ceph/src/fmt/include/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 <type_traits>
  17
  18 #include "format.h"
  19
  20 FMT_BEGIN_NAMESPACE
  21
  22 template <typename Char, typename Enable = void> struct formatting_range {
  23 #ifdef FMT_DEPRECATED_BRACED_RANGES
  24   Char prefix = '{';
  25   Char postfix = '}';
  26 #else
  27   Char prefix = '[';
  28   Char postfix = ']';
  29 #endif
  30
  31   template <typename ParseContext>
  32   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
  33     return ctx.begin();
  34   }
  35 };
  36
  37 template <typename Char, typename Enable = void> struct formatting_tuple {
  38   Char prefix = '(';
  39   Char postfix = ')';
  40
  41   template <typename ParseContext>
  42   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
  43     return ctx.begin();
  44   }
  45 };
  46
  47 namespace detail {
  48
  49 template <typename RangeT, typename OutputIterator>
  50 OutputIterator copy(const RangeT& range, OutputIterator out) {
  51   for (auto it = range.begin(), end = range.end(); it != end; ++it)
  52     *out++ = *it;
  53   return out;
  54 }
  55
  56 template <typename OutputIterator>
  57 OutputIterator copy(const char* str, OutputIterator out) {
  58   while (*str) *out++ = *str++;
  59   return out;
  60 }
  61
  62 template <typename OutputIterator>
  63 OutputIterator copy(char ch, OutputIterator out) {
  64   *out++ = ch;
  65   return out;
  66 }
  67
  68 template <typename OutputIterator>
  69 OutputIterator copy(wchar_t ch, OutputIterator out) {
  70   *out++ = ch;
  71   return out;
  72 }
  73
  74 /// Return true value if T has std::string interface, like std::string_view.
  75 template <typename T> class is_std_string_like {
  76   template <typename U>
  77   static auto check(U* p)
  78       -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
  79   template <typename> static void check(...);
  80
  81  public:
  82   static FMT_CONSTEXPR_DECL const bool value =
  83       is_string<T>::value || !std::is_void<decltype(check<T>(nullptr))>::value;
  84 };
  85
  86 template <typename Char>
  87 struct is_std_string_like<fmt::basic_string_view<Char>> : std::true_type {};
  88
  89 template <typename... Ts> struct conditional_helper {};
  90
  91 template <typename T, typename _ = void> struct is_range_ : std::false_type {};
  92
  93 #if !FMT_MSC_VER || FMT_MSC_VER > 1800
  94
  95 #  define FMT_DECLTYPE_RETURN(val)  \
  96     ->decltype(val) { return val; } \
  97     static_assert(                  \
  98         true, "")  // This makes it so that a semicolon is required after the
  99                    // macro, which helps clang-format handle the formatting.
 100
 101 // C array overload
 102 template <typename T, std::size_t N>
 103 auto range_begin(const T (&arr)[N]) -> const T* {
 104   return arr;
 105 }
 106 template <typename T, std::size_t N>
 107 auto range_end(const T (&arr)[N]) -> const T* {
 108   return arr + N;
 109 }
 110
 111 template <typename T, typename Enable = void>
 112 struct has_member_fn_begin_end_t : std::false_type {};
 113
 114 template <typename T>
 115 struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
 116                                            decltype(std::declval<T>().end())>>
 117     : std::true_type {};
 118
 119 // Member function overload
 120 template <typename T>
 121 auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
 122 template <typename T>
 123 auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
 124
 125 // ADL overload. Only participates in overload resolution if member functions
 126 // are not found.
