From: Akim Demaille <akim@epita.fr>
Date: Mon, 2 Oct 2000 08:04:25 +0000 (+0000)
Subject: * src/reduce.h: New file.
X-Git-Tag: BISON-1_28b~116
X-Git-Url: https://git.saurik.com/bison.git/commitdiff_plain/015acc48342cb75448f918f72463608aa4cb6eba

* src/reduce.h: New file.
Propagate its inclusion.
* src/reduce.c: Topological sort and other formatting changes.
(bool, TRUE, FALSE): Move their definition to...
* src/system.h: here.
---

diff --git a/ChangeLog b/ChangeLog
index 9d959f87..b6b05ee1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2000-10-02  Akim Demaille  <akim@epita.fr>
+
+	* src/reduce.h: New file.
+	Propagate its inclusion.
+	* src/reduce.c: Topological sort and other formatting changes.
+	(bool, TRUE, FALSE): Move their definition to...
+	* src/system.h: here.
+
+
 2000-10-02  Akim Demaille  <akim@epita.fr>
 
 	* src/files.c: Formatting changes.
@@ -7,7 +16,7 @@
 	* src/files.h: Complete the list of exported symbols.
 	Propagate its use.
 
-	
+
 2000-10-02  Akim Demaille  <akim@epita.fr>
 
 	* src/reader.h: New file.
@@ -25,21 +34,21 @@
 	(safegetc): Rename as...
 	(xgetc): this.
 
-	
+
 2000-10-02  Akim Demaille  <akim@epita.fr>
 
 	* src/lalr.h: New file.
 	Propagate its inclusion instead of prototypes and `extern'.
 	* src/lalr.c: Formatting changes, topological sorting etc.
 
-	
+
 2000-10-02  Akim Demaille  <akim@epita.fr>
 
 	* src/output.c (token_actions): Introduce a temporary array,
 	YYDEFACT, that makes it possible for this function to use
 	output_short_table.
 
-	
+
 2000-10-02  Akim Demaille  <akim@epita.fr>
 
 	`user_toknums' is output as a `short[]' in `output.c', while it is
diff --git a/src/Makefile.am b/src/Makefile.am
index ad5f69d2..a8f53d8c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -22,7 +22,7 @@ noinst_HEADERS = alloc.h closure.h complain.h \
  derives.h \
  files.h getargs.h gram.h lalr.h lex.h \
  output.h state.h	\
- reader.h symtab.h system.h types.h
+ reader.h reduce.h symtab.h system.h types.h
 
 data_DATA = bison.simple bison.hairy
 
diff --git a/src/main.c b/src/main.c
index c344119d..8ca5a672 100644
--- a/src/main.c
+++ b/src/main.c
@@ -28,6 +28,7 @@
 #include "output.h"
 #include "reader.h"
 #include "lalr.h"
+#include "reduce.h"
 
 #if 0				/* XXX currently unused.  */
 /* Nonzero means failure has been detected; don't write a parser file.  */
@@ -41,7 +42,6 @@ extern void berror PARAMS((const char *));
 
 extern char *printable_version PARAMS ((int));
 
-extern void reduce_grammar PARAMS ((void));
 extern void set_nullable PARAMS ((void));
 extern void free_nullable PARAMS ((void));
 extern void generate_states PARAMS ((void));
diff --git a/src/reduce.c b/src/reduce.c
index a654f0c7..d160f9d6 100644
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -1,33 +1,29 @@
 /* Grammar reduction for Bison.
-   Copyright (C) 1988, 1989 Free Software Foundation, Inc.
+   Copyright (C) 1988, 1989, 2000 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.  */
 
 
-/*
- * Reduce the grammar:  Find and eliminate unreachable terminals,
- * nonterminals, and productions.  David S. Bakin.
- */
+/* Reduce the grammar: Find and eliminate unreachable terminals,
+   nonterminals, and productions.  David S. Bakin.  */
 
