gcc/tristate.h

   1 /* "True" vs "False" vs "Unknown".
   2    Copyright (C) 2019-2023 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_unknown () const { return m_value == TS_UNKNOWN; }
  42   bool is_true () const { return m_value == TS_TRUE; }
  43   bool is_false () const { return m_value == TS_FALSE; }
  44
  45   tristate not_ () const;
  46   tristate or_ (tristate other) const;
  47   tristate and_ (tristate other) const;
  48
  49   bool operator== (const tristate &other) const
  50   {
  51     return m_value == other.m_value;
  52   }
  53
  54   bool operator!= (const tristate &other) const
  55   {
  56     return m_value != other.m_value;
  57   }
  58
  59   enum value get_value () const { return m_value; }
  60
  61  private:
  62   enum value m_value;
  63 };
  64
  65 /* Overloaded boolean operators on tristates.  */
  66
  67 inline tristate
  68 operator ! (tristate t)
  69 {
  70   return t.not_ ();
  71 }
  72
  73 inline tristate
  74 operator || (tristate a, tristate b)
  75 {
  76   return a.or_ (b);
  77 }
  78
  79 inline tristate
  80 operator && (tristate a, tristate b)
  81 {
  82   return a.and_ (b);
  83 }
  84
  85 #endif /* GCC_TRISTATE_H */