// Formatting library for C++ - formatters for standard library types
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
// For the license information refer to format.h.
#ifndef FMT_STD_H_
#define FMT_STD_H_
#include <atomic>
#include <bitset>
#include <cstdlib>
#include <exception>
#include <memory>
#include <thread>
#include <type_traits>
#include <typeinfo>
#include <utility>
#include <vector>
#include "format.h"
#include "ostream.h"
#if FMT_HAS_INCLUDE(<version>)
# include <version>
#endif
// Checking FMT_CPLUSPLUS for warning suppression in MSVC.
#if FMT_CPLUSPLUS >= 201703L
# if FMT_HAS_INCLUDE(<filesystem>)
# include <filesystem>
# endif
# if FMT_HAS_INCLUDE(<variant>)
# include <variant>
# if FMT_HAS_INCLUDE(<optional>)
# include <optional>
// GCC 4 does not support FMT_HAS_INCLUDE.
#if FMT_HAS_INCLUDE(<cxxabi.h>) || defined(__GLIBCXX__)
# include <cxxabi.h>
// Android NDK with gabi++ library on some architectures does not implement
// abi::__cxa_demangle().
# ifndef __GABIXX_CXXABI_H__
# define FMT_HAS_ABI_CXA_DEMANGLE
// Check if typeid is available.
#ifndef FMT_USE_TYPEID
// __RTTI is for EDG compilers. In MSVC typeid is available without RTTI.
# if defined(__GXX_RTTI) || FMT_HAS_FEATURE(cxx_rtti) || FMT_MSC_VERSION || \
defined(__INTEL_RTTI__) || defined(__RTTI)
# define FMT_USE_TYPEID 1
# else
# define FMT_USE_TYPEID 0
#ifdef __cpp_lib_filesystem
FMT_BEGIN_NAMESPACE
namespace detail {
template <typename Char> auto get_path_string(const std::filesystem::path& p) {
return p.string<Char>();
}
template <typename Char>
void write_escaped_path(basic_memory_buffer<Char>& quoted,
const std::filesystem::path& p) {
write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
# ifdef _WIN32
template <>
inline auto get_path_string<char>(const std::filesystem::path& p) {
return to_utf8<wchar_t>(p.native(), to_utf8_error_policy::replace);
inline void write_escaped_path<char>(memory_buffer& quoted,
auto buf = basic_memory_buffer<wchar_t>();
write_escaped_string<wchar_t>(std::back_inserter(buf), p.native());
bool valid = to_utf8<wchar_t>::convert(quoted, {buf.data(), buf.size()});
FMT_ASSERT(valid, "invalid utf16");
# endif // _WIN32
inline void write_escaped_path<std::filesystem::path::value_type>(
basic_memory_buffer<std::filesystem::path::value_type>& quoted,
write_escaped_string<std::filesystem::path::value_type>(
std::back_inserter(quoted), p.native());
} // namespace detail
FMT_EXPORT
template <typename Char> struct formatter<std::filesystem::path, Char> {
private:
format_specs<Char> specs_;
detail::arg_ref<Char> width_ref_;
bool debug_ = false;
public:
FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
auto it = ctx.begin(), end = ctx.end();
if (it == end) return it;
it = detail::parse_align(it, end, specs_);
it = detail::parse_dynamic_spec(it, end, specs_.width, width_ref_, ctx);
if (it != end && *it == '?') {
debug_ = true;
++it;
return it;
template <typename FormatContext>
auto format(const std::filesystem::path& p, FormatContext& ctx) const {
auto specs = specs_;
detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
ctx);
if (!debug_) {
auto s = detail::get_path_string<Char>(p);
return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
auto quoted = basic_memory_buffer<Char>();
detail::write_escaped_path(quoted, p);
return detail::write(ctx.out(),
basic_string_view<Char>(quoted.data(), quoted.size()),
specs);
};
FMT_END_NAMESPACE
struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
#ifdef __cpp_lib_optional
template <typename T, typename Char>
struct formatter<std::optional<T>, Char,
std::enable_if_t<is_formattable<T, Char>::value>> {
formatter<T, Char> underlying_;
static constexpr basic_string_view<Char> optional =
detail::string_literal<Char, 'o', 'p', 't', 'i', 'o', 'n', 'a', 'l',
'('>{};
static constexpr basic_string_view<Char> none =
detail::string_literal<Char, 'n', 'o', 'n', 'e'>{};
template <class U>
FMT_CONSTEXPR static auto maybe_set_debug_format(U& u, bool set)
-> decltype(u.set_debug_format(set)) {
u.set_debug_format(set);
FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
maybe_set_debug_format(underlying_, true);
return underlying_.parse(ctx);
auto format(std::optional<T> const& opt, FormatContext& ctx) const
-> decltype(ctx.out()) {
if (!opt) return detail::write<Char>(ctx.out(), none);
auto out = ctx.out();
out = detail::write<Char>(out, optional);
ctx.advance_to(out);
out = underlying_.format(*opt, ctx);
return detail::write(out, ')');
#endif // __cpp_lib_optional
#ifdef __cpp_lib_variant
template <typename T>
using variant_index_sequence =
std::make_index_sequence<std::variant_size<T>::value>;
template <typename> struct is_variant_like_ : std::false_type {};
template <typename... Types>
struct is_variant_like_<std::variant<Types...>> : std::true_type {};
// formattable element check.
