src/cpp-common/vendor/fmt/ranges.h

   1 // Formatting library for C++ - experimental range support
   2 //
   3 // Copyright (c) 2012 - present, Victor Zverovich
   4 // All rights reserved.
   5 //
   6 // For the license information refer to format.h.
   7 //
   8 // Copyright (c) 2018 - present, Remotion (Igor Schulz)
   9 // All Rights Reserved
  10 // {fmt} support for ranges, containers and types tuple interface.
  11
  12 #ifndef FMT_RANGES_H_
  13 #define FMT_RANGES_H_
  14
  15 #include <initializer_list>
  16 #include <tuple>
  17 #include <type_traits>
  18
  19 #include "format.h"
  20
  21 FMT_BEGIN_NAMESPACE
  22
  23 namespace detail {
  24
  25 template <typename Range, typename OutputIt>
  26 auto copy(const Range& range, OutputIt out) -> OutputIt {
  27   for (auto it = range.begin(), end = range.end(); it != end; ++it)
  28     *out++ = *it;
  29   return out;
  30 }
  31
  32 template <typename OutputIt>
  33 auto copy(const char* str, OutputIt out) -> OutputIt {
  34   while (*str) *out++ = *str++;
  35   return out;
  36 }
  37
  38 template <typename OutputIt> auto copy(char ch, OutputIt out) -> OutputIt {
  39   *out++ = ch;
  40   return out;
  41 }
  42
  43 template <typename OutputIt> auto copy(wchar_t ch, OutputIt out) -> OutputIt {
  44   *out++ = ch;
  45   return out;
  46 }
  47
  48 // Returns true if T has a std::string-like interface, like std::string_view.
  49 template <typename T> class is_std_string_like {
  50   template <typename U>
  51   static auto check(U* p)
  52       -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
  53   template <typename> static void check(...);
  54
  55  public:
  56   static constexpr const bool value =
  57       is_string<T>::value ||
  58       std::is_convertible<T, std_string_view<char>>::value ||
  59       !std::is_void<decltype(check<T>(nullptr))>::value;
  60 };
  61
  62 template <typename Char>
  63 struct is_std_string_like<fmt::basic_string_view<Char>> : std::true_type {};
  64
  65 template <typename T> class is_map {
  66   template <typename U> static auto check(U*) -> typename U::mapped_type;
  67   template <typename> static void check(...);
  68
  69  public:
  70 #ifdef FMT_FORMAT_MAP_AS_LIST  // DEPRECATED!
  71   static constexpr const bool value = false;
  72 #else
  73   static constexpr const bool value =
  74       !std::is_void<decltype(check<T>(nullptr))>::value;
  75 #endif
  76 };
  77
  78 template <typename T> class is_set {
  79   template <typename U> static auto check(U*) -> typename U::key_type;
  80   template <typename> static void check(...);
  81
  82  public:
  83 #ifdef FMT_FORMAT_SET_AS_LIST  // DEPRECATED!
  84   static constexpr const bool value = false;
  85 #else
  86   static constexpr const bool value =
  87       !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
  88 #endif
  89 };
  90
  91 template <typename... Ts> struct conditional_helper {};
  92
  93 template <typename T, typename _ = void> struct is_range_ : std::false_type {};
  94
  95 #if !FMT_MSC_VERSION || FMT_MSC_VERSION > 1800
  96
  97 #  define FMT_DECLTYPE_RETURN(val)  \
  98     ->decltype(val) { return val; } \
  99     static_assert(                  \
 100         true, "")  // This makes it so that a semicolon is required after the
 101                    // macro, which helps clang-format handle the formatting.
