src/3rdparty/fmt/ranges.h

   1 // Formatting library for C++ - range and tuple support
   2 //
   3 // Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
   4 // All rights reserved.
   5 //
   6 // For the license information refer to format.h.
   7
   8 #ifndef FMT_RANGES_H_
   9 #define FMT_RANGES_H_
  10
  11 #include <initializer_list>
  12 #include <tuple>
  13 #include <type_traits>
  14
  15 #include "format.h"
  16
  17 FMT_BEGIN_NAMESPACE
  18
  19 namespace detail {
  20
  21 template <typename Range, typename OutputIt>
  22 auto copy(const Range& range, OutputIt out) -> OutputIt {
  23   for (auto it = range.begin(), end = range.end(); it != end; ++it)
  24     *out++ = *it;
  25   return out;
  26 }
  27
  28 template <typename OutputIt>
  29 auto copy(const char* str, OutputIt out) -> OutputIt {
  30   while (*str) *out++ = *str++;
  31   return out;
  32 }
  33
  34 template <typename OutputIt> auto copy(char ch, OutputIt out) -> OutputIt {
  35   *out++ = ch;
  36   return out;
  37 }
  38
  39 template <typename OutputIt> auto copy(wchar_t ch, OutputIt out) -> OutputIt {
  40   *out++ = ch;
  41   return out;
  42 }
  43
  44 // Returns true if T has a std::string-like interface, like std::string_view.
  45 template <typename T> class is_std_string_like {
  46   template <typename U>
  47   static auto check(U* p)
  48       -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
  49   template <typename> static void check(...);
  50
  51  public:
  52   static constexpr const bool value =
  53       is_string<T>::value ||
  54       std::is_convertible<T, std_string_view<char>>::value ||
  55       !std::is_void<decltype(check<T>(nullptr))>::value;
  56 };
  57
  58 template <typename Char>
  59 struct is_std_string_like<fmt::basic_string_view<Char>> : std::true_type {};
  60
  61 template <typename T> class is_map {
  62   template <typename U> static auto check(U*) -> typename U::mapped_type;
  63   template <typename> static void check(...);
  64
  65  public:
  66 #ifdef FMT_FORMAT_MAP_AS_LIST  // DEPRECATED!
  67   static constexpr const bool value = false;
  68 #else
  69   static constexpr const bool value =
  70       !std::is_void<decltype(check<T>(nullptr))>::value;
  71 #endif
  72 };
  73
  74 template <typename T> class is_set {
  75   template <typename U> static auto check(U*) -> typename U::key_type;
  76   template <typename> static void check(...);
  77
  78  public:
  79 #ifdef FMT_FORMAT_SET_AS_LIST  // DEPRECATED!
  80   static constexpr const bool value = false;
  81 #else
  82   static constexpr const bool value =
  83       !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
  84 #endif
  85 };
  86
  87 template <typename... Ts> struct conditional_helper {};
  88
  89 template <typename T, typename _ = void> struct is_range_ : std::false_type {};
  90
  91 #if !FMT_MSC_VERSION || FMT_MSC_VERSION > 1800
  92
  93 #  define FMT_DECLTYPE_RETURN(val)  \
  94     ->decltype(val) { return val; } \
  95     static_assert(                  \
  96         true, "")  // This makes it so that a semicolon is required after the
  97                    // macro, which helps clang-format handle the formatting.
  98
  99 // C array overload
 100 template <typename T, std::size_t N>
 101 auto range_begin(const T (&arr)[N]) -> const T* {
 102   return arr;
 103 }
 104 template <typename T, std::size_t N>
 105 auto range_end(const T (&arr)[N]) -> const T* {
 106   return arr + N;
 107 }
 108
 109 template <typename T, typename Enable = void>
 110 struct has_member_fn_begin_end_t : std::false_type {};
 111
 112 template <typename T>
 113 struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
 114                                            decltype(std::declval<T>().end())>>
 115     : std::true_type {};
 116
 117 // Member function overload
 118 template <typename T>
 119 auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
 120 template <typename T>
 121 auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
 122
 123 // ADL overload. Only participates in overload resolution if member functions
 124 // are not found.
