fmtlegacy/include/fmt/core.h

/*
 Formatting library for C++

 Copyright (c) 2012 - 2016, Victor Zverovich
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:

 1. Redistributions of source code must retain the above copyright notice, this
    list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef FMT_CORE_H_
#define FMT_CORE_H_

#include <cassert>
#include <cstdio>
#include <string>
#include <type_traits>

#ifdef __has_feature
# define FMT_HAS_FEATURE(x) __has_feature(x)
#else
# define FMT_HAS_FEATURE(x) 0
#endif

#ifdef __GNUC__
# define FMT_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
#endif

#ifdef _MSC_VER
# define FMT_MSC_VER _MSC_VER
#else
# define FMT_MSC_VER 0
#endif

// Check if exceptions are disabled.
#if defined(__GNUC__) && !defined(__EXCEPTIONS)
# define FMT_EXCEPTIONS 0
#endif
#if FMT_MSC_VER && !_HAS_EXCEPTIONS
# define FMT_EXCEPTIONS 0
#endif
#ifndef FMT_EXCEPTIONS
# define FMT_EXCEPTIONS 1
#endif

// Define FMT_USE_NOEXCEPT to make fmt use noexcept (C++11 feature).
#ifndef FMT_USE_NOEXCEPT
# define FMT_USE_NOEXCEPT 0
#endif

#ifndef FMT_NOEXCEPT
# if FMT_EXCEPTIONS
#  if FMT_USE_NOEXCEPT || FMT_HAS_FEATURE(cxx_noexcept) || \
    FMT_GCC_VERSION >= 408 || FMT_MSC_VER >= 1900
#   define FMT_NOEXCEPT noexcept
#  else
#   define FMT_NOEXCEPT throw()
#  endif
# else
#  define FMT_NOEXCEPT
# endif
#endif

#if !defined(FMT_HEADER_ONLY) && defined(_WIN32)
# ifdef FMT_EXPORT
#  define FMT_API __declspec(dllexport)
# elif defined(FMT_SHARED)
#  define FMT_API __declspec(dllimport)
# endif
#endif
#ifndef FMT_API
# define FMT_API
#endif

#ifndef FMT_ASSERT
# define FMT_ASSERT(condition, message) assert((condition) && message)
#endif

// A macro to disallow the copy construction and assignment.
#define FMT_DISALLOW_COPY_AND_ASSIGN(TypeName) \
    TypeName(const TypeName&) = delete; \
    TypeName& operator=(const TypeName&) = delete
#define FMT_DELETED_OR_UNDEFINED = delete

namespace fmt {

template <typename T>
class basic_buffer;

using buffer = basic_buffer<char>;
using wbuffer = basic_buffer<wchar_t>;

template <typename Context>
class basic_arg;

template <typename Context>
class basic_format_args;

template <typename Char>
class basic_context;

using context = basic_context<char>;
using wcontext = basic_context<wchar_t>;

// A formatter for objects of type T.
template <typename T, typename Char = char, typename Enable = void>
struct formatter;

/**
  \rst
  An implementation of ``std::basic_string_view`` for pre-C++17. It provides a
  subset of the API.
  \endrst
 */
template <typename Char>
class basic_string_view {
 private:
  const Char *data_;
  size_t size_;

 public:
  using char_type = Char;
  using iterator = const Char *;

  constexpr basic_string_view() noexcept : data_(0), size_(0) {}

  /** Constructs a string reference object from a C string and a size. */
  constexpr basic_string_view(const Char *s, size_t size) noexcept
    : data_(s), size_(size) {}

  /**
    \rst
    Constructs a string reference object from a C string computing
    the size with ``std::char_traits<Char>::length``.
    \endrst
   */
  basic_string_view(const Char *s)
    : data_(s), size_(std::char_traits<Char>::length(s)) {}