-/*
- * Don't eliminate unreachable terminals:  They may be used by the user's
- * parser.
- */
+/* Don't eliminate unreachable terminals: They may be used by the
+   user's parser.  */
 
 #include "system.h"
 #include "getargs.h"
@@ -35,49 +31,27 @@ Boston, MA 02111-1307, USA.  */
 #include "gram.h"
 #include "alloc.h"
 #include "complain.h"
+#include "reduce.h"
 
+extern char **tags;		/* reader.c */
+static int statisticsflag;	/* XXXXXXX */
+extern int fixed_outfiles;
 
-extern char   **tags;		/* reader.c */
-static int      statisticsflag;	/* XXXXXXX */
-extern int      fixed_outfiles;
-
-#ifndef TRUE
-#define TRUE	(1)
-#define FALSE	(0)
-#endif
-typedef int bool;
 typedef unsigned *BSet;
-typedef short  *rule;
-
-
-/*
- * N is set of all nonterminals which are not useless.  P is set of all rules
- * which have no useless nonterminals in their RHS.  V is the set of all
- * accessible symbols.
- */
+typedef short *rule;
 
-static BSet     N, P, V, V1;
 
-static int      nuseful_productions, nuseless_productions,
-                nuseful_nonterminals, nuseless_nonterminals;
+/* N is set of all nonterminals which are not useless.  P is set of
+   all rules which have no useless nonterminals in their RHS.  V is
+   the set of all accessible symbols.  */
 
+static BSet N, P, V, V1;
 
-extern void reduce_grammar PARAMS((void));
-static bool bits_equal PARAMS((BSet, BSet, int));
-static int nbits PARAMS((unsigned));
-static int bits_size PARAMS((BSet, int));
-static void useless_nonterminals PARAMS((void));
-static void inaccessable_symbols PARAMS((void));
-static void reduce_grammar_tables PARAMS((void));
-static void print_results PARAMS((void));
-static void print_notices PARAMS((void));
-
-#if 0                           /* XXX currently unused.  */
-static void dump_grammar PARAMS((void));
-#endif
-
+static int nuseful_productions;
+static int nuseless_productions;
+static int nuseful_nonterminals;
+static int nuseless_nonterminals;
 
-
 static bool
 bits_equal (BSet L, BSet R, int n)
 {
@@ -95,10 +69,11 @@ nbits (unsigned i)
 {
   int count = 0;
 
-  while (i != 0) {
-    i ^= (i & ((unsigned) (- (int) i)));
-    ++count;
-  }
+  while (i != 0)
+    {
+      i ^= (i & ((unsigned) (-(int) i)));
+      ++count;
+    }
   return count;
 }
 
@@ -109,214 +84,151 @@ bits_size (BSet S, int n)
   int i, count = 0;
 
   for (i = n - 1; i >= 0; i--)
-    count += nbits(S[i]);
+    count += nbits (S[i]);
   return count;
 }
 
-void
-reduce_grammar (void)
-{
-  bool reduced;
-
-  /* Allocate the global sets used to compute the reduced grammar */
-
-  N = NEW2(WORDSIZE(nvars), unsigned);
-  P = NEW2(WORDSIZE(nrules + 1), unsigned);
-  V = NEW2(WORDSIZE(nsyms), unsigned);
-  V1 = NEW2(WORDSIZE(nsyms), unsigned);
-
-  useless_nonterminals();
-  inaccessable_symbols();
-
-  reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0);
-
-  if (verboseflag)
-    print_results();
-
-  if (reduced == FALSE)
-    goto done_reducing;
-
-  print_notices();
-
-  if (!BITISSET(N, start_symbol - ntokens))
-    fatal (_("Start symbol %s does not derive any sentence"),
-	   tags[start_symbol]);
-
-  reduce_grammar_tables();
-#if 0
-  if (verboseflag)
-    {
-      fprintf(foutput, "REDUCED GRAMMAR\n\n");
-      dump_grammar();
-    }
-#endif
-  /**/ statisticsflag = FALSE; /* someday getopts should handle this */
-  if (statisticsflag == TRUE)
-    fprintf(stderr,
-	    _("reduced %s defines %d terminal%s, %d nonterminal%s\
-, and %d production%s.\n"), infile,
-	    ntokens, (ntokens == 1 ? "" : "s"),
-	    nvars,   (nvars   == 1 ? "" : "s"),
-	    nrules,  (nrules  == 1 ? "" : "s"));
-
- done_reducing:
-
-  /* Free the global sets used to compute the reduced grammar */
-
-  FREE(N);
-  FREE(V);
-  FREE(P);
-
-}
-
-/*
- * Another way to do this would be with a set for each production and then do
- * subset tests against N0, but even for the C grammar the whole reducing
- * process takes only 2 seconds on my 8Mhz AT.
- */
+/*-------------------------------------------------------------------.
+| Another way to do this would be with a set for each production and |
+| then do subset tests against N0, but even for the C grammar the    |
+| whole reducing process takes only 2 seconds on my 8Mhz AT.         |
+`-------------------------------------------------------------------*/
 