 125 template <typename T>
 126 auto range_begin(T&& rng)
 127     -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
 128                    decltype(begin(static_cast<T&&>(rng)))> {
 129   return begin(static_cast<T&&>(rng));
 130 }
 131 template <typename T>
 132 auto range_end(T&& rng) -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
 133                                        decltype(end(static_cast<T&&>(rng)))> {
 134   return end(static_cast<T&&>(rng));
 135 }
 136
 137 template <typename T, typename Enable = void>
 138 struct has_const_begin_end : std::false_type {};
 139 template <typename T, typename Enable = void>
 140 struct has_mutable_begin_end : std::false_type {};
 141
 142 template <typename T>
 143 struct has_const_begin_end<
 144     T,
 145     void_t<
 146         decltype(detail::range_begin(std::declval<const remove_cvref_t<T>&>())),
 147         decltype(detail::range_end(std::declval<const remove_cvref_t<T>&>()))>>
 148     : std::true_type {};
 149
 150 template <typename T>
 151 struct has_mutable_begin_end<
 152     T, void_t<decltype(detail::range_begin(std::declval<T>())),
 153               decltype(detail::range_end(std::declval<T>())),
 154               // the extra int here is because older versions of MSVC don't
 155               // SFINAE properly unless there are distinct types
 156               int>> : std::true_type {};
 157
 158 template <typename T>
 159 struct is_range_<T, void>
 160     : std::integral_constant<bool, (has_const_begin_end<T>::value ||
 161                                     has_mutable_begin_end<T>::value)> {};
 162 #  undef FMT_DECLTYPE_RETURN
 163 #endif
 164
 165 // tuple_size and tuple_element check.
 166 template <typename T> class is_tuple_like_ {
 167   template <typename U>
 168   static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
 169   template <typename> static void check(...);
 170
 171  public:
 172   static constexpr const bool value =
 173       !std::is_void<decltype(check<T>(nullptr))>::value;
 174 };
 175
 176 // Check for integer_sequence
 177 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VERSION >= 1900
 178 template <typename T, T... N>
 179 using integer_sequence = std::integer_sequence<T, N...>;
 180 template <size_t... N> using index_sequence = std::index_sequence<N...>;
 181 template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
 182 #else
 183 template <typename T, T... N> struct integer_sequence {
 184   using value_type = T;
 185
 186   static FMT_CONSTEXPR auto size() -> size_t { return sizeof...(N); }
 187 };
 188
 189 template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
 190
 191 template <typename T, size_t N, T... Ns>
 192 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
 193 template <typename T, T... Ns>
 194 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
 195
 196 template <size_t N>
 197 using make_index_sequence = make_integer_sequence<size_t, N>;
 198 #endif
 199
 200 template <typename T>
 201 using tuple_index_sequence = make_index_sequence<std::tuple_size<T>::value>;
 202
 203 template <typename T, typename C, bool = is_tuple_like_<T>::value>
 204 class is_tuple_formattable_ {
 205  public:
 206   static constexpr const bool value = false;
 207 };
 208 template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
 209   template <std::size_t... Is>
 210   static auto check2(index_sequence<Is...>,
 211                      integer_sequence<bool, (Is == Is)...>) -> std::true_type;
 212   static auto check2(...) -> std::false_type;
 213   template <std::size_t... Is>
 214   static auto check(index_sequence<Is...>) -> decltype(check2(
 215       index_sequence<Is...>{},
 216       integer_sequence<bool,
 217                        (is_formattable<typename std::tuple_element<Is, T>::type,
 218                                        C>::value)...>{}));
 219
 220  public:
 221   static constexpr const bool value =
 222       decltype(check(tuple_index_sequence<T>{}))::value;
 223 };
 224
 225 template <typename Tuple, typename F, size_t... Is>
 226 FMT_CONSTEXPR void for_each(index_sequence<Is...>, Tuple&& t, F&& f) {
 227   using std::get;
 228   // Using a free function get<Is>(Tuple) now.
