X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/3628146521aa93cdd499fa5058d21c7be33014bf..300f275f23b65c09f69a437c635c48ddd126f21a:/src/lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 27e3d286..42cd05ef 100644
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,103 +1,60 @@
 /* Compute look-ahead criteria for bison,
-   Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc.
+   Copyright 1984, 1986, 1989, 2000, 2001  Free Software Foundation, Inc.
 
-This file is part of Bison, the GNU Compiler Compiler.
+   This file is part of Bison, the GNU Compiler Compiler.
 
-Bison 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.
+   Bison 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.
 
-Bison 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.
+   Bison 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.  */
+   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.  */
 
 
-/* Compute how to make the finite state machine deterministic;
- find which rules need lookahead in each state, and which lookahead tokens they accept.
+/* Compute how to make the finite state machine deterministic; find
+   which rules need lookahead in each state, and which lookahead
+   tokens they accept.  */
 
-lalr(), the entry point, builds these data structures:
-
-goto_map, from_state and to_state
- record each shift transition which accepts a variable (a nonterminal).
-ngotos is the number of such transitions.
-from_state[t] is the state number which a transition leads from
-and to_state[t] is the state number it leads to.
-All the transitions that accept a particular variable are grouped together and
-goto_map[i - ntokens] is the index in from_state and to_state of the first of them.
-
-consistent[s] is nonzero if no lookahead is needed to decide what to do in state s.
-
-LAruleno is a vector which records the rules that need lookahead in various states.
-The elements of LAruleno that apply to state s are those from
- lookaheads[s] through lookaheads[s+1]-1.
-Each element of LAruleno is a rule number.
-
-If lr is the length of LAruleno, then a number from 0 to lr-1
-can specify both a rule and a state where the rule might be applied.
-
-LA is a lr by ntokens matrix of bits.
-LA[l, i] is 1 if the rule LAruleno[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.
-*/
-
-#include <stdio.h>
 #include "system.h"
-#include "machine.h"
 #include "types.h"
-#include "state.h"
-#include "alloc.h"
+#include "LR0.h"
 #include "gram.h"
 #include "complain.h"
+#include "lalr.h"
+#include "nullable.h"
+#include "derives.h"
 
-extern short **derives;
-extern char *nullable;
-
+/* 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;
 
 int tokensetsize;
-short *lookaheads;
 short *LAruleno;
 unsigned *LA;
-short *accessing_symbol;
-char *consistent;
-core **state_table;
-shifts **shift_table;
-reductions **reduction_table;
+
 short *goto_map;
 short *from_state;
 short *to_state;
 
-void lalr PARAMS((void));
-short **transpose PARAMS((short **, int));
-void set_state_table PARAMS((void));
-void set_accessing_symbol PARAMS((void));
-void set_shift_table PARAMS((void));
-void set_reduction_table PARAMS((void));
-void set_maxrhs PARAMS((void));
-void initialize_LA PARAMS((void));
-void set_goto_map PARAMS((void));
-int map_goto PARAMS((int, int));
-void initialize_F PARAMS((void));
-void build_relations PARAMS((void));
-void add_lookback_edge PARAMS((int, int, int));
-void compute_FOLLOWS PARAMS((void));
-void compute_lookaheads PARAMS((void));
-void digraph PARAMS((short **));
-void traverse PARAMS((register int));
-
-extern void berror PARAMS((char *));
+extern void berror PARAMS ((const char *));
 
 static int infinity;
-static int maxrhs;
 static int ngotos;
-static unsigned *F;
+
+/* And for the famous F variable, which named is so descriptive that a
+   comment is hardly needed.  <grin>.  */
+static unsigned *F = NULL;
+#define F(Rule)  (F + (Rule) * tokensetsize)
+
 static short **includes;
 static shorts **lookback;
 static short **R;
@@ -106,79 +63,162 @@ static short *VERTICES;
 static int top;
 