 102
 103 // C array overload
 104 template <typename T, std::size_t N>
 105 auto range_begin(const T (&arr)[N]) -> const T* {
 106   return arr;
 107 }
 108 template <typename T, std::size_t N>
 109 auto range_end(const T (&arr)[N]) -> const T* {
 110   return arr + N;
 111 }
 112
 113 template <typename T, typename Enable = void>
 114 struct has_member_fn_begin_end_t : std::false_type {};
 115
 116 template <typename T>
 117 struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
 118                                            decltype(std::declval<T>().end())>>
 119     : std::true_type {};
 120
 121 // Member function overload
 122 template <typename T>
 123 auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
 124 template <typename T>
 125 auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
 126
 127 // ADL overload. Only participates in overload resolution if member functions
 128 // are not found.
 129 template <typename T>
 130 auto range_begin(T&& rng)
 131     -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
 132                    decltype(begin(static_cast<T&&>(rng)))> {
 133   return begin(static_cast<T&&>(rng));
 134 }
 135 template <typename T>
 136 auto range_end(T&& rng) -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
 137                                        decltype(end(static_cast<T&&>(rng)))> {
 138   return end(static_cast<T&&>(rng));
 139 }
 140
 141 template <typename T, typename Enable = void>
 142 struct has_const_begin_end : std::false_type {};
 143 template <typename T, typename Enable = void>
 144 struct has_mutable_begin_end : std::false_type {};
 145
 146 template <typename T>
 147 struct has_const_begin_end<
 148     T,
 149     void_t<
 150         decltype(detail::range_begin(std::declval<const remove_cvref_t<T>&>())),
 151         decltype(detail::range_end(std::declval<const remove_cvref_t<T>&>()))>>
 152     : std::true_type {};
 153
 154 template <typename T>
 155 struct has_mutable_begin_end<
 156     T, void_t<decltype(detail::range_begin(std::declval<T>())),
 157               decltype(detail::range_end(std::declval<T>())),
 158               // the extra int here is because older versions of MSVC don't
 159               // SFINAE properly unless there are distinct types
 160               int>> : std::true_type {};
 161
 162 template <typename T>
 163 struct is_range_<T, void>
 164     : std::integral_constant<bool, (has_const_begin_end<T>::value ||
 165                                     has_mutable_begin_end<T>::value)> {};
 166 #  undef FMT_DECLTYPE_RETURN
 167 #endif
 168
 169 // tuple_size and tuple_element check.
 170 template <typename T> class is_tuple_like_ {
 171   template <typename U>
 172   static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
 173   template <typename> static void check(...);
 174
 175  public:
 176   static constexpr const bool value =
 177       !std::is_void<decltype(check<T>(nullptr))>::value;
 178 };
 179
 180 // Check for integer_sequence
 181 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VERSION >= 1900
 182 template <typename T, T... N>
 183 using integer_sequence = std::integer_sequence<T, N...>;
 184 template <size_t... N> using index_sequence = std::index_sequence<N...>;
 185 template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
 186 #else
 187 template <typename T, T... N> struct integer_sequence {
 188   using value_type = T;
 189
 190   static FMT_CONSTEXPR size_t size() { return sizeof...(N); }
 191 };
 192
 193 template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
 194
 195 template <typename T, size_t N, T... Ns>
 196 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
 197 template <typename T, T... Ns>
 198 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
 199
 200 template <size_t N>
 201 using make_index_sequence = make_integer_sequence<size_t, N>;
 202 #endif
 203
 204 template <typename T>
 205 using tuple_index_sequence = make_index_sequence<std::tuple_size<T>::value>;
 206
 207 template <typename T, typename C, bool = is_tuple_like_<T>::value>
 208 class is_tuple_formattable_ {
 209  public:
 210   static constexpr const bool value = false;
 211 };
 212 template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
 213   template <std::size_t... Is>
 214   static std::true_type check2(index_sequence<Is...>,
 215                                integer_sequence<bool, (Is == Is)...>);
 216   static std::false_type check2(...);
 217   template <std::size_t... Is>
 218   static decltype(check2(
 219       index_sequence<Is...>{},
 220       integer_sequence<
 221           bool, (is_formattable<typename std::tuple_element<Is, T>::type,
 222                                 C>::value)...>{})) check(index_sequence<Is...>);
 223
 224  public:
 225   static constexpr const bool value =
 226       decltype(check(tuple_index_sequence<T>{}))::value;
 227 };
 228
 229 template <typename Tuple, typename F, size_t... Is>
 230 FMT_CONSTEXPR void for_each(index_sequence<Is...>, Tuple&& t, F&& f) {
 231   using std::get;
 232   // Using a free function get<Is>(Tuple) now.