 229   const int unused[] = {0, ((void)f(get<Is>(t)), 0)...};
 230   ignore_unused(unused);
 231 }
 232
 233 template <typename Tuple, typename F>
 234 FMT_CONSTEXPR void for_each(Tuple&& t, F&& f) {
 235   for_each(tuple_index_sequence<remove_cvref_t<Tuple>>(),
 236            std::forward<Tuple>(t), std::forward<F>(f));
 237 }
 238
 239 template <typename Tuple1, typename Tuple2, typename F, size_t... Is>
 240 void for_each2(index_sequence<Is...>, Tuple1&& t1, Tuple2&& t2, F&& f) {
 241   using std::get;
 242   const int unused[] = {0, ((void)f(get<Is>(t1), get<Is>(t2)), 0)...};
 243   ignore_unused(unused);
 244 }
 245
 246 template <typename Tuple1, typename Tuple2, typename F>
 247 void for_each2(Tuple1&& t1, Tuple2&& t2, F&& f) {
 248   for_each2(tuple_index_sequence<remove_cvref_t<Tuple1>>(),
 249             std::forward<Tuple1>(t1), std::forward<Tuple2>(t2),
 250             std::forward<F>(f));
 251 }
 252
 253 namespace tuple {
 254 // Workaround a bug in MSVC 2019 (v140).
 255 template <typename Char, typename... T>
 256 using result_t = std::tuple<formatter<remove_cvref_t<T>, Char>...>;
 257
 258 using std::get;
 259 template <typename Tuple, typename Char, std::size_t... Is>
 260 auto get_formatters(index_sequence<Is...>)
 261     -> result_t<Char, decltype(get<Is>(std::declval<Tuple>()))...>;
 262 }  // namespace tuple
 263
 264 #if FMT_MSC_VERSION && FMT_MSC_VERSION < 1920
 265 // Older MSVC doesn't get the reference type correctly for arrays.
 266 template <typename R> struct range_reference_type_impl {
 267   using type = decltype(*detail::range_begin(std::declval<R&>()));
 268 };
 269
 270 template <typename T, std::size_t N> struct range_reference_type_impl<T[N]> {
 271   using type = T&;
 272 };
 273
 274 template <typename T>
 275 using range_reference_type = typename range_reference_type_impl<T>::type;
 276 #else
 277 template <typename Range>
 278 using range_reference_type =
 279     decltype(*detail::range_begin(std::declval<Range&>()));
 280 #endif
 281
 282 // We don't use the Range's value_type for anything, but we do need the Range's
 283 // reference type, with cv-ref stripped.
 284 template <typename Range>
 285 using uncvref_type = remove_cvref_t<range_reference_type<Range>>;
 286
 287 template <typename Formatter>
 288 FMT_CONSTEXPR auto maybe_set_debug_format(Formatter& f, bool set)
 289     -> decltype(f.set_debug_format(set)) {
 290   f.set_debug_format(set);
 291 }
 292 template <typename Formatter>
 293 FMT_CONSTEXPR void maybe_set_debug_format(Formatter&, ...) {}
 294
 295 // These are not generic lambdas for compatibility with C++11.