  /**
    \rst
    Constructs a string reference from an ``std::string`` object.
    \endrst
   */
  constexpr basic_string_view(const std::basic_string<Char> &s) noexcept
  : data_(s.c_str()), size_(s.size()) {}

  /**
    \rst
    Converts a string reference to an ``std::string`` object.
    \endrst
   */
  std::basic_string<Char> to_string() const {
    return std::basic_string<Char>(data_, size_);
  }

  /** Returns a pointer to the string data. */
  const Char *data() const { return data_; }

  /** Returns the string size. */
  constexpr size_t size() const { return size_; }

  constexpr iterator begin() const { return data_; }
  constexpr iterator end() const { return data_ + size_; }

  constexpr void remove_prefix(size_t n) {
    data_ += n;
    size_ -= n;
  }

  // Lexicographically compare this string reference to other.
  int compare(basic_string_view other) const {
    size_t size = size_ < other.size_ ? size_ : other.size_;
    int result = std::char_traits<Char>::compare(data_, other.data_, size);
    if (result == 0)
      result = size_ == other.size_ ? 0 : (size_ < other.size_ ? -1 : 1);
    return result;
  }

  friend bool operator==(basic_string_view lhs, basic_string_view rhs) {
    return lhs.compare(rhs) == 0;
  }
  friend bool operator!=(basic_string_view lhs, basic_string_view rhs) {
    return lhs.compare(rhs) != 0;
  }
  friend bool operator<(basic_string_view lhs, basic_string_view rhs) {
    return lhs.compare(rhs) < 0;
  }
  friend bool operator<=(basic_string_view lhs, basic_string_view rhs) {
    return lhs.compare(rhs) <= 0;
  }
  friend bool operator>(basic_string_view lhs, basic_string_view rhs) {
    return lhs.compare(rhs) > 0;
  }
  friend bool operator>=(basic_string_view lhs, basic_string_view rhs) {
    return lhs.compare(rhs) >= 0;
  }
};

using string_view = basic_string_view<char>;
using wstring_view = basic_string_view<wchar_t>;

namespace internal {

template <typename T>
inline const T *as_const(T *p) { return p; }

// A helper function to suppress bogus "conditional expression is constant"
// warnings.
template <typename T>
inline T const_check(T value) { return value; }

struct error_handler {
  constexpr error_handler() {}
  constexpr error_handler(const error_handler &) {}

  // This function is intentionally not constexpr to give a compile-time error.
  void on_error(const char *message);
};

// Formatting of wide characters and strings into a narrow output is disallowed:
//   fmt::format("{}", L"test"); // error
// To fix this, use a wide format string:
//   fmt::format(L"{}", L"test");
template <typename Char>
inline void require_wchar() {
  static_assert(
      std::is_same<wchar_t, Char>::value,
      "formatting of wide characters into a narrow output is disallowed");
}

using yes = char[1];
using no = char[2];

yes &convert(unsigned long long);
no &convert(...);

template<typename T, bool ENABLE_CONVERSION>
struct convert_to_int_impl {
  enum { value = ENABLE_CONVERSION };
};

template<typename T, bool ENABLE_CONVERSION>
struct convert_to_int_impl2 {
  enum { value = false };
};

template<typename T>
struct convert_to_int_impl2<T, true> {
  enum {
    // Don't convert arithmetic types.
    value = convert_to_int_impl<T, !std::is_arithmetic<T>::value>::value
  };
};

template<typename T>
struct convert_to_int {
  enum {
    enable_conversion = sizeof(convert(std::declval<T>())) == sizeof(yes)
  };
  enum { value = convert_to_int_impl2<T, enable_conversion>::value };
};

#define FMT_DISABLE_CONVERSION_TO_INT(Type) \
  template <> \
  struct convert_to_int<Type> { enum { value = 0 }; }

