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 */