fmt-11.0.2/include/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 #ifndef FMT_MODULE
  12 #  include <initializer_list>
  13 #  include <iterator>
  14 #  include <string>
  15 #  include <tuple>
  16 #  include <type_traits>
  17 #  include <utility>
  18 #endif
  19
  20 #include "format.h"
  21
  22 FMT_BEGIN_NAMESPACE
  23
  24 FMT_EXPORT
  25 enum class range_format { disabled, map, set, sequence, string, debug_string };
  26
  27 namespace detail {
  28
  29 template <typename T> class is_map {
  30   template <typename U> static auto check(U*) -> typename U::mapped_type;
  31   template <typename> static void check(...);
  32
  33  public:
  34   static constexpr const bool value =
  35       !std::is_void<decltype(check<T>(nullptr))>::value;
  36 };
  37
  38 template <typename T> class is_set {
  39   template <typename U> static auto check(U*) -> typename U::key_type;
  40   template <typename> static void check(...);
  41
  42  public:
  43   static constexpr const bool value =
  44       !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
  45 };
  46
  47 template <typename... Ts> struct conditional_helper {};
  48
  49 template <typename T, typename _ = void> struct is_range_ : std::false_type {};
  50
  51 #if !FMT_MSC_VERSION || FMT_MSC_VERSION > 1800
  52
  53 #  define FMT_DECLTYPE_RETURN(val)  \
  54     ->decltype(val) { return val; } \
  55     static_assert(                  \
  56         true, "")  // This makes it so that a semicolon is required after the
  57                    // macro, which helps clang-format handle the formatting.
  58
  59 // C array overload
  60 template <typename T, std::size_t N>
  61 auto range_begin(const T (&arr)[N]) -> const T* {
  62   return arr;
  63 }
  64 template <typename T, std::size_t N>
  65 auto range_end(const T (&arr)[N]) -> const T* {
  66   return arr + N;
  67 }
  68
  69 template <typename T, typename Enable = void>
  70 struct has_member_fn_begin_end_t : std::false_type {};
  71
  72 template <typename T>
  73 struct has_member_fn_begin_end_t<T, void_t<decltype(*std::declval<T>().begin()),
  74                                            decltype(std::declval<T>().end())>>
  75     : std::true_type {};
  76
  77 // Member function overloads.
  78 template <typename T>
  79 auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
  80 template <typename T>
  81 auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
  82
  83 // ADL overloads. Only participate in overload resolution if member functions
  84 // are not found.
  85 template <typename T>
  86 auto range_begin(T&& rng)
  87     -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
  88                    decltype(begin(static_cast<T&&>(rng)))> {
  89   return begin(static_cast<T&&>(rng));
  90 }
  91 template <typename T>
  92 auto range_end(T&& rng) -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
  93                                        decltype(end(static_cast<T&&>(rng)))> {
  94   return end(static_cast<T&&>(rng));
  95 }
  96
  97 template <typename T, typename Enable = void>
  98 struct has_const_begin_end : std::false_type {};
  99 template <typename T, typename Enable = void>
 100 struct has_mutable_begin_end : std::false_type {};
 101
 102 template <typename T>
 103 struct has_const_begin_end<
 104     T, void_t<decltype(*detail::range_begin(
 105                   std::declval<const remove_cvref_t<T>&>())),
 106               decltype(detail::range_end(
 107                   std::declval<const remove_cvref_t<T>&>()))>>
 108     : std::true_type {};
 109
 110 template <typename T>
 111 struct has_mutable_begin_end<
 112     T, void_t<decltype(*detail::range_begin(std::declval<T&>())),
 113               decltype(detail::range_end(std::declval<T&>())),
 114               // the extra int here is because older versions of MSVC don't
 115               // SFINAE properly unless there are distinct types
 116               int>> : std::true_type {};
 117
 118 template <typename T>
 119 struct is_range_<T, void>
 120     : std::integral_constant<bool, (has_const_begin_end<T>::value ||
 121                                     has_mutable_begin_end<T>::value)> {};
 122 #  undef FMT_DECLTYPE_RETURN
 123 #endif
 124
 125 // tuple_size and tuple_element check.
