X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/7215de245c9b1ebb91efb16c91ff21e5f983f6d2..616429b50868bf9225d55143526442a024e32969:/src/lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 6042eca8..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"
@@ -33,14 +35,13 @@
 #include "derives.h"
 #include "getargs.h"
 
-/* All the decorated states, indexed by the state number.  Warning:
-   there is a state_TABLE in LR0.c, but it is different and static.
-   */
-state_t **state_table = NULL;
+/* All the decorated states, indexed by the state number.  */
+state_t **states = NULL;
 
 int tokensetsize;
 short *LAruleno;
 unsigned *LA;
+size_t nLA;
 
 static int ngotos;
 short *goto_map;
@@ -103,7 +104,7 @@ traverse (int i)
 	  break;
 
 	for (k = 0; k < size; ++k)
-	  F (i)[k] = F (j)[k];
+	  F (j)[k] = F (i)[k];
       }
 }
 
@@ -132,77 +133,14 @@ digraph (short **relation)
 }
 
 
-/*--------------------.
-| Build STATE_TABLE.  |
-`--------------------*/
-
-static void
-set_state_table (void)
-{
-  /* NSTATES + 1 because lookahead for the pseudo state number NSTATES
-     might be used (see conflicts.c).  It is too opaque for me to
-     provide a probably less hacky implementation. --akim */
-  state_table = XCALLOC (state_t *, nstates + 1);
-
-  {
-    state_t *sp;
-    for (sp = first_state; sp; sp = sp->next)
-      state_table[sp->number] = sp;
-  }
-
-  /* Pessimization, but simplification of the code: make sure all the
-     states have a shifts, even if reduced to 0 shifts.  */
-  {
-    int i;
-    for (i = 0; i < nstates; i++)
-      if (!state_table[i]->shifts)
-	state_table[i]->shifts = shifts_new (0);
-  }
-
-  /* Initializing the lookaheads members.  Please note that it must be
-     performed after having set some of the other members which are
-     used below.  Change with extreme caution.  */
-  {
-    int i;
-    int count = 0;
-    for (i = 0; i < nstates; i++)
-      {
-	int k;
-	reductions *rp = state_table[i]->reductions;
-	shifts *sp = state_table[i]->shifts;
-
-	state_table[i]->lookaheads = count;
-
-	if (rp
-	    && (rp->nreds > 1 || (sp->nshifts && SHIFT_IS_SHIFT (sp, 0))))
-	  count += rp->nreds;
-	else
-	  state_table[i]->consistent = 1;
-
-	for (k = 0; k < sp->nshifts; k++)
-	  if (SHIFT_IS_ERROR (sp, k))
-	    {
-	      state_table[i]->consistent = 0;
-	      break;
-	    }
-      }
-
-    /* Seems to be needed by conflicts.c. */
-    state_table[nstates] = STATE_ALLOC (0);
-    state_table[nstates]->lookaheads = count;
-  }
-}
-
-
 static void
 initialize_LA (void)
 {
   int i;
   int j;
   short *np;
-  reductions *rp;
 
-  size_t nLA = state_table[nstates]->lookaheads;
+  /* Avoid having to special case 0.  */
   if (!nLA)
     nLA = 1;
 
@@ -212,22 +150,17 @@ 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];
 }
 
 
 static void
 set_goto_map (void)
 {
-  int state;
-  int i;
-  int symbol;
-  int k;
+  int state, i;
   short *temp_map;
-  int state2;
 
   goto_map = XCALLOC (short, nvars + 1) - ntokens;
   temp_map = XCALLOC (short, nvars + 1) - ntokens;
@@ -235,49 +168,43 @@ 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)
 	{
-	  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)]++;
 	}
     }
 
-  k = 0;
-  for (i = ntokens; i < nsyms; i++)
-    {
-      temp_map[i] = k;
-      k += goto_map[i];
-    }
+  {
+    int k = 0;
+    for (i = ntokens; i < nsyms; i++)
+      {
+	temp_map[i] = k;
+	k += goto_map[i];
+      }
 
