src/derives.c

   1 /* Match rules with nonterminals for bison,
   2    Copyright 1984, 1989, 2000, 2001  Free Software Foundation, Inc.
   3
   4    This file is part of Bison, the GNU Compiler Compiler.
   5
   6    Bison is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    Bison is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with Bison; see the file COPYING.  If not, write to
  18    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21
  22 /* set_derives finds, for each variable (nonterminal), which rules can
  23    derive it.  It sets up the value of derives so that derives[i -
  24    ntokens] points to a vector of rule numbers, terminated with -1.
  25    */
  26
  27 #include "system.h"
  28 #include "getargs.h"
  29 #include "types.h"
  30 #include "reader.h"
  31 #include "gram.h"
  32 #include "derives.h"
  33
  34 short **derives;
  35
  36
  37 static void
  38 print_derives (void)
  39 {
  40   int i;
  41
  42   fputs ("DERIVES\n", stderr);
  43
  44   for (i = ntokens; i < nsyms; i++)
  45     {
  46       short *sp;
  47       fprintf (stderr, "\t%s derives\n", tags[i]);
  48       for (sp = derives[i]; *sp > 0; sp++)
  49         {
  50           short *rhsp;
  51           fprintf (stderr, "\t\t%d:", *sp);
  52           for (rhsp = ritem + rule_table[*sp].rhs; *rhsp > 0; ++rhsp)
  53             fprintf (stderr, " %s", tags[*rhsp]);
  54           fputc ('\n', stderr);
  55         }
  56     }
  57
  58   fputs ("\n\n", stderr);
  59 }
  60
  61
  62 void
  63 set_derives (void)
  64 {
  65   int i;
  66   int lhs;
  67   shorts *p;
  68   short *q;
  69   shorts **dset;
  70   shorts *delts;
  71
  72   dset = XCALLOC (shorts *, nvars) - ntokens;
  73   delts = XCALLOC (shorts, nrules + 1);
  74
  75   p = delts;
  76   for (i = nrules; i > 0; i--)
  77     {
  78       lhs = rule_table[i].lhs;
  79       if (lhs >= 0)
  80         {
  81           p->next = dset[lhs];
  82           p->value = i;
  83           dset[lhs] = p;
  84           p++;
  85         }
  86     }
  87
  88   derives = XCALLOC (short *, nvars) - ntokens;
  89   q = XCALLOC (short, nvars + nrules);
  90
  91   for (i = ntokens; i < nsyms; i++)
  92     {
  93       derives[i] = q;
  94       p = dset[i];
  95       while (p)
  96         {
  97           *q++ = p->value;
  98           p = p->next;
  99         }
 100       *q++ = -1;
 101     }
 102
 103   if (trace_flag)
 104     print_derives ();
 105
 106   XFREE (dset + ntokens);
 107   XFREE (delts);
 108 }
 109
 110 void
 111 free_derives (void)
 112 {
 113   XFREE (derives[ntokens]);
 114   XFREE (derives + ntokens);
 115 }