llvm-project/libcxx/include/format

// -*- C++ -*-
//===--------------------------- format -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_FORMAT
#define _LIBCPP_FORMAT

/*

namespace std {
  // [format.context], class template basic_format_context
  template<class Out, class charT>
  class basic_format_context {
    basic_format_args<basic_format_context> args_;      // exposition only
    Out out_;                                           // exposition only

  public:
    using iterator = Out;
    using char_type = charT;
    template<class T> using formatter_type = formatter<T, charT>;

    basic_format_arg<basic_format_context> arg(size_t id) const;
    std::locale locale();

    iterator out();
    void advance_to(iterator it);
  };
  using format_context = basic_format_context<unspecified, char>;
  using wformat_context = basic_format_context<unspecified, wchar_t>;

  // [format.args], class template basic_format_args
  template<class Context>
  class basic_format_args {
    size_t size_;                               // exposition only
    const basic_format_arg<Context>* data_;     // exposition only

  public:
    basic_format_args() noexcept;

    template<class... Args>
      basic_format_args(const format-arg-store<Context, Args...>& store) noexcept;

    basic_format_arg<Context> get(size_t i) const noexcept;
  };
  using format_args = basic_format_args<format_context>;
  using wformat_args = basic_format_args<wformat_context>;


  template<class Out, class charT>
    using format_args_t = basic_format_args<basic_format_context<Out, charT>>;

  // [format.parse.ctx], class template basic_format_parse_context
  template<class charT>
  class basic_format_parse_context {
  public:
    using char_type = charT;
    using const_iterator = typename basic_string_view<charT>::const_iterator;
    using iterator = const_iterator;

  private:
    iterator begin_;                                    // exposition only
    iterator end_;                                      // exposition only
    enum indexing { unknown, manual, automatic };       // exposition only
    indexing indexing_;                                 // exposition only
    size_t next_arg_id_;                                // exposition only
    size_t num_args_;                                   // exposition only

  public:
    constexpr explicit basic_format_parse_context(basic_string_view<charT> fmt,
                                                  size_t num_args = 0) noexcept;
    basic_format_parse_context(const basic_format_parse_context&) = delete;
    basic_format_parse_context& operator=(const basic_format_parse_context&) = delete;

    constexpr const_iterator begin() const noexcept;
    constexpr const_iterator end() const noexcept;
    constexpr void advance_to(const_iterator it);

    constexpr size_t next_arg_id();
    constexpr void check_arg_id(size_t id);
  };
  using format_parse_context = basic_format_parse_context<char>;
  using wformat_parse_context = basic_format_parse_context<wchar_t>;

  // [format.arguments], arguments
  // [format.arg], class template basic_format_arg
  template<class Context>
  class basic_format_arg {
  public:
    class handle;

  private:
    using char_type = typename Context::char_type;                              // exposition only

    variant<monostate, bool, char_type,
            int, unsigned int, long long int, unsigned long long int,
            float, double, long double,
            const char_type*, basic_string_view<char_type>,
            const void*, handle> value;                                         // exposition only

    template<class T> explicit basic_format_arg(const T& v) noexcept;           // exposition only
    explicit basic_format_arg(float n) noexcept;                                // exposition only
    explicit basic_format_arg(double n) noexcept;                               // exposition only
    explicit basic_format_arg(long double n) noexcept;                          // exposition only
    explicit basic_format_arg(const char_type* s);                              // exposition only

    template<class traits>
      explicit basic_format_arg(
        basic_string_view<char_type, traits> s) noexcept;                       // exposition only

    template<class traits, class Allocator>
      explicit basic_format_arg(
        const basic_string<char_type, traits, Allocator>& s) noexcept;          // exposition only

    explicit basic_format_arg(nullptr_t) noexcept;                              // exposition only

    template<class T>
      explicit basic_format_arg(const T* p) noexcept;                           // exposition only

  public:
    basic_format_arg() noexcept;

    explicit operator bool() const noexcept;
  };

  template<class Visitor, class Context>
    see below visit_format_arg(Visitor&& vis, basic_format_arg<Context> arg);