 static bool
 useful_production (int i, BSet N0)
 {
-  rule  r;
+  rule r;
   short n;
 
-  /*
-   * A production is useful if all of the nonterminals in its RHS
-   * appear in the set of useful nonterminals.
-   */
+  /* A production is useful if all of the nonterminals in its appear
+     in the set of useful nonterminals.  */
 
   for (r = &ritem[rrhs[i]]; *r > 0; r++)
-    if (ISVAR(n = *r))
-      if (!BITISSET(N0, n - ntokens))
+    if (ISVAR (n = *r))
+      if (!BITISSET (N0, n - ntokens))
 	return FALSE;
   return TRUE;
 }
 
 
-/* Remember that rules are 1-origin, symbols are 0-origin. */
+/*---------------------------------------------------------.
+| Remember that rules are 1-origin, symbols are 0-origin.  |
+`---------------------------------------------------------*/
 
 static void
 useless_nonterminals (void)
 {
   BSet Np, Ns;
-  int  i, n;
-
-  /*
-   * N is set as built.  Np is set being built this iteration. P is set
-   * of all productions which have a RHS all in N.
-   */
-
-  Np = NEW2(WORDSIZE(nvars), unsigned);
-
-  /*
-   * The set being computed is a set of nonterminals which can derive
-   * the empty string or strings consisting of all terminals. At each
-   * iteration a nonterminal is added to the set if there is a
-   * production with that nonterminal as its LHS for which all the
-   * nonterminals in its RHS are already in the set.  Iterate until the
-   * set being computed remains unchanged.  Any nonterminals not in the
-   * set at that point are useless in that they will never be used in
-   * deriving a sentence of the language.
-   *
-   * This iteration doesn't use any special traversal over the
-   * productions.  A set is kept of all productions for which all the
-   * nonterminals in the RHS are in useful.  Only productions not in
-   * this set are scanned on each iteration.  At the end, this set is
-   * saved to be used when finding useful productions: only productions
-   * in this set will appear in the final grammar.
-   */
+  int i, n;
+
+  /* N is set as built.  Np is set being built this iteration. P is
+     set of all productions which have a RHS all in N.  */
+
+  Np = NEW2 (WORDSIZE (nvars), unsigned);
+
+  /* The set being computed is a set of nonterminals which can derive
+     the empty string or strings consisting of all terminals. At each
+     iteration a nonterminal is added to the set if there is a
+     production with that nonterminal as its LHS for which all the
+     nonterminals in its RHS are already in the set.  Iterate until
+     the set being computed remains unchanged.  Any nonterminals not
+     in the set at that point are useless in that they will never be
+     used in deriving a sentence of the language.
+
+     This iteration doesn't use any special traversal over the
+     productions.  A set is kept of all productions for which all the
+     nonterminals in the RHS are in useful.  Only productions not in
+     this set are scanned on each iteration.  At the end, this set is
+     saved to be used when finding useful productions: only
+     productions in this set will appear in the final grammar.  */
 