 233   const int unused[] = {0, ((void)f(get<Is>(t)), 0)...};
 234   ignore_unused(unused);
 235 }
 236
 237 template <typename Tuple, typename F>
 238 FMT_CONSTEXPR void for_each(Tuple&& t, F&& f) {
 239   for_each(tuple_index_sequence<remove_cvref_t<Tuple>>(),
 240            std::forward<Tuple>(t), std::forward<F>(f));
 241 }
 242
 243 template <typename Tuple1, typename Tuple2, typename F, size_t... Is>
 244 void for_each2(index_sequence<Is...>, Tuple1&& t1, Tuple2&& t2, F&& f) {
 245   using std::get;
 246   const int unused[] = {0, ((void)f(get<Is>(t1), get<Is>(t2)), 0)...};
 247   ignore_unused(unused);
 248 }
 249
 250 template <typename Tuple1, typename Tuple2, typename F>
 251 void for_each2(Tuple1&& t1, Tuple2&& t2, F&& f) {
 252   for_each2(tuple_index_sequence<remove_cvref_t<Tuple1>>(),
 253             std::forward<Tuple1>(t1), std::forward<Tuple2>(t2),
 254             std::forward<F>(f));
 255 }
 256
 257 namespace tuple {
 258 // Workaround a bug in MSVC 2019 (v140).
 259 template <typename Char, typename... T>
 260 using result_t = std::tuple<formatter<remove_cvref_t<T>, Char>...>;
 261
 262 using std::get;
 263 template <typename Tuple, typename Char, std::size_t... Is>
 264 auto get_formatters(index_sequence<Is...>)
 265     -> result_t<Char, decltype(get<Is>(std::declval<Tuple>()))...>;
 266 }  // namespace tuple
 267
 268 #if FMT_MSC_VERSION && FMT_MSC_VERSION < 1920
 269 // Older MSVC doesn't get the reference type correctly for arrays.
 270 template <typename R> struct range_reference_type_impl {
 271   using type = decltype(*detail::range_begin(std::declval<R&>()));
 272 };
 273
 274 template <typename T, std::size_t N> struct range_reference_type_impl<T[N]> {
 275   using type = T&;
 276 };
 277
 278 template <typename T>
 279 using range_reference_type = typename range_reference_type_impl<T>::type;
 280 #else
 281 template <typename Range>
 282 using range_reference_type =
 283     decltype(*detail::range_begin(std::declval<Range&>()));
 284 #endif
 285
 286 // We don't use the Range's value_type for anything, but we do need the Range's
 287 // reference type, with cv-ref stripped.
 288 template <typename Range>
 289 using uncvref_type = remove_cvref_t<range_reference_type<Range>>;
 290
 291 template <typename Formatter>
 292 FMT_CONSTEXPR auto maybe_set_debug_format(Formatter& f, bool set)
 293     -> decltype(f.set_debug_format(set)) {
 294   f.set_debug_format(set);
 295 }
 296 template <typename Formatter>
 297 FMT_CONSTEXPR void maybe_set_debug_format(Formatter&, ...) {}
 298
 299 // These are not generic lambdas for compatibility with C++11.