 296 template <typename ParseContext> struct parse_empty_specs {
 297   template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
 298     f.parse(ctx);
 299     detail::maybe_set_debug_format(f, true);
 300   }
 301   ParseContext& ctx;
 302 };
 303 template <typename FormatContext> struct format_tuple_element {
 304   using char_type = typename FormatContext::char_type;
 305
 306   template <typename T>
 307   void operator()(const formatter<T, char_type>& f, const T& v) {
 308     if (i > 0)
 309       ctx.advance_to(detail::copy_str<char_type>(separator, ctx.out()));
 310     ctx.advance_to(f.format(v, ctx));
 311     ++i;
 312   }
 313
 314   int i;
 315   FormatContext& ctx;
 316   basic_string_view<char_type> separator;
 317 };
 318
 319 }  // namespace detail
 320
 321 template <typename T> struct is_tuple_like {
 322   static constexpr const bool value =
 323       detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
 324 };
 325
 326 template <typename T, typename C> struct is_tuple_formattable {
 327   static constexpr const bool value =
 328       detail::is_tuple_formattable_<T, C>::value;
 329 };
 330
 331 template <typename Tuple, typename Char>
 332 struct formatter<Tuple, Char,
 333                  enable_if_t<fmt::is_tuple_like<Tuple>::value &&
 334                              fmt::is_tuple_formattable<Tuple, Char>::value>> {
 335  private:
 336   decltype(detail::tuple::get_formatters<Tuple, Char>(
 337       detail::tuple_index_sequence<Tuple>())) formatters_;
 338
 339   basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
 340   basic_string_view<Char> opening_bracket_ =
 341       detail::string_literal<Char, '('>{};
 342   basic_string_view<Char> closing_bracket_ =
 343       detail::string_literal<Char, ')'>{};
 344
 345  public:
 346   FMT_CONSTEXPR formatter() {}
 347
 348   FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
 349     separator_ = sep;
 350   }
 351
 352   FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
 353                                   basic_string_view<Char> close) {
 354     opening_bracket_ = open;
 355     closing_bracket_ = close;
 356   }
 357
 358   template <typename ParseContext>
 359   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 360     auto it = ctx.begin();
 361     if (it != ctx.end() && *it != '}')
 362       FMT_THROW(format_error("invalid format specifier"));
 363     detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
 364     return it;
 365   }
 366
 367   template <typename FormatContext>
 368   auto format(const Tuple& value, FormatContext& ctx) const
 369       -> decltype(ctx.out()) {
 370     ctx.advance_to(detail::copy_str<Char>(opening_bracket_, ctx.out()));
 371     detail::for_each2(
 372         formatters_, value,
 373         detail::format_tuple_element<FormatContext>{0, ctx, separator_});
 374     return detail::copy_str<Char>(closing_bracket_, ctx.out());
 375   }
 376 };
 377
 378 template <typename T, typename Char> struct is_range {
 379   static constexpr const bool value =
 380       detail::is_range_<T>::value && !detail::is_std_string_like<T>::value &&
 381       !std::is_convertible<T, std::basic_string<Char>>::value &&
 382       !std::is_convertible<T, detail::std_string_view<Char>>::value;
 383 };
 384
 385 namespace detail {
 386 template <typename Context> struct range_mapper {
 387   using mapper = arg_mapper<Context>;
 388
 389   template <typename T,
 390             FMT_ENABLE_IF(has_formatter<remove_cvref_t<T>, Context>::value)>
 391   static auto map(T&& value) -> T&& {
 392     return static_cast<T&&>(value);
 393   }
 394   template <typename T,
 395             FMT_ENABLE_IF(!has_formatter<remove_cvref_t<T>, Context>::value)>
 396   static auto map(T&& value)
 397       -> decltype(mapper().map(static_cast<T&&>(value))) {
 398     return mapper().map(static_cast<T&&>(value));
 399   }
 400 };
 401
 402 template <typename Char, typename Element>
 403 using range_formatter_type =
 404     formatter<remove_cvref_t<decltype(range_mapper<buffer_context<Char>>{}.map(
 405                   std::declval<Element>()))>,
 406               Char>;
 407
 408 template <typename R>
 409 using maybe_const_range =
 410     conditional_t<has_const_begin_end<R>::value, const R, R>;
 411
 412 // Workaround a bug in MSVC 2015 and earlier.
