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.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>;
}

*/

#include <__config>
#include <stdexcept>
#include <string_view>
#include <version>

#ifdef _LIBCPP_NO_EXCEPTIONS
#include <cstdlib>
#endif

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

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER > 17

class _LIBCPP_EXCEPTION_ABI format_error : public runtime_error {
public:
  _LIBCPP_INLINE_VISIBILITY explicit format_error(const string& __s)
      : runtime_error(__s) {}
  _LIBCPP_INLINE_VISIBILITY explicit format_error(const char* __s)
      : runtime_error(__s) {}
  virtual ~format_error() noexcept;
};

// 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) && !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED)

_LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY void
__throw_format_error(const char* __s) {
#ifndef _LIBCPP_NO_EXCEPTIONS
  throw format_error(__s);
#else
  (void)__s;
  _VSTD::abort();
#endif
}

template <class _CharT>
class _LIBCPP_TEMPLATE_VIS basic_format_parse_context {
public:
  using char_type = _CharT;
  using const_iterator =
      typename _VSTD::basic_string_view<_CharT>::const_iterator;
  using iterator = const_iterator;

public:
  _LIBCPP_INLINE_VISIBILITY
  constexpr explicit basic_format_parse_context(
      _VSTD::basic_string_view<_CharT> __fmt, size_t __num_args = 0) noexcept
      : __begin_(__fmt.begin()),
        __end_(__fmt.end()),
        __indexing_(__unknown),
        __next_arg_id_(0),
        __num_args_(__num_args) {}

  basic_format_parse_context(const basic_format_parse_context&) = delete;
  basic_format_parse_context&
  operator=(const basic_format_parse_context&) = delete;

  _LIBCPP_INLINE_VISIBILITY constexpr const_iterator begin() const noexcept {
    return __begin_;
  }
  _LIBCPP_INLINE_VISIBILITY constexpr const_iterator end() const noexcept {
    return __end_;
  }
  _LIBCPP_INLINE_VISIBILITY constexpr void advance_to(const_iterator __it) {
    __begin_ = __it;
  }

  _LIBCPP_INLINE_VISIBILITY constexpr size_t next_arg_id() {
    if (__indexing_ == __manual)
      __throw_format_error("Using automatic argument numbering in manual "
                           "argument numbering mode");

    if (__indexing_ == __unknown)
      __indexing_ = __automatic;
    return __next_arg_id_++;
  }
  _LIBCPP_INLINE_VISIBILITY constexpr void check_arg_id(size_t __id) {
    if (__indexing_ == __automatic)
      __throw_format_error("Using manual argument numbering in automatic "
                           "argument numbering mode");

    if (__indexing_ == __unknown)
      __indexing_ = __manual;

    // Throws an exception to make the expression a non core constant
    // expression as required by:
    // [format.parse.ctx]/11
    //   Remarks: Call expressions where id >= num_args_ are not core constant
    //   expressions ([expr.const]).
    // Note: the Throws clause [format.parse.ctx]/10 doesn't specify the
    // behavior when id >= num_args_.
    if (_VSTD::is_constant_evaluated() && __id >= __num_args_)
      __throw_format_error("Argument index outside the valid range");
  }

private:
  iterator __begin_;
  iterator __end_;
  enum _Indexing { __unknown, __manual, __automatic };
  _Indexing __indexing_;
  size_t __next_arg_id_;
  size_t __num_args_;
};

using format_parse_context = basic_format_parse_context<char>;
using wformat_parse_context = basic_format_parse_context<wchar_t>;

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

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP_FORMAT