 126 template <typename T> class is_tuple_like_ {
 127   template <typename U>
 128   static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
 129   template <typename> static void check(...);
 130
 131  public:
 132   static constexpr const bool value =
 133       !std::is_void<decltype(check<T>(nullptr))>::value;
 134 };
 135
 136 // Check for integer_sequence
 137 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VERSION >= 1900
 138 template <typename T, T... N>
 139 using integer_sequence = std::integer_sequence<T, N...>;
 140 template <size_t... N> using index_sequence = std::index_sequence<N...>;
 141 template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
 142 #else
 143 template <typename T, T... N> struct integer_sequence {
 144   using value_type = T;
 145
 146   static FMT_CONSTEXPR auto size() -> size_t { return sizeof...(N); }
 147 };
 148
 149 template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
 150
 151 template <typename T, size_t N, T... Ns>
 152 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
 153 template <typename T, T... Ns>
 154 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
 155
 156 template <size_t N>
 157 using make_index_sequence = make_integer_sequence<size_t, N>;
 158 #endif
 159
 160 template <typename T>
 161 using tuple_index_sequence = make_index_sequence<std::tuple_size<T>::value>;
 162
 163 template <typename T, typename C, bool = is_tuple_like_<T>::value>
 164 class is_tuple_formattable_ {
 165  public:
 166   static constexpr const bool value = false;
 167 };
 168 template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
 169   template <size_t... Is>
 170   static auto all_true(index_sequence<Is...>,
 171                        integer_sequence<bool, (Is >= 0)...>) -> std::true_type;
 172   static auto all_true(...) -> std::false_type;
 173
 174   template <size_t... Is>
 175   static auto check(index_sequence<Is...>) -> decltype(all_true(
 176       index_sequence<Is...>{},
 177       integer_sequence<bool,
 178                        (is_formattable<typename std::tuple_element<Is, T>::type,
 179                                        C>::value)...>{}));
 180
 181  public:
 182   static constexpr const bool value =
 183       decltype(check(tuple_index_sequence<T>{}))::value;
 184 };
 185
 186 template <typename Tuple, typename F, size_t... Is>
 187 FMT_CONSTEXPR void for_each(index_sequence<Is...>, Tuple&& t, F&& f) {
 188   using std::get;
 189   // Using a free function get<Is>(Tuple) now.
 190   const int unused[] = {0, ((void)f(get<Is>(t)), 0)...};
 191   ignore_unused(unused);
 192 }
 193
 194 template <typename Tuple, typename F>
 195 FMT_CONSTEXPR void for_each(Tuple&& t, F&& f) {
 196   for_each(tuple_index_sequence<remove_cvref_t<Tuple>>(),
 197            std::forward<Tuple>(t), std::forward<F>(f));
 198 }
 199
 200 template <typename Tuple1, typename Tuple2, typename F, size_t... Is>
 201 void for_each2(index_sequence<Is...>, Tuple1&& t1, Tuple2&& t2, F&& f) {
 202   using std::get;
 203   const int unused[] = {0, ((void)f(get<Is>(t1), get<Is>(t2)), 0)...};
 204   ignore_unused(unused);
 205 }
 206
 207 template <typename Tuple1, typename Tuple2, typename F>
 208 void for_each2(Tuple1&& t1, Tuple2&& t2, F&& f) {
 209   for_each2(tuple_index_sequence<remove_cvref_t<Tuple1>>(),
 210             std::forward<Tuple1>(t1), std::forward<Tuple2>(t2),
 211             std::forward<F>(f));
 212 }
 213
 214 namespace tuple {
 215 // Workaround a bug in MSVC 2019 (v140).
 216 template <typename Char, typename... T>
 217 using result_t = std::tuple<formatter<remove_cvref_t<T>, Char>...>;
 218
 219 using std::get;
 220 template <typename Tuple, typename Char, std::size_t... Is>
 221 auto get_formatters(index_sequence<Is...>)
 222     -> result_t<Char, decltype(get<Is>(std::declval<Tuple>()))...>;
 223 }  // namespace tuple
 224
 225 #if FMT_MSC_VERSION && FMT_MSC_VERSION < 1920
 226 // Older MSVC doesn't get the reference type correctly for arrays.
