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 // output only up to N items from the range.
21 #ifndef FMT_RANGE_OUTPUT_LENGTH_LIMIT
22 #  define FMT_RANGE_OUTPUT_LENGTH_LIMIT 256
23 #endif
24 
25 FMT_BEGIN_NAMESPACE
26 
27 template <typename Char> struct formatting_base {
28   template <typename ParseContext>
29   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
30     return ctx.begin();
31   }
32 };
33 
34 template <typename Char, typename Enable = void>
35 struct formatting_range : formatting_base<Char> {
36   static FMT_CONSTEXPR_DECL const std::size_t range_length_limit =
37       FMT_RANGE_OUTPUT_LENGTH_LIMIT;  // output only up to N items from the
38                                       // range.
39   Char prefix;
40   Char delimiter;
41   Char postfix;
formatting_rangeformatting_range42   formatting_range() : prefix('{'), delimiter(','), postfix('}') {}
43   static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
44   static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
45 };
46 
47 template <typename Char, typename Enable = void>
48 struct formatting_tuple : formatting_base<Char> {
49   Char prefix;
50   Char delimiter;
51   Char postfix;
formatting_tupleformatting_tuple52   formatting_tuple() : prefix('('), delimiter(','), postfix(')') {}
53   static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
54   static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
55 };
56 
57 namespace internal {
58 
59 template <typename RangeT, typename OutputIterator>
copy(const RangeT & range,OutputIterator out)60 OutputIterator copy(const RangeT& range, OutputIterator out) {
61   for (auto it = range.begin(), end = range.end(); it != end; ++it)
62     *out++ = *it;
63   return out;
64 }
65 
66 template <typename OutputIterator>
copy(const char * str,OutputIterator out)67 OutputIterator copy(const char* str, OutputIterator out) {
68   while (*str) *out++ = *str++;
69   return out;
70 }
71 
72 template <typename OutputIterator>
copy(char ch,OutputIterator out)73 OutputIterator copy(char ch, OutputIterator out) {
74   *out++ = ch;
75   return out;
76 }
77 
78 /// Return true value if T has std::string interface, like std::string_view.
79 template <typename T> class is_like_std_string {
80   template <typename U>
81   static auto check(U* p)
82       -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
83   template <typename> static void check(...);
84 
85  public:
86   static FMT_CONSTEXPR_DECL const bool value =
87       is_string<T>::value || !std::is_void<decltype(check<T>(nullptr))>::value;
88 };
89 
90 template <typename Char>
91 struct is_like_std_string<fmt::basic_string_view<Char>> : std::true_type {};
92 
93 template <typename... Ts> struct conditional_helper {};
94 
95 template <typename T, typename _ = void> struct is_range_ : std::false_type {};
96 
97 #if !FMT_MSC_VER || FMT_MSC_VER > 1800
98 template <typename T>
99 struct is_range_<
100     T, conditional_t<false,
101                      conditional_helper<decltype(std::declval<T>().begin()),
102                                         decltype(std::declval<T>().end())>,
103                      void>> : std::true_type {};
104 #endif
105 
106 /// tuple_size and tuple_element check.
107 template <typename T> class is_tuple_like_ {
108   template <typename U>
109   static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
110   template <typename> static void check(...);
111 
112  public:
113   static FMT_CONSTEXPR_DECL const bool value =
114       !std::is_void<decltype(check<T>(nullptr))>::value;
115 };
116 
117 // Check for integer_sequence
118 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
119 template <typename T, T... N>
120 using integer_sequence = std::integer_sequence<T, N...>;
121 template <std::size_t... N> using index_sequence = std::index_sequence<N...>;
122 template <std::size_t N>
123 using make_index_sequence = std::make_index_sequence<N>;
124 #else
125 template <typename T, T... N> struct integer_sequence {
126   using value_type = T;
127 
128   static FMT_CONSTEXPR std::size_t size() { return sizeof...(N); }
129 };
130 
131 template <std::size_t... N>
132 using index_sequence = integer_sequence<std::size_t, N...>;
133 
134 template <typename T, std::size_t N, T... Ns>
135 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
136 template <typename T, T... Ns>
137 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
138 
139 template <std::size_t N>
140 using make_index_sequence = make_integer_sequence<std::size_t, N>;
141 #endif
142 
143 template <class Tuple, class F, size_t... Is>
144 void for_each(index_sequence<Is...>, Tuple&& tup, F&& f) FMT_NOEXCEPT {
145   using std::get;
146   // using free function get<I>(T) now.
147   const int _[] = {0, ((void)f(get<Is>(tup)), 0)...};
148   (void)_;  // blocks warnings
149 }
150 
151 template <class T>
152 FMT_CONSTEXPR make_index_sequence<std::tuple_size<T>::value> get_indexes(
153     T const&) {
154   return {};
155 }
156 
157 template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
158   const auto indexes = get_indexes(tup);
159   for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
160 }
161 
162 template <typename Arg, FMT_ENABLE_IF(!is_like_std_string<
163                                       typename std::decay<Arg>::type>::value)>
164 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
165   return add_space ? " {}" : "{}";
166 }
167 
168 template <typename Arg, FMT_ENABLE_IF(is_like_std_string<
169                                       typename std::decay<Arg>::type>::value)>
170 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
171   return add_space ? " \"{}\"" : "\"{}\"";
172 }
173 
174 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char*) {
175   return add_space ? " \"{}\"" : "\"{}\"";
176 }
177 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t*) {
178   return add_space ? L" \"{}\"" : L"\"{}\"";
179 }
180 
181 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char) {
182   return add_space ? " '{}'" : "'{}'";
183 }
184 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
185   return add_space ? L" '{}'" : L"'{}'";
186 }
187 
188 }  // namespace internal
189 
190 template <typename T> struct is_tuple_like {
191   static FMT_CONSTEXPR_DECL const bool value =
192       internal::is_tuple_like_<T>::value && !internal::is_range_<T>::value;
193 };
194 
195 template <typename TupleT, typename Char>
196 struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
197  private:
198   // C++11 generic lambda for format()
199   template <typename FormatContext> struct format_each {
200     template <typename T> void operator()(const T& v) {
201       if (i > 0) {
202         if (formatting.add_prepostfix_space) {
203           *out++ = ' ';
204         }
205         out = internal::copy(formatting.delimiter, out);
206       }
207       out = format_to(out,
208                       internal::format_str_quoted(
209                           (formatting.add_delimiter_spaces && i > 0), v),
210                       v);
211       ++i;
212     }
213 
214     formatting_tuple<Char>& formatting;
215     std::size_t& i;
216     typename std::add_lvalue_reference<decltype(
217         std::declval<FormatContext>().out())>::type out;
218   };
219 
220  public:
221   formatting_tuple<Char> formatting;
222 
223   template <typename ParseContext>
224   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
225     return formatting.parse(ctx);
226   }
227 
228   template <typename FormatContext = format_context>
229   auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
230     auto out = ctx.out();
231     std::size_t i = 0;
232     internal::copy(formatting.prefix, out);
233 
234     internal::for_each(values, format_each<FormatContext>{formatting, i, out});
235     if (formatting.add_prepostfix_space) {
236       *out++ = ' ';
237     }
238     internal::copy(formatting.postfix, out);
239 
240     return ctx.out();
241   }
242 };
243 
244 template <typename T, typename Char> struct is_range {
245   static FMT_CONSTEXPR_DECL const bool value =
246       internal::is_range_<T>::value &&
247       !internal::is_like_std_string<T>::value &&
248       !std::is_convertible<T, std::basic_string<Char>>::value &&
249       !std::is_constructible<internal::std_string_view<Char>, T>::value;
250 };
251 
252 template <typename RangeT, typename Char>
253 struct formatter<RangeT, Char,
254                  enable_if_t<fmt::is_range<RangeT, Char>::value>> {
255   formatting_range<Char> formatting;
256 
257   template <typename ParseContext>
258   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
259     return formatting.parse(ctx);
260   }
261 
262   template <typename FormatContext>
263   typename FormatContext::iterator format(const RangeT& values,
264                                           FormatContext& ctx) {
265     auto out = internal::copy(formatting.prefix, ctx.out());
266     std::size_t i = 0;
