codac2_BoolInterval.h

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#pragma once
 
#include <ostream>
 
namespace codac2
{
  enum class BoolInterval
  {
    FALSE = 0x01,
    TRUE = 0x02,
    EMPTY = 0x00,
    UNKNOWN = 0x01 | 0x02
  };

  constexpr BoolInterval operator&(BoolInterval x, BoolInterval y)
  {
    return static_cast<BoolInterval>(static_cast<int>(x) & static_cast<int>(y));
  }

  constexpr BoolInterval operator|(BoolInterval x, BoolInterval y)
  {
    return static_cast<BoolInterval>(static_cast<int>(x) | static_cast<int>(y));
  }

  constexpr BoolInterval operator&&(BoolInterval x, BoolInterval y)
  {
    if((x == BoolInterval::EMPTY) || (y == BoolInterval::EMPTY))
      return BoolInterval::EMPTY;
    if((x == BoolInterval::FALSE) || (y == BoolInterval::FALSE))
      return BoolInterval::FALSE;
    if((x == BoolInterval::UNKNOWN) || (y == BoolInterval::UNKNOWN))
      return BoolInterval::UNKNOWN;
    return BoolInterval::TRUE;
  }

  constexpr BoolInterval operator||(BoolInterval x, BoolInterval y)
  {
    if((x == BoolInterval::EMPTY) || (y == BoolInterval::EMPTY))
      return BoolInterval::EMPTY;
    if((x == BoolInterval::TRUE) || (y == BoolInterval::TRUE))
      return BoolInterval::TRUE;
    if((x == BoolInterval::UNKNOWN) || (y == BoolInterval::UNKNOWN))
      return BoolInterval::UNKNOWN;
    return BoolInterval::FALSE;
  }

  inline BoolInterval operator~(BoolInterval x)
  {
    switch(x)
    {
      case BoolInterval::FALSE:
        return BoolInterval::TRUE;
      case BoolInterval::TRUE:
        return BoolInterval::FALSE;
      default:
        return x;
    }
  }
  
  inline std::ostream& operator<<(std::ostream& os, const BoolInterval& x)
  {
    switch(x)
    {
      case BoolInterval::EMPTY:
        os << "[ empty ]";
        break;
      case BoolInterval::FALSE:
        os << "[ false ]";
        break;
      case BoolInterval::TRUE:
        os << "[ true ]";
        break;
      case BoolInterval::UNKNOWN:
        os << "[ true, false ]";
        break;
    }
    return os;
  }
}