std.h

// 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 <cstdlib>
#include <exception>
#include <memory>
#include <thread>
#include <type_traits>
#include <typeinfo>
#include <utility>

#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>
#  endif
#endif

// 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 archtectures does not implement
// abi::__cxa_demangle().
#  ifndef __GABIXX_CXXABI_H__
#    define FMT_HAS_ABI_CXA_DEMANGLE
#  endif
#endif

#ifdef __cpp_lib_filesystem
FMT_BEGIN_NAMESPACE

namespace detail {

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 void write_escaped_path<char>(basic_memory_buffer<char>& quoted,
                                     const std::filesystem::path& p) {
  auto s = p.u8string();
  write_escaped_string<char>(
      std::back_inserter(quoted),
      string_view(reinterpret_cast<const char*>(s.c_str()), s.size()));
}
#  endif
template <>
inline void write_escaped_path<std::filesystem::path::value_type>(
    basic_memory_buffer<std::filesystem::path::value_type>& quoted,
    const std::filesystem::path& p) {
  write_escaped_string<std::filesystem::path::value_type>(
      std::back_inserter(quoted), p.native());
}

}  // namespace detail

template <typename Char>
struct formatter<std::filesystem::path, Char>
    : formatter<basic_string_view<Char>> {
  template <typename FormatContext>
  auto format(const std::filesystem::path& p, FormatContext& ctx) const ->
      typename FormatContext::iterator {
    basic_memory_buffer<Char> quoted;
    detail::write_escaped_path(quoted, p);
    return formatter<basic_string_view<Char>>::format(
        basic_string_view<Char>(quoted.data(), quoted.size()), ctx);
  }
};
FMT_END_NAMESPACE
#endif

FMT_BEGIN_NAMESPACE
template <typename Char>
struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
FMT_END_NAMESPACE

#ifdef __cpp_lib_variant
FMT_BEGIN_NAMESPACE
template <typename Char> struct formatter<std::monostate, Char> {
  template <typename ParseContext>
  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
    return ctx.begin();
  }

  template <typename FormatContext>
  auto format(const std::monostate&, FormatContext& ctx) const
      -> decltype(ctx.out()) {
    auto out = ctx.out();
    out = detail::write<Char>(out, "monostate");
    return out;
  }
};

namespace detail {

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...>);

 public:
  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);
}

}  // namespace detail

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 {
  static constexpr const bool value =
      detail::is_variant_formattable_<T, C>::value;
};

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>>>> {
  template <typename ParseContext>
  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
    return ctx.begin();
  }

  template <typename FormatContext>
  auto format(const Variant& value, FormatContext& ctx) const
      -> decltype(ctx.out()) {
    auto out = ctx.out();

    out = detail::write<Char>(out, "variant(");
    std::visit(
        [&](const auto& v) {
          out = detail::write_variant_alternative<Char>(out, v);
        },
        value);
    *out++ = ')';
    return out;
  }
};
FMT_END_NAMESPACE
#endif  // __cpp_lib_variant

FMT_BEGIN_NAMESPACE
template <typename T, typename Char>
struct formatter<
    T, Char,
    typename std::enable_if<std::is_base_of<std::exception, T>::value>::type> {
 private:
  bool with_typename_ = false;

 public:
  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') {
      ++it;
      with_typename_ = true;
    }
    return it;
  }

  template <typename OutputIt>
  auto format(const std::exception& ex,
              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
    basic_format_specs<Char> spec;
    auto out = ctx.out();
    if (!with_typename_)
      return detail::write_bytes(out, string_view(ex.what()), spec);

    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, demangled_name_view, spec);
#else
    out = detail::write_bytes(out, string_view(ti.name()), spec);
#endif
    out = detail::write<Char>(out, Char(':'));
    out = detail::write<Char>(out, Char(' '));
    out = detail::write_bytes(out, string_view(ex.what()), spec);

    return out;
  }
};
FMT_END_NAMESPACE

#endif  // FMT_STD_H_