Error handling

Dettagli

Categoria: TSL

Pubblicato Lunedì, 21 Ottobre 2013 23:25

Scritto da Giampiero Gabbiani

Visite: 1837

During parsing of an XML or JSON file, in case of error, an exception of type tsl::ParseError is thrown.

The definition of the class is the following:

class ParseError : public std::runtime_error {
public:
  ParseError(const std::string &msg,size_t r,size_t c);
  const size_t row,col;
};

The two members ParseError::row and ParseError::col will contain the point of the error while the result of the std::runtime_error::what() method invocation will report the error coordinates plus a simple explanation. In the example below we try to deserialize into a std::tuple of one string and one unsigned int a collection of two strings, producing a ParseError catched and dumped to cerr:

typedef std::tuple<string,unsigned int> WrongSequence; 

std::stringstream stream( 
"{\n"                           // row 1
" \"correct\": \"string 1\",\n" // row 2
" \"wrong\" : \"string 2\"\n"   // row 3
"}\n");

WrongSequence restored; 

try {
  stream.unsetf(ios::skipws);
  tsl::IJsonArchive archive(stream);
  archive & get<0>(restored) & get<1>(restored);
} catch (const tsl::ParseError &error) {
  cerr << error.what() << endl
       << "row --> " << error.row << ",column --> " << error.col << endl;
}

the result is below:

error at line 3 column 13 unmarshalling unsigned int value.

row --> 3,column --> 13

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