 127 template <typename T>
 128 auto range_begin(T&& rng)
 129     -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
 130                    decltype(begin(static_cast<T&&>(rng)))> {
 131   return begin(static_cast<T&&>(rng));
 132 }
 133 template <typename T>
 134 auto range_end(T&& rng) -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
 135                                        decltype(end(static_cast<T&&>(rng)))> {
 136   return end(static_cast<T&&>(rng));
 137 }
 138
 139 template <typename T, typename Enable = void>
 140 struct has_const_begin_end : std::false_type {};
 141 template <typename T, typename Enable = void>
 142 struct has_mutable_begin_end : std::false_type {};
 143
 144 template <typename T>
 145 struct has_const_begin_end<
 146     T, void_t<decltype(detail::range_begin(
 147                   std::declval<const remove_cvref_t<T>&>())),
 148               decltype(detail::range_begin(
 149                   std::declval<const remove_cvref_t<T>&>()))>>
 150     : std::true_type {};
 151
 152 template <typename T>
 153 struct has_mutable_begin_end<
 154     T, void_t<decltype(detail::range_begin(std::declval<T>())),
 155               decltype(detail::range_begin(std::declval<T>())),
 156               enable_if_t<std::is_copy_constructible<T>::value>>>
 157     : std::true_type {};
 158
 159 template <typename T>
 160 struct is_range_<T, void>
 161     : std::integral_constant<bool, (has_const_begin_end<T>::value ||
 162                                     has_mutable_begin_end<T>::value)> {};
 163
 164 template <typename T, typename Enable = void> struct range_to_view;
 165 template <typename T>
 166 struct range_to_view<T, enable_if_t<has_const_begin_end<T>::value>> {
 167   struct view_t {
 168     const T* m_range_ptr;
 169
 170     auto begin() const FMT_DECLTYPE_RETURN(detail::range_begin(*m_range_ptr));
 171     auto end() const FMT_DECLTYPE_RETURN(detail::range_end(*m_range_ptr));
 172   };
 173   static auto view(const T& range) -> view_t { return {&range}; }
 174 };
 175
 176 template <typename T>
 177 struct range_to_view<T, enable_if_t<!has_const_begin_end<T>::value &&
 178                                     has_mutable_begin_end<T>::value>> {
 179   struct view_t {
 180     T m_range_copy;
 181
 182     auto begin() FMT_DECLTYPE_RETURN(detail::range_begin(m_range_copy));
 183     auto end() FMT_DECLTYPE_RETURN(detail::range_end(m_range_copy));
 184   };
 185   static auto view(const T& range) -> view_t { return {range}; }
 186 };
 187 #  undef FMT_DECLTYPE_RETURN
 188 #endif
 189
 190 /// tuple_size and tuple_element check.
 191 template <typename T> class is_tuple_like_ {
 192   template <typename U>
 193   static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
 194   template <typename> static void check(...);
 195
 196  public:
 197   static FMT_CONSTEXPR_DECL const bool value =
 198       !std::is_void<decltype(check<T>(nullptr))>::value;
 199 };
 200
 201 // Check for integer_sequence
 202 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
 203 template <typename T, T... N>
 204 using integer_sequence = std::integer_sequence<T, N...>;
 205 template <size_t... N> using index_sequence = std::index_sequence<N...>;
 206 template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
 207 #else
 208 template <typename T, T... N> struct integer_sequence {
 209   using value_type = T;
 210
 211   static FMT_CONSTEXPR size_t size() { return sizeof...(N); }
 212 };
 213
 214 template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
 215
 216 template <typename T, size_t N, T... Ns>
 217 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
 218 template <typename T, T... Ns>
 219 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
 220
 221 template <size_t N>
 222 using make_index_sequence = make_integer_sequence<size_t, N>;
 223 #endif
 224
 225 template <class Tuple, class F, size_t... Is>
 226 void for_each(index_sequence<Is...>, Tuple&& tup, F&& f) FMT_NOEXCEPT {
 227   using std::get;
 228   // using free function get<I>(T) now.