 227 template <typename R> struct range_reference_type_impl {
 228   using type = decltype(*detail::range_begin(std::declval<R&>()));
 229 };
 230
 231 template <typename T, std::size_t N> struct range_reference_type_impl<T[N]> {
 232   using type = T&;
 233 };
 234
 235 template <typename T>
 236 using range_reference_type = typename range_reference_type_impl<T>::type;
 237 #else
 238 template <typename Range>
 239 using range_reference_type =
 240     decltype(*detail::range_begin(std::declval<Range&>()));
 241 #endif
 242
 243 // We don't use the Range's value_type for anything, but we do need the Range's
 244 // reference type, with cv-ref stripped.
 245 template <typename Range>
 246 using uncvref_type = remove_cvref_t<range_reference_type<Range>>;
 247
 248 template <typename Formatter>
 249 FMT_CONSTEXPR auto maybe_set_debug_format(Formatter& f, bool set)
 250     -> decltype(f.set_debug_format(set)) {
 251   f.set_debug_format(set);
 252 }
 253 template <typename Formatter>
 254 FMT_CONSTEXPR void maybe_set_debug_format(Formatter&, ...) {}
 255
 256 template <typename T>
 257 struct range_format_kind_
 258     : std::integral_constant<range_format,
 259                              std::is_same<uncvref_type<T>, T>::value
 260                                  ? range_format::disabled
 261                              : is_map<T>::value ? range_format::map
 262                              : is_set<T>::value ? range_format::set
 263                                                 : range_format::sequence> {};
 264
 265 template <range_format K>
 266 using range_format_constant = std::integral_constant<range_format, K>;
 267
 268 // These are not generic lambdas for compatibility with C++11.
 269 template <typename ParseContext> struct parse_empty_specs {
 270   template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
 271     f.parse(ctx);
 272     detail::maybe_set_debug_format(f, true);
 273   }
 274   ParseContext& ctx;
 275 };
 276 template <typename FormatContext> struct format_tuple_element {
 277   using char_type = typename FormatContext::char_type;
 278
 279   template <typename T>
 280   void operator()(const formatter<T, char_type>& f, const T& v) {
 281     if (i > 0) ctx.advance_to(detail::copy<char_type>(separator, ctx.out()));
 282     ctx.advance_to(f.format(v, ctx));
 283     ++i;
 284   }
 285
 286   int i;
 287   FormatContext& ctx;
 288   basic_string_view<char_type> separator;
 289 };
 290
 291 }  // namespace detail
 292
 293 template <typename T> struct is_tuple_like {
 294   static constexpr const bool value =
 295       detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
 296 };
 297
 298 template <typename T, typename C> struct is_tuple_formattable {
 299   static constexpr const bool value =
 300       detail::is_tuple_formattable_<T, C>::value;
 301 };
 302
 303 template <typename Tuple, typename Char>
 304 struct formatter<Tuple, Char,
 305                  enable_if_t<fmt::is_tuple_like<Tuple>::value &&
 306                              fmt::is_tuple_formattable<Tuple, Char>::value>> {
 307  private:
 308   decltype(detail::tuple::get_formatters<Tuple, Char>(
 309       detail::tuple_index_sequence<Tuple>())) formatters_;
 310
 311   basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
 312   basic_string_view<Char> opening_bracket_ =
 313       detail::string_literal<Char, '('>{};
 314   basic_string_view<Char> closing_bracket_ =
 315       detail::string_literal<Char, ')'>{};
 316
 317  public:
 318   FMT_CONSTEXPR formatter() {}
 319
 320   FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
 321     separator_ = sep;
 322   }
 323
 324   FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
 325                                   basic_string_view<Char> close) {
 326     opening_bracket_ = open;
 327     closing_bracket_ = close;
 328   }
 329
 330   template <typename ParseContext>
 331   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 332     auto it = ctx.begin();
 333     if (it != ctx.end() && *it != '}') report_error("invalid format specifier");
 334     detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
 335     return it;
 336   }
 337