// Silence warnings about convering float to int.
FMT_DISABLE_CONVERSION_TO_INT(float);
FMT_DISABLE_CONVERSION_TO_INT(double);
FMT_DISABLE_CONVERSION_TO_INT(long double);

template <typename Context>
struct named_arg;

template <typename T>
struct is_named_arg : std::false_type {};

template <typename Context>
struct is_named_arg<named_arg<Context>> : std::true_type {};

enum type {
  NONE, NAMED_ARG,
  // Integer types should go first,
  INT, UINT, LONG_LONG, ULONG_LONG, BOOL, CHAR, LAST_INTEGER_TYPE = CHAR,
  // followed by floating-point types.
  DOUBLE, LONG_DOUBLE, LAST_NUMERIC_TYPE = LONG_DOUBLE,
  CSTRING, STRING, POINTER, CUSTOM
};

constexpr bool is_integral(type t) {
  FMT_ASSERT(t != internal::NAMED_ARG, "invalid argument type");
  return t > internal::NONE && t <= internal::LAST_INTEGER_TYPE;
}

constexpr bool is_arithmetic(type t) {
  FMT_ASSERT(t != internal::NAMED_ARG, "invalid argument type");
  return t > internal::NONE && t <= internal::LAST_NUMERIC_TYPE;
}

template <typename T>
constexpr type get_type() {
  return std::is_reference<T>::value || std::is_array<T>::value ?
        get_type<typename std::decay<T>::type>() :
        (is_named_arg<T>::value ?
           NAMED_ARG : (convert_to_int<T>::value ? INT : CUSTOM));
}

template <> constexpr type get_type<bool>() { return BOOL; }
template <> constexpr type get_type<short>() { return INT; }
template <> constexpr type get_type<unsigned short>() { return UINT; }
template <> constexpr type get_type<int>() { return INT; }
template <> constexpr type get_type<unsigned>() { return UINT; }
template <> constexpr type get_type<long>() {
  return sizeof(long) == sizeof(int) ? INT : LONG_LONG;
}
template <> constexpr type get_type<unsigned long>() {
  return sizeof(unsigned long) == sizeof(unsigned) ? UINT : ULONG_LONG;
}
template <> constexpr type get_type<long long>() { return LONG_LONG; }
template <> constexpr type get_type<unsigned long long>() { return ULONG_LONG; }
template <> constexpr type get_type<float>() { return DOUBLE; }
template <> constexpr type get_type<double>() { return DOUBLE; }
template <> constexpr type get_type<long double>() { return LONG_DOUBLE; }
template <> constexpr type get_type<signed char>() { return INT; }
template <> constexpr type get_type<unsigned char>() { return UINT; }
template <> constexpr type get_type<char>() { return CHAR; }

#if !defined(_MSC_VER) || defined(_NATIVE_WCHAR_T_DEFINED)
template <> constexpr type get_type<wchar_t>() { return CHAR; }
#endif

template <> constexpr type get_type<char *>() { return CSTRING; }
template <> constexpr type get_type<const char *>() { return CSTRING; }
template <> constexpr type get_type<signed char *>() { return CSTRING; }
template <> constexpr type get_type<const signed char *>() { return CSTRING; }
template <> constexpr type get_type<unsigned char *>() { return CSTRING; }
template <> constexpr type get_type<const unsigned char *>() { return CSTRING; }
template <> constexpr type get_type<std::string>() { return STRING; }
template <> constexpr type get_type<string_view>() { return STRING; }
template <> constexpr type get_type<wchar_t *>() { return CSTRING; }
template <> constexpr type get_type<const wchar_t *>() { return CSTRING; }
template <> constexpr type get_type<std::wstring>() { return STRING; }
template <> constexpr type get_type<wstring_view>() { return STRING; }
template <> constexpr type get_type<void *>() { return POINTER; }
template <> constexpr type get_type<const void *>() { return POINTER; }
template <> constexpr type get_type<std::nullptr_t>() { return POINTER; }

template <typename Arg, typename... Args>
constexpr uint64_t get_types() {
  return get_type<Arg>() | (get_types<Args...>() << 4);
}

template <>
constexpr uint64_t get_types<void>() { return 0; }

template <typename Char>
struct string_value {
  const Char *value;
  std::size_t size;
};

template <typename Context>
struct custom_value {
  using format_func = void (*)(
      basic_buffer<typename Context::char_type> &buffer,
      const void *arg, Context &ctx);

  const void *value;
  format_func format;
};

