sign.hh

#ifndef __DUNE_ACFEM_EXPRESSIONS_SIGN_HH__
#define __DUNE_ACFEM_EXPRESSIONS_SIGN_HH__
 
#include <ostream>
 
namespace Dune {
 
  namespace ACFem {
 
    namespace Expressions {
 
      template<bool nonSingular, bool semiPositive, bool semiNegative,
               std::ptrdiff_t offset = 0>
      struct ExpressionSign
      {
        static constexpr bool isNonSingular = nonSingular;
        static constexpr bool isSemiPositive = semiPositive;
        static constexpr bool isSemiNegative = semiNegative;
        static constexpr bool isZero = !isNonSingular && isSemiPositive && isSemiNegative;
        static constexpr bool isNonZero = nonSingular;
        static constexpr bool isPositive = isNonZero && isSemiPositive;
        static constexpr bool isNegative = isNonZero && isSemiNegative;
        static constexpr std::ptrdiff_t reference = offset;
        using Sign = ExpressionSign;
      };
 
      template<bool nonSingular, bool semiPositive, bool semiNegative, ssize_t offset>
      std::ostream& operator<<(std::ostream& out, const ExpressionSign<nonSingular, semiPositive, semiNegative, offset>&)
      {
        using Sign = ExpressionSign<nonSingular, semiPositive, semiNegative, offset>;
        out << "{";
        Sign::isSemiPositive && out << "(>=" << Sign::reference << ")";
        Sign::isSemiNegative && out << "(<=" << Sign::reference << ")";
        Sign::isZero && out << "(==" << Sign::reference << ")";
        Sign::isNonZero && out << "(!=" << Sign::reference << ")";
        Sign::isNonSingular && out << "(!/" << Sign::reference << ")";
        Sign::isPositive && out << "(>" << Sign::reference << ")";
        Sign::isNegative && out << "(<" << Sign::reference << ")";
        out << "}";
        return out;
      };
 
    } // Expressions::
 
    using Expressions::ExpressionSign;
 
    using UnknownExpressionSign = ExpressionSign<false, false, false>;
    using ZeroExpressionSign = ExpressionSign<false, true, true>;
    using NonZeroExpressionSign = ExpressionSign<true, false, false>;
    using PositiveExpressionSign = ExpressionSign<true, true, false>;
    using NegativeExpressionSign = ExpressionSign<true, false, true>;
    using SemiPositiveExpressionSign = ExpressionSign<false, true, false>;
    using SemiNegativeExpressionSign = ExpressionSign<false, false, true>;
    using RegularZeroExpressionSign = ExpressionSign<true, true, true>;
 
  } // ACFem::
 
} // Dune::
 
#endif // __DUNE_ACFEM_EXPRESSIONS_SIGN_HH__