  // [format.arg.store], class template format-arg-store
  template<class Context, class... Args>
  struct format-arg-store {      // exposition only
    array<basic_format_arg<Context>, sizeof...(Args)> args;
  };

  template<class Context = format_context, class... Args>
    format-arg-store<Context, Args...>
      make_format_args(const Args&... args);
  template<class... Args>
    format-arg-store<wformat_context, Args...>
      make_wformat_args(const Args&... args);

  // [format.error], class format_error
  class format_error : public runtime_error {
  public:
    explicit format_error(const string& what_arg);
    explicit format_error(const char* what_arg);
  };

  // [format.parse.ctx], class template basic_format_parse_context
  template<class charT>
  class basic_format_parse_context {
  public:
    using char_type = charT;
    using const_iterator = typename basic_string_view<charT>::const_iterator;
    using iterator = const_iterator;

  private:
    iterator begin_;                                    // exposition only
    iterator end_;                                      // exposition only
    enum indexing { unknown, manual, automatic };       // exposition only
    indexing indexing_;                                 // exposition only
    size_t next_arg_id_;                                // exposition only
    size_t num_args_;                                   // exposition only

  public:
    constexpr explicit basic_format_parse_context(basic_string_view<charT> fmt,
                                                  size_t num_args = 0) noexcept;
    basic_format_parse_context(const basic_format_parse_context&) = delete;
    basic_format_parse_context& operator=(const basic_format_parse_context&) = delete;

    constexpr const_iterator begin() const noexcept;
    constexpr const_iterator end() const noexcept;
    constexpr void advance_to(const_iterator it);

    constexpr size_t next_arg_id();
    constexpr void check_arg_id(size_t id);
  };
  using format_parse_context = basic_format_parse_context<char>;
  using wformat_parse_context = basic_format_parse_context<wchar_t>;
}

*/

// Make sure all feature-test macros are available.
#include <version>
// Enable the contents of the header only when libc++ was built with LIBCXX_ENABLE_INCOMPLETE_FEATURES.
#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)

#include <__config>
#include <__format/format_arg.h>
#include <__format/format_args.h>
#include <__format/format_context.h>
#include <__format/format_error.h>
#include <__format/format_parse_context.h>
#include <array>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER > 17

// TODO FMT Remove this once we require compilers with proper C++20 support.
// If the compiler has no concepts support, the format header will be disabled.
// Without concepts support enable_if needs to be used and that too much effort
// to support compilers with partial C++20 support.
#if !defined(_LIBCPP_HAS_NO_CONCEPTS)

// TODO FMT Evaluate which templates should be external templates. This
// improves the efficiency of the header. However since the header is still
// under heavy development and not all classes are stable it makes no sense
// to do this optimization now.

using format_args = basic_format_args<format_context>;
using wformat_args = basic_format_args<wformat_context>;

template <class _OutIt, class _CharT>
using format_args_t = basic_format_args<basic_format_context<_OutIt, _CharT>>;

template <class _Context, class... _Args>
struct _LIBCPP_TEMPLATE_VIS __format_arg_store {
  // TODO FMT Use a built-in array.
  array<basic_format_arg<_Context>, sizeof...(_Args)> __args;
};

template <class _Context = format_context, class... _Args>
_LIBCPP_HIDE_FROM_ABI __format_arg_store<_Context, _Args...>
make_format_args(const _Args&... __args) {
  return {basic_format_arg<_Context>(__args)...};
}

template <class... _Args>
_LIBCPP_HIDE_FROM_ABI __format_arg_store<wformat_context, _Args...>
make_wformat_args(const _Args&... __args) {
  return _VSTD::make_format_args<wformat_context>(__args...);
}

#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
#endif //_LIBCPP_STD_VER > 17

_LIBCPP_END_NAMESPACE_STD

#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)

#endif // _LIBCPP_FORMAT