// A formatting argument value.
template <typename Context>
class value {
 public:
  using char_type = typename Context::char_type;

  union {
    int int_value;
    unsigned uint_value;
    long long long_long_value;
    unsigned long long ulong_long_value;
    double double_value;
    long double long_double_value;
    const void *pointer;
    string_value<char_type> string;
    string_value<signed char> sstring;
    string_value<unsigned char> ustring;
    custom_value<Context> custom;
  };

  constexpr value() : int_value(0) {}
  value(bool val) { set<BOOL>(int_value, val); }
  value(short val) { set<INT>(int_value, val); }
  value(unsigned short val) { set<UINT>(uint_value, val); }
  constexpr value(int val) : int_value(val) {}
  value(unsigned val) { set<UINT>(uint_value, val); }

  value(long val) {
    // To minimize the number of types we need to deal with, long is
    // translated either to int or to long long depending on its size.
    if (const_check(sizeof(val) == sizeof(int)))
      int_value = static_cast<int>(val);
    else
      long_long_value = val;
  }

  value(unsigned long val) {
    if (const_check(sizeof(val) == sizeof(unsigned)))
      uint_value = static_cast<unsigned>(val);
    else
      ulong_long_value = val;
  }

  value(long long val) { set<LONG_LONG>(long_long_value, val); }
  value(unsigned long long val) { set<ULONG_LONG>(ulong_long_value, val); }
  value(float val) { set<DOUBLE>(double_value, val); }
  value(double val) { set<DOUBLE>(double_value, val); }
  value(long double val) { set<LONG_DOUBLE>(long_double_value, val); }
  value(signed char val) { set<INT>(int_value, val); }
  value(unsigned char val) { set<UINT>(uint_value, val); }
  value(char val) { set<CHAR>(int_value, val); }

#if !defined(_MSC_VER) || defined(_NATIVE_WCHAR_T_DEFINED)
  value(wchar_t value) {
    require_wchar<char_type>();
    set<CHAR>(int_value, value);
  }
#endif

  // Formatting of wide strings into a narrow buffer and multibyte strings
  // into a wide buffer is disallowed (https://github.com/fmtlib/fmt/pull/606).
  value(char_type *s) { set<CSTRING>(string.value, s); }
  value(const char_type *s) { set<CSTRING>(string.value, s); }
  value(signed char *s) { set_cstring(sstring.value, s); }
  value(const signed char *s) { set_cstring(sstring.value, s); }
  value(unsigned char *s) { set_cstring(ustring.value, s); }
  value(const unsigned char *s) { set_cstring(ustring.value, s); }
  value(basic_string_view<char_type> s) { set_string(s); }
  value(const std::basic_string<char_type> &s) { set_string(s); }

  // Formatting of arbitrary pointers is disallowed. If you want to output a
  // pointer cast it to "void *" or "const void *". In particular, this forbids
  // formatting of "[const] volatile char *" which is printed as bool by
  // iostreams.
  template <typename T>
  value(const T *p) {
    static_assert(std::is_same<T, void>::value,
                  "formatting of non-void pointers is disallowed");
    set<POINTER>(pointer, p);
  }

  template <typename T>
  value(T *p) : value(as_const(p)) {}

  value(std::nullptr_t) { pointer = nullptr; }

  template <typename T>
  value(const T &value,
        typename std::enable_if<convert_to_int<T>::value, int>::type = 0) {
    static_assert(get_type<T>() == INT, "invalid type");
    int_value = value;
  }

  template <typename T>
  value(const T &value,
        typename std::enable_if<!convert_to_int<T>::value, int>::type = 0) {
    static_assert(get_type<T>() == CUSTOM, "invalid type");
    custom.value = &value;
    custom.format = &format_custom_arg<T>;
  }