   n = 0;
   while (1)
     {
-      for (i = WORDSIZE(nvars) - 1; i >= 0; i--)
+      for (i = WORDSIZE (nvars) - 1; i >= 0; i--)
 	Np[i] = N[i];
       for (i = 1; i <= nrules; i++)
 	{
-	  if (!BITISSET(P, i))
+	  if (!BITISSET (P, i))
 	    {
-	      if (useful_production(i, N))
+	      if (useful_production (i, N))
 		{
-		  SETBIT(Np, rlhs[i] - ntokens);
-		  SETBIT(P, i);
+		  SETBIT (Np, rlhs[i] - ntokens);
+		  SETBIT (P, i);
 		}
 	    }
 	}
-      if (bits_equal(N, Np, WORDSIZE(nvars)))
+      if (bits_equal (N, Np, WORDSIZE (nvars)))
 	break;
       Ns = Np;
       Np = N;
       N = Ns;
     }
-  FREE(N);
+  FREE (N);
   N = Np;
 }
-
+
+
 static void
 inaccessable_symbols (void)
 {
-  BSet  Vp, Vs, Pp;
-  int   i, n;
+  BSet Vp, Vs, Pp;
+  int i, n;
   short t;
-  rule  r;
-
-  /*
-   * Find out which productions are reachable and which symbols are
-   * used.  Starting with an empty set of productions and a set of
-   * symbols which only has the start symbol in it, iterate over all
-   * productions until the set of productions remains unchanged for an
-   * iteration.  For each production which has a LHS in the set of
-   * reachable symbols, add the production to the set of reachable
-   * productions, and add all of the nonterminals in the RHS of the
-   * production to the set of reachable symbols.
-   *
-   * Consider only the (partially) reduced grammar which has only
-   * nonterminals in N and productions in P.
-   *
-   * The result is the set P of productions in the reduced grammar, and
-   * the set V of symbols in the reduced grammar.
-   *
-   * Although this algorithm also computes the set of terminals which are
-   * reachable, no terminal will be deleted from the grammar. Some
-   * terminals might not be in the grammar but might be generated by
-   * semantic routines, and so the user might want them available with
-   * specified numbers.  (Is this true?)  However, the nonreachable
-   * terminals are printed (if running in verbose mode) so that the user
-   * can know.
-   */
-
-  Vp = NEW2(WORDSIZE(nsyms), unsigned);
-  Pp = NEW2(WORDSIZE(nrules + 1), unsigned);
+  rule r;
+
+  /* Find out which productions are reachable and which symbols are
+     used.  Starting with an empty set of productions and a set of
+     symbols which only has the start symbol in it, iterate over all
+     productions until the set of productions remains unchanged for an
+     iteration.  For each production which has a LHS in the set of
+     reachable symbols, add the production to the set of reachable
+     productions, and add all of the nonterminals in the RHS of the
+     production to the set of reachable symbols.
+
+     Consider only the (partially) reduced grammar which has only
+     nonterminals in N and productions in P.
+
+     The result is the set P of productions in the reduced grammar,
+     and the set V of symbols in the reduced grammar.
+
+     Although this algorithm also computes the set of terminals which
+     are reachable, no terminal will be deleted from the grammar. Some
+     terminals might not be in the grammar but might be generated by
+     semantic routines, and so the user might want them available with
+     specified numbers.  (Is this true?)  However, the nonreachable
+     terminals are printed (if running in verbose mode) so that the
+     user can know.  */
+
+  Vp = NEW2 (WORDSIZE (nsyms), unsigned);
+  Pp = NEW2 (WORDSIZE (nrules + 1), unsigned);
 
   /* If the start symbol isn't useful, then nothing will be useful. */
-  if (!BITISSET(N, start_symbol - ntokens))
+  if (!BITISSET (N, start_symbol - ntokens))
     goto end_iteration;
 