 300 template <typename ParseContext> struct parse_empty_specs {
 301   template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
 302     f.parse(ctx);
 303     detail::maybe_set_debug_format(f, true);
 304   }
 305   ParseContext& ctx;
 306 };
 307 template <typename FormatContext> struct format_tuple_element {
 308   using char_type = typename FormatContext::char_type;
 309
 310   template <typename T>
 311   void operator()(const formatter<T, char_type>& f, const T& v) {
 312     if (i > 0)
 313       ctx.advance_to(detail::copy_str<char_type>(separator, ctx.out()));
 314     ctx.advance_to(f.format(v, ctx));
 315     ++i;
 316   }
 317
 318   int i;
 319   FormatContext& ctx;
 320   basic_string_view<char_type> separator;
 321 };
 322
 323 }  // namespace detail
 324
 325 template <typename T> struct is_tuple_like {
 326   static constexpr const bool value =
 327       detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
 328 };
 329
 330 template <typename T, typename C> struct is_tuple_formattable {
 331   static constexpr const bool value =
 332       detail::is_tuple_formattable_<T, C>::value;
 333 };
 334
 335 template <typename Tuple, typename Char>
 336 struct formatter<Tuple, Char,
 337                  enable_if_t<fmt::is_tuple_like<Tuple>::value &&
 338                              fmt::is_tuple_formattable<Tuple, Char>::value>> {
 339  private:
 340   decltype(detail::tuple::get_formatters<Tuple, Char>(
 341       detail::tuple_index_sequence<Tuple>())) formatters_;
 342
 343   basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
 344   basic_string_view<Char> opening_bracket_ =
 345       detail::string_literal<Char, '('>{};
 346   basic_string_view<Char> closing_bracket_ =
 347       detail::string_literal<Char, ')'>{};
 348
 349  public:
 350   FMT_CONSTEXPR formatter() {}
 351
 352   FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
 353     separator_ = sep;
 354   }
 355
 356   FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
 357                                   basic_string_view<Char> close) {
 358     opening_bracket_ = open;
 359     closing_bracket_ = close;
 360   }
 361
 362   template <typename ParseContext>
 363   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 364     auto it = ctx.begin();
 365     if (it != ctx.end() && *it != '}')
 366       FMT_THROW(format_error("invalid format specifier"));
 367     detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
 368     return it;
 369   }
 370
 371   template <typename FormatContext>
 372   auto format(const Tuple& value, FormatContext& ctx) const
 373       -> decltype(ctx.out()) {
 374     ctx.advance_to(detail::copy_str<Char>(opening_bracket_, ctx.out()));
 375     detail::for_each2(
 376         formatters_, value,
 377         detail::format_tuple_element<FormatContext>{0, ctx, separator_});
 378     return detail::copy_str<Char>(closing_bracket_, ctx.out());
 379   }
 380 };
 381
 382 template <typename T, typename Char> struct is_range {
 383   static constexpr const bool value =
 384       detail::is_range_<T>::value && !detail::is_std_string_like<T>::value &&
 385       !std::is_convertible<T, std::basic_string<Char>>::value &&
 386       !std::is_convertible<T, detail::std_string_view<Char>>::value;
 387 };
 388
 389 namespace detail {
 390 template <typename Context> struct range_mapper {
 391   using mapper = arg_mapper<Context>;
 392
 393   template <typename T,
 394             FMT_ENABLE_IF(has_formatter<remove_cvref_t<T>, Context>::value)>
 395   static auto map(T&& value) -> T&& {
 396     return static_cast<T&&>(value);
 397   }
 398   template <typename T,
 399             FMT_ENABLE_IF(!has_formatter<remove_cvref_t<T>, Context>::value)>
 400   static auto map(T&& value)
 401       -> decltype(mapper().map(static_cast<T&&>(value))) {
 402     return mapper().map(static_cast<T&&>(value));
 403   }
 404 };
 405
 406 template <typename Char, typename Element>
 407 using range_formatter_type =
 408     formatter<remove_cvref_t<decltype(range_mapper<buffer_context<Char>>{}.map(
 409                   std::declval<Element>()))>,
 410               Char>;
 411
 412 template <typename R>
 413 using maybe_const_range =
 414     conditional_t<has_const_begin_end<R>::value, const R, R>;
 415
 416 // Workaround a bug in MSVC 2015 and earlier.