  // Additional template param `Ctx` is needed here because get_type always
  // uses basic_context<char>.
  template <typename Ctx>
  value(const named_arg<Ctx> &value) {
    static_assert(
      get_type<const named_arg<Ctx> &>() == NAMED_ARG, "invalid type");
    pointer = &value;
  }

 private:
  template <type TYPE, typename T, typename U>
  constexpr void set(T &field, const U &value) {
    static_assert(get_type<U>() == TYPE, "invalid type");
    field = value;
  }

  template <typename T>
  void set_string(const T &value) {
    static_assert(get_type<T>() == STRING, "invalid type");
    string.value = value.data();
    string.size = value.size();
  }

  template <typename T, typename U>
  constexpr void set_cstring(T &field, const U *str) {
    static_assert(std::is_same<char, char_type>::value,
                  "incompatible string types");
    set<CSTRING>(field, str);
  }

  // Formats an argument of a custom type, such as a user-defined class.
  template <typename T>
  static void format_custom_arg(
      basic_buffer<char_type> &buffer, const void *arg, Context &ctx) {
    // Get the formatter type through the context to allow different contexts
    // have different extension points, e.g. `formatter<T>` for `format` and
    // `printf_formatter<T>` for `printf`.
    typename Context::template formatter_type<T> f;
    auto &&parse_ctx = ctx.parse_context();
    parse_ctx.advance_to(f.parse(parse_ctx));
    f.format(buffer, *static_cast<const T*>(arg), ctx);
  }
};

// Maximum number of arguments with packed types.
enum { MAX_PACKED_ARGS = 15 };

template <typename Context>
class arg_map;

template <typename Context, typename T>
constexpr basic_arg<Context> make_arg(const T &value);
}

// A formatting argument. It is a trivially copyable/constructible type to
// allow storage in basic_memory_buffer.
template <typename Context>
class basic_arg {
 private:
  internal::value<Context> value_;
  internal::type type_;

  template <typename ContextType, typename T>
  friend constexpr basic_arg<ContextType> internal::make_arg(const T &value);

  template <typename Visitor, typename Ctx>
  friend constexpr typename std::result_of<Visitor(int)>::type
    visit(Visitor &&vis, basic_arg<Ctx> arg);

  friend class basic_format_args<Context>;
  friend class internal::arg_map<Context>;

  using char_type = typename Context::char_type;

 public:
  class handle {
   public:
    explicit handle(internal::custom_value<Context> custom)
      : custom_(custom) {}

    void format(basic_buffer<char_type> &buf, Context &ctx) {
      custom_.format(buf, custom_.value, ctx);
    }

   private:
    internal::custom_value<Context> custom_;
  };

  constexpr basic_arg() : type_(internal::NONE) {}

  explicit operator bool() const noexcept { return type_ != internal::NONE; }

  internal::type type() const { return type_; }

  bool is_integral() const { return internal::is_integral(type_); }
  bool is_arithmetic() const { return internal::is_arithmetic(type_); }
  bool is_pointer() const { return type_ == internal::POINTER; }
};

// Parsing context consisting of a format string range being parsed and an
// argument counter for automatic indexing.
template <typename Char, typename ErrorHandler = internal::error_handler>
class basic_parse_context : private ErrorHandler {
 private:
  basic_string_view<Char> format_str_;
  int next_arg_id_;

 protected:
  constexpr bool check_no_auto_index() {
    if (next_arg_id_ > 0) {
      on_error("cannot switch from automatic to manual argument indexing");
      return false;
    }
    next_arg_id_ = -1;
    return true;
  }

 public:
  using char_type = Char;
  using iterator = typename basic_string_view<Char>::iterator;

  explicit constexpr basic_parse_context(
      basic_string_view<Char> format_str, ErrorHandler eh = ErrorHandler())
    : ErrorHandler(eh), format_str_(format_str), next_arg_id_(0) {}

