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 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 postfix = '}';
41 };
42
43 template <typename Char, typename Enable = void>
44 struct formatting_tuple : formatting_base<Char> {
45 Char prefix = '(';
46 Char postfix = ')';
47 };
48
49 namespace detail {
50
51 template <typename RangeT, typename OutputIterator>
copy(const RangeT & range,OutputIterator out)52 OutputIterator copy(const RangeT& range, OutputIterator out) {
53 for (auto it = range.begin(), end = range.end(); it != end; ++it)
54 *out++ = *it;
55 return out;
56 }
57
58 template <typename OutputIterator>
copy(const char * str,OutputIterator out)59 OutputIterator copy(const char* str, OutputIterator out) {
60 while (*str) *out++ = *str++;
61 return out;
62 }
63
64 template <typename OutputIterator>
copy(char ch,OutputIterator out)65 OutputIterator copy(char ch, OutputIterator out) {
66 *out++ = ch;
67 return out;
68 }
69
70 /// Return true value if T has std::string interface, like std::string_view.
71 template <typename T> class is_like_std_string {
72 template <typename U>
73 static auto check(U* p)
74 -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
75 template <typename> static void check(...);
76
77 public:
78 static FMT_CONSTEXPR_DECL const bool value =
79 is_string<T>::value || !std::is_void<decltype(check<T>(nullptr))>::value;
80 };
81
82 template <typename Char>
83 struct is_like_std_string<axom::fmt::basic_string_view<Char>> : std::true_type {};
84
85 template <typename... Ts> struct conditional_helper {};
86
87 template <typename T, typename _ = void> struct is_range_ : std::false_type {};
88
89 #if !FMT_MSC_VER || FMT_MSC_VER > 1800
90
91 # define FMT_DECLTYPE_RETURN(val) \
92 ->decltype(val) { return val; } \
93 static_assert( \
94 true, "") // This makes it so that a semicolon is required after the
95 // macro, which helps clang-format handle the formatting.
96
97 // C array overload
98 template <typename T, std::size_t N>
99 auto range_begin(const T (&arr)[N]) -> const T* {
100 return arr;
101 }
102 template <typename T, std::size_t N>
103 auto range_end(const T (&arr)[N]) -> const T* {
104 return arr + N;
105 }
106
107 template <typename T, typename Enable = void>
108 struct has_member_fn_begin_end_t : std::false_type {};
109
110 template <typename T>
111 struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
112 decltype(std::declval<T>().end())>>
113 : std::true_type {};
114
115 // Member function overload
116 template <typename T>
117 auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
118 template <typename T>
119 auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
120
121 // ADL overload. Only participates in overload resolution if member functions
122 // are not found.
123 template <typename T>
124 auto range_begin(T&& rng)
125 -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
126 decltype(begin(static_cast<T&&>(rng)))> {
127 return begin(static_cast<T&&>(rng));
128 }
129 template <typename T>
130 auto range_end(T&& rng) -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
131 decltype(end(static_cast<T&&>(rng)))> {
132 return end(static_cast<T&&>(rng));
133 }
134
135 template <typename T, typename Enable = void>
136 struct has_const_begin_end : std::false_type {};
137 template <typename T, typename Enable = void>
138 struct has_mutable_begin_end : std::false_type {};
139
140 template <typename T>
141 struct has_const_begin_end<
142 T, void_t<decltype(detail::range_begin(
143 std::declval<const remove_cvref_t<T>&>())),
144 decltype(detail::range_begin(
145 std::declval<const remove_cvref_t<T>&>()))>>
146 : std::true_type {};
147
148 template <typename T>
149 struct has_mutable_begin_end<
150 T, void_t<decltype(detail::range_begin(std::declval<T>())),
151 decltype(detail::range_begin(std::declval<T>())),
152 enable_if_t<std::is_copy_constructible<T>::value>>>
153 : std::true_type {};
154
155 template <typename T>
156 struct is_range_<T, void>
157 : std::integral_constant<bool, (has_const_begin_end<T>::value ||
158 has_mutable_begin_end<T>::value)> {};
159
160 template <typename T, typename Enable = void> struct range_to_view;
161 template <typename T>
162 struct range_to_view<T, enable_if_t<has_const_begin_end<T>::value>> {
163 struct view_t {
164 const T* m_range_ptr;
165
166 auto begin() const FMT_DECLTYPE_RETURN(detail::range_begin(*m_range_ptr));
167 auto end() const FMT_DECLTYPE_RETURN(detail::range_end(*m_range_ptr));
168 };
169 static auto view(const T& range) -> view_t { return {&range}; }
170 };
171
172 template <typename T>
173 struct range_to_view<T, enable_if_t<!has_const_begin_end<T>::value &&
174 has_mutable_begin_end<T>::value>> {
175 struct view_t {
176 T m_range_copy;
177
178 auto begin() FMT_DECLTYPE_RETURN(detail::range_begin(m_range_copy));
179 auto end() FMT_DECLTYPE_RETURN(detail::range_end(m_range_copy));
180 };
181 static auto view(const T& range) -> view_t { return {range}; }
182 };
183 # undef FMT_DECLTYPE_RETURN
184 #endif
185
186 /// tuple_size and tuple_element check.
