Convert reverse_iterator to iterator?

Question

I am writing an XML interpreter in C++, when I find a bad formation in XML I would like to show the error row and column. I am working with string Iterators and created a function to format the error as follows:

string msgLocalizadaXML(string::const_iterator aItIni, string::const_iterator aItFim, string::const_iterator aItMsg)
{
   string linha = "Linha...: " + to_string(count(aItIni, aItMsg, '\n') + 1) + '\n';
   constexpr auto numCaracteres = 25;

   auto itQuebra = find(reverse_iterator<string::const_iterator> { aItMsg },
                        reverse_iterator<string::const_iterator> { aItIni },
                        '\n');                                 
   // Linha do erro
   string coluna = "Coluna..: " + to_string(distance(itQuebra, aItMsg) + 1) + '\n';

   string contexto { max(aItIni, aItMsg - numCaracteres), min(aItFim, aItMsg + numCaracteres) };
   replace(contexto.begin(), contexto.end(), '\n', ' ');
   contexto = "Contexto: " + contexto + "\n"
              "          " + string(static_cast<size_t>(distance(max(aItIni, aItMsg - numCaracteres), aItMsg)), '~') + '^';

   return linha + coluna + contexto;
}

The error returned GCC 4.8.1:

XMLDocumento.cpp:420:86: error: no matching function for call to 'distance(std::reverse_iterator<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> > >&, std::basic_string<char>::const_iterator&)'

The error is because the Iterators for the Distance function have to be of the same type, but as I search backwards it returns me a Reverse, as I convert to an iterator?

I tried to build a Std::string::iterator with itQuebra but it didn’t let me.

Answer 1

As specified in the question comments, the resolution occurred using itQuebra.base().

Thus, the code was changed from:

string coluna = "Coluna..: " + to_string(distance(itQuebra, aItMsg) + 1) + '\n';

To:

string coluna = "Coluna..: " + to_string(distance(itQuebra.base(), aItMsg) + 1) + '\n';