  // Returns an iterator to the beginning of the format string range being
  // parsed.
  constexpr iterator begin() const FMT_NOEXCEPT { return format_str_.begin(); }

  // Returns an iterator past the end of the format string range being parsed.
  constexpr iterator end() const FMT_NOEXCEPT { return format_str_.end(); }

  // Advances the begin iterator to ``it``.
  constexpr void advance_to(iterator it) {
    format_str_.remove_prefix(it - begin());
  }

  // Returns the next argument index.
  constexpr unsigned next_arg_id();

  constexpr void check_arg_id(unsigned) { check_no_auto_index(); }
  void check_arg_id(basic_string_view<Char>) {}

  constexpr void on_error(const char *message) {
    ErrorHandler::on_error(message);
  }

  constexpr ErrorHandler error_handler() const { return *this; }
};

using parse_context = basic_parse_context<char>;
using wparse_context = basic_parse_context<wchar_t>;

namespace internal {
template <typename Context, typename T>
constexpr basic_arg<Context> make_arg(const T &value) {
  basic_arg<Context> arg;
  arg.type_ = get_type<T>();
  arg.value_ = value;
  return arg;
}

template <bool IS_PACKED, typename Context, typename T>
inline typename std::enable_if<IS_PACKED, value<Context>>::type
    make_arg(const T& value) {
  return value;
}

template <bool IS_PACKED, typename Context, typename T>
inline typename std::enable_if<!IS_PACKED, basic_arg<Context>>::type
    make_arg(const T& value) {
  return make_arg<Context>(value);
}

template <typename Context>
struct named_arg : basic_arg<Context> {
  using char_type = typename Context::char_type;

  basic_string_view<char_type> name;

  template <typename T>
  named_arg(basic_string_view<char_type> argname, const T &value)
  : basic_arg<Context>(make_arg<Context>(value)), name(argname) {}
};

template <typename Context>
class arg_map {
 private:
  FMT_DISALLOW_COPY_AND_ASSIGN(arg_map);

  using char_type = typename Context::char_type;

  struct arg {
    fmt::basic_string_view<char_type> name;
    basic_arg<Context> value;
  };

  arg *map_ = nullptr;
  unsigned size_ = 0;

  void push_back(arg a) {
    map_[size_] = a;
    ++size_;
  }

 public:
  arg_map() {}
  void init(const basic_format_args<Context> &args);
  ~arg_map() { delete [] map_; }

  const basic_arg<Context>
      *find(const fmt::basic_string_view<char_type> &name) const {
    // The list is unsorted, so just return the first matching name.
    for (auto it = map_, end = map_ + size_; it != end; ++it) {
      if (it->name == name)
        return &it->value;
    }
    return 0;
  }
};

template <typename Char, typename Context>
class context_base : public basic_parse_context<Char>{
 private:
  basic_format_args<Context> args_;

 protected:
  using format_arg = basic_arg<Context>;

  context_base(basic_string_view<Char> format_str,
               basic_format_args<Context> args)
  : basic_parse_context<Char>(format_str), args_(args) {}
  ~context_base() {}

  basic_format_args<Context> args() const { return args_; }

  // Returns the argument with specified index.
  format_arg do_get_arg(unsigned arg_id) {
    format_arg arg = args_[arg_id];
    if (!arg)
      this->on_error("argument index out of range");
    return arg;
  }

  // Checks if manual indexing is used and returns the argument with
  // specified index.
  format_arg get_arg(unsigned arg_id) {
    return this->check_no_auto_index() ?
      this->do_get_arg(arg_id) : format_arg();
  }

 public:
  basic_parse_context<Char> &parse_context() { return *this; }
};
}  // namespace internal

template <typename Char>
class basic_context :
  public internal::context_base<Char, basic_context<Char>> {
 public:
  /** The character type for the output. */
  using char_type = Char;

  template <typename T>
  using formatter_type = formatter<T, Char>;

 private:
  internal::arg_map<basic_context<Char>> map_;