 
-void
-lalr (void)
+static void
+traverse (int i)
 {
-  tokensetsize = WORDSIZE(ntokens);
-
-  set_state_table();
-  set_accessing_symbol();
-  set_shift_table();
-  set_reduction_table();
-  set_maxrhs();
-  initialize_LA();
-  set_goto_map();
-  initialize_F();
-  build_relations();
-  compute_FOLLOWS();
-  compute_lookaheads();
-}
+  unsigned *fp1;
+  unsigned *fp2;
+  unsigned *fp3;
+  int j;
+  short *rp;
 
+  int height;
+  unsigned *base;
 
-void
-set_state_table (void)
-{
-  register core *sp;
+  VERTICES[++top] = i;
+  INDEX[i] = height = top;
 
-  state_table = NEW2(nstates, core *);
+  base = F (i);
+  fp3 = F (i + 1);
 
-  for (sp = first_state; sp; sp = sp->next)
-    state_table[sp->number] = sp;
-}
+  rp = R[i];
+  if (rp)
+    {
+      while ((j = *rp++) >= 0)
+	{
+	  if (INDEX[j] == 0)
+	    traverse (j);
 
+	  if (INDEX[i] > INDEX[j])
+	    INDEX[i] = INDEX[j];
 
-void
-set_accessing_symbol (void)
-{
-  register core *sp;
+	  fp1 = base;
+	  fp2 = F (j);
 
-  accessing_symbol = NEW2(nstates, short);
+	  while (fp1 < fp3)
+	    *fp1++ |= *fp2++;
+	}
+    }
 
-  for (sp = first_state; sp; sp = sp->next)
-    accessing_symbol[sp->number] = sp->accessing_symbol;
+  if (INDEX[i] == height)
+    {
+      for (;;)
+	{
+	  j = VERTICES[top--];
+	  INDEX[j] = infinity;
+
+	  if (i == j)
+	    break;
+
+	  fp1 = base;
+	  fp2 = F (j);
+
+	  while (fp1 < fp3)
+	    *fp2++ = *fp1++;
+	}
+    }
 }
 
 
-void
-set_shift_table (void)
+static void
+digraph (short **relation)
 {
-  register shifts *sp;
+  int i;
 
-  shift_table = NEW2(nstates, shifts *);
+  infinity = ngotos + 2;
+  INDEX = XCALLOC (short, ngotos + 1);
+  VERTICES = XCALLOC (short, ngotos + 1);
+  top = 0;
 
-  for (sp = first_shift; sp; sp = sp->next)
-    shift_table[sp->number] = sp;
-}
+  R = relation;
 
+  for (i = 0; i < ngotos; i++)
+    INDEX[i] = 0;
+
+  for (i = 0; i < ngotos; i++)
+    if (INDEX[i] == 0 && R[i])
+      traverse (i);
+
+  XFREE (INDEX);
+  XFREE (VERTICES);
+}
 
-void
-set_reduction_table (void)
-{
-  register reductions *rp;
 
-  reduction_table = NEW2(nstates, reductions *);
+/*--------------------.
+| Build STATE_TABLE.  |
+`--------------------*/
 
-  for (rp = first_reduction; rp; rp = rp->next)
-    reduction_table[rp->number] = rp;
+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);
+
+  {
+    core *sp;
+    for (sp = first_state; sp; sp = sp->next)
+      {
+	state_table[sp->number].state = sp;
+	state_table[sp->number].accessing_symbol = sp->accessing_symbol;
+      }
+  }
+
+  {
+    shifts *sp;
+    for (sp = first_shift; sp; sp = sp->next)
+      state_table[sp->number].shift_table = sp;
+  }
+
+  {
+    reductions *rp;
+    for (rp = first_reduction; rp; rp = rp->next)
+      state_table[rp->number].reduction_table = rp;
+  }
+
+  /* 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].reduction_table;
+	shifts *sp = state_table[i].shift_table;
+
+	state_table[i].lookaheads = count;
+
+	if (rp
+	    && (rp->nreds > 1
+		|| (sp && !ISVAR (state_table[sp->shifts[0]].accessing_symbol))))
+	  count += rp->nreds;
+	else
+	  state_table[i].consistent = 1;
+
+	if (sp)
+	  for (k = 0; k < sp->nshifts; k++)
+	    if (state_table[sp->shifts[k]].accessing_symbol
+		== error_token_number)
+	      {
+		state_table[i].consistent = 0;
+		break;
+	      }
+      }
+     state_table[nstates].lookaheads = count;
+  }
 }
 
