libgfortran/intrinsics/extends_type_of.c

   1 /* Implementation of the EXTENDS_TYPE_OF intrinsic.
   2    Copyright (C) 2004-2021 Free Software Foundation, Inc.
   3    Contributed by Janus Weil <janus@gcc.gnu.org>.
   4
   5 This file is part of the GNU Fortran runtime library (libgfortran).
   6
   7 Libgfortran is free software; you can redistribute it and/or
   8 modify it under the terms of the GNU General Public
   9 License as published by the Free Software Foundation; either
  10 version 3 of the License, or (at your option) any later version.
  11
  12 Libgfortran is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26
  27 #include "libgfortran.h"
  28
  29
  30 typedef struct vtype
  31 {
  32   GFC_INTEGER_4 hash;
  33   size_t size;
  34   struct vtype *extends;
  35 }
  36 vtype;
  37
  38
  39 extern GFC_LOGICAL_4 is_extension_of (struct vtype *, struct vtype *);
  40 export_proto(is_extension_of);
  41
  42
  43 /* This is a helper function for the F2003 intrinsic EXTENDS_TYPE_OF.
  44    While EXTENDS_TYPE_OF accepts CLASS or TYPE arguments, this one here gets
  45    passed the corresponding vtabs. Each call to EXTENDS_TYPE_OF is translated
  46    to a call to is_extension_of.  */
  47
  48 GFC_LOGICAL_4
  49 is_extension_of (struct vtype *v1, struct vtype *v2)
  50 {
  51   /* Assume that only unlimited polymorphic entities will pass NULL v1 or v2
  52      if they are unallocated or disassociated.  */
  53
  54   if (!v2)
  55     return 1;
  56   if (!v1)
  57     return 0;
  58
  59   while (v1)
  60     {
  61       if (v1->hash == v2->hash) return 1;
  62       v1 = v1->extends;
  63     }
  64   return 0;
  65 }