  FMT_DISALLOW_COPY_AND_ASSIGN(basic_context);

  using Base = internal::context_base<Char, basic_context<Char>>;

  using format_arg = typename Base::format_arg;
  using Base::get_arg;

 public:
  /**
   \rst
   Constructs a ``basic_context`` object. References to the arguments are
   stored in the object so make sure they have appropriate lifetimes.
   \endrst
   */
  basic_context(
      basic_string_view<Char> format_str, basic_format_args<basic_context> args)
    : Base(format_str, args) {}

  format_arg next_arg() { return this->do_get_arg(this->next_arg_id()); }
  format_arg get_arg(unsigned arg_id) { return this->do_get_arg(arg_id); }

  // Checks if manual indexing is used and returns the argument with
  // specified name.
  format_arg get_arg(basic_string_view<Char> name);
};

template <typename Context, typename ...Args>
class arg_store {
 private:
  static const size_t NUM_ARGS = sizeof...(Args);

  // Packed is a macro on MinGW so use IS_PACKED instead.
  static const bool IS_PACKED = NUM_ARGS < internal::MAX_PACKED_ARGS;

  using value_type = typename std::conditional<
    IS_PACKED, internal::value<Context>, basic_arg<Context>>::type;

  // If the arguments are not packed, add one more element to mark the end.
  value_type data_[NUM_ARGS + (IS_PACKED ? 0 : 1)];

 public:
  static const uint64_t TYPES = IS_PACKED ?
      internal::get_types<Args..., void>() : -static_cast<int64_t>(NUM_ARGS);

  arg_store(const Args &... args)
    : data_{internal::make_arg<IS_PACKED, Context>(args)...} {}

  const value_type *data() const { return data_; }
};

template <typename Context, typename ...Args>
inline arg_store<Context, Args...> make_args(const Args & ... args) {
  return arg_store<Context, Args...>(args...);
}

template <typename ...Args>
inline arg_store<context, Args...> make_args(const Args & ... args) {
  return arg_store<context, Args...>(args...);
}

/** Formatting arguments. */
template <typename Context>
class basic_format_args {
 public:
  using size_type = unsigned;
  using format_arg = basic_arg<Context> ;

 private:
  // To reduce compiled code size per formatting function call, types of first
  // MAX_PACKED_ARGS arguments are passed in the types_ field.
  uint64_t types_;
  union {
    // If the number of arguments is less than MAX_PACKED_ARGS, the argument
    // values are stored in values_, otherwise they are stored in args_.
    // This is done to reduce compiled code size as storing larger objects
    // may require more code (at least on x86-64) even if the same amount of
    // data is actually copied to stack. It saves ~10% on the bloat test.
    const internal::value<Context> *values_;
    const format_arg *args_;
  };

  typename internal::type type(unsigned index) const {
    unsigned shift = index * 4;
    uint64_t mask = 0xf;
    return static_cast<typename internal::type>(
      (types_ & (mask << shift)) >> shift);
  }

  friend class internal::arg_map<Context>;

  void set_data(const internal::value<Context> *values) { values_ = values; }
  void set_data(const format_arg *args) { args_ = args; }

  format_arg get(size_type index) const {
    int64_t signed_types = static_cast<int64_t>(types_);
    if (signed_types < 0) {
      uint64_t num_args = -signed_types;
      return index < num_args ? args_[index] : format_arg();
    }
    format_arg arg;
    if (index > internal::MAX_PACKED_ARGS)
      return arg;
    arg.type_ = type(index);
    if (arg.type_ == internal::NONE)
      return arg;
    internal::value<Context> &val = arg.value_;
    val = values_[index];
    return arg;
  }

 public:
  basic_format_args() : types_(0) {}

  template <typename... Args>
  basic_format_args(const arg_store<Context, Args...> &store)
  : types_(store.TYPES) {
    set_data(store.data());
  }

