states1[--length], *rp);
 		  if (nullable[*rp])
 		    done = 0;
 		}
@@ -474,7 +464,7 @@ build_relations (void)
     }
 
   XFREE (edge);
-  XFREE (states);
+  XFREE (states1);
 
   includes = transpose (includes, ngotos);
 }
@@ -532,28 +522,57 @@ initialize_lookaheads (void)
     {
       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)
+{
+  int i, 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 (BITISSET (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)
 {
@@ -566,4 +585,7 @@ lalr (void)
   build_relations ();
   compute_FOLLOWS ();
   compute_lookaheads ();
+
+  if (trace_flag)
+    lookaheads_print (stderr);
 }