-  for (i = ntokens; i < nsyms; i++)
-    goto_map[i] = temp_map[i];
+    for (i = ntokens; i < nsyms; i++)
+      goto_map[i] = temp_map[i];
 
-  goto_map[nsyms] = ngotos;
-  temp_map[nsyms] = ngotos;
+    goto_map[nsyms] = ngotos;
+    temp_map[nsyms] = ngotos;
+  }
 
   from_state = XCALLOC (short, ngotos);
   to_state = XCALLOC (short, ngotos);
 
   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)
 	{
-	  for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
-	    {
-	      state2 = sp->shifts[i];
-	      symbol = state_table[state2]->accessing_symbol;
-
-	      k = temp_map[symbol]++;
-	      from_state[k] = state;
-	      to_state[k] = state2;
-	    }
+	  int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
+	  from_state[k] = state;
+	  to_state[k] = sp->shifts[i];
 	}
     }
 
@@ -333,18 +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);
 	}
@@ -369,30 +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;
-  int k;
-  int found;
   shorts *sp;
 
-  i = state_table[stateno]->lookaheads;
-  k = state_table[stateno + 1]->lookaheads;
-  found = 0;
-  while (!found && i < k)
-    {
-      if (LAruleno[i] == ruleno)
-	found = 1;
-      else
-	i++;
-    }
+  for (i = 0; i < state->nlookaheads; ++i)
+    if (LAruleno[state->lookaheadsp + i] == ruleno)
+      break;
 
-  assert (found);
+  assert (LAruleno[state->lookaheadsp + i] == ruleno);
 
   sp = XCALLOC (shorts, 1);
-  sp->next = lookback[i];
+  sp->next = lookback[state->lookaheadsp + i];
   sp->value = gotono;
-  lookback[i] = sp;
+  lookback[state->lookaheadsp + i] = sp;
 }
 
 
@@ -486,7 +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);
@@ -494,34 +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;
@@ -532,8 +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;
 		}
@@ -551,7 +464,7 @@ build_relations (void)
     }
 
   XFREE (edge);
-  XFREE (states);
+  XFREE (states1);
 
   includes = transpose (includes, ngotos);
 }
@@ -575,10 +488,10 @@ compute_FOLLOWS (void)
 static void
 compute_lookaheads (void)
 {
-  int i;
+  size_t i;
   shorts *sp;
 
-  for (i = 0; i < state_table[nstates]->lookaheads; i++)
+  for (i = 0; i < nLA; i++)
     for (sp = lookback[i]; sp; sp = sp->next)
       {
 	int size = LA (i + 1) - LA (i);
@@ -588,7 +501,7 @@ compute_lookaheads (void)
       }
 
   /* Free LOOKBACK. */
-  for (i = 0; i < state_table[nstates]->lookaheads; i++)
+  for (i = 0; i < nLA; i++)
     LIST_FREE (shorts, lookback[i]);
 
   XFREE (lookback);
@@ -596,16 +509,83 @@ compute_lookaheads (void)
 }
 
 
+/*--------------------------------------.
+| Initializing the lookaheads members.  |
+`--------------------------------------*/
+
+static void
+initialize_lookaheads (void)
+{
+  int i;
+  nLA = 0;
+  for (i = 0; i < nstates; i++)
+    {
+      int k;
+      int nlookaheads = 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
+	states[i]->consistent = 1;
+
+      for (k = 0; k < sp->nshifts; k++)
+	if (SHIFT_IS_ERROR (sp, k))
+	  {
+	    states[i]->consistent = 0;
+	    break;
+	  }
+
+      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)
 {
   tokensetsize = WORDSIZE (ntokens);
 
-  set_state_table ();
+  initialize_lookaheads ();
   initialize_LA ();
   set_goto_map ();
   initialize_F ();
   build_relations ();
   compute_FOLLOWS ();
   compute_lookaheads ();
+
+  if (trace_flag)
+    lookaheads_print (stderr);
 }