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#ifndef UTIL_EXCEPTION__
#define UTIL_EXCEPTION__
#include "util/string_piece.hh"
#include <exception>
#include <sstream>
#include <string>
namespace util {
template <class Except, class Data> typename Except::template ExceptionTag<Except&>::Identity operator<<(Except &e, const Data &data);
class Exception : public std::exception {
public:
Exception() throw();
virtual ~Exception() throw();
Exception(const Exception &from);
Exception &operator=(const Exception &from);
// Not threadsafe, but probably doesn't matter. FWIW, Boost's exception guidance implies that what() isn't threadsafe.
const char *what() const throw();
private:
template <class Except, class Data> friend typename Except::template ExceptionTag<Except&>::Identity operator<<(Except &e, const Data &data);
// This helps restrict operator<< defined below.
template <class T> struct ExceptionTag {
typedef T Identity;
};
std::stringstream stream_;
mutable std::string text_;
};
/* This implements the normal operator<< for Exception and all its children.
* SNIFAE means it only applies to Exception. Think of this as an ersatz
* boost::enable_if.
*/
template <class Except, class Data> typename Except::template ExceptionTag<Except&>::Identity operator<<(Except &e, const Data &data) {
e.stream_ << data;
return e;
}
#define UTIL_THROW(Exception, Modify) { Exception UTIL_e; {UTIL_e << Modify;} throw UTIL_e; }
class ErrnoException : public Exception {
public:
ErrnoException() throw();
virtual ~ErrnoException() throw();
int Error() { return errno_; }
private:
int errno_;
};
} // namespace util
#endif // UTIL_EXCEPTION__
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