1 #ifndef MSP_STRINGS_LEXICALCAST_H_
2 #define MSP_STRINGS_LEXICALCAST_H_
7 #include <msp/core/meta.h>
13 Thrown for errors in lexical conversions.
15 class lexical_error: public std::runtime_error
18 lexical_error(const std::string &w): runtime_error(w) { }
19 virtual ~lexical_error() throw() { }
24 Thrown when the format is unsuitable for the type being converted.
26 class format_mismatch: public lexical_error
29 format_mismatch(const std::string &w): lexical_error(w) { }
30 virtual ~format_mismatch() throw() { }
35 Helper class for lexical_cast to facilitate operator overloading.
37 class LexicalConverter
45 LexicalConverter(const Fmt &f): fmt(f), filled(false) { }
46 LexicalConverter(const std::string &s, const Fmt &f): fmt(f), filled(true), buf(s) { }
48 const Fmt &get_fmt() const { return fmt; }
49 const std::string &get() const;
50 void result(const std::string &);
54 void operator<<(LexicalConverter &, char);
55 void operator<<(LexicalConverter &, signed char);
56 void operator<<(LexicalConverter &, short);
57 void operator<<(LexicalConverter &, int);
58 void operator<<(LexicalConverter &, long);
59 void operator<<(LexicalConverter &, unsigned char);
60 void operator<<(LexicalConverter &, unsigned short);
61 void operator<<(LexicalConverter &, unsigned);
62 void operator<<(LexicalConverter &, unsigned long);
64 void operator<<(LexicalConverter &, long long);
65 void operator<<(LexicalConverter &, unsigned long long);
67 void operator<<(LexicalConverter &, bool);
68 void operator<<(LexicalConverter &, float);
69 void operator<<(LexicalConverter &, double);
70 void operator<<(LexicalConverter &, long double);
71 void operator<<(LexicalConverter &, const std::string &);
72 void operator<<(LexicalConverter &, const char *);
73 void operator<<(LexicalConverter &, const void *);
75 void operator>>(const LexicalConverter &, char &);
76 void operator>>(const LexicalConverter &, signed char &);
77 void operator>>(const LexicalConverter &, short &);
78 void operator>>(const LexicalConverter &, int &);
79 void operator>>(const LexicalConverter &, long &);
80 void operator>>(const LexicalConverter &, unsigned char &);
81 void operator>>(const LexicalConverter &, unsigned short &);
82 void operator>>(const LexicalConverter &, unsigned int &);
83 void operator>>(const LexicalConverter &, unsigned long &);
85 void operator>>(const LexicalConverter &, long long &);
86 void operator>>(const LexicalConverter &, unsigned long long &);
88 void operator>>(const LexicalConverter &, bool &);
89 void operator>>(const LexicalConverter &, float &);
90 void operator>>(const LexicalConverter &, double &);
91 void operator>>(const LexicalConverter &, long double &);
92 void operator>>(const LexicalConverter &, std::string &);
94 // Generic operators using stringstream
97 struct HasFormattedOutput: Sfinae
99 static std::ostream &s;
102 /* The expression must depend on the template parameter, or the compiler
103 will give an error. */
105 static Yes f(int (*)[sizeof(s<<HasFormattedOutput<U>::v)]);
109 enum { value = Evaluate<sizeof(f<T>(0))>::value };
113 struct HasFormattedInput: Sfinae
115 static std::istream &s;
119 static Yes f(int (*)[sizeof(s>>HasFormattedOutput<U>::v)]);
123 enum { value = Evaluate<sizeof(f<T>(0))>::value };
128 typename EnableIf<HasFormattedOutput<T>::value, void>::Yes
129 operator<<(LexicalConverter &c, const T &v)
131 std::ostringstream ss;
137 typename EnableIf<HasFormattedInput<T>::value, void>::Yes
138 operator>>(const LexicalConverter &c, T &v)
140 std::istringstream ss(c.get());
141 ss.setf(std::ios_base::fmtflags(0), std::ios_base::skipws);
143 if(ss.fail() || !ss.eof())
144 throw lexical_error("conversion failure");
148 Helper struct to provide partial template specialization.
150 template<typename T, typename F>
154 struct LexicalCast<T, std::string>
156 static T cast(const std::string &s, const Fmt &f = Fmt())
158 LexicalConverter conv(s, f);
166 struct LexicalCast<std::string, F>
168 static std::string cast(const F &v, const Fmt &f = Fmt())
170 LexicalConverter conv(f);
177 struct LexicalCast<std::string, std::string>
179 static std::string cast(const std::string &v, const Fmt &f = Fmt())
181 LexicalConverter conv(f);
187 /** Perform a lexical conversion between a string and another type. The source
188 type can normally be deduced by the compiler, so this can be used just like the
189 standard C++ casts. A format may additionally be specified to force a specific
191 template<typename T, typename F>
192 inline T lexical_cast(const F &v, const Fmt &f = Fmt())
194 return LexicalCast<T, F>::cast(v, f);