-  SETBIT(V, start_symbol);
+  SETBIT (V, start_symbol);
 
   n = 0;
   while (1)
     {
-      for (i = WORDSIZE(nsyms) - 1; i >= 0; i--)
+      for (i = WORDSIZE (nsyms) - 1; i >= 0; i--)
 	Vp[i] = V[i];
       for (i = 1; i <= nrules; i++)
 	{
-	  if (!BITISSET(Pp, i) && BITISSET(P, i) &&
-	      BITISSET(V, rlhs[i]))
+	  if (!BITISSET (Pp, i) && BITISSET (P, i) && BITISSET (V, rlhs[i]))
 	    {
 	      for (r = &ritem[rrhs[i]]; *r >= 0; r++)
 		{
-		  if (ISTOKEN(t = *r)
-		      || BITISSET(N, t - ntokens))
+		  if (ISTOKEN (t = *r) || BITISSET (N, t - ntokens))
 		    {
-		      SETBIT(Vp, t);
+		      SETBIT (Vp, t);
 		    }
 		}
-	      SETBIT(Pp, i);
+	      SETBIT (Pp, i);
 	    }
 	}
-      if (bits_equal(V, Vp, WORDSIZE(nsyms)))
+      if (bits_equal (V, Vp, WORDSIZE (nsyms)))
 	{
 	  break;
 	}
@@ -324,34 +236,34 @@ inaccessable_symbols (void)
       Vp = V;
       V = Vs;
     }
- end_iteration:
+end_iteration:
 
-  FREE(V);
+  FREE (V);
   V = Vp;
 
   /* Tokens 0, 1, and 2 are internal to Bison.  Consider them useful. */
-  SETBIT(V, 0);			/* end-of-input token */
-  SETBIT(V, 1);			/* error token */
-  SETBIT(V, 2);			/* some undefined token */
+  SETBIT (V, 0);		/* end-of-input token */
+  SETBIT (V, 1);		/* error token */
+  SETBIT (V, 2);		/* some undefined token */
 
-  FREE(P);
+  FREE (P);
   P = Pp;
 
-  nuseful_productions = bits_size(P, WORDSIZE(nrules + 1));
+  nuseful_productions = bits_size (P, WORDSIZE (nrules + 1));
   nuseless_productions = nrules - nuseful_productions;
 
   nuseful_nonterminals = 0;
   for (i = ntokens; i < nsyms; i++)
-    if (BITISSET(V, i))
+    if (BITISSET (V, i))
       nuseful_nonterminals++;
   nuseless_nonterminals = nvars - nuseful_nonterminals;
 
   /* A token that was used in %prec should not be warned about.  */
   for (i = 1; i < nrules; i++)
     if (rprecsym[i] != 0)
-      SETBIT(V1, rprecsym[i]);
+      SETBIT (V1, rprecsym[i]);
 }
-
+
 static void
 reduce_grammar_tables (void)
 {
@@ -367,7 +279,7 @@ reduce_grammar_tables (void)
       ni = 0;
       for (pn = 1; pn <= nrules; pn++)
 	{
-	  if (BITISSET(P, pn))
+	  if (BITISSET (P, pn))
 	    {
 	      np++;
 	      if (pn != np)
@@ -385,7 +297,9 @@ reduce_grammar_tables (void)
 			ritem[ni++] = ritem[pi++];
 		      ritem[ni++] = -np;
 		    }
-		} else {
+		}
+	      else
+		{
 		  while (ritem[ni++] >= 0);
 		}
 	    }
@@ -394,10 +308,8 @@ reduce_grammar_tables (void)
       nrules -= nuseless_productions;
       nitems = ni;
 
-      /*
-       * Is it worth it to reduce the amount of memory for the
-       * grammar? Probably not.
-       */
+      /* Is it worth it to reduce the amount of memory for the
+         grammar? Probably not.  */
 
