1 // Copyright 2016 Google Inc. All Rights Reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #ifndef ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_
16 #define ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_
17
18 #include <cstdint>
19 #include <limits>
20 #include <ostream>
21 #include <type_traits>
22
23 // Disable constexpr support unless we are in C++14 mode.
24 #if __cpp_constexpr >= 201304 || _MSC_VER >= 1910
25 #define CONSTEXPR_D constexpr // data
26 #define CONSTEXPR_F constexpr // function
27 #define CONSTEXPR_M constexpr // member
28 #else
29 #define CONSTEXPR_D const
30 #define CONSTEXPR_F inline
31 #define CONSTEXPR_M
32 #endif
33
34 namespace absl {
35 namespace time_internal {
36 namespace cctz {
37
38 // Support years that at least span the range of 64-bit time_t values.
39 using year_t = std::int_fast64_t;
40
41 // Type alias that indicates an argument is not normalized (e.g., the
42 // constructor parameters and operands/results of addition/subtraction).
43 using diff_t = std::int_fast64_t;
44
45 namespace detail {
46
47 // Type aliases that indicate normalized argument values.
48 using month_t = std::int_fast8_t; // [1:12]
49 using day_t = std::int_fast8_t; // [1:31]
50 using hour_t = std::int_fast8_t; // [0:23]
51 using minute_t = std::int_fast8_t; // [0:59]
52 using second_t = std::int_fast8_t; // [0:59]
53
54 // Normalized civil-time fields: Y-M-D HH:MM:SS.
55 struct fields {
fieldsfields56 CONSTEXPR_M fields(year_t year, month_t month, day_t day,
57 hour_t hour, minute_t minute, second_t second)
58 : y(year), m(month), d(day), hh(hour), mm(minute), ss(second) {}
59 std::int_least64_t y;
60 std::int_least8_t m;
61 std::int_least8_t d;
62 std::int_least8_t hh;
63 std::int_least8_t mm;
64 std::int_least8_t ss;
65 };
66
67 struct second_tag {};
68 struct minute_tag : second_tag {};
69 struct hour_tag : minute_tag {};
70 struct day_tag : hour_tag {};
71 struct month_tag : day_tag {};
72 struct year_tag : month_tag {};
73
74 ////////////////////////////////////////////////////////////////////////
75
76 // Field normalization (without avoidable overflow).
77
78 namespace impl {
79
is_leap_year(year_t y)80 CONSTEXPR_F bool is_leap_year(year_t y) noexcept {
81 return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0);
82 }
year_index(year_t y,month_t m)83 CONSTEXPR_F int year_index(year_t y, month_t m) noexcept {
84 return (static_cast<int>((y + (m > 2)) % 400) + 400) % 400;
85 }
days_per_century(year_t y,month_t m)86 CONSTEXPR_F int days_per_century(year_t y, month_t m) noexcept {
87 const int yi = year_index(y, m);
88 return 36524 + (yi == 0 || yi > 300);
89 }
days_per_4years(year_t y,month_t m)90 CONSTEXPR_F int days_per_4years(year_t y, month_t m) noexcept {
91 const int yi = year_index(y, m);
92 return 1460 + (yi == 0 || yi > 300 || (yi - 1) % 100 < 96);
93 }
days_per_year(year_t y,month_t m)94 CONSTEXPR_F int days_per_year(year_t y, month_t m) noexcept {
95 return is_leap_year(y + (m > 2)) ? 366 : 365;
96 }
days_per_month(year_t y,month_t m)97 CONSTEXPR_F int days_per_month(year_t y, month_t m) noexcept {
98 CONSTEXPR_D int k_days_per_month[1 + 12] = {
99 -1, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 // non leap year
100 };
101 return k_days_per_month[m] + (m == 2 && is_leap_year(y));
102 }
103
n_day(year_t y,month_t m,diff_t d,diff_t cd,hour_t hh,minute_t mm,second_t ss)104 CONSTEXPR_F fields n_day(year_t y, month_t m, diff_t d, diff_t cd,
105 hour_t hh, minute_t mm, second_t ss) noexcept {
106 y += (cd / 146097) * 400;
107 cd %= 146097;
108 if (cd < 0) {
109 y -= 400;
110 cd += 146097;
111 }
112 y += (d / 146097) * 400;
113 d = d % 146097 + cd;
114 if (d > 0) {
115 if (d > 146097) {
116 y += 400;
117 d -= 146097;
118 }
119 } else {
120 if (d > -365) {
121 // We often hit the previous year when stepping a civil time backwards,
122 // so special case it to avoid counting up by 100/4/1-year chunks.