 417 #if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
 418 template <typename R, typename Char>
 419 struct is_formattable_delayed
 420     : is_formattable<uncvref_type<maybe_const_range<R>>, Char> {};
 421 #endif
 422 }  // namespace detail
 423
 424 template <typename T, typename Char, typename Enable = void>
 425 struct range_formatter;
 426
 427 template <typename T, typename Char>
 428 struct range_formatter<
 429     T, Char,
 430     enable_if_t<conjunction<std::is_same<T, remove_cvref_t<T>>,
 431                             is_formattable<T, Char>>::value>> {
 432  private:
 433   detail::range_formatter_type<Char, T> underlying_;
 434   basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
 435   basic_string_view<Char> opening_bracket_ =
 436       detail::string_literal<Char, '['>{};
 437   basic_string_view<Char> closing_bracket_ =
 438       detail::string_literal<Char, ']'>{};
 439
 440  public:
 441   FMT_CONSTEXPR range_formatter() {}
 442
 443   FMT_CONSTEXPR auto underlying() -> detail::range_formatter_type<Char, T>& {
 444     return underlying_;
 445   }
 446
 447   FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
 448     separator_ = sep;
 449   }
 450
 451   FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
 452                                   basic_string_view<Char> close) {
 453     opening_bracket_ = open;
 454     closing_bracket_ = close;
 455   }
 456
 457   template <typename ParseContext>
 458   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 459     auto it = ctx.begin();
 460     auto end = ctx.end();
 461
 462     if (it != end && *it == 'n') {
 463       set_brackets({}, {});
 464       ++it;
 465     }
 466
 467     if (it != end && *it != '}') {
 468       if (*it != ':') FMT_THROW(format_error("invalid format specifier"));
 469       ++it;
 470     } else {
 471       detail::maybe_set_debug_format(underlying_, true);
 472     }
 473
 474     ctx.advance_to(it);
 475     return underlying_.parse(ctx);
 476   }
 477
 478   template <typename R, typename FormatContext>
 479   auto format(R&& range, FormatContext& ctx) const -> decltype(ctx.out()) {
 480     detail::range_mapper<buffer_context<Char>> mapper;
 481     auto out = ctx.out();
 482     out = detail::copy_str<Char>(opening_bracket_, out);
 483     int i = 0;
 484     auto it = detail::range_begin(range);
 485     auto end = detail::range_end(range);
 486     for (; it != end; ++it) {
 487       if (i > 0) out = detail::copy_str<Char>(separator_, out);
 488       ctx.advance_to(out);
 489       out = underlying_.format(mapper.map(*it), ctx);
 490       ++i;
 491     }
 492     out = detail::copy_str<Char>(closing_bracket_, out);
 493     return out;
 494   }
 495 };
 496
 497 enum class range_format { disabled, map, set, sequence, string, debug_string };
 498
 499 namespace detail {
 500 template <typename T>
 501 struct range_format_kind_
 502     : std::integral_constant<range_format,
 503                              std::is_same<uncvref_type<T>, T>::value
 504                                  ? range_format::disabled
 505                              : is_map<T>::value ? range_format::map
 506                              : is_set<T>::value ? range_format::set
 507                                                 : range_format::sequence> {};
 508
 509 template <range_format K, typename R, typename Char, typename Enable = void>
 510 struct range_default_formatter;
 511
 512 template <range_format K>
 513 using range_format_constant = std::integral_constant<range_format, K>;
 514
 515 template <range_format K, typename R, typename Char>
 516 struct range_default_formatter<
 517     K, R, Char,
 518     enable_if_t<(K == range_format::sequence || K == range_format::map ||
 519                  K == range_format::set)>> {
 520   using range_type = detail::maybe_const_range<R>;
 521   range_formatter<detail::uncvref_type<range_type>, Char> underlying_;
 522
 523   FMT_CONSTEXPR range_default_formatter() { init(range_format_constant<K>()); }
 524
 525   FMT_CONSTEXPR void init(range_format_constant<range_format::set>) {
 526     underlying_.set_brackets(detail::string_literal<Char, '{'>{},
 527                              detail::string_literal<Char, '}'>{});
 528   }
 529
 530   FMT_CONSTEXPR void init(range_format_constant<range_format::map>) {
 531     underlying_.set_brackets(detail::string_literal<Char, '{'>{},
 532                              detail::string_literal<Char, '}'>{});
 533     underlying_.underlying().set_brackets({}, {});
 534     underlying_.underlying().set_separator(
 535         detail::string_literal<Char, ':', ' '>{});