267     for (auto it = values.begin(), end = values.end(); it != end; ++it) {
268       if (i > 0) {
269         if (formatting.add_prepostfix_space) *out++ = ' ';
270         out = internal::copy(formatting.delimiter, out);
271       }
272       out = format_to(out,
273                       internal::format_str_quoted(
274                           (formatting.add_delimiter_spaces && i > 0), *it),
275                       *it);
276       if (++i > formatting.range_length_limit) {
277         out = format_to(out, " ... <other elements>");
278         break;
279       }
280     }
281     if (formatting.add_prepostfix_space) *out++ = ' ';
282     return internal::copy(formatting.postfix, out);
283   }
284 };
285 
286 template <typename Char, typename... T> struct tuple_arg_join : internal::view {
287   const std::tuple<T...>& tuple;
288   basic_string_view<Char> sep;
289 
290   tuple_arg_join(const std::tuple<T...>& t, basic_string_view<Char> s)
291       : tuple{t}, sep{s} {}
292 };
293 
294 template <typename Char, typename... T>
295 struct formatter<tuple_arg_join<Char, T...>, Char> {
296   template <typename ParseContext>
297   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
298     return ctx.begin();
299   }
300 
301   template <typename FormatContext>
302   typename FormatContext::iterator format(
303       const tuple_arg_join<Char, T...>& value, FormatContext& ctx) {
304     return format(value, ctx, internal::make_index_sequence<sizeof...(T)>{});
305   }
306 
307  private:
308   template <typename FormatContext, size_t... N>
309   typename FormatContext::iterator format(
310       const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
311       internal::index_sequence<N...>) {
312     return format_args(value, ctx, std::get<N>(value.tuple)...);
313   }
314 
315   template <typename FormatContext>
316   typename FormatContext::iterator format_args(
317       const tuple_arg_join<Char, T...>&, FormatContext& ctx) {
318     // NOTE: for compilers that support C++17, this empty function instantiation
319     // can be replaced with a constexpr branch in the variadic overload.
320     return ctx.out();
321   }
322 
323   template <typename FormatContext, typename Arg, typename... Args>
324   typename FormatContext::iterator format_args(
325       const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
326       const Arg& arg, const Args&... args) {
327     using base = formatter<typename std::decay<Arg>::type, Char>;
328     auto out = ctx.out();
329     out = base{}.format(arg, ctx);
330     if (sizeof...(Args) > 0) {
331       out = std::copy(value.sep.begin(), value.sep.end(), out);
332       ctx.advance_to(out);
333       return format_args(value, ctx, args...);
334     }
335     return out;
336   }
337 };
338 
339 /**
340   \rst
341   Returns an object that formats `tuple` with elements separated by `sep`.
342 
343   **Example**::
344 
345     std::tuple<int, char> t = {1, 'a'};
346     fmt::print("{}", fmt::join(t, ", "));
347     // Output: "1, a"
348   \endrst
349  */
350 template <typename... T>
351 FMT_CONSTEXPR tuple_arg_join<char, T...> join(const std::tuple<T...>& tuple,
352                                               string_view sep) {
353   return {tuple, sep};
354 }
355 
356 template <typename... T>
357 FMT_CONSTEXPR tuple_arg_join<wchar_t, T...> join(const std::tuple<T...>& tuple,
358                                                  wstring_view sep) {
359   return {tuple, sep};
360 }
361 
362 /**
363   \rst
364   Returns an object that formats `initializer_list` with elements separated by
365   `sep`.
366 
367   **Example**::
368 
369     fmt::print("{}", fmt::join({1, 2, 3}, ", "));
370     // Output: "1, 2, 3"
371   \endrst
372  */
373 template <typename T>
374 arg_join<internal::iterator_t<const std::initializer_list<T>>, char> join(
375     std::initializer_list<T> list, string_view sep) {
376   return join(std::begin(list), std::end(list), sep);
377 }
378 
379 template <typename T>
380 arg_join<internal::iterator_t<const std::initializer_list<T>>, wchar_t> join(
381     std::initializer_list<T> list, wstring_view sep) {
382   return join(std::begin(list), std::end(list), sep);
383 }
384 
385 FMT_END_NAMESPACE
386 
387 #endif  // FMT_RANGES_H_
388