 338   template <typename FormatContext>
 339   auto format(const Tuple& value, FormatContext& ctx) const
 340       -> decltype(ctx.out()) {
 341     ctx.advance_to(detail::copy<Char>(opening_bracket_, ctx.out()));
 342     detail::for_each2(
 343         formatters_, value,
 344         detail::format_tuple_element<FormatContext>{0, ctx, separator_});
 345     return detail::copy<Char>(closing_bracket_, ctx.out());
 346   }
 347 };
 348
 349 template <typename T, typename Char> struct is_range {
 350   static constexpr const bool value =
 351       detail::is_range_<T>::value && !detail::has_to_string_view<T>::value;
 352 };
 353
 354 namespace detail {
 355 template <typename Context> struct range_mapper {
 356   using mapper = arg_mapper<Context>;
 357
 358   template <typename T,
 359             FMT_ENABLE_IF(has_formatter<remove_cvref_t<T>, Context>::value)>
 360   static auto map(T&& value) -> T&& {
 361     return static_cast<T&&>(value);
 362   }
 363   template <typename T,
 364             FMT_ENABLE_IF(!has_formatter<remove_cvref_t<T>, Context>::value)>
 365   static auto map(T&& value)
 366       -> decltype(mapper().map(static_cast<T&&>(value))) {
 367     return mapper().map(static_cast<T&&>(value));
 368   }
 369 };
 370
 371 template <typename Char, typename Element>
 372 using range_formatter_type =
 373     formatter<remove_cvref_t<decltype(range_mapper<buffered_context<Char>>{}
 374                                           .map(std::declval<Element>()))>,
 375               Char>;
 376
 377 template <typename R>
 378 using maybe_const_range =
 379     conditional_t<has_const_begin_end<R>::value, const R, R>;
 380
 381 // Workaround a bug in MSVC 2015 and earlier.
 382 #if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
 383 template <typename R, typename Char>
 384 struct is_formattable_delayed
 385     : is_formattable<uncvref_type<maybe_const_range<R>>, Char> {};
 386 #endif
 387 }  // namespace detail
 388
 389 template <typename...> struct conjunction : std::true_type {};
 390 template <typename P> struct conjunction<P> : P {};
 391 template <typename P1, typename... Pn>
 392 struct conjunction<P1, Pn...>
 393     : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};
 394
 395 template <typename T, typename Char, typename Enable = void>
 396 struct range_formatter;
 397
 398 template <typename T, typename Char>
 399 struct range_formatter<
 400     T, Char,
 401     enable_if_t<conjunction<std::is_same<T, remove_cvref_t<T>>,
 402                             is_formattable<T, Char>>::value>> {
 403  private:
 404   detail::range_formatter_type<Char, T> underlying_;
 405   basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
 406   basic_string_view<Char> opening_bracket_ =
 407       detail::string_literal<Char, '['>{};
 408   basic_string_view<Char> closing_bracket_ =
 409       detail::string_literal<Char, ']'>{};
 410   bool is_debug = false;
 411
 412   template <typename Output, typename It, typename Sentinel, typename U = T,
 413             FMT_ENABLE_IF(std::is_same<U, Char>::value)>
 414   auto write_debug_string(Output& out, It it, Sentinel end) const -> Output {
 415     auto buf = basic_memory_buffer<Char>();
 416     for (; it != end; ++it) buf.push_back(*it);
 417     auto specs = format_specs();
 418     specs.type = presentation_type::debug;
 419     return detail::write<Char>(
 420         out, basic_string_view<Char>(buf.data(), buf.size()), specs);
 421   }
 422
 423   template <typename Output, typename It, typename Sentinel, typename U = T,
 424             FMT_ENABLE_IF(!std::is_same<U, Char>::value)>
 425   auto write_debug_string(Output& out, It, Sentinel) const -> Output {
 426     return out;
 427   }
 428
 429  public:
 430   FMT_CONSTEXPR range_formatter() {}
 431
 432   FMT_CONSTEXPR auto underlying() -> detail::range_formatter_type<Char, T>& {
 433     return underlying_;
 434   }
 435
 436   FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
 437     separator_ = sep;
 438   }
 439
 440   FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
 441                                   basic_string_view<Char> close) {
 442     opening_bracket_ = open;