 
-void
-set_maxrhs (void)
+/* Return the size of the longest ride hand side of the rules. */
+static size_t
+maxrhs (void)
 {
-  register short *itemp;
-  register int length;
-  register int max;
+  short *itemp;
+  int length;
+  int max;
 
   length = 0;
   max = 0;
@@ -190,111 +230,71 @@ set_maxrhs (void)
 	}
       else
 	{
-	  if (length > max) max = length;
+	  if (length > max)
+	    max = length;
 	  length = 0;
 	}
     }
 
-  maxrhs = max;
+  return max;
 }
 
 
-void
+static void
 initialize_LA (void)
 {
-  register int i;
-  register int j;
-  register int count;
-  register reductions *rp;
-  register shifts *sp;
-  register short *np;
-
-  consistent = NEW2(nstates, char);
-  lookaheads = NEW2(nstates + 1, short);
-
-  count = 0;
-  for (i = 0; i < nstates; i++)
-    {
-      register int k;
+  int i;
+  int j;
+  short *np;
+  reductions *rp;
 
-      lookaheads[i] = count;
+  size_t nLA = state_table[nstates].lookaheads;
+  if (!nLA)
+    nLA = 1;
 
-      rp = reduction_table[i];
-      sp = shift_table[i];
-      if (rp && (rp->nreds > 1
-          || (sp && ! ISVAR(accessing_symbol[sp->shifts[0]]))))
-	count += rp->nreds;
-      else
-	consistent[i] = 1;
-
-      if (sp)
-	for (k = 0; k < sp->nshifts; k++)
-	  {
-	    if (accessing_symbol[sp->shifts[k]] == error_token_number)
-	      {
-		consistent[i] = 0;
-		break;
-	      }
-	  }
-    }
-
-  lookaheads[nstates] = count;
-
-  if (count == 0)
-    {
-      LA = NEW2(1 * tokensetsize, unsigned);
-      LAruleno = NEW2(1, short);
-      lookback = NEW2(1, shorts *);
-    }
-  else
-    {
-      LA = NEW2(count * tokensetsize, unsigned);
-      LAruleno = NEW2(count, short);
-      lookback = NEW2(count, shorts *);
-    }
+  LA = XCALLOC (unsigned, nLA * tokensetsize);
+  LAruleno = XCALLOC (short, nLA);
+  lookback = XCALLOC (shorts *, nLA);
 
   np = LAruleno;
   for (i = 0; i < nstates; i++)
-    {
-      if (!consistent[i])
-	{
-	  if ((rp = reduction_table[i]))
-	    for (j = 0; j < rp->nreds; j++)
-	      *np++ = rp->rules[j];
-	}
-    }
+    if (!state_table[i].consistent)
+      if ((rp = state_table[i].reduction_table))
+	for (j = 0; j < rp->nreds; j++)
+	  *np++ = rp->rules[j];
 }
 
 
-void
+static void
 set_goto_map (void)
 {
-  register shifts *sp;
-  register int i;
-  register int symbol;
-  register int k;
-  register short *temp_map;
-  register int state2;
-  register int state1;
+  shifts *sp;
+  int i;
+  int symbol;
+  int k;
+  short *temp_map;
+  int state2;
+  int state1;
 
-  goto_map = NEW2(nvars + 1, short) - ntokens;
-  temp_map = NEW2(nvars + 1, short) - ntokens;
+  goto_map = XCALLOC (short, nvars + 1) - ntokens;
+  temp_map = XCALLOC (short, nvars + 1) - ntokens;
 
   ngotos = 0;
   for (sp = first_shift; sp; sp = sp->next)
     {
       for (i = sp->nshifts - 1; i >= 0; i--)
 	{
-	  symbol = accessing_symbol[sp->shifts[i]];
+	  symbol = state_table[sp->shifts[i]].accessing_symbol;
 
