namespace Msp {
/**
-Thrown for errors in lexical conversions
+Thrown for errors in lexical conversions.
*/
class lexical_error: public std::runtime_error
{
};
+/**
+Thrown when the format is unsuitable for the type being converted.
+*/
class format_mismatch: public lexical_error
{
public:
// Generic operators using stringstream
-template<typename T>
-struct HasFormattedOutput: Sfinae
+struct CheckFormattedOutput: Sfinae
{
static std::ostream &s;
- static T &v;
-
- /* The expression must depend on the template parameter, or the compiler
- will give an error. */
- template<typename U>
- static Yes f(int (*)[sizeof(s<<HasFormattedOutput<U>::v)]);
- template<typename U>
- static No f(...);
-
- enum { value = Evaluate<sizeof(f<T>(0))>::value };
+ template<typename T>
+ static Yes f(int (*)[sizeof(s<<reinterpret_cast<const T &>(s))]);
+ using Sfinae::f;
};
-template<typename T>
-struct HasFormattedInput: Sfinae
+struct CheckFormattedInput: Sfinae
{
static std::istream &s;
- static T &v;
-
- template<typename U>
- static Yes f(int (*)[sizeof(s>>HasFormattedOutput<U>::v)]);
- template<typename U>
- static No f(...);
-
- enum { value = Evaluate<sizeof(f<T>(0))>::value };
+ template<typename T>
+ static Yes f(int (*)[sizeof(s>>reinterpret_cast<T &>(s))]);
+ using Sfinae::f;
};
+template<typename T> struct HasFormattedOutput: Sfinae::Evaluate<CheckFormattedOutput, T> { };
+template<typename T> struct HasFormattedInput: Sfinae::Evaluate<CheckFormattedInput, T> { };
+
template<typename T>
-typename EnableIf<HasFormattedOutput<T>::value, void>::Yes
+typename std::enable_if<HasFormattedOutput<T>::value>::type
operator<<(LexicalConverter &c, const T &v)
{
std::ostringstream ss;
- ss<<c.get_fmt()<<v;
+ ss << c.get_fmt() << v;
c.result(ss.str());
}
template<typename T>
-typename EnableIf<HasFormattedInput<T>::value, void>::Yes
+typename std::enable_if<HasFormattedInput<T>::value>::type
operator>>(const LexicalConverter &c, T &v)
{
std::istringstream ss(c.get());
ss.setf(std::ios_base::fmtflags(0), std::ios_base::skipws);
- ss>>v;
+ ss >> v;
if(ss.fail() || !ss.eof())
throw lexical_error("conversion failure");
}
-// Helper struct to provide partial template specialization
-
+/**
+Helper struct to provide partial template specialization.
+*/
template<typename T, typename F>
struct LexicalCast;
{
LexicalConverter conv(s, f);
T result;
- conv>>result;
+ conv >> result;
return result;
}
};
static std::string cast(const F &v, const Fmt &f = Fmt())
{
LexicalConverter conv(f);
- conv<<v;
+ conv << v;
return conv.get();
}
};
static std::string cast(const std::string &v, const Fmt &f = Fmt())
{
LexicalConverter conv(f);
- conv<<v;
+ conv << v;
return conv.get();
}
};
-// The main interface to the lexical conversion machinery
-
+/** Perform a lexical conversion between a string and another type. The source
+type can normally be deduced by the compiler, so this can be used just like the
+standard C++ casts. A format may additionally be specified to force a specific
+interpretation. */
template<typename T, typename F>
inline T lexical_cast(const F &v, const Fmt &f = Fmt())
{