 443     closing_bracket_ = close;
 444   }
 445
 446   template <typename ParseContext>
 447   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 448     auto it = ctx.begin();
 449     auto end = ctx.end();
 450     detail::maybe_set_debug_format(underlying_, true);
 451     if (it == end) return underlying_.parse(ctx);
 452
 453     switch (detail::to_ascii(*it)) {
 454     case 'n':
 455       set_brackets({}, {});
 456       ++it;
 457       break;
 458     case '?':
 459       is_debug = true;
 460       set_brackets({}, {});
 461       ++it;
 462       if (it == end || *it != 's') report_error("invalid format specifier");
 463       FMT_FALLTHROUGH;
 464     case 's':
 465       if (!std::is_same<T, Char>::value)
 466         report_error("invalid format specifier");
 467       if (!is_debug) {
 468         set_brackets(detail::string_literal<Char, '"'>{},
 469                      detail::string_literal<Char, '"'>{});
 470         set_separator({});
 471         detail::maybe_set_debug_format(underlying_, false);
 472       }
 473       ++it;
 474       return it;
 475     }
 476
 477     if (it != end && *it != '}') {
 478       if (*it != ':') report_error("invalid format specifier");
 479       detail::maybe_set_debug_format(underlying_, false);
 480       ++it;
 481     }
 482
 483     ctx.advance_to(it);
 484     return underlying_.parse(ctx);
 485   }
 486
 487   template <typename R, typename FormatContext>
 488   auto format(R&& range, FormatContext& ctx) const -> decltype(ctx.out()) {
 489     auto mapper = detail::range_mapper<buffered_context<Char>>();
 490     auto out = ctx.out();
 491     auto it = detail::range_begin(range);
 492     auto end = detail::range_end(range);
 493     if (is_debug) return write_debug_string(out, std::move(it), end);
 494
 495     out = detail::copy<Char>(opening_bracket_, out);
 496     int i = 0;
 497     for (; it != end; ++it) {
 498       if (i > 0) out = detail::copy<Char>(separator_, out);
 499       ctx.advance_to(out);
 500       auto&& item = *it;  // Need an lvalue
 501       out = underlying_.format(mapper.map(item), ctx);
 502       ++i;
 503     }
 504     out = detail::copy<Char>(closing_bracket_, out);
 505     return out;
 506   }
 507 };
 508
 509 FMT_EXPORT
 510 template <typename T, typename Char, typename Enable = void>
 511 struct range_format_kind
 512     : conditional_t<
 513           is_range<T, Char>::value, detail::range_format_kind_<T>,
 514           std::integral_constant<range_format, range_format::disabled>> {};
 515
 516 template <typename R, typename Char>
 517 struct formatter<
 518     R, Char,
 519     enable_if_t<conjunction<
 520         bool_constant<
 521             range_format_kind<R, Char>::value != range_format::disabled &&
 522             range_format_kind<R, Char>::value != range_format::map &&
 523             range_format_kind<R, Char>::value != range_format::string &&
 524             range_format_kind<R, Char>::value != range_format::debug_string>
 525 // Workaround a bug in MSVC 2015 and earlier.
 526 #if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
 527         ,
 528         detail::is_formattable_delayed<R, Char>
 529 #endif
 530         >::value>> {
 531  private:
 532   using range_type = detail::maybe_const_range<R>;
 533   range_formatter<detail::uncvref_type<range_type>, Char> range_formatter_;
 534
 535  public:
 536   using nonlocking = void;
 537
 538   FMT_CONSTEXPR formatter() {
 539     if (detail::const_check(range_format_kind<R, Char>::value !=
 540                             range_format::set))
 541       return;
 542     range_formatter_.set_brackets(detail::string_literal<Char, '{'>{},
 543                                   detail::string_literal<Char, '}'>{});
 544   }
 545
 546   template <typename ParseContext>
 547   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 548     return range_formatter_.parse(ctx);
 549   }
 550
 551   template <typename FormatContext>
 552   auto format(range_type& range, FormatContext& ctx) const
 553       -> decltype(ctx.out()) {
 554     return range_formatter_.format(range, ctx);
 555   }
 556 };
 557
 558 // A map formatter.