123 y -= 1;
124 d += days_per_year(y, m);
125 } else {
126 y -= 400;
127 d += 146097;
128 }
129 }
130 if (d > 365) {
131 for (int n = days_per_century(y, m); d > n; n = days_per_century(y, m)) {
132 d -= n;
133 y += 100;
134 }
135 for (int n = days_per_4years(y, m); d > n; n = days_per_4years(y, m)) {
136 d -= n;
137 y += 4;
138 }
139 for (int n = days_per_year(y, m); d > n; n = days_per_year(y, m)) {
140 d -= n;
141 ++y;
142 }
143 }
144 if (d > 28) {
145 for (int n = days_per_month(y, m); d > n; n = days_per_month(y, m)) {
146 d -= n;
147 if (++m > 12) {
148 ++y;
149 m = 1;
150 }
151 }
152 }
153 return fields(y, m, static_cast<day_t>(d), hh, mm, ss);
154 }
n_mon(year_t y,diff_t m,diff_t d,diff_t cd,hour_t hh,minute_t mm,second_t ss)155 CONSTEXPR_F fields n_mon(year_t y, diff_t m, diff_t d, diff_t cd,
156 hour_t hh, minute_t mm, second_t ss) noexcept {
157 if (m != 12) {
158 y += m / 12;
159 m %= 12;
160 if (m <= 0) {
161 y -= 1;
162 m += 12;
163 }
164 }
165 return n_day(y, static_cast<month_t>(m), d, cd, hh, mm, ss);
166 }
n_hour(year_t y,diff_t m,diff_t d,diff_t cd,diff_t hh,minute_t mm,second_t ss)167 CONSTEXPR_F fields n_hour(year_t y, diff_t m, diff_t d, diff_t cd,
168 diff_t hh, minute_t mm, second_t ss) noexcept {
169 cd += hh / 24;
170 hh %= 24;
171 if (hh < 0) {
172 cd -= 1;
173 hh += 24;
174 }
175 return n_mon(y, m, d, cd, static_cast<hour_t>(hh), mm, ss);
176 }
n_min(year_t y,diff_t m,diff_t d,diff_t hh,diff_t ch,diff_t mm,second_t ss)177 CONSTEXPR_F fields n_min(year_t y, diff_t m, diff_t d, diff_t hh, diff_t ch,
178 diff_t mm, second_t ss) noexcept {
179 ch += mm / 60;
180 mm %= 60;
181 if (mm < 0) {
182 ch -= 1;
183 mm += 60;
184 }
185 return n_hour(y, m, d, hh / 24 + ch / 24, hh % 24 + ch % 24,
186 static_cast<minute_t>(mm), ss);
187 }
n_sec(year_t y,diff_t m,diff_t d,diff_t hh,diff_t mm,diff_t ss)188 CONSTEXPR_F fields n_sec(year_t y, diff_t m, diff_t d, diff_t hh, diff_t mm,
189 diff_t ss) noexcept {
190 // Optimization for when (non-constexpr) fields are already normalized.
191 if (0 <= ss && ss < 60) {
192 const second_t nss = static_cast<second_t>(ss);
193 if (0 <= mm && mm < 60) {
194 const minute_t nmm = static_cast<minute_t>(mm);
195 if (0 <= hh && hh < 24) {
196 const hour_t nhh = static_cast<hour_t>(hh);
197 if (1 <= d && d <= 28 && 1 <= m && m <= 12) {
198 const day_t nd = static_cast<day_t>(d);
199 const month_t nm = static_cast<month_t>(m);
200 return fields(y, nm, