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 <type_traits>
  16 #include "format.h"
  17
  18 // output only up to N items from the range.
  19 #ifndef FMT_RANGE_OUTPUT_LENGTH_LIMIT
  20 #  define FMT_RANGE_OUTPUT_LENGTH_LIMIT 256
  21 #endif
  22
  23 FMT_BEGIN_NAMESPACE
  24
  25 template <typename Char> struct formatting_base {
  26   template <typename ParseContext>
  27   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
  28     return ctx.begin();
  29   }
  30 };
  31
  32 template <typename Char, typename Enable = void>
  33 struct formatting_range : formatting_base<Char> {
  34   static FMT_CONSTEXPR_DECL const std::size_t range_length_limit =
  35       FMT_RANGE_OUTPUT_LENGTH_LIMIT;  // output only up to N items from the
  36                                       // range.
  37   Char prefix;
  38   Char delimiter;
  39   Char postfix;
  40   formatting_range() : prefix('{'), delimiter(','), postfix('}') {}
  41   static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
  42   static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
  43 };
  44
  45 template <typename Char, typename Enable = void>
  46 struct formatting_tuple : formatting_base<Char> {
  47   Char prefix;
  48   Char delimiter;
  49   Char postfix;
  50   formatting_tuple() : prefix('('), delimiter(','), postfix(')') {}
  51   static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
  52   static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
  53 };
  54
  55 namespace internal {
  56
  57 template <typename RangeT, typename OutputIterator>
  58 OutputIterator copy(const RangeT& range, OutputIterator out) {
  59   for (auto it = range.begin(), end = range.end(); it != end; ++it)
  60     *out++ = *it;
  61   return out;
  62 }
  63
  64 template <typename OutputIterator>
  65 OutputIterator copy(const char* str, OutputIterator out) {
  66   while (*str) *out++ = *str++;
  67   return out;
  68 }
  69
  70 template <typename OutputIterator>
  71 OutputIterator copy(char ch, OutputIterator out) {
  72   *out++ = ch;
  73   return out;
  74 }
  75
  76 /// Return true value if T has std::string interface, like std::string_view.
  77 template <typename T> class is_like_std_string {
  78   template <typename U>
  79   static auto check(U* p)
  80       -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
  81   template <typename> static void check(...);
  82
  83  public:
  84   static FMT_CONSTEXPR_DECL const bool value =
  85       !std::is_void<decltype(check<T>(FMT_NULL))>::value;
  86 };
  87
  88 template <typename Char>
  89 struct is_like_std_string<fmt::basic_string_view<Char>> : std::true_type {};
  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_VER || FMT_MSC_VER > 1800
  96 template <typename T>
  97 struct is_range_<
  98     T, typename std::conditional<
  99            false,
 100            conditional_helper<decltype(internal::declval<T>().begin()),
 101                               decltype(internal::declval<T>().end())>,
 102            void>::type> : std::true_type {};
 103 #endif
 104
 105 /// tuple_size and tuple_element check.
 106 template <typename T> class is_tuple_like_ {
 107   template <typename U>
 108   static auto check(U* p) -> decltype(
 109       std::tuple_size<U>::value,
 110       (void)internal::declval<typename std::tuple_element<0, U>::type>(),
 111       int());
 112   template <typename> static void check(...);
 113
 114  public:
 115   static FMT_CONSTEXPR_DECL const bool value =
 116       !std::is_void<decltype(check<T>(FMT_NULL))>::value;
 117 };
 118
 119 // Check for integer_sequence
 120 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
 121 template <typename T, T... N>
 122 using integer_sequence = std::integer_sequence<T, N...>;
 123 template <std::size_t... N> using index_sequence = std::index_sequence<N...>;
 124 template <std::size_t N>
 125 using make_index_sequence = std::make_index_sequence<N>;
 126 #else
 127 template <typename T, T... N> struct integer_sequence {
 128   typedef T value_type;
 129
 130   static FMT_CONSTEXPR std::size_t size() { return sizeof...(N); }
 131 };
 132
 133 template <std::size_t... N>
 134 using index_sequence = integer_sequence<std::size_t, N...>;
 135
 136 template <typename T, std::size_t N, T... Ns>
 137 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
 138 template <typename T, T... Ns>
 139 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
 140
 141 template <std::size_t N>
 142 using make_index_sequence = make_integer_sequence<std::size_t, N>;
 143 #endif
 144
 145 template <class Tuple, class F, size_t... Is>
 146 void for_each(index_sequence<Is...>, Tuple&& tup, F&& f) FMT_NOEXCEPT {
 147   using std::get;
 148   // using free function get<I>(T) now.