 413 #if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
 414 template <typename R, typename Char>
 415 struct is_formattable_delayed
 416     : is_formattable<uncvref_type<maybe_const_range<R>>, Char> {};
 417 #endif
 418 }  // namespace detail
 419
 420 template <typename...> struct conjunction : std::true_type {};
 421 template <typename P> struct conjunction<P> : P {};
 422 template <typename P1, typename... Pn>
 423 struct conjunction<P1, Pn...>
 424     : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};
 425
 426 template <typename T, typename Char, typename Enable = void>
 427 struct range_formatter;
 428
 429 template <typename T, typename Char>
 430 struct range_formatter<
 431     T, Char,
 432     enable_if_t<conjunction<std::is_same<T, remove_cvref_t<T>>,
 433                             is_formattable<T, Char>>::value>> {
 434  private:
 435   detail::range_formatter_type<Char, T> underlying_;
 436   basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
 437   basic_string_view<Char> opening_bracket_ =
 438       detail::string_literal<Char, '['>{};
 439   basic_string_view<Char> closing_bracket_ =
 440       detail::string_literal<Char, ']'>{};
 441
 442  public:
 443   FMT_CONSTEXPR range_formatter() {}
 444
 445   FMT_CONSTEXPR auto underlying() -> detail::range_formatter_type<Char, T>& {
 446     return underlying_;
 447   }
 448
 449   FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
 450     separator_ = sep;
 451   }
 452
 453   FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
 454                                   basic_string_view<Char> close) {
 455     opening_bracket_ = open;
 456     closing_bracket_ = close;
 457   }
 458
 459   template <typename ParseContext>
 460   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 461     auto it = ctx.begin();
 462     auto end = ctx.end();
 463
 464     if (it != end && *it == 'n') {
 465       set_brackets({}, {});
 466       ++it;
 467     }
 468
 469     if (it != end && *it != '}') {
 470       if (*it != ':') FMT_THROW(format_error("invalid format specifier"));
 471       ++it;
 472     } else {
 473       detail::maybe_set_debug_format(underlying_, true);
 474     }
 475
 476     ctx.advance_to(it);
 477     return underlying_.parse(ctx);
 478   }
 479
 480   template <typename R, typename FormatContext>
 481   auto format(R&& range, FormatContext& ctx) const -> decltype(ctx.out()) {
 482     detail::range_mapper<buffer_context<Char>> mapper;
 483     auto out = ctx.out();
 484     out = detail::copy_str<Char>(opening_bracket_, out);
 485     int i = 0;
 486     auto it = detail::range_begin(range);
 487     auto end = detail::range_end(range);
 488     for (; it != end; ++it) {
 489       if (i > 0) out = detail::copy_str<Char>(separator_, out);
 490       ctx.advance_to(out);
 491       auto&& item = *it;
 492       out = underlying_.format(mapper.map(item), ctx);
 493       ++i;
 494     }
 495     out = detail::copy_str<Char>(closing_bracket_, out);
 496     return out;
 497   }
 498 };
 499
 500 enum class range_format { disabled, map, set, sequence, string, debug_string };
 501
 502 namespace detail {
 503 template <typename T>
 504 struct range_format_kind_
 505     : std::integral_constant<range_format,
 506                              std::is_same<uncvref_type<T>, T>::value
 507                                  ? range_format::disabled
 508                              : is_map<T>::value ? range_format::map
 509                              : is_set<T>::value ? range_format::set
 510                                                 : range_format::sequence> {};
 511
 512 template <range_format K, typename R, typename Char, typename Enable = void>
 513 struct range_default_formatter;
 514
 515 template <range_format K>
 516 using range_format_constant = std::integral_constant<range_format, K>;
 517
 518 template <range_format K, typename R, typename Char>
 519 struct range_default_formatter<
 520     K, R, Char,
 521     enable_if_t<(K == range_format::sequence || K == range_format::map ||
 522                  K == range_format::set)>> {
 523   using range_type = detail::maybe_const_range<R>;
 524   range_formatter<detail::uncvref_type<range_type>, Char> underlying_;
 525
 526   FMT_CONSTEXPR range_default_formatter() { init(range_format_constant<K>()); }
 527
 528   FMT_CONSTEXPR void init(range_format_constant<range_format::set>) {
 529     underlying_.set_brackets(detail::string_literal<Char, '{'>{},
 530                              detail::string_literal<Char, '}'>{});
 531   }
 532
 533   FMT_CONSTEXPR void init(range_format_constant<range_format::map>) {
 534     underlying_.set_brackets(detail::string_literal<Char, '{'>{},
 535                              detail::string_literal<Char, '}'>{});