     }
 #endif /* 0 */
@@ -410,7 +322,7 @@ reduce_grammar_tables (void)
 
       for (pn = 1; pn <= nrules; pn++)
 	{
-	  if (!BITISSET(P, pn))
+	  if (!BITISSET (P, pn))
 	    {
 	      rlhs[pn] = -1;
 	    }
@@ -421,24 +333,22 @@ reduce_grammar_tables (void)
   if (nuseless_nonterminals > 0)
     {
 
-      int    i, n;
+      int i, n;
 /*      short  j; JF unused */
       short *nontermmap;
-      rule   r;
+      rule r;
 
-      /*
-       * create a map of nonterminal number to new nonterminal
-       * number. -1 in the map means it was useless and is being
-       * eliminated.
-       */
+      /* Create a map of nonterminal number to new nonterminal
+	 number. -1 in the map means it was useless and is being
+	 eliminated.  */
 
-      nontermmap = NEW2(nvars, short) - ntokens;
+      nontermmap = NEW2 (nvars, short) - ntokens;
       for (i = ntokens; i < nsyms; i++)
 	nontermmap[i] = -1;
 
       n = ntokens;
       for (i = ntokens; i < nsyms; i++)
-	if (BITISSET(V, i))
+	if (BITISSET (V, i))
 	  nontermmap[i] = n++;
 
       /* Shuffle elements of tables indexed by symbol number.  */
@@ -451,8 +361,10 @@ reduce_grammar_tables (void)
 	      sassoc[n] = sassoc[i];
 	      sprec[n] = sprec[i];
 	      tags[n] = tags[i];
-	    } else {
-	      free(tags[i]);
+	    }
+	  else
+	    {
+	      free (tags[i]);
 	    }
 	}
 
@@ -469,7 +381,7 @@ reduce_grammar_tables (void)
 	}
 
       for (r = ritem; *r; r++)
-	if (ISVAR(*r))
+	if (ISVAR (*r))
 	  *r = nontermmap[*r];
 
       start_symbol = nontermmap[start_symbol];
@@ -477,96 +389,96 @@ reduce_grammar_tables (void)
       nsyms -= nuseless_nonterminals;
       nvars -= nuseless_nonterminals;
 
-      free(&nontermmap[ntokens]);
+      free (&nontermmap[ntokens]);
     }
 }
-
+
 static void
 print_results (void)
 {
-  int   i;
+  int i;
 /*  short j; JF unused */
-  rule  r;
-  bool  b;
+  rule r;
+  bool b;
 
   if (nuseless_nonterminals > 0)
     {
-      fprintf(foutput, _("Useless nonterminals:\n\n"));
+      fprintf (foutput, _("Useless nonterminals:\n\n"));
       for (i = ntokens; i < nsyms; i++)
-	if (!BITISSET(V, i))
-	  fprintf(foutput, "   %s\n", tags[i]);
+	if (!BITISSET (V, i))
+	  fprintf (foutput, "   %s\n", tags[i]);
     }
   b = FALSE;
   for (i = 0; i < ntokens; i++)
     {
-      if (!BITISSET(V, i) && !BITISSET(V1, i))
+      if (!BITISSET (V, i) && !BITISSET (V1, i))
 	{
 	  if (!b)
 	    {
-	      fprintf(foutput, _("\n\nTerminals which are not used:\n\n"));
+	      fprintf (foutput, _("\n\nTerminals which are not used:\n\n"));
 	      b = TRUE;
 	    }
-	  fprintf(foutput, "   %s\n", tags[i]);
+	  fprintf (foutput, "   %s\n", tags[i]);
 	}
     }
 