187 template <typename T> class is_tuple_like_ {
188 template <typename U>
189 static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
190 template <typename> static void check(...);
191
192 public:
193 static FMT_CONSTEXPR_DECL const bool value =
194 !std::is_void<decltype(check<T>(nullptr))>::value;
195 };
196
197 // Check for integer_sequence
198 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
199 template <typename T, T... N>
200 using integer_sequence = std::integer_sequence<T, N...>;
201 template <size_t... N> using index_sequence = std::index_sequence<N...>;
202 template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
203 #else
204 template <typename T, T... N> struct integer_sequence {
205 using value_type = T;
206
207 static FMT_CONSTEXPR size_t size() { return sizeof...(N); }
208 };
209
210 template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
211
212 template <typename T, size_t N, T... Ns>
213 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
214 template <typename T, T... Ns>
215 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
216
217 template <size_t N>
218 using make_index_sequence = make_integer_sequence<size_t, N>;
219 #endif
220
221 template <class Tuple, class F, size_t... Is>
222 void for_each(index_sequence<Is...>, Tuple&& tup, F&& f) FMT_NOEXCEPT {
223 using std::get;
224 // using free function get<I>(T) now.
225 const int _[] = {0, ((void)f(get<Is>(tup)), 0)...};
226 (void)_; // blocks warnings
227 }
228
229 template <class T>
230 FMT_CONSTEXPR make_index_sequence<std::tuple_size<T>::value> get_indexes(
231 T const&) {
232 return {};
233 }
234
235 template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
236 const auto indexes = get_indexes(tup);
237 for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
238 }
239
240 template <typename Range>
241 using value_type =
242 remove_cvref_t<decltype(*detail::range_begin(std::declval<Range>()))>;
243
244 template <typename OutputIt> OutputIt write_delimiter(OutputIt out) {
245 *out++ = ',';
246 *out++ = ' ';
247 return out;
248 }
249
250 template <
251 typename Char, typename OutputIt, typename Arg,
252 FMT_ENABLE_IF(is_like_std_string<typename std::decay<Arg>::type>::value)>
253 OutputIt write_range_entry(OutputIt out, const Arg& v) {
254 *out++ = '"';
255 out = write<Char>(out, v);
256 *out++ = '"';
257 return out;
258 }
259
260 template <typename Char, typename OutputIt, typename Arg,
261 FMT_ENABLE_IF(std::is_same<Arg, Char>::value)>
262 OutputIt write_range_entry(OutputIt out, const Arg v) {
263 *out++ = '\'';
264 *out++ = v;
265 *out++ = '\'';
266 return out;
267 }
268
269 template <
270 typename Char, typename OutputIt, typename Arg,
271 FMT_ENABLE_IF(!is_like_std_string<typename std::decay<Arg>::type>::value &&
272 !std::is_same<Arg, Char>::value)>
273 OutputIt write_range_entry(OutputIt out, const Arg& v) {
274 return write<Char>(out, v);
275 }
276
277 } // namespace detail
278
279 template <typename T> struct is_tuple_like {
280 static FMT_CONSTEXPR_DECL const bool value =
281 detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
282 };
283
284 template <typename TupleT, typename Char>
285 struct formatter<TupleT, Char, enable_if_t<axom::fmt::is_tuple_like<TupleT>::value>> {
286 private:
287 // C++11 generic lambda for format()
288 template <typename FormatContext> struct format_each {
289 template <typename T> void operator()(const T& v) {
290 if (i > 0) out = detail::write_delimiter(out);
291 out = detail::write_range_entry<Char>(out, v);
292 ++i;
293 }
294 formatting_tuple<Char>& formatting;
295 size_t& i;
296 typename std::add_lvalue_reference<decltype(
297 std::declval<FormatContext>().out())>::type out;
298 };
299
300 public:
301 formatting_tuple<Char> formatting;
302
303 template <typename ParseContext>
304 FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
305 return formatting.parse(ctx);
306 }
307
308 template <typename FormatContext = format_context>
309 auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
310 auto out = ctx.out();
311 size_t i = 0;
312
313 detail::copy(formatting.prefix, out);
314 detail::for_each(values, format_each<FormatContext>{formatting, i, out});
315 detail::copy(formatting.postfix, out);
316
317 return ctx.out();
318 }
319 };
320
321 template <typename T, typename Char> struct is_range {
322 static FMT_CONSTEXPR_DECL const bool value =
323 detail::is_range_<T>::value && !detail::is_like_std_string<T>::value &&
324 !std::is_convertible<T, std::basic_string<Char>>::value &&
325 !std::is_constructible<detail::std_string_view<Char>, T>::value;
326 };
327
328 template <typename T, typename Char>
329 struct formatter<
330 T, Char,
331 enable_if_t<axom::fmt::is_range<T, Char>::value
332 // Workaround a bug in MSVC 2017 and earlier.
