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Simplify udl_formatter with FMT_STRING

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This commit is contained in:
Victor Zverovich 2020-04-22 11:26:05 -07:00
parent 811b0f9054
commit 4a1d5931cb
1 changed files with 48 additions and 51 deletions
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99
include/fmt/format.h
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@ -2677,6 +2677,52 @@ class format_string_checker {
parse_func parse_funcs_[num_args > 0 ? num_args : 1];
};
// Converts string literals to basic_string_view.
template <typename Char, size_t N>
FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
const Char (&s)[N]) {
// Remove trailing null character if needed. Won't be present if this is used
// with raw character array (i.e. not defined as a string).
return {s,
N - ((std::char_traits<Char>::to_int_type(s[N - 1]) == 0) ? 1 : 0)};
}
// Converts string_view to basic_string_view.
template <typename Char>
FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
const std_string_view<Char>& s) {
return {s.data(), s.size()};
}
#define FMT_STRING_IMPL(s, ...) \
[] { \
/* Use a macro-like name to avoid shadowing warnings. */ \
struct FMT_COMPILE_STRING : fmt::compile_string { \
using char_type = fmt::remove_cvref_t<decltype(s[0])>; \
FMT_MAYBE_UNUSED __VA_ARGS__ FMT_CONSTEXPR \
operator fmt::basic_string_view<char_type>() const { \
return fmt::internal::compile_string_to_view<char_type>(s); \
} \
}; \
return FMT_COMPILE_STRING(); \
}()
/**
\rst
Constructs a compile-time format string from a string literal *s*.
**Example**::
// A compile-time error because 'd' is an invalid specifier for strings.
std::string s = format(FMT_STRING("{:d}"), "foo");
\endrst
*/
#define FMT_STRING(s) FMT_STRING_IMPL(s, )
#if defined(FMT_STRING_ALIAS) && FMT_STRING_ALIAS
# define fmt(s) FMT_STRING_IMPL(s, [[deprecated]])
#endif
template <typename Char, typename ErrorHandler, typename... Args>
FMT_CONSTEXPR bool do_check_format_string(basic_string_view<Char> s,
ErrorHandler eh = ErrorHandler()) {
@ -3490,11 +3536,8 @@ template <typename Char, Char... CHARS> class udl_formatter {
public:
template <typename... Args>
std::basic_string<Char> operator()(Args&&... args) const {
FMT_CONSTEXPR_DECL Char s[] = {CHARS..., '\0'};
FMT_CONSTEXPR_DECL bool invalid_format =
do_check_format_string<Char, error_handler, remove_cvref_t<Args>...>(
basic_string_view<Char>(s, sizeof...(CHARS)));
(void)invalid_format;
static FMT_CONSTEXPR_DECL Char s[] = {CHARS..., '\0'};
check_format_string<remove_cvref_t<Args>...>(FMT_STRING(s));
return format(s, std::forward<Args>(args)...);
}
};
@ -3516,23 +3559,6 @@ template <typename Char> struct udl_arg {
return {str, std::forward<T>(value)};
}
};
// Converts string literals to basic_string_view.
template <typename Char, size_t N>
FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
const Char (&s)[N]) {
// Remove trailing null character if needed. Won't be present if this is used
// with raw character array (i.e. not defined as a string).
return {s,
N - ((std::char_traits<Char>::to_int_type(s[N - 1]) == 0) ? 1 : 0)};
}
// Converts string_view to basic_string_view.
template <typename Char>
FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
const std_string_view<Char>& s) {
return {s.data(), s.size()};
}
} // namespace internal
inline namespace literals {
@ -3590,35 +3616,6 @@ FMT_CONSTEXPR internal::udl_arg<wchar_t> operator"" _a(const wchar_t* s,
#endif // FMT_USE_USER_DEFINED_LITERALS
FMT_END_NAMESPACE
#define FMT_STRING_IMPL(s, ...) \
[] { \
/* Use a macro-like name to avoid shadowing warnings. */ \
struct FMT_COMPILE_STRING : fmt::compile_string { \
using char_type = fmt::remove_cvref_t<decltype(s[0])>; \
FMT_MAYBE_UNUSED __VA_ARGS__ FMT_CONSTEXPR \
operator fmt::basic_string_view<char_type>() const { \
return fmt::internal::compile_string_to_view<char_type>(s); \
} \
}; \
return FMT_COMPILE_STRING(); \
}()
/**
\rst
Constructs a compile-time format string from a string literal *s*.
**Example**::
// A compile-time error because 'd' is an invalid specifier for strings.
std::string s = format(FMT_STRING("{:d}"), "foo");
\endrst
*/
#define FMT_STRING(s) FMT_STRING_IMPL(s, )
#if defined(FMT_STRING_ALIAS) && FMT_STRING_ALIAS
# define fmt(s) FMT_STRING_IMPL(s, [[deprecated]])
#endif
#ifdef FMT_HEADER_ONLY
# define FMT_FUNC inline
# include "format-inl.h"