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   shorts *p;
  67   short *q;
  68   shorts **dset;
  69   shorts *delts;
  70
  71   dset = XCALLOC (shorts *, nvars) - ntokens;
  72   delts = XCALLOC (shorts, nrules + 1);
  73
  74   p = delts;
  75   for (i = nrules; i > 0; i--)
  76     if (rule_table[i].useful)
  77       {
  78         int lhs = rule_table[i].lhs;
  79         p->next = dset[lhs];
  80         p->value = i;
  81         dset[lhs] = p;
  82         p++;
  83       }
  84
  85   derives = XCALLOC (short *, nvars) - ntokens;
  86   q = XCALLOC (short, nvars + nrules);
  87
  88   for (i = ntokens; i < nsyms; i++)
  89     {
  90       derives[i] = q;
  91       p = dset[i];
  92       while (p)
  93         {
  94           *q++ = p->value;
  95           p = p->next;
  96         }
  97       *q++ = -1;
  98     }
  99
 100   if (trace_flag)
 101     print_derives ();
 102
 103   XFREE (dset + ntokens);
 104   XFREE (delts);
 105 }
 106
 107 void
 108 free_derives (void)
 109 {
 110   XFREE (derives[ntokens]);
 111   XFREE (derives + ntokens);
 112 }