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;
formatting_rangeformatting_range40 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;
formatting_tupleformatting_tuple50 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>
copy(const RangeT & range,OutputIterator out)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>
copy(const char * str,OutputIterator out)65 OutputIterator copy(const char* str, OutputIterator out) {
66 while (*str) *out++ = *str++;
67 return out;
68 }
69
70 template <typename OutputIterator>
copy(char ch,OutputIterator out)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 is_string<T>::value || !std::is_void<decltype(check<T>(nullptr))>::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, conditional_t<false,
99 conditional_helper<decltype(std::declval<T>().begin()),
100 decltype(std::declval<T>().end())>,
101 void>> : std::true_type {};
102 #endif
103
104 /// tuple_size and tuple_element check.
105 template <typename T> class is_tuple_like_ {
106 template <typename U>
107 static auto check(U* p)
108 -> decltype(std::tuple_size<U>::value,
109 (void)std::declval<typename std::tuple_element<0, U>::type>(),
110 int());
111 template <typename> static void check(...);
112
113 public:
114 static FMT_CONSTEXPR_DECL const bool value =
115 !std::is_void<decltype(check<T>(nullptr))>::value;
116 };
117
118 // Check for integer_sequence
119 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
120 template <typename T, T... N>
121 using integer_sequence = std::integer_sequence<T, N...>;
122 template <std::size_t... N> using index_sequence = std::index_sequence<N...>;
123 template <std::size_t N>
124 using make_index_sequence = std::make_index_sequence<N>;
125 #else
126 template <typename T, T... N> struct integer_sequence {
127 using value_type = T;
128
129 static FMT_CONSTEXPR std::size_t size() { return sizeof...(N); }
130 };
131
132 template <std::size_t... N>
133 using index_sequence = integer_sequence<std::size_t, N...>;
134
135 template <typename T, std::size_t N, T... Ns>
136 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
137 template <typename T, T... Ns>
138 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
139
140 template <std::size_t N>
141 using make_index_sequence = make_integer_sequence<std::size_t, N>;
142 #endif
143
144 template <class Tuple, class F, size_t... Is>
145 void for_each(index_sequence<Is...>, Tuple&& tup, F&& f) FMT_NOEXCEPT {
146 using std::get;
147 // using free function get<I>(T) now.
148 const int _[] = {0, ((void)f(get<Is>(tup)), 0)...};
149 (void)_; // blocks warnings
150 }
151
152 template <class T>
153 FMT_CONSTEXPR make_index_sequence<std::tuple_size<T>::value> get_indexes(
154 T const&) {
155 return {};
156 }
157
158 template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
159 const auto indexes = get_indexes(tup);
160 for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
161 }
162
163 template <typename Arg, FMT_ENABLE_IF(!is_like_std_string<
164 typename std::decay<Arg>::type>::value)>
165 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
166 return add_space ? " {}" : "{}";
167 }
168
169 template <typename Arg, FMT_ENABLE_IF(is_like_std_string<
170 typename std::decay<Arg>::type>::value)>
171 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
172 return add_space ? " \"{}\"" : "\"{}\"";
173 }
174
175 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char*) {
176 return add_space ? " \"{}\"" : "\"{}\"";
177 }
178 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t*) {
179 return add_space ? L" \"{}\"" : L"\"{}\"";
180 }
181
182 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char) {
183 return add_space ? " '{}'" : "'{}'";
184 }
185 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
186 return add_space ? L" '{}'" : L"'{}'";
187 }
188
189 } // namespace internal
190
191 template <typename T> struct is_tuple_like {
192 static FMT_CONSTEXPR_DECL const bool value =
193 internal::is_tuple_like_<T>::value && !internal::is_range_<T>::value;
194 };
195
196 template <typename TupleT, typename Char>
197 struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
198 private:
199 // C++11 generic lambda for format()
200 template <typename FormatContext> struct format_each {