-	  if (ISTOKEN(symbol)) break;
+	  if (ISTOKEN (symbol))
+	    break;
 
 	  if (ngotos == MAXSHORT)
 	    fatal (_("too many gotos (max %d)"), MAXSHORT);
 
 	  ngotos++;
 	  goto_map[symbol]++;
-        }
+	}
     }
 
   k = 0;
@@ -310,8 +310,8 @@ set_goto_map (void)
   goto_map[nsyms] = ngotos;
   temp_map[nsyms] = ngotos;
 
-  from_state = NEW2(ngotos, short);
-  to_state = NEW2(ngotos, short);
+  from_state = XCALLOC (short, ngotos);
+  to_state = XCALLOC (short, ngotos);
 
   for (sp = first_shift; sp; sp = sp->next)
     {
@@ -319,9 +319,10 @@ set_goto_map (void)
       for (i = sp->nshifts - 1; i >= 0; i--)
 	{
 	  state2 = sp->shifts[i];
-	  symbol = accessing_symbol[state2];
+	  symbol = state_table[state2].accessing_symbol;
 
-	  if (ISTOKEN(symbol)) break;
+	  if (ISTOKEN (symbol))
+	    break;
 
 	  k = temp_map[symbol]++;
 	  from_state[k] = state1;
@@ -329,20 +330,22 @@ set_goto_map (void)
 	}
     }
 
-  FREE(temp_map + ntokens);
+  XFREE (temp_map + ntokens);
 }
 
 
 
-/*  Map_goto maps a state/symbol pair into its numeric representation.	*/
+/*----------------------------------------------------------.
+| Map a state/symbol pair into its numeric representation.  |
+`----------------------------------------------------------*/
 
-int
+static int
 map_goto (int state, int symbol)
 {
-  register int high;
-  register int low;
-  register int middle;
-  register int s;
+  int high;
+  int low;
+  int middle;
+  int s;
 
   low = goto_map[symbol];
   high = goto_map[symbol + 1] - 1;
@@ -359,40 +362,40 @@ map_goto (int state, int symbol)
 	high = middle - 1;
     }
 
-  berror("map_goto");
-/* NOTREACHED */
+  assert (0);
+  /* NOTREACHED */
   return 0;
 }
 
 
-void
+static void
 initialize_F (void)
 {
-  register int i;
-  register int j;
-  register int k;
-  register shifts *sp;
-  register short *edge;
-  register unsigned *rowp;
-  register short *rp;
-  register short **reads;
-  register int nedges;
-  register int stateno;
-  register int symbol;
-  register int nwords;
+  int i;
+  int j;
+  int k;
+  shifts *sp;
+  short *edge;
+  unsigned *rowp;
+  short *rp;
+  short **reads;
+  int nedges;
+  int stateno;
+  int symbol;
+  int nwords;
 
   nwords = ngotos * tokensetsize;
-  F = NEW2(nwords, unsigned);
+  F = XCALLOC (unsigned, nwords);
 
-  reads = NEW2(ngotos, short *);
-  edge = NEW2(ngotos + 1, short);
+  reads = XCALLOC (short *, ngotos);
+  edge = XCALLOC (short, ngotos + 1);
   nedges = 0;
 
   rowp = F;
   for (i = 0; i < ngotos; i++)
     {
       stateno = to_state[i];
-      sp = shift_table[stateno];
+      sp = state_table[stateno].shift_table;
 
       if (sp)
 	{
@@ -400,22 +403,22 @@ initialize_F (void)
 
 	  for (j = 0; j < k; j++)
 	    {
-	      symbol = accessing_symbol[sp->shifts[j]];
-	      if (ISVAR(symbol))
+	      symbol = state_table[sp->shifts[j]].accessing_symbol;
+	      if (ISVAR (symbol))
 		break;
-	      SETBIT(rowp, symbol);
+	      SETBIT (rowp, symbol);
 	    }
 
 	  for (; j < k; j++)
 	    {
-	      symbol = accessing_symbol[sp->shifts[j]];
+	      symbol = state_table[sp->shifts[j]].accessing_symbol;
 	      if (nullable[symbol])
-		edge[nedges++] = map_goto(stateno, symbol);
+		edge[nedges++] = map_goto (stateno, symbol);
 	    }
 
 	  if (nedges)
 	    {
-	      reads[i] = rp = NEW2(nedges + 1, short);
+	      reads[i] = rp = XCALLOC (short, nedges + 1);
 
 	      for (j = 0; j < nedges; j++)
 		rp[j] = edge[j];
@@ -428,124 +431,26 @@ initialize_F (void)
       rowp += tokensetsize;
     }
 
