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 #include "system.h"
  23 #include "getargs.h"
  24 #include "symtab.h"
  25 #include "types.h"
  26 #include "reader.h"
  27 #include "gram.h"
  28 #include "derives.h"
  29
  30 short **derives = NULL;
  31
  32 static void
  33 print_derives (void)
  34 {
  35   int i;
  36
  37   fputs ("DERIVES\n", stderr);
  38
  39   for (i = ntokens; i < nsyms; i++)
  40     {
  41       short *sp;
  42       fprintf (stderr, "\t%s derives\n", symbols[i]->tag);
  43       for (sp = derives[i]; *sp > 0; sp++)
  44         {
  45           short *rhsp;
  46           fprintf (stderr, "\t\t%d:", *sp);
  47           for (rhsp = &ritem[rules[*sp].rhs]; *rhsp >= 0; ++rhsp)
  48             fprintf (stderr, " %s", symbols[*rhsp]->tag);
  49           fprintf (stderr, " (rule %d)\n", -*rhsp - 1);
  50         }
  51     }
  52
  53   fputs ("\n\n", stderr);
  54 }
  55
  56
  57 void
  58 set_derives (void)
  59 {
  60   int i;
  61   shorts *p;
  62   short *q;
  63   shorts **dset;
  64   shorts *delts;
  65
  66   dset = XCALLOC (shorts *, nvars) - ntokens;
  67   delts = XCALLOC (shorts, nrules + 1);
  68
  69   p = delts;
  70   for (i = nrules; i > 0; i--)
  71     if (rules[i].useful)
  72       {
  73         int lhs = rules[i].lhs;
  74         p->next = dset[lhs];
  75         p->value = i;
  76         dset[lhs] = p;
  77         p++;
  78       }
  79
  80   derives = XCALLOC (short *, nvars) - ntokens;
  81   q = XCALLOC (short, nvars + nrules);
  82
  83   for (i = ntokens; i < nsyms; i++)
  84     {
  85       derives[i] = q;
  86       p = dset[i];
  87       while (p)
  88         {
  89           *q++ = p->value;
  90           p = p->next;
  91         }
  92       *q++ = -1;
  93     }
  94
  95   if (trace_flag)
  96     print_derives ();
  97
  98   XFREE (dset + ntokens);
  99   XFREE (delts);
 100 }
 101
 102 void
 103 free_derives (void)
 104 {
 105   XFREE (derives[ntokens]);
 106   XFREE (derives + ntokens);
 107 }