 559 template <typename R, typename Char>
 560 struct formatter<
 561     R, Char,
 562     enable_if_t<range_format_kind<R, Char>::value == range_format::map>> {
 563  private:
 564   using map_type = detail::maybe_const_range<R>;
 565   using element_type = detail::uncvref_type<map_type>;
 566
 567   decltype(detail::tuple::get_formatters<element_type, Char>(
 568       detail::tuple_index_sequence<element_type>())) formatters_;
 569   bool no_delimiters_ = false;
 570
 571  public:
 572   FMT_CONSTEXPR formatter() {}
 573
 574   template <typename ParseContext>
 575   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 576     auto it = ctx.begin();
 577     auto end = ctx.end();
 578     if (it != end) {
 579       if (detail::to_ascii(*it) == 'n') {
 580         no_delimiters_ = true;
 581         ++it;
 582       }
 583       if (it != end && *it != '}') {
 584         if (*it != ':') report_error("invalid format specifier");
 585         ++it;
 586       }
 587       ctx.advance_to(it);
 588     }
 589     detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
 590     return it;
 591   }
 592
 593   template <typename FormatContext>
 594   auto format(map_type& map, FormatContext& ctx) const -> decltype(ctx.out()) {
 595     auto out = ctx.out();
 596     basic_string_view<Char> open = detail::string_literal<Char, '{'>{};
 597     if (!no_delimiters_) out = detail::copy<Char>(open, out);
 598     int i = 0;
 599     auto mapper = detail::range_mapper<buffered_context<Char>>();
 600     basic_string_view<Char> sep = detail::string_literal<Char, ',', ' '>{};
 601     for (auto&& value : map) {
 602       if (i > 0) out = detail::copy<Char>(sep, out);
 603       ctx.advance_to(out);
 604       detail::for_each2(formatters_, mapper.map(value),
 605                         detail::format_tuple_element<FormatContext>{
 606                             0, ctx, detail::string_literal<Char, ':', ' '>{}});
 607       ++i;
 608     }
 609     basic_string_view<Char> close = detail::string_literal<Char, '}'>{};
 610     if (!no_delimiters_) out = detail::copy<Char>(close, out);
 611     return out;
 612   }
 613 };
 614
 615 // A (debug_)string formatter.
 616 template <typename R, typename Char>
 617 struct formatter<
 618     R, Char,
 619     enable_if_t<range_format_kind<R, Char>::value == range_format::string ||
 620                 range_format_kind<R, Char>::value ==
 621                     range_format::debug_string>> {
 622  private:
 623   using range_type = detail::maybe_const_range<R>;
 624   using string_type =
 625       conditional_t<std::is_constructible<
 626                         detail::std_string_view<Char>,
 627                         decltype(detail::range_begin(std::declval<R>())),
 628                         decltype(detail::range_end(std::declval<R>()))>::value,
 629                     detail::std_string_view<Char>, std::basic_string<Char>>;
 630
 631   formatter<string_type, Char> underlying_;
 632
 633  public:
 634   template <typename ParseContext>
 635   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 636     return underlying_.parse(ctx);
 637   }
 638
 639   template <typename FormatContext>
 640   auto format(range_type& range, FormatContext& ctx) const
 641       -> decltype(ctx.out()) {
 642     auto out = ctx.out();
 643     if (detail::const_check(range_format_kind<R, Char>::value ==
 644                             range_format::debug_string))
 645       *out++ = '"';
 646     out = underlying_.format(