 229   const int _[] = {0, ((void)f(get<Is>(tup)), 0)...};
 230   (void)_;  // blocks warnings
 231 }
 232
 233 template <class T>
 234 FMT_CONSTEXPR make_index_sequence<std::tuple_size<T>::value> get_indexes(
 235     T const&) {
 236   return {};
 237 }
 238
 239 template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
 240   const auto indexes = get_indexes(tup);
 241   for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
 242 }
 243
 244 template <typename Range>
 245 using value_type =
 246     remove_cvref_t<decltype(*detail::range_begin(std::declval<Range>()))>;
 247
 248 template <typename OutputIt> OutputIt write_delimiter(OutputIt out) {
 249   *out++ = ',';
 250   *out++ = ' ';
 251   return out;
 252 }
 253
 254 template <
 255     typename Char, typename OutputIt, typename Arg,
 256     FMT_ENABLE_IF(is_std_string_like<typename std::decay<Arg>::type>::value)>
 257 OutputIt write_range_entry(OutputIt out, const Arg& v) {
 258   *out++ = '"';
 259   out = write<Char>(out, v);
 260   *out++ = '"';
 261   return out;
 262 }
 263
 264 template <typename Char, typename OutputIt, typename Arg,
 265           FMT_ENABLE_IF(std::is_same<Arg, Char>::value)>
 266 OutputIt write_range_entry(OutputIt out, const Arg v) {
 267   *out++ = '\'';
 268   *out++ = v;
 269   *out++ = '\'';
 270   return out;
 271 }
 272
 273 template <
 274     typename Char, typename OutputIt, typename Arg,
 275     FMT_ENABLE_IF(!is_std_string_like<typename std::decay<Arg>::type>::value &&
 276                   !std::is_same<Arg, Char>::value)>
 277 OutputIt write_range_entry(OutputIt out, const Arg& v) {
 278   return write<Char>(out, v);
 279 }
 280
 281 }  // namespace detail
 282
 283 template <typename T> struct is_tuple_like {
 284   static FMT_CONSTEXPR_DECL const bool value =
 285       detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
 286 };
 287
 288 template <typename TupleT, typename Char>
 289 struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
 290  private:
 291   // C++11 generic lambda for format()
 292   template <typename FormatContext> struct format_each {
 293     template <typename T> void operator()(const T& v) {
 294       if (i > 0) out = detail::write_delimiter(out);
 295       out = detail::write_range_entry<Char>(out, v);
 296       ++i;
 297     }
 298     formatting_tuple<Char>& formatting;
 299     size_t& i;
 300     typename std::add_lvalue_reference<
 301         decltype(std::declval<FormatContext>().out())>::type out;
 302   };
 303
 304  public:
 305   formatting_tuple<Char> formatting;
 306
 307   template <typename ParseContext>
 308   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 309     return formatting.parse(ctx);
 310   }
 311
 312   template <typename FormatContext = format_context>
 313   auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
 314     auto out = ctx.out();
 315     size_t i = 0;
 316
 317     detail::copy(formatting.prefix, out);
 318     detail::for_each(values, format_each<FormatContext>{formatting, i, out});
 319     detail::copy(formatting.postfix, out);
 320
 321     return ctx.out();
 322   }
 323 };
 324
 325 template <typename T, typename Char> struct is_range {
 326   static FMT_CONSTEXPR_DECL const bool value =
 327       detail::is_range_<T>::value && !detail::is_std_string_like<T>::value &&
 328       !std::is_convertible<T, std::basic_string<Char>>::value &&
 329       !std::is_constructible<detail::std_string_view<Char>, T>::value;
 330 };
 331
 332 template <typename T, typename Char>
 333 struct formatter<
 334     T, Char,
 335     enable_if_t<
 336         fmt::is_range<T, Char>::value
 337 // Workaround a bug in MSVC 2017 and earlier.