template <typename T, typename C> class is_variant_formattable_ {
template <std::size_t... Is>
static std::conjunction<
is_formattable<std::variant_alternative_t<Is, T>, C>...>
check(std::index_sequence<Is...>);
static constexpr const bool value =
decltype(check(variant_index_sequence<T>{}))::value;
template <typename Char, typename OutputIt, typename T>
auto write_variant_alternative(OutputIt out, const T& v) -> OutputIt {
if constexpr (is_string<T>::value)
return write_escaped_string<Char>(out, detail::to_string_view(v));
else if constexpr (std::is_same_v<T, Char>)
return write_escaped_char(out, v);
else
return write<Char>(out, v);
template <typename T> struct is_variant_like {
static constexpr const bool value = detail::is_variant_like_<T>::value;
template <typename T, typename C> struct is_variant_formattable {
detail::is_variant_formattable_<T, C>::value;
template <typename Char> struct formatter<std::monostate, Char> {
template <typename ParseContext>
FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
return ctx.begin();
auto format(const std::monostate&, FormatContext& ctx) const
return detail::write<Char>(ctx.out(), "monostate");
template <typename Variant, typename Char>
struct formatter<
Variant, Char,
std::enable_if_t<std::conjunction_v<
is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
auto format(const Variant& value, FormatContext& ctx) const
out = detail::write<Char>(out, "variant(");
FMT_TRY {
std::visit(
[&](const auto& v) {
out = detail::write_variant_alternative<Char>(out, v);
},
value);
FMT_CATCH(const std::bad_variant_access&) {
detail::write<Char>(out, "valueless by exception");
*out++ = ')';
return out;
#endif // __cpp_lib_variant
template <typename Char> struct formatter<std::error_code, Char> {
FMT_CONSTEXPR auto format(const std::error_code& ec, FormatContext& ctx) const
out = detail::write_bytes(out, ec.category().name(), format_specs<Char>());
out = detail::write<Char>(out, Char(':'));
out = detail::write<Char>(out, ec.value());
T, Char,
typename std::enable_if<std::is_base_of<std::exception, T>::value>::type> {
bool with_typename_ = false;
FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-> decltype(ctx.begin()) {
auto it = ctx.begin();
auto end = ctx.end();
if (it == end || *it == '}') return it;
if (*it == 't') {
with_typename_ = FMT_USE_TYPEID != 0;
template <typename OutputIt>
auto format(const std::exception& ex,
basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
format_specs<Char> spec;
if (!with_typename_)
return detail::write_bytes(out, string_view(ex.what()), spec);
#if FMT_USE_TYPEID
const std::type_info& ti = typeid(ex);
# ifdef FMT_HAS_ABI_CXA_DEMANGLE
int status = 0;
std::size_t size = 0;
std::unique_ptr<char, decltype(&std::free)> demangled_name_ptr(
abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
string_view demangled_name_view;
if (demangled_name_ptr) {
demangled_name_view = demangled_name_ptr.get();
// Normalization of stdlib inline namespace names.
// libc++ inline namespaces.
// std::__1::* -> std::*
// std::__1::__fs::* -> std::*
// libstdc++ inline namespaces.
// std::__cxx11::* -> std::*
// std::filesystem::__cxx11::* -> std::filesystem::*
if (demangled_name_view.starts_with("std::")) {
char* begin = demangled_name_ptr.get();
char* to = begin + 5; // std::
for (char *from = to, *end = begin + demangled_name_view.size();
from < end;) {
// This is safe, because demangled_name is NUL-terminated.
if (from[0] == '_' && from[1] == '_') {
char* next = from + 1;
while (next < end && *next != ':') next++;
if (next[0] == ':' && next[1] == ':') {
from = next + 2;
continue;
*to++ = *from++;
demangled_name_view = {begin, detail::to_unsigned(to - begin)};
} else {
demangled_name_view = string_view(ti.name());
out = detail::write_bytes(out, demangled_name_view, spec);
# elif FMT_MSC_VERSION
string_view demangled_name_view(ti.name());
if (demangled_name_view.starts_with("class "))
demangled_name_view.remove_prefix(6);
else if (demangled_name_view.starts_with("struct "))
demangled_name_view.remove_prefix(7);
out = detail::write_bytes(out, string_view(ti.name()), spec);
*out++ = ':';
*out++ = ' ';
template <typename T, typename Enable = void>
struct has_flip : std::false_type {};
struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
: std::true_type {};
template <typename T> struct is_bit_reference_like {
std::is_convertible<T, bool>::value &&
std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
#ifdef _LIBCPP_VERSION
// Workaround for libc++ incompatibility with C++ standard.
// According to the Standard, `bitset::operator[] const` returns bool.
template <typename C>
struct is_bit_reference_like<std::__bit_const_reference<C>> {
static constexpr const bool value = true;
// We can't use std::vector<bool, Allocator>::reference and
// std::bitset<N>::reference because the compiler can't deduce Allocator and N
// in partial specialization.
template <typename BitRef, typename Char>
struct formatter<BitRef, Char,
enable_if_t<detail::is_bit_reference_like<BitRef>::value>>
: formatter<bool, Char> {
FMT_CONSTEXPR auto format(const BitRef& v, FormatContext& ctx) const
return formatter<bool, Char>::format(v, ctx);
struct formatter<std::atomic<T>, Char,
enable_if_t<is_formattable<T, Char>::value>>
: formatter<T, Char> {
auto format(const std::atomic<T>& v, FormatContext& ctx) const
return formatter<T, Char>::format(v.load(), ctx);
#ifdef __cpp_lib_atomic_flag_test
struct formatter<std::atomic_flag, Char>
auto format(const std::atomic_flag& v, FormatContext& ctx) const
return formatter<bool, Char>::format(v.test(), ctx);
#endif // __cpp_lib_atomic_flag_test
#endif // FMT_STD_H_