-  digraph(reads);
+  digraph (reads);
 
   for (i = 0; i < ngotos; i++)
-    {
-      if (reads[i])
-	FREE(reads[i]);
-    }
+    XFREE (reads[i]);
 
-  FREE(reads);
-  FREE(edge);
+  XFREE (reads);
+  XFREE (edge);
 }
 
 
-void
-build_relations (void)
-{
-  register int i;
-  register int j;
-  register int k;
-  register short *rulep;
-  register short *rp;
-  register shifts *sp;
-  register int length;
-  register int nedges;
-  register int done;
-  register int state1;
-  register int stateno;
-  register int symbol1;
-  register int symbol2;
-  register short *shortp;
-  register short *edge;
-  register short *states;
-  register short **new_includes;
-
-  includes = NEW2(ngotos, short *);
-  edge = NEW2(ngotos + 1, short);
-  states = NEW2(maxrhs + 1, short);
-
-  for (i = 0; i < ngotos; i++)
-    {
-      nedges = 0;
-      state1 = from_state[i];
-      symbol1 = accessing_symbol[to_state[i]];
-
-      for (rulep = derives[symbol1]; *rulep > 0; rulep++)
-	{
-	  length = 1;
-	  states[0] = state1;
-	  stateno = state1;
-
-	  for (rp = ritem + rrhs[*rulep]; *rp > 0; rp++)
-	    {
-	      symbol2 = *rp;
-	      sp = shift_table[stateno];
-	      k = sp->nshifts;
-
-	      for (j = 0; j < k; j++)
-		{
-		  stateno = sp->shifts[j];
-		  if (accessing_symbol[stateno] == symbol2) break;
-		}
-
-	      states[length++] = stateno;
-	    }
-
-	  if (!consistent[stateno])
-	    add_lookback_edge(stateno, *rulep, i);
-
-	  length--;
-	  done = 0;
-	  while (!done)
-	    {
-	      done = 1;
-	      rp--;
-			/* JF added rp>=ritem &&   I hope to god its right! */
-	      if (rp>=ritem && ISVAR(*rp))
-		{
-		  stateno = states[--length];
-		  edge[nedges++] = map_goto(stateno, *rp);
-		  if (nullable[*rp]) done = 0;
-		}
-	    }
-	}
-
-      if (nedges)
-	{
-	  includes[i] = shortp = NEW2(nedges + 1, short);
-	  for (j = 0; j < nedges; j++)
-	    shortp[j] = edge[j];
-	  shortp[nedges] = -1;
-	}
-    }
-
-  new_includes = transpose(includes, ngotos);
-
-  for (i = 0; i < ngotos; i++)
-    if (includes[i])
-      FREE(includes[i]);
-
-  FREE(includes);
-
-  includes = new_includes;
-
-  FREE(edge);
-  FREE(states);
-}
-
-
-void
+static void
 add_lookback_edge (int stateno, int ruleno, int gotono)
 {
-  register int i;
-  register int k;
-  register int found;
-  register shorts *sp;
+  int i;
+  int k;
+  int found;
+  shorts *sp;
 
-  i = lookaheads[stateno];
-  k = lookaheads[stateno + 1];
+  i = state_table[stateno].lookaheads;
+  k = state_table[stateno + 1].lookaheads;
   found = 0;
   while (!found && i < k)
     {
@@ -555,28 +460,26 @@ add_lookback_edge (int stateno, int ruleno, int gotono)
 	i++;
     }
 
-  if (found == 0)
-    berror("add_lookback_edge");
+  assert (found);
 
-  sp = NEW(shorts);
+  sp = XCALLOC (shorts, 1);
   sp->next = lookback[i];
   sp->value = gotono;
   lookback[i] = sp;
 }
 
