parser.hh

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#ifndef DUNE_FEM_IO_PARAMETER_PARSER_HH
#define DUNE_FEM_IO_PARAMETER_PARSER_HH
 
#include <sstream>
#include <string>
#include <type_traits>
 
#include <dune/common/fmatrix.hh>
 
namespace Dune
{
 
  namespace Fem
  {
 
    // ParameterParser
    // ---------------
 
    template< class T >
    struct ParameterParser
    {
      static bool parse ( const std::string &s, T &value )
      {
        if constexpr ( std::is_same< T, std::string >::value )
        {
          // if string is non-empty just copy completely
          if( ! s.empty() )
            value = s;
          return true;
        }
 
        std::istringstream in( s );
        in >> value;
 
        if( in.fail() )
          return false;
 
        char eof;
        in >> eof;
        return in.eof();
      }
 
      static std::string toString ( const T &value )
      {
        std::ostringstream out;
        out << value;
        return out.str();
      }
    };
 
    template<>
    struct ParameterParser< bool >
    {
      static bool parse ( const std::string &s, bool &value )
      {
        std::string w;
        if( ParameterParser< std::string >::parse( s, w ) )
        {
          std::transform(w.begin(), w.end(), w.begin(), ::tolower);
          if( (w == std::string( "false" )) || (w == std::string( "no" )) || (w == std::string( "0" )) )
          {
            value = false;
            return true;
          }
 
          if( (w == std::string( "true" )) || (w == std::string( "yes" )) || (w == std::string( "1" )) )
          {
            value = true;
            return true;
          }
        }
        return false;
      }
 
      static std::string toString ( const bool &value )
      {
        return std::string( value ? "true" : "false" );
      }
    };
 
    template< class F, int m, int n >
    struct ParameterParser< FieldMatrix< F, m, n > >
    {
      static bool parse ( const std::string &s, FieldMatrix< F, m, n > &value )
      {
        std::istringstream in( s );
        char c;
        for( int i = 0; i < m; ++i )
        {
          if( i > 0 )
          {
            in >> c;
            if( c != ',' )
              return false;
          }
 
          for( int j = 0; j < n; ++j )
            in >> value[ i ][ j ];
        }
        in >> c; // read eof
        return in.eof();
      }
 
      static std::string toString ( const FieldMatrix< F, m, n > &value )
      {
        std::ostringstream out;
        for( int i = 0; i < m; ++i )
        {
          out << (i > 0 ? "," : "");
          for( int j = 0; j< n; ++j )
            out << " " << value[ i ][ j ];
        }
        return out.str();
      }
    };
 
  } // namespace Fem
 
} // namespace Dune
 
#endif // #ifndef DUNE_FEM_IO_PARAMETER_PARSER_HH