 647         string_type{detail::range_begin(range), detail::range_end(range)}, ctx);
 648     if (detail::const_check(range_format_kind<R, Char>::value ==
 649                             range_format::debug_string))
 650       *out++ = '"';
 651     return out;
 652   }
 653 };
 654
 655 template <typename It, typename Sentinel, typename Char = char>
 656 struct join_view : detail::view {
 657   It begin;
 658   Sentinel end;
 659   basic_string_view<Char> sep;
 660
 661   join_view(It b, Sentinel e, basic_string_view<Char> s)
 662       : begin(std::move(b)), end(e), sep(s) {}
 663 };
 664
 665 template <typename It, typename Sentinel, typename Char>
 666 struct formatter<join_view<It, Sentinel, Char>, Char> {
 667  private:
 668   using value_type =
 669 #ifdef __cpp_lib_ranges
 670       std::iter_value_t<It>;
 671 #else
 672       typename std::iterator_traits<It>::value_type;
 673 #endif
 674   formatter<remove_cvref_t<value_type>, Char> value_formatter_;
 675
 676   using view_ref = conditional_t<std::is_copy_constructible<It>::value,
 677                                  const join_view<It, Sentinel, Char>&,
 678                                  join_view<It, Sentinel, Char>&&>;
 679
 680  public:
 681   using nonlocking = void;
 682
 683   template <typename ParseContext>
 684   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const Char* {
 685     return value_formatter_.parse(ctx);
 686   }
 687
 688   template <typename FormatContext>
 689   auto format(view_ref& value, FormatContext& ctx) const
 690       -> decltype(ctx.out()) {
 691     auto it = std::forward<view_ref>(value).begin;
 692     auto out = ctx.out();
 693     if (it == value.end) return out;
 694     out = value_formatter_.format(*it, ctx);
 695     ++it;
 696     while (it != value.end) {
 697       out = detail::copy<Char>(value.sep.begin(), value.sep.end(), out);
 698       ctx.advance_to(out);
 699       out = value_formatter_.format(*it, ctx);
 700       ++it;
 701     }
 702     return out;
 703   }
 704 };
 705
 706 /// Returns a view that formats the iterator range `[begin, end)` with elements
 707 /// separated by `sep`.
 708 template <typename It, typename Sentinel>
 709 auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
 710   return {std::move(begin), end, sep};
 711 }
 712
 713 /**
 714  * Returns a view that formats `range` with elements separated by `sep`.
 715  *
 716  * **Example**:
 717  *
 718  *     auto v = std::vector<int>{1, 2, 3};
 719  *     fmt::print("{}", fmt::join(v, ", "));
 720  *     // Output: 1, 2, 3
 721  *
 722  * `fmt::join` applies passed format specifiers to the range elements:
 723  *
 724  *     fmt::print("{:02}", fmt::join(v, ", "));
 725  *     // Output: 01, 02, 03
 726  */
 727 template <typename Range>
 728 auto join(Range&& r, string_view sep)
 729     -> join_view<decltype(detail::range_begin(r)),
 730                  decltype(detail::range_end(r))> {
 731   return {detail::range_begin(r), detail::range_end(r), sep};
 732 }
 733
 734 template <typename Char, typename... T> struct tuple_join_view : detail::view {
 735   const std::tuple<T...>& tuple;
 736   basic_string_view<Char> sep;
 737
 738   tuple_join_view(const std::tuple<T...>& t, basic_string_view<Char> s)
 739       : tuple(t), sep{s} {}
 740 };
 741
 742 // Define FMT_TUPLE_JOIN_SPECIFIERS to enable experimental format specifiers
 743 // support in tuple_join. It is disabled by default because of issues with
 744 // the dynamic width and precision.