 
-
-short **
+static short **
 transpose (short **R_arg, int n)
 {
-  register short **new_R;
-  register short **temp_R;
-  register short *nedges;
-  register short *sp;
-  register int i;
-  register int k;
+  short **new_R;
+  short **temp_R;
+  short *nedges;
+  short *sp;
+  int i;
+  int k;
 
-  nedges = NEW2(n, short);
+  nedges = XCALLOC (short, n);
 
   for (i = 0; i < n; i++)
     {
@@ -588,22 +491,22 @@ transpose (short **R_arg, int n)
 	}
     }
 
-  new_R = NEW2(n, short *);
-  temp_R = NEW2(n, short *);
+  new_R = XCALLOC (short *, n);
+  temp_R = XCALLOC (short *, n);
 
   for (i = 0; i < n; i++)
     {
       k = nedges[i];
       if (k > 0)
 	{
-	  sp = NEW2(k + 1, short);
+	  sp = XCALLOC (short, k + 1);
 	  new_R[i] = sp;
 	  temp_R[i] = sp;
 	  sp[k] = -1;
 	}
     }
 
-  FREE(nedges);
+  XFREE (nedges);
 
   for (i = 0; i < n; i++)
     {
@@ -615,149 +518,158 @@ transpose (short **R_arg, int n)
 	}
     }
 
-  FREE(temp_R);
+  XFREE (temp_R);
 
   return new_R;
 }
 
 
-void
-compute_FOLLOWS (void)
+static void
+build_relations (void)
 {
-  register int i;
-
-  digraph(includes);
+  int i;
+  int j;
+  int k;
+  short *rulep;
+  short *rp;
+  shifts *sp;
+  int length;
+  int nedges;
+  int done;
+  int state1;
+  int stateno;
+  int symbol1;
+  int symbol2;
+  short *shortp;
+  short *edge;
+  short *states;
+  short **new_includes;
+
+  includes = XCALLOC (short *, ngotos);
+  edge = XCALLOC (short, ngotos + 1);
+  states = XCALLOC (short, maxrhs () + 1);
 
   for (i = 0; i < ngotos; i++)
     {
-      if (includes[i]) FREE(includes[i]);
-    }
-
-  FREE(includes);
-}
-
+      nedges = 0;
+      state1 = from_state[i];
+      symbol1 = state_table[to_state[i]].accessing_symbol;
 
-void
-compute_lookaheads (void)
-{
-  register int i;
-  register int n;
-  register unsigned *fp1;
-  register unsigned *fp2;
-  register unsigned *fp3;
-  register shorts *sp;
-  register unsigned *rowp;
-/*   register short *rulep; JF unused */
-/*  register int count; JF unused */
-  register shorts *sptmp;/* JF */
-
-  rowp = LA;
-  n = lookaheads[nstates];
-  for (i = 0; i < n; i++)
-    {
-      fp3 = rowp + tokensetsize;
-      for (sp = lookback[i]; sp; sp = sp->next)
+      for (rulep = derives[symbol1]; *rulep > 0; rulep++)
 	{
-	  fp1 = rowp;
-	  fp2 = F + tokensetsize * sp->value;
-	  while (fp1 < fp3)
-	    *fp1++ |= *fp2++;
-	}
+	  length = 1;
+	  states[0] = state1;
+	  stateno = state1;
 
-      rowp = fp3;
-    }
+	  for (rp = ritem + rule_table[*rulep].rhs; *rp > 0; rp++)
+	    {
+	      symbol2 = *rp;
+	      sp = state_table[stateno].shift_table;
+	      k = sp->nshifts;
 
-  for (i = 0; i < n; i++)
-    {/* JF removed ref to freed storage */
-      for (sp = lookback[i]; sp; sp = sptmp) {
-	sptmp=sp->next;
-	FREE(sp);
-      }
-    }
+	      for (j = 0; j < k; j++)
+		{
+		  stateno = sp->shifts[j];
+		  if (state_table[stateno].accessing_symbol == symbol2)
+		    break;
+		}
 
