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Improve handling of named arguments

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This commit is contained in:
Victor Zverovich 2024-08-31 19:18:20 -07:00
parent 621e9c17c5
commit fec2cc7af1
2 changed files with 71 additions and 52 deletions
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100
include/fmt/base.h
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@ -1341,7 +1341,6 @@ template <bool B1, bool B2, bool... Tail> constexpr auto count() -> size_t {
template <typename... Args> constexpr auto count_named_args() -> size_t {
return count<is_named_arg<Args>::value...>();
}
template <typename... Args>
constexpr auto count_statically_named_args() -> size_t {
return count<is_statically_named_arg<Args>::value...>();
@ -1758,6 +1757,20 @@ void init_named_arg(named_arg_info<Char>* named_args, int& arg_index,
named_args[named_arg_index++] = {arg.name, arg_index++};
}
template <typename T, typename Char,
FMT_ENABLE_IF(!is_statically_named_arg<T>::value)>
FMT_CONSTEXPR void init_statically_named_arg(named_arg_info<Char>*,
int& arg_index, int&) {
++arg_index;
}
template <typename T, typename Char,
FMT_ENABLE_IF(is_statically_named_arg<T>::value)>
FMT_CONSTEXPR void init_statically_named_arg(named_arg_info<Char>* named_args,
int& arg_index,
int& named_arg_index) {
named_args[named_arg_index++] = {T::name, arg_index++};
}
// An array of references to arguments. It can be implicitly converted to
// `fmt::basic_format_args` for passing into type-erased formatting functions
// such as `fmt::vformat`.
@ -2857,35 +2870,13 @@ FMT_CONSTEXPR inline auto check_char_specs(const format_specs& specs) -> bool {
return true;
}
#if FMT_USE_NONTYPE_TEMPLATE_ARGS
template <int N, typename T, typename... Args, typename Char>
constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
if constexpr (is_statically_named_arg<T>()) {
if (name == T::name) return N;
}
if constexpr (sizeof...(Args) > 0)
return get_arg_index_by_name<N + 1, Args...>(name);
(void)name; // Workaround an MSVC bug about "unused" parameter.
return -1;
}
#endif
template <typename... Args, typename Char>
FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
#if FMT_USE_NONTYPE_TEMPLATE_ARGS
if constexpr (sizeof...(Args) > 0)
return get_arg_index_by_name<0, Args...>(name);
#endif
(void)name;
return -1;
}
template <typename Char, typename... Args> class format_string_checker {
private:
using parse_context_type = compile_parse_context<Char>;
static constexpr int num_args = sizeof...(Args);
static constexpr int num_named_args = count_statically_named_args<Args...>();
// Format specifier parsing function.
// Format specifiers parsing function.
// In the future basic_format_parse_context will replace compile_parse_context
// here and will use is_constant_evaluated and downcasting to access the data
// needed for compile-time checks: https://godbolt.org/z/GvWzcTjh1.
@ -2894,12 +2885,21 @@ template <typename Char, typename... Args> class format_string_checker {
type types_[num_args > 0 ? static_cast<size_t>(num_args) : 1];
parse_context_type context_;
parse_func parse_funcs_[num_args > 0 ? static_cast<size_t>(num_args) : 1];
named_arg_info<Char> named_args_[num_named_args > 0 ? num_named_args : 1];
public:
explicit FMT_CONSTEXPR format_string_checker(basic_string_view<Char> fmt)
: types_{mapped_type_constant<Args, buffered_context<Char>>::value...},
context_(fmt, num_args, types_),
parse_funcs_{&parse_format_specs<Args, parse_context_type>...} {}
parse_funcs_{&parse_format_specs<Args, parse_context_type>...},
named_args_{} {
using dummy = int[];
int arg_index = 0, named_arg_index = 0;
(void)dummy{0, (init_statically_named_arg<Args>(named_args_, arg_index,
named_arg_index),
0)...};
ignore_unused(arg_index, named_arg_index);
}
FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
@ -2908,15 +2908,11 @@ template <typename Char, typename... Args> class format_string_checker {
return context_.check_arg_id(id), id;
}
FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
#if FMT_USE_NONTYPE_TEMPLATE_ARGS
auto index = get_arg_index_by_name<Args...>(id);
if (index < 0) on_error("named argument is not found");
return index;
#else
(void)id;
on_error("compile-time checks for named arguments require C++20 support");
return 0;
#endif
for (int i = 0; i < num_named_args; ++i) {
if (named_args_[i].name == id) return i;
}
on_error("named argument is not found");
return -1;
}
FMT_CONSTEXPR void on_replacement_field(int id, const Char* begin) {
@ -2938,23 +2934,6 @@ template <typename Char, typename... Args> class format_string_checker {
// A base class for compile-time strings.
struct compile_string {};
// Use vformat_args and avoid type_identity to keep symbols short.
template <typename Char = char> struct vformat_args {
using type = basic_format_args<buffered_context<Char>>;
};
template <> struct vformat_args<char> {
using type = format_args;
};
template <typename Char>
void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
typename vformat_args<Char>::type args, locale_ref loc = {});
FMT_API void vprint_mojibake(FILE*, string_view, format_args, bool = false);
#ifndef _WIN32
inline void vprint_mojibake(FILE*, string_view, format_args, bool) {}
#endif
// TYPE can be different from type_constant<T>, e.g. for __float128.
template <typename T, typename Char, type TYPE> struct native_formatter {
private:
@ -2982,6 +2961,23 @@ template <typename T, typename Char, type TYPE> struct native_formatter {
FMT_CONSTEXPR auto format(const T& val, FormatContext& ctx) const
-> decltype(ctx.out());
};
// Use vformat_args and avoid type_identity to keep symbols short.
template <typename Char = char> struct vformat_args {
using type = basic_format_args<buffered_context<Char>>;
};
template <> struct vformat_args<char> {
using type = format_args;
};
template <typename Char>
void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
typename vformat_args<Char>::type args, locale_ref loc = {});
FMT_API void vprint_mojibake(FILE*, string_view, format_args, bool = false);
#ifndef _WIN32
inline void vprint_mojibake(FILE*, string_view, format_args, bool) {}
#endif
} // namespace detail
FMT_BEGIN_EXPORT

23
include/fmt/compile.h
View File

@ -71,6 +71,29 @@ constexpr const auto& get([[maybe_unused]] const T& first,
return detail::get<N - 1>(rest...);
}
#if FMT_USE_NONTYPE_TEMPLATE_ARGS
template <int N, typename T, typename... Args, typename Char>
constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
if constexpr (is_statically_named_arg<T>()) {
if (name == T::name) return N;
}
if constexpr (sizeof...(Args) > 0)
return get_arg_index_by_name<N + 1, Args...>(name);
(void)name; // Workaround an MSVC bug about "unused" parameter.
return -1;
}
#endif
template <typename... Args, typename Char>
FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
#if FMT_USE_NONTYPE_TEMPLATE_ARGS
if constexpr (sizeof...(Args) > 0)
return get_arg_index_by_name<0, Args...>(name);
#endif
(void)name;
return -1;
}
template <typename Char, typename... Args>
constexpr int get_arg_index_by_name(basic_string_view<Char> name,
type_list<Args...>) {