   if (nuseless_productions > 0)
     {
-      fprintf(foutput, _("\n\nUseless rules:\n\n"));
+      fprintf (foutput, _("\n\nUseless rules:\n\n"));
       for (i = 1; i <= nrules; i++)
 	{
-	  if (!BITISSET(P, i))
+	  if (!BITISSET (P, i))
 	    {
-	      fprintf(foutput, "#%-4d  ", i);
-	      fprintf(foutput, "%s :\t", tags[rlhs[i]]);
+	      fprintf (foutput, "#%-4d  ", i);
+	      fprintf (foutput, "%s :\t", tags[rlhs[i]]);
 	      for (r = &ritem[rrhs[i]]; *r >= 0; r++)
 		{
-		  fprintf(foutput, " %s", tags[*r]);
+		  fprintf (foutput, " %s", tags[*r]);
 		}
-	      fprintf(foutput, ";\n");
+	      fprintf (foutput, ";\n");
 	    }
 	}
     }
   if (nuseless_nonterminals > 0 || nuseless_productions > 0 || b)
-    fprintf(foutput, "\n\n");
+    fprintf (foutput, "\n\n");
 }
 
-#if 0                           /* XXX currently unused.  */
+#if 0				/* XXX currently unused.  */
 static void
 dump_grammar (void)
 {
   int i;
   rule r;
 
-  fprintf(foutput,
-	  "ntokens = %d, nvars = %d, nsyms = %d, nrules = %d, nitems = %d\n\n",
-	  ntokens, nvars, nsyms, nrules, nitems);
-  fprintf(foutput, _("Variables\n---------\n\n"));
-  fprintf(foutput, _("Value  Sprec    Sassoc    Tag\n"));
+  fprintf (foutput,
+	   "ntokens = %d, nvars = %d, nsyms = %d, nrules = %d, nitems = %d\n\n",
+	   ntokens, nvars, nsyms, nrules, nitems);
+  fprintf (foutput, _("Variables\n---------\n\n"));
+  fprintf (foutput, _("Value  Sprec    Sassoc    Tag\n"));
   for (i = ntokens; i < nsyms; i++)
-    fprintf(foutput, "%5d  %5d  %5d  %s\n",
-	    i, sprec[i], sassoc[i], tags[i]);
-  fprintf(foutput, "\n\n");
-  fprintf(foutput, _("Rules\n-----\n\n"));
+    fprintf (foutput, "%5d  %5d  %5d  %s\n", i, sprec[i], sassoc[i], tags[i]);
+  fprintf (foutput, "\n\n");
+  fprintf (foutput, _("Rules\n-----\n\n"));
   for (i = 1; i <= nrules; i++)
     {
-      fprintf(foutput, "%-5d(%5d%5d)%5d : (@%-5d)",
-	      i, rprec[i], rassoc[i], rlhs[i], rrhs[i]);
+      fprintf (foutput, "%-5d(%5d%5d)%5d : (@%-5d)",
+	       i, rprec[i], rassoc[i], rlhs[i], rrhs[i]);
       for (r = &ritem[rrhs[i]]; *r > 0; r++)
-	fprintf(foutput, "%5d", *r);
-      fprintf(foutput, " [%d]\n", -(*r));
+	fprintf (foutput, "%5d", *r);
+      fprintf (foutput, " [%d]\n", -(*r));
     }
-  fprintf(foutput, "\n\n");
-  fprintf(foutput, _("Rules interpreted\n-----------------\n\n"));
+  fprintf (foutput, "\n\n");
+  fprintf (foutput, _("Rules interpreted\n-----------------\n\n"));
   for (i = 1; i <= nrules; i++)
     {
-      fprintf(foutput, "%-5d  %s :", i, tags[rlhs[i]]);
+      fprintf (foutput, "%-5d  %s :", i, tags[rlhs[i]]);
       for (r = &ritem[rrhs[i]]; *r > 0; r++)
-	fprintf(foutput, " %s", tags[*r]);
-      fprintf(foutput, "\n");
+	fprintf (foutput, " %s", tags[*r]);
+      fprintf (foutput, "\n");
     }
-  fprintf(foutput, "\n\n");
+  fprintf (foutput, "\n\n");
 }
+
 #endif
 
