gcc/tristate.h

   1 /* "True" vs "False" vs "Unknown".
   2    Copyright (C) 2019-2020 Free Software Foundation, Inc.
   3    Contributed by David Malcolm <dmalcolm@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it
   8 under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_TRISTATE_H
  22 #define GCC_TRISTATE_H
  23
  24 /* "True" vs "False" vs "Unknown".  */
  25
  26 class tristate {
  27  public:
  28   enum value {
  29     TS_UNKNOWN,
  30     TS_TRUE,
  31     TS_FALSE
  32   };
  33
  34   tristate (enum value val) : m_value (val) {}
  35   tristate (bool val) : m_value (val ? TS_TRUE : TS_FALSE) {}
  36   static tristate unknown () { return tristate (TS_UNKNOWN); }
  37
  38   const char *as_string () const;
  39
  40   bool is_known () const { return m_value != TS_UNKNOWN; }
  41   bool is_true () const { return m_value == TS_TRUE; }
  42   bool is_false () const { return m_value == TS_FALSE; }
  43
  44   tristate not_ () const;
  45   tristate or_ (tristate other) const;
  46   tristate and_ (tristate other) const;
  47
  48   bool operator== (const tristate &other) const
  49   {
  50     return m_value == other.m_value;
  51   }
  52
  53   bool operator!= (const tristate &other) const
  54   {
  55     return m_value != other.m_value;
  56   }
  57
  58  private:
  59   enum value m_value;
  60 };
  61
  62 /* Overloaded boolean operators on tristates.  */
  63
  64 inline tristate
  65 operator ! (tristate t)
  66 {
  67   return t.not_ ();
  68 }
  69
  70 inline tristate
  71 operator || (tristate a, tristate b)
  72 {
  73   return a.or_ (b);
  74 }
  75
  76 inline tristate
  77 operator && (tristate a, tristate b)
  78 {
  79   return a.and_ (b);
  80 }
  81
  82 #endif /* GCC_TRISTATE_H */