 536     underlying_.underlying().set_brackets({}, {});
 537     underlying_.underlying().set_separator(
 538         detail::string_literal<Char, ':', ' '>{});
 539   }
 540
 541   FMT_CONSTEXPR void init(range_format_constant<range_format::sequence>) {}
 542
 543   template <typename ParseContext>
 544   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 545     return underlying_.parse(ctx);
 546   }
 547
 548   template <typename FormatContext>
 549   auto format(range_type& range, FormatContext& ctx) const
 550       -> decltype(ctx.out()) {
 551     return underlying_.format(range, ctx);
 552   }
 553 };
 554 }  // namespace detail
 555
 556 template <typename T, typename Char, typename Enable = void>
 557 struct range_format_kind
 558     : conditional_t<
 559           is_range<T, Char>::value, detail::range_format_kind_<T>,
 560           std::integral_constant<range_format, range_format::disabled>> {};
 561
 562 template <typename R, typename Char>
 563 struct formatter<
 564     R, Char,
 565     enable_if_t<conjunction<bool_constant<range_format_kind<R, Char>::value !=
 566                                           range_format::disabled>
 567 // Workaround a bug in MSVC 2015 and earlier.
 568 #if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
 569                             ,
 570                             detail::is_formattable_delayed<R, Char>
 571 #endif
 572                             >::value>>
 573     : detail::range_default_formatter<range_format_kind<R, Char>::value, R,
 574                                       Char> {
 575 };
 576
 577 template <typename Char, typename... T> struct tuple_join_view : detail::view {
 578   const std::tuple<T...>& tuple;
 579   basic_string_view<Char> sep;
 580
 581   tuple_join_view(const std::tuple<T...>& t, basic_string_view<Char> s)
 582       : tuple(t), sep{s} {}
 583 };
 584
 585 // Define FMT_TUPLE_JOIN_SPECIFIERS to enable experimental format specifiers
 586 // support in tuple_join. It is disabled by default because of issues with
 587 // the dynamic width and precision.
 588 #ifndef FMT_TUPLE_JOIN_SPECIFIERS
 589 #  define FMT_TUPLE_JOIN_SPECIFIERS 0
 590 #endif
 591
 592 template <typename Char, typename... T>
 593 struct formatter<tuple_join_view<Char, T...>, Char> {
 594   template <typename ParseContext>
 595   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 596     return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>());
 597   }
 598
 599   template <typename FormatContext>
 600   auto format(const tuple_join_view<Char, T...>& value,
 601               FormatContext& ctx) const -> typename FormatContext::iterator {
 602     return do_format(value, ctx,
 603                      std::integral_constant<size_t, sizeof...(T)>());
 604   }
 605
 606  private:
 607   std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
 608
 609   template <typename ParseContext>
 610   FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
 611                               std::integral_constant<size_t, 0>)
 612       -> decltype(ctx.begin()) {
 613     return ctx.begin();
 614   }
 615
 616   template <typename ParseContext, size_t N>
 617   FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
 618                               std::integral_constant<size_t, N>)
 619       -> decltype(ctx.begin()) {
 620     auto end = ctx.begin();
 621 #if FMT_TUPLE_JOIN_SPECIFIERS
 622     end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);
 623     if (N > 1) {
 624       auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
 625       if (end != end1)
 626         FMT_THROW(format_error("incompatible format specs for tuple elements"));
 627     }
 628 #endif
 629     return end;
 630   }
 631
 632   template <typename FormatContext>
 633   auto do_format(const tuple_join_view<Char, T...>&, FormatContext& ctx,
 634                  std::integral_constant<size_t, 0>) const ->
 635       typename FormatContext::iterator {
 636     return ctx.out();
 637   }
 638
 639   template <typename FormatContext, size_t N>
 640   auto do_format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
 641                  std::integral_constant<size_t, N>) const ->
 642       typename FormatContext::iterator {
 643     auto out = std::get<sizeof...(T) - N>(formatters_)
 644                    .format(std::get<sizeof...(T) - N>(value.tuple), ctx);
 645     if (N > 1) {
 646       out = std::copy(value.sep.begin(), value.sep.end(), out);
 647       ctx.advance_to(out);
 648       return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
 649     }
 650     return out;
 651   }
 652 };
 653
 654 namespace detail {
 655 // Check if T has an interface like a container adaptor (e.g. std::stack,
 656 // std::queue, std::priority_queue).