201 template <typename T> void operator()(const T& v) {
202 if (i > 0) {
203 if (formatting.add_prepostfix_space) {
204 *out++ = ' ';
205 }
206 out = internal::copy(formatting.delimiter, out);
207 }
208 out = format_to(out,
209 internal::format_str_quoted(
210 (formatting.add_delimiter_spaces && i > 0), v),
211 v);
212 ++i;
213 }
214
215 formatting_tuple<Char>& formatting;
216 std::size_t& i;
217 typename std::add_lvalue_reference<decltype(
218 std::declval<FormatContext>().out())>::type out;
219 };
220
221 public:
222 formatting_tuple<Char> formatting;
223
224 template <typename ParseContext>
225 FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
226 return formatting.parse(ctx);
227 }
228
229 template <typename FormatContext = format_context>
230 auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
231 auto out = ctx.out();
232 std::size_t i = 0;
233 internal::copy(formatting.prefix, out);
234
235 internal::for_each(values, format_each<FormatContext>{formatting, i, out});
236 if (formatting.add_prepostfix_space) {
237 *out++ = ' ';
238 }
239 internal::copy(formatting.postfix, out);
240
241 return ctx.out();
242 }
243 };
244
245 template <typename T, typename Char> struct is_range {
246 static FMT_CONSTEXPR_DECL const bool value =
247 internal::is_range_<T>::value &&
248 !internal::is_like_std_string<T>::value &&
249 !std::is_convertible<T, std::basic_string<Char>>::value &&
250 !std::is_constructible<internal::std_string_view<Char>, T>::value;
251 };
252
253 template <typename RangeT, typename Char>
254 struct formatter<RangeT, Char,
255 enable_if_t<fmt::is_range<RangeT, Char>::value>> {
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 template <typename Char, typename... T> struct tuple_arg_join : internal::view {
288 const std::tuple<T...>& tuple;
289 basic_string_view<Char> sep;
290
291 tuple_arg_join(const std::tuple<T...>& t, basic_string_view<Char> s)
292 : tuple{t}, sep{s} {}
293 };
294
295 template <typename Char, typename... T>
296 struct formatter<tuple_arg_join<Char, T...>, Char> {
297 template <typename ParseContext>
298 FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
299 return ctx.begin();
300 }
301
302 template <typename FormatContext>
303 typename FormatContext::iterator format(
304 const tuple_arg_join<Char, T...>& value, FormatContext& ctx) {
305 return format(value, ctx, internal::make_index_sequence<sizeof...(T)>{});
306 }
307
308 private:
309 template <typename FormatContext, size_t... N>
310 typename FormatContext::iterator format(
311 const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
312 internal::index_sequence<N...>) {
313 return format_args(value, ctx, std::get<N>(value.tuple)...);
314 }
315
316 template <typename FormatContext>
317 typename FormatContext::iterator format_args(
318 const tuple_arg_join<Char, T...>&, FormatContext& ctx) {
319 // NOTE: for compilers that support C++17, this empty function instantiation
320 // can be replaced with a constexpr branch in the variadic overload.
321 return ctx.out();
322 }
323
324 template <typename FormatContext, typename Arg, typename... Args>
325 typename FormatContext::iterator format_args(
326 const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
327 const Arg& arg, const Args&... args) {
328 using base = formatter<typename std::decay<Arg>::type, Char>;
329 auto out = ctx.out();
330 out = base{}.format(arg, ctx);
331 if (sizeof...(Args) > 0) {
332 out = std::copy(value.sep.begin(), value.sep.end(), out);
333 ctx.advance_to(out);
334 return format_args(value, ctx, args...);
335 }
336 return out;
337 }
338 };
339
340 /**
341 \rst
342 Returns an object that formats `tuple` with elements separated by `sep`.
343
344 **Example**::
345
346 std::tuple<int, char> t = {1, 'a'};
347 fmt::print("{}", fmt::join(t, ", "));
348 // Output: "1, a"
349 \endrst
350 */
351 template <typename... T>
352 FMT_CONSTEXPR tuple_arg_join<char, T...> join(const std::tuple<T...>& tuple,
353 string_view sep) {
354 return {tuple, sep};
355 }
356
357 template <typename... T>
358 FMT_CONSTEXPR tuple_arg_join<wchar_t, T...> join(const std::tuple<T...>& tuple,
359 wstring_view sep) {
360 return {tuple, sep};
361 }
362
363 FMT_END_NAMESPACE
364
365 #endif // FMT_RANGES_H_
366