333 #if !FMT_MSC_VER || FMT_MSC_VER >= 1927
334 &&
335 (has_formatter<detail::value_type<T>, format_context>::value ||
336 detail::has_fallback_formatter<detail::value_type<T>,
337 format_context>::value)
338 #endif
339 >> {
340 formatting_range<Char> formatting;
341
342 template <typename ParseContext>
343 FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
344 return formatting.parse(ctx);
345 }
346
347 template <typename FormatContext>
348 typename FormatContext::iterator format(const T& values, FormatContext& ctx) {
349 auto out = detail::copy(formatting.prefix, ctx.out());
350 size_t i = 0;
351 auto view = detail::range_to_view<T>::view(values);
352 auto it = view.begin();
353 auto end = view.end();
354 for (; it != end; ++it) {
355 if (i > 0) out = detail::write_delimiter(out);
356 out = detail::write_range_entry<Char>(out, *it);
357 if (++i > formatting.range_length_limit) {
358 out = format_to(out, FMT_STRING("{}"), " ... <other elements>");
359 break;
360 }
361 }
362 return detail::copy(formatting.postfix, out);
363 }
364 };
365
366 template <typename Char, typename... T> struct tuple_arg_join : detail::view {
367 const std::tuple<T...>& tuple;
368 basic_string_view<Char> sep;
369
370 tuple_arg_join(const std::tuple<T...>& t, basic_string_view<Char> s)
371 : tuple(t), sep{s} {}
372 };
373
374 template <typename Char, typename... T>
375 struct formatter<tuple_arg_join<Char, T...>, Char> {
376 template <typename ParseContext>
377 FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
378 return ctx.begin();
379 }
380
381 template <typename FormatContext>
382 typename FormatContext::iterator format(
383 const tuple_arg_join<Char, T...>& value, FormatContext& ctx) {
384 return format(value, ctx, detail::make_index_sequence<sizeof...(T)>{});
385 }
386
387 private:
388 template <typename FormatContext, size_t... N>
389 typename FormatContext::iterator format(
390 const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
391 detail::index_sequence<N...>) {
392 return format_args(value, ctx, std::get<N>(value.tuple)...);
393 }
394
395 template <typename FormatContext>
396 typename FormatContext::iterator format_args(
397 const tuple_arg_join<Char, T...>&, FormatContext& ctx) {
398 // NOTE: for compilers that support C++17, this empty function instantiation
399 // can be replaced with a constexpr branch in the variadic overload.
400 return ctx.out();
401 }
402
403 template <typename FormatContext, typename Arg, typename... Args>
404 typename FormatContext::iterator format_args(
405 const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
406 const Arg& arg, const Args&... args) {
407 using base = formatter<typename std::decay<Arg>::type, Char>;
408 auto out = ctx.out();
409 out = base{}.format(arg, ctx);
410 if (sizeof...(Args) > 0) {
411 out = std::copy(value.sep.begin(), value.sep.end(), out);
412 ctx.advance_to(out);
413 return format_args(value, ctx, args...);
414 }
415 return out;
416 }
417 };
418
419 /**
420 \rst
421 Returns an object that formats `tuple` with elements separated by `sep`.
422
423 **Example**::
424
425 std::tuple<int, char> t = {1, 'a'};
426 axom::fmt::print("{}", axom::fmt::join(t, ", "));
427 // Output: "1, a"
428 \endrst
429 */
430 template <typename... T>
431 FMT_CONSTEXPR tuple_arg_join<char, T...> join(const std::tuple<T...>& tuple,
432 string_view sep) {
433 return {tuple, sep};
434 }
435
436 template <typename... T>
437 FMT_CONSTEXPR tuple_arg_join<wchar_t, T...> join(const std::tuple<T...>& tuple,
438 wstring_view sep) {
439 return {tuple, sep};
440 }
441
442 /**
443 \rst
444 Returns an object that formats `initializer_list` with elements separated by
445 `sep`.
446
447 **Example**::
448
449 axom::fmt::print("{}", axom::fmt::join({1, 2, 3}, ", "));
450 // Output: "1, 2, 3"
451 \endrst
452 */
453 template <typename T>
454 arg_join<const T*, const T*, char> join(std::initializer_list<T> list,
455 string_view sep) {
456 return join(std::begin(list), std::end(list), sep);
457 }
458
459 template <typename T>
460 arg_join<const T*, const T*, wchar_t> join(std::initializer_list<T> list,
461 wstring_view sep) {
462 return join(std::begin(list), std::end(list), sep);
463 }
464
465 FMT_END_NAMESPACE
466
467 #endif // FMT_RANGES_H_
468