 149   const int _[] = {0, ((void)f(get<Is>(tup)), 0)...};
 150   (void)_;  // blocks warnings
 151 }
 152
 153 template <class T>
 154 FMT_CONSTEXPR make_index_sequence<std::tuple_size<T>::value> get_indexes(
 155     T const&) {
 156   return {};
 157 }
 158
 159 template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
 160   const auto indexes = get_indexes(tup);
 161   for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
 162 }
 163
 164 template <typename Arg, FMT_ENABLE_IF(!is_like_std_string<
 165                                       typename std::decay<Arg>::type>::value)>
 166 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
 167   return add_space ? " {}" : "{}";
 168 }
 169
 170 template <typename Arg, FMT_ENABLE_IF(is_like_std_string<
 171                                       typename std::decay<Arg>::type>::value)>
 172 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
 173   return add_space ? " \"{}\"" : "\"{}\"";
 174 }
 175
 176 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char*) {
 177   return add_space ? " \"{}\"" : "\"{}\"";
 178 }
 179 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t*) {
 180   return add_space ? L" \"{}\"" : L"\"{}\"";
 181 }
 182
 183 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char) {
 184   return add_space ? " '{}'" : "'{}'";
 185 }
 186 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
 187   return add_space ? L" '{}'" : L"'{}'";
 188 }
 189
 190 }  // namespace internal
 191
 192 template <typename T> struct is_tuple_like {
 193   static FMT_CONSTEXPR_DECL const bool value =
 194       internal::is_tuple_like_<T>::value && !internal::is_range_<T>::value;
 195 };
 196
 197 template <typename TupleT, typename Char>
 198 struct formatter<
 199     TupleT, Char,
 200     typename std::enable_if<fmt::is_tuple_like<TupleT>::value>::type> {
 201  private:
 202   // C++11 generic lambda for format()
 203   template <typename FormatContext> struct format_each {
 204     template <typename T> void operator()(const T& v) {
 205       if (i > 0) {
 206         if (formatting.add_prepostfix_space) {
 207           *out++ = ' ';
 208         }
 209         out = internal::copy(formatting.delimiter, out);
 210       }
 211       out = format_to(out,
 212                       internal::format_str_quoted(
 213                           (formatting.add_delimiter_spaces && i > 0), v),
 214                       v);
 215       ++i;
 216     }
 217
 218     formatting_tuple<Char>& formatting;
 219     std::size_t& i;
 220     typename std::add_lvalue_reference<decltype(
 221         std::declval<FormatContext>().out())>::type out;
 222   };
 223
 224  public:
 225   formatting_tuple<Char> formatting;
 226
 227   template <typename ParseContext>
 228   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 229     return formatting.parse(ctx);
 230   }
 231
 232   template <typename FormatContext = format_context>
 233   auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
 234     auto out = ctx.out();
 235     std::size_t i = 0;
 236     internal::copy(formatting.prefix, out);
 237
 238     internal::for_each(values, format_each<FormatContext>{formatting, i, out});
 239     if (formatting.add_prepostfix_space) {
 240       *out++ = ' ';
 241     }
 242     internal::copy(formatting.postfix, out);
 243
 244     return ctx.out();
 245   }
 246 };
 247
 248 template <typename T> struct is_range {
 249   static FMT_CONSTEXPR_DECL const bool value =
 250       internal::is_range_<T>::value && !internal::is_like_std_string<T>::value;
 251 };
 252
 253 template <typename RangeT, typename Char>
 254 struct formatter<RangeT, Char,
 255                  typename std::enable_if<fmt::is_range<RangeT>::value>::type> {
 256   formatting_range<Char> formatting;
 257
 258   template <typename ParseContext>
 259   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
 260     return formatting.parse(ctx);
 261   }
 262
 263   template <typename FormatContext>
 264   typename FormatContext::iterator format(const RangeT& values,
 265                                           FormatContext& ctx) {
 266     auto out = internal::copy(formatting.prefix, ctx.out());
 267     std::size_t i = 0;
 268     for (auto it = values.begin(), end = values.end(); it != end; ++it) {
 269       if (i > 0) {
 270         if (formatting.add_prepostfix_space) *out++ = ' ';
 271         out = internal::copy(formatting.delimiter, out);
 272       }
 273       out = format_to(out,
 274                       internal::format_str_quoted(
 275                           (formatting.add_delimiter_spaces && i > 0), *it),
 276                       *it);
 277       if (++i > formatting.range_length_limit) {
 278         out = format_to(out, " ... <other elements>");
 279         break;
 280       }
 281     }
 282     if (formatting.add_prepostfix_space) *out++ = ' ';
 283     return internal::copy(formatting.postfix, out);
 284   }
 285 };
 286
 287 FMT_END_NAMESPACE
 288
 289 #endif  // FMT_RANGES_H_