 536   }
 537
 538   FMT_CONSTEXPR void init(range_format_constant<range_format::sequence>) {}
 539
 540   template <typename ParseContext>
 541   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 542     return underlying_.parse(ctx);
 543   }
 544
 545   template <typename FormatContext>
 546   auto format(range_type& range, FormatContext& ctx) const
 547       -> decltype(ctx.out()) {
 548     return underlying_.format(range, ctx);
 549   }
 550 };
 551 }  // namespace detail
 552
 553 template <typename T, typename Char, typename Enable = void>
 554 struct range_format_kind
 555     : conditional_t<
 556           is_range<T, Char>::value, detail::range_format_kind_<T>,
 557           std::integral_constant<range_format, range_format::disabled>> {};
 558
 559 template <typename R, typename Char>
 560 struct formatter<
 561     R, Char,
 562     enable_if_t<conjunction<bool_constant<range_format_kind<R, Char>::value !=
 563                                           range_format::disabled>
 564 // Workaround a bug in MSVC 2015 and earlier.
 565 #if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
 566                             ,
 567                             detail::is_formattable_delayed<R, Char>
 568 #endif
 569                             >::value>>
 570     : detail::range_default_formatter<range_format_kind<R, Char>::value, R,
 571                                       Char> {
 572 };
 573
 574 template <typename Char, typename... T> struct tuple_join_view : detail::view {
 575   const std::tuple<T...>& tuple;
 576   basic_string_view<Char> sep;
 577
 578   tuple_join_view(const std::tuple<T...>& t, basic_string_view<Char> s)
 579       : tuple(t), sep{s} {}
 580 };
 581
 582 // Define FMT_TUPLE_JOIN_SPECIFIERS to enable experimental format specifiers
 583 // support in tuple_join. It is disabled by default because of issues with
 584 // the dynamic width and precision.
 585 #ifndef FMT_TUPLE_JOIN_SPECIFIERS
 586 #  define FMT_TUPLE_JOIN_SPECIFIERS 0
 587 #endif
 588
 589 template <typename Char, typename... T>
 590 struct formatter<tuple_join_view<Char, T...>, Char> {
 591   template <typename ParseContext>
 592   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 593     return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>());
 594   }
 595
 596   template <typename FormatContext>
 597   auto format(const tuple_join_view<Char, T...>& value,
 598               FormatContext& ctx) const -> typename FormatContext::iterator {
 599     return do_format(value, ctx,
 600                      std::integral_constant<size_t, sizeof...(T)>());
 601   }
 602
 603  private:
 604   std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
 605
 606   template <typename ParseContext>
 607   FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
 608                               std::integral_constant<size_t, 0>)
 609       -> decltype(ctx.begin()) {
 610     return ctx.begin();
 611   }
 612
 613   template <typename ParseContext, size_t N>
 614   FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
 615                               std::integral_constant<size_t, N>)
 616       -> decltype(ctx.begin()) {
 617     auto end = ctx.begin();
 618 #if FMT_TUPLE_JOIN_SPECIFIERS
 619     end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);
 620     if (N > 1) {
 621       auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
 622       if (end != end1)
 623         FMT_THROW(format_error("incompatible format specs for tuple elements"));
 624     }
 625 #endif
 626     return end;
 627   }
 628
 629   template <typename FormatContext>
 630   auto do_format(const tuple_join_view<Char, T...>&, FormatContext& ctx,
 631                  std::integral_constant<size_t, 0>) const ->
 632       typename FormatContext::iterator {
 633     return ctx.out();
 634   }
 635
 636   template <typename FormatContext, size_t N>
 637   auto do_format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
 638                  std::integral_constant<size_t, N>) const ->
 639       typename FormatContext::iterator {
 640     auto out = std::get<sizeof...(T) - N>(formatters_)
 641                    .format(std::get<sizeof...(T) - N>(value.tuple), ctx);
 642     if (N > 1) {
 643       out = std::copy(value.sep.begin(), value.sep.end(), out);
 644       ctx.advance_to(out);
 645       return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
 646     }
 647     return out;
 648   }
 649 };
 650
 651 namespace detail {
 652 // Check if T has an interface like a container adaptor (e.g. std::stack,
 653 // std::queue, std::priority_queue).