 745 #ifndef FMT_TUPLE_JOIN_SPECIFIERS
 746 #  define FMT_TUPLE_JOIN_SPECIFIERS 0
 747 #endif
 748
 749 template <typename Char, typename... T>
 750 struct formatter<tuple_join_view<Char, T...>, Char> {
 751   template <typename ParseContext>
 752   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 753     return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>());
 754   }
 755
 756   template <typename FormatContext>
 757   auto format(const tuple_join_view<Char, T...>& value,
 758               FormatContext& ctx) const -> typename FormatContext::iterator {
 759     return do_format(value, ctx,
 760                      std::integral_constant<size_t, sizeof...(T)>());
 761   }
 762
 763  private:
 764   std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
 765
 766   template <typename ParseContext>
 767   FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
 768                               std::integral_constant<size_t, 0>)
 769       -> decltype(ctx.begin()) {
 770     return ctx.begin();
 771   }
 772
 773   template <typename ParseContext, size_t N>
 774   FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
 775                               std::integral_constant<size_t, N>)
 776       -> decltype(ctx.begin()) {
 777     auto end = ctx.begin();
 778 #if FMT_TUPLE_JOIN_SPECIFIERS
 779     end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);
 780     if (N > 1) {
 781       auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
 782       if (end != end1)
 783         report_error("incompatible format specs for tuple elements");
 784     }
 785 #endif
 786     return end;
 787   }
 788
 789   template <typename FormatContext>
 790   auto do_format(const tuple_join_view<Char, T...>&, FormatContext& ctx,
 791                  std::integral_constant<size_t, 0>) const ->
 792       typename FormatContext::iterator {
 793     return ctx.out();
 794   }
 795
 796   template <typename FormatContext, size_t N>
 797   auto do_format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
 798                  std::integral_constant<size_t, N>) const ->
 799       typename FormatContext::iterator {
 800     auto out = std::get<sizeof...(T) - N>(formatters_)
 801                    .format(std::get<sizeof...(T) - N>(value.tuple), ctx);
 802     if (N <= 1) return out;
 803     out = detail::copy<Char>(value.sep, out);
 804     ctx.advance_to(out);
 805     return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
 806   }
 807 };
 808
 809 namespace detail {
 810 // Check if T has an interface like a container adaptor (e.g. std::stack,
 811 // std::queue, std::priority_queue).
 812 template <typename T> class is_container_adaptor_like {
 813   template <typename U> static auto check(U* p) -> typename U::container_type;
 814   template <typename> static void check(...);
 815
 816  public:
 817   static constexpr const bool value =
 818       !std::is_void<decltype(check<T>(nullptr))>::value;
 819 };
 820
 821 template <typename Container> struct all {
 822   const Container& c;
 823   auto begin() const -> typename Container::const_iterator { return c.begin(); }
 824   auto end() const -> typename Container::const_iterator { return c.end(); }
 825 };
 826 }  // namespace detail
 827
 828 template <typename T, typename Char>
 829 struct formatter<
 830     T, Char,
 831     enable_if_t<conjunction<detail::is_container_adaptor_like<T>,
 832                             bool_constant<range_format_kind<T, Char>::value ==
 833                                           range_format::disabled>>::value>>
 834     : formatter<detail::all<typename T::container_type>, Char> {
 835   using all = detail::all<typename T::container_type>;
 836   template <typename FormatContext>
 837   auto format(const T& t, FormatContext& ctx) const -> decltype(ctx.out()) {
 838     struct getter : T {
 839       static auto get(const T& t) -> all {
 840         return {t.*(&getter::c)};  // Access c through the derived class.
 841       }
 842     };
 843     return formatter<all>::format(getter::get(t), ctx);
 844   }
 845 };
 846
 847 FMT_BEGIN_EXPORT
 848
 849 /**
 850  * Returns an object that formats `std::tuple` with elements separated by `sep`.
 851  *
 852  * **Example**:
 853  *
 854  *     auto t = std::tuple<int, char>{1, 'a'};
 855  *     fmt::print("{}", fmt::join(t, ", "));
 856  *     // Output: 1, a
 857  */
 858 template <typename... T>
 859 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
 860     -> tuple_join_view<char, T...> {
 861   return {tuple, sep};
 862 }
 863
 864 /**
 865  * Returns an object that formats `std::initializer_list` with elements
 866  * separated by `sep`.
 867  *
 868  * **Example**:
 869  *
 870  *     fmt::print("{}", fmt::join({1, 2, 3}, ", "));
 871  *     // Output: "1, 2, 3"
 872  */
 873 template <typename T>
 874 auto join(std::initializer_list<T> list, string_view sep)
 875     -> join_view<const T*, const T*> {
 876   return join(std::begin(list), std::end(list), sep);
 877 }
 878
 879 FMT_END_EXPORT
 880 FMT_END_NAMESPACE
 881
 882 #endif  // FMT_RANGES_H_