 657 template <typename T> class is_container_adaptor_like {
 658   template <typename U> static auto check(U* p) -> typename U::container_type;
 659   template <typename> static void check(...);
 660
 661  public:
 662   static constexpr const bool value =
 663       !std::is_void<decltype(check<T>(nullptr))>::value;
 664 };
 665
 666 template <typename Container> struct all {
 667   const Container& c;
 668   auto begin() const -> typename Container::const_iterator { return c.begin(); }
 669   auto end() const -> typename Container::const_iterator { return c.end(); }
 670 };
 671 }  // namespace detail
 672
 673 template <typename T, typename Char>
 674 struct formatter<
 675     T, Char,
 676     enable_if_t<conjunction<detail::is_container_adaptor_like<T>,
 677                             bool_constant<range_format_kind<T, Char>::value ==
 678                                           range_format::disabled>>::value>>
 679     : formatter<detail::all<typename T::container_type>, Char> {
 680   using all = detail::all<typename T::container_type>;
 681   template <typename FormatContext>
 682   auto format(const T& t, FormatContext& ctx) const -> decltype(ctx.out()) {
 683     struct getter : T {
 684       static auto get(const T& t) -> all {
 685         return {t.*(&getter::c)};  // Access c through the derived class.
 686       }
 687     };
 688     return formatter<all>::format(getter::get(t), ctx);
 689   }
 690 };
 691
 692 FMT_BEGIN_EXPORT
 693
 694 /**
 695   \rst
 696   Returns an object that formats `tuple` with elements separated by `sep`.
 697
 698   **Example**::
 699
 700     std::tuple<int, char> t = {1, 'a'};
 701     fmt::print("{}", fmt::join(t, ", "));
 702     // Output: "1, a"
 703   \endrst
 704  */
 705 template <typename... T>
 706 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
 707     -> tuple_join_view<char, T...> {
 708   return {tuple, sep};
 709 }
 710
 711 template <typename... T>
 712 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple,
 713                         basic_string_view<wchar_t> sep)
 714     -> tuple_join_view<wchar_t, T...> {
 715   return {tuple, sep};
 716 }
 717
 718 /**
 719   \rst
 720   Returns an object that formats `initializer_list` with elements separated by
 721   `sep`.
 722
 723   **Example**::
 724
 725     fmt::print("{}", fmt::join({1, 2, 3}, ", "));
 726     // Output: "1, 2, 3"
 727   \endrst
 728  */
 729 template <typename T>
 730 auto join(std::initializer_list<T> list, string_view sep)
 731     -> join_view<const T*, const T*> {
 732   return join(std::begin(list), std::end(list), sep);
 733 }
 734
 735 FMT_END_EXPORT
 736 FMT_END_NAMESPACE
 737
 738 #endif  // FMT_RANGES_H_