 654 template <typename T> class is_container_adaptor_like {
 655   template <typename U> static auto check(U* p) -> typename U::container_type;
 656   template <typename> static void check(...);
 657
 658  public:
 659   static constexpr const bool value =
 660       !std::is_void<decltype(check<T>(nullptr))>::value;
 661 };
 662
 663 template <typename Container> struct all {
 664   const Container& c;
 665   auto begin() const -> typename Container::const_iterator { return c.begin(); }
 666   auto end() const -> typename Container::const_iterator { return c.end(); }
 667 };
 668 }  // namespace detail
 669
 670 template <typename T, typename Char>
 671 struct formatter<
 672     T, Char,
 673     enable_if_t<conjunction<detail::is_container_adaptor_like<T>,
 674                             bool_constant<range_format_kind<T, Char>::value ==
 675                                           range_format::disabled>>::value>>
 676     : formatter<detail::all<typename T::container_type>, Char> {
 677   using all = detail::all<typename T::container_type>;
 678   template <typename FormatContext>
 679   auto format(const T& t, FormatContext& ctx) const -> decltype(ctx.out()) {
 680     struct getter : T {
 681       static auto get(const T& t) -> all {
 682         return {t.*(&getter::c)};  // Access c through the derived class.
 683       }
 684     };
 685     return formatter<all>::format(getter::get(t), ctx);
 686   }
 687 };
 688
 689 FMT_BEGIN_EXPORT
 690
 691 /**
 692   \rst
 693   Returns an object that formats `tuple` with elements separated by `sep`.
 694
 695   **Example**::
 696
 697     std::tuple<int, char> t = {1, 'a'};
 698     fmt::print("{}", fmt::join(t, ", "));
 699     // Output: "1, a"
 700   \endrst
 701  */
 702 template <typename... T>
 703 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
 704     -> tuple_join_view<char, T...> {
 705   return {tuple, sep};
 706 }
 707
 708 template <typename... T>
 709 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple,
 710                         basic_string_view<wchar_t> sep)
 711     -> tuple_join_view<wchar_t, T...> {
 712   return {tuple, sep};
 713 }
 714
 715 /**
 716   \rst
 717   Returns an object that formats `initializer_list` with elements separated by
 718   `sep`.
 719
 720   **Example**::
 721
 722     fmt::print("{}", fmt::join({1, 2, 3}, ", "));
 723     // Output: "1, 2, 3"
 724   \endrst
 725  */
 726 template <typename T>
 727 auto join(std::initializer_list<T> list, string_view sep)
 728     -> join_view<const T*, const T*> {
 729   return join(std::begin(list), std::end(list), sep);
 730 }
 731
 732 FMT_END_EXPORT
 733 FMT_END_NAMESPACE
 734
 735 #endif  // FMT_RANGES_H_