 
@@ -574,25 +486,81 @@ static void
 print_notices (void)
 {
   if (fixed_outfiles && nuseless_productions)
-    fprintf(stderr, _("%d rules never reduced\n"), nuseless_productions);
+    fprintf (stderr, _("%d rules never reduced\n"), nuseless_productions);
 
-  fprintf(stderr, _("%s contains "), infile);
+  fprintf (stderr, _("%s contains "), infile);
 
   if (nuseless_nonterminals > 0)
     {
-      fprintf(stderr, _("%d useless nonterminal%s"),
-	      nuseless_nonterminals,
-	      (nuseless_nonterminals == 1 ? "" : "s"));
+      fprintf (stderr, _("%d useless nonterminal%s"),
+	       nuseless_nonterminals,
+	       (nuseless_nonterminals == 1 ? "" : "s"));
     }
   if (nuseless_nonterminals > 0 && nuseless_productions > 0)
-    fprintf(stderr, _(" and "));
+    fprintf (stderr, _(" and "));
 
   if (nuseless_productions > 0)
     {
-      fprintf(stderr, _("%d useless rule%s"),
-	      nuseless_productions,
-	      (nuseless_productions == 1 ? "" : "s"));
+      fprintf (stderr, _("%d useless rule%s"),
+	       nuseless_productions, (nuseless_productions == 1 ? "" : "s"));
     }
-  fprintf(stderr, "\n");
-  fflush(stderr);
+  fprintf (stderr, "\n");
+  fflush (stderr);
+}
+
+void
+reduce_grammar (void)
+{
+  bool reduced;
+
+  /* Allocate the global sets used to compute the reduced grammar */
+
+  N = NEW2 (WORDSIZE (nvars), unsigned);
+  P = NEW2 (WORDSIZE (nrules + 1), unsigned);
+  V = NEW2 (WORDSIZE (nsyms), unsigned);
+  V1 = NEW2 (WORDSIZE (nsyms), unsigned);
+
+  useless_nonterminals ();
+  inaccessable_symbols ();
+
+  reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0);
+
+  if (verboseflag)
+    print_results ();
+
+  if (reduced == FALSE)
+    goto done_reducing;
+
+  print_notices ();
+
+  if (!BITISSET (N, start_symbol - ntokens))
+    fatal (_("Start symbol %s does not derive any sentence"),
+	   tags[start_symbol]);
+
+  reduce_grammar_tables ();
+#if 0
+  if (verboseflag)
+    {
+      fprintf (foutput, "REDUCED GRAMMAR\n\n");
+      dump_grammar ();
+    }
+#endif
+  statisticsflag = FALSE;	/* someday getopts should handle this */
+  if (statisticsflag == TRUE)
+    fprintf (stderr, _("reduced %s defines %d terminal%s, %d nonterminal%s\
+, and %d production%s.\n"),
+	     infile,
+	     ntokens,
+	     (ntokens == 1 ? "" : "s"),
+	     nvars,
+	     (nvars == 1 ? "" : "s"),
+	     nrules,
+	     (nrules == 1 ? "" : "s"));
+
+done_reducing:
+  /* Free the global sets used to compute the reduced grammar */
+
+  FREE (N);
+  FREE (V);
+  FREE (P);
 }
diff --git a/src/system.h b/src/system.h
index 56a0ba0e..ae02b619 100644
--- a/src/system.h
+++ b/src/system.h
@@ -148,3 +148,14 @@ extern int errno;
 #define	SETBIT(x, i)	((x)[(i)/BITS_PER_WORD] |= (1<<((i) % BITS_PER_WORD)))
 #define RESETBIT(x, i)	((x)[(i)/BITS_PER_WORD] &= ~(1<<((i) % BITS_PER_WORD)))
 #define BITISSET(x, i)	(((x)[(i)/BITS_PER_WORD] & (1<<((i) % BITS_PER_WORD))) != 0)
+
+
+/*-----------.
+| Booleans.  |
+`-----------*/
+
+#ifndef TRUE
+# define TRUE	(1)
+# define FALSE	(0)
+#endif
+typedef int bool;