-  FREE(lookback);
-  FREE(F);
-}
+	      states[length++] = stateno;
+	    }
 
+	  if (!state_table[stateno].consistent)
+	    add_lookback_edge (stateno, *rulep, i);
 
-void
-digraph (short **relation)
-{
-  register int i;
+	  length--;
+	  done = 0;
+	  while (!done)
+	    {
+	      done = 1;
+	      rp--;
+	      /* JF added rp>=ritem &&   I hope to god its right! */
+	      if (rp >= ritem && ISVAR (*rp))
+		{
+		  stateno = states[--length];
+		  edge[nedges++] = map_goto (stateno, *rp);
+		  if (nullable[*rp])
+		    done = 0;
+		}
+	    }
+	}
 
-  infinity = ngotos + 2;
-  INDEX = NEW2(ngotos + 1, short);
-  VERTICES = NEW2(ngotos + 1, short);
-  top = 0;
+      if (nedges)
+	{
+	  includes[i] = shortp = XCALLOC (short, nedges + 1);
+	  for (j = 0; j < nedges; j++)
+	    shortp[j] = edge[j];
+	  shortp[nedges] = -1;
+	}
+    }
 
-  R = relation;
+  new_includes = transpose (includes, ngotos);
 
   for (i = 0; i < ngotos; i++)
-    INDEX[i] = 0;
+    if (includes[i])
+      XFREE (includes[i]);
 
-  for (i = 0; i < ngotos; i++)
-    {
-      if (INDEX[i] == 0 && R[i])
-	traverse(i);
-    }
+  XFREE (includes);
 
-  FREE(INDEX);
-  FREE(VERTICES);
+  includes = new_includes;
+
+  XFREE (edge);
+  XFREE (states);
 }
 
 
-void
-traverse (register int i)
-{
-  register unsigned *fp1;
-  register unsigned *fp2;
-  register unsigned *fp3;
-  register int j;
-  register short *rp;
 
-  int height;
-  unsigned *base;
-
-  VERTICES[++top] = i;
-  INDEX[i] = height = top;
+static void
+compute_FOLLOWS (void)
+{
+  int i;
 
-  base = F + i * tokensetsize;
-  fp3 = base + tokensetsize;
+  digraph (includes);
 
-  rp = R[i];
-  if (rp)
-    {
-      while ((j = *rp++) >= 0)
-	{
-	  if (INDEX[j] == 0)
-	    traverse(j);
+  for (i = 0; i < ngotos; i++)
+    XFREE (includes[i]);
 
-	  if (INDEX[i] > INDEX[j])
-	    INDEX[i] = INDEX[j];
+  XFREE (includes);
+}
 
-	  fp1 = base;
-	  fp2 = F + j * tokensetsize;
 
-	  while (fp1 < fp3)
-	    *fp1++ |= *fp2++;
-	}
-    }
+static void
+compute_lookaheads (void)
+{
+  int i;
+  shorts *sp;
+
+  for (i = 0; i < state_table[nstates].lookaheads; i++)
+    for (sp = lookback[i]; sp; sp = sp->next)
+      {
+	unsigned *fp1 = LA (i);
+	unsigned *fp2 = F (sp->value);
+	while (fp1 < LA (i + 1))
+	  *fp1++ |= *fp2++;
+      }
 
-  if (INDEX[i] == height)
-    {
-      for (;;)
-	{
-	  j = VERTICES[top--];
-	  INDEX[j] = infinity;
+  /* Free LOOKBACK. */
+  for (i = 0; i < state_table[nstates].lookaheads; i++)
+    LIST_FREE (shorts, lookback[i]);
 
-	  if (i == j)
-	    break;
+  XFREE (lookback);
+  XFREE (F);
+}
 
-	  fp1 = base;
-	  fp2 = F + j * tokensetsize;
 
-	  while (fp1 < fp3)
-	    *fp2++ = *fp1++;
-	}
-    }
+void
+lalr (void)
+{
+  tokensetsize = WORDSIZE (ntokens);
+
+  set_state_table ();
+  initialize_LA ();
+  set_goto_map ();
+  initialize_F ();
+  build_relations ();
+  compute_FOLLOWS ();
+  compute_lookaheads ();
 }