 338 #if !FMT_MSC_VER || FMT_MSC_VER >= 1927
 339         && (has_formatter<detail::value_type<T>, format_context>::value ||
 340             detail::has_fallback_formatter<detail::value_type<T>, Char>::value)
 341 #endif
 342         >> {
 343   formatting_range<Char> formatting;
 344
 345   template <typename ParseContext>
 346   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 347     return formatting.parse(ctx);
 348   }
 349
 350   template <typename FormatContext>
 351   typename FormatContext::iterator format(const T& values, FormatContext& ctx) {
 352     auto out = detail::copy(formatting.prefix, ctx.out());
 353     size_t i = 0;
 354     auto view = detail::range_to_view<T>::view(values);
 355     auto it = view.begin();
 356     auto end = view.end();
 357     for (; it != end; ++it) {
 358       if (i > 0) out = detail::write_delimiter(out);
 359       out = detail::write_range_entry<Char>(out, *it);
 360       ++i;
 361     }
 362     return detail::copy(formatting.postfix, out);
 363   }
 364 };
 365
 366 template <typename Char, typename... T> struct tuple_join_view : detail::view {
 367   const std::tuple<T...>& tuple;
 368   basic_string_view<Char> sep;
 369
 370   tuple_join_view(const std::tuple<T...>& t, basic_string_view<Char> s)
 371       : tuple(t), sep{s} {}
 372 };
 373
 374 template <typename Char, typename... T>
 375 using tuple_arg_join = tuple_join_view<Char, T...>;
 376
 377 template <typename Char, typename... T>
 378 struct formatter<tuple_join_view<Char, T...>, Char> {
 379   template <typename ParseContext>
 380   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 381     return ctx.begin();
 382   }
 383
 384   template <typename FormatContext>
 385   auto format(const tuple_join_view<Char, T...>& value, FormatContext& ctx) ->
 386       typename FormatContext::iterator {
 387     return format(value, ctx, detail::make_index_sequence<sizeof...(T)>{});
 388   }
 389
 390  private:
 391   template <typename FormatContext, size_t... N>
 392   auto format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
 393               detail::index_sequence<N...>) ->
 394       typename FormatContext::iterator {
 395     return format_args(value, ctx, std::get<N>(value.tuple)...);
 396   }
 397
 398   template <typename FormatContext>
 399   auto format_args(const tuple_join_view<Char, T...>&, FormatContext& ctx) ->
 400       typename FormatContext::iterator {
 401     // NOTE: for compilers that support C++17, this empty function instantiation
 402     // can be replaced with a constexpr branch in the variadic overload.
 403     return ctx.out();
 404   }
 405
 406   template <typename FormatContext, typename Arg, typename... Args>
 407   auto format_args(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
 408                    const Arg& arg, const Args&... args) ->
 409       typename FormatContext::iterator {
 410     using base = formatter<typename std::decay<Arg>::type, Char>;
 411     auto out = base().format(arg, ctx);
 412     if (sizeof...(Args) > 0) {
 413       out = std::copy(value.sep.begin(), value.sep.end(), out);
 414       ctx.advance_to(out);
 415       return format_args(value, ctx, args...);
 416     }
 417     return out;
 418   }
 419 };
 420
 421 FMT_MODULE_EXPORT_BEGIN
 422
 423 /**
 424   \rst
 425   Returns an object that formats `tuple` with elements separated by `sep`.
 426
 427   **Example**::
 428
 429     std::tuple<int, char> t = {1, 'a'};
 430     fmt::print("{}", fmt::join(t, ", "));
 431     // Output: "1, a"
 432   \endrst
 433  */
 434 template <typename... T>
 435 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
 436     -> tuple_join_view<char, T...> {
 437   return {tuple, sep};
 438 }
 439
 440 template <typename... T>
 441 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple,
 442                         basic_string_view<wchar_t> sep)
 443     -> tuple_join_view<wchar_t, T...> {
 444   return {tuple, sep};
 445 }
 446
 447 /**
 448   \rst
 449   Returns an object that formats `initializer_list` with elements separated by
 450   `sep`.
 451
 452   **Example**::
 453
 454     fmt::print("{}", fmt::join({1, 2, 3}, ", "));
 455     // Output: "1, 2, 3"
 456   \endrst
 457  */
 458 template <typename T>
 459 auto join(std::initializer_list<T> list, string_view sep)
 460     -> join_view<const T*, const T*> {
 461   return join(std::begin(list), std::end(list), sep);
 462 }
 463
 464 FMT_MODULE_EXPORT_END
 465 FMT_END_NAMESPACE
 466
 467 #endif  // FMT_RANGES_H_