  /** Returns the argument at specified index. */
  format_arg operator[](size_type index) const {
    format_arg arg = get(index);
    return arg.type_ == internal::NAMED_ARG ?
      *static_cast<const format_arg*>(arg.value_.pointer) : arg;
  }

  unsigned max_size() const {
    int64_t signed_types = static_cast<int64_t>(types_);
    return signed_types < 0 ? -signed_types : internal::MAX_PACKED_ARGS;
  }
};

using format_args = basic_format_args<context>;
using wformat_args = basic_format_args<wcontext>;

/**
  \rst
  Returns a named argument for formatting functions.

  **Example**::

    print("Elapsed time: {s:.2f} seconds", arg("s", 1.23));

  \endrst
 */
template <typename T>
inline internal::named_arg<context> arg(string_view name, const T &arg) {
  return internal::named_arg<context>(name, arg);
}

template <typename T>
inline internal::named_arg<wcontext> arg(wstring_view name, const T &arg) {
  return internal::named_arg<wcontext>(name, arg);
}

// The following two functions are deleted intentionally to disable
// nested named arguments as in ``format("{}", arg("a", arg("b", 42)))``.
template <typename Context>
void arg(string_view, internal::named_arg<Context>) FMT_DELETED_OR_UNDEFINED;
template <typename Context>
void arg(wstring_view, internal::named_arg<Context>) FMT_DELETED_OR_UNDEFINED;

enum Color { BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE };

FMT_API void vprint_colored(Color c, string_view format, format_args args);

/**
  Formats a string and prints it to stdout using ANSI escape sequences
  to specify color (experimental).
  Example:
    print_colored(fmt::RED, "Elapsed time: {0:.2f} seconds", 1.23);
 */
template <typename... Args>
inline void print_colored(Color c, string_view format_str,
                          const Args & ... args) {
  vprint_colored(c, format_str, make_args(args...));
}

void vformat_to(buffer &buf, string_view format_str, format_args args);
void vformat_to(wbuffer &buf, wstring_view format_str, wformat_args args);

template <typename... Args>
inline void format_to(buffer &buf, string_view format_str,
                      const Args & ... args) {
  vformat_to(buf, format_str, make_args(args...));
}

template <typename... Args>
inline void format_to(wbuffer &buf, wstring_view format_str,
                      const Args & ... args) {
  vformat_to(buf, format_str, make_args<wcontext>(args...));
}

std::string vformat(string_view format_str, format_args args);
std::wstring vformat(wstring_view format_str, wformat_args args);

/**
  \rst
  Formats arguments and returns the result as a string.

  **Example**::

    std::string message = format("The answer is {}", 42);
  \endrst
*/
template <typename... Args>
inline std::string format(string_view format_str, const Args & ... args) {
  return vformat(format_str, make_args(args...));
}
template <typename... Args>
inline std::wstring format(wstring_view format_str, const Args & ... args) {
  return vformat(format_str, make_args<wcontext>(args...));
}

FMT_API void vprint(std::FILE *f, string_view format_str, format_args args);

/**
  \rst
  Prints formatted data to the file *f*.

  **Example**::

    print(stderr, "Don't {}!", "panic");
  \endrst
 */
template <typename... Args>
inline void print(std::FILE *f, string_view format_str, const Args & ... args) {
  vprint(f, format_str, make_args(args...));
}

FMT_API void vprint(string_view format_str, format_args args);

/**
  \rst
  Prints formatted data to ``stdout``.

  **Example**::

    print("Elapsed time: {0:.2f} seconds", 1.23);
  \endrst
 */
template <typename... Args>
inline void print(string_view format_str, const Args & ... args) {
  vprint(format_str, make_args(args...));
}
}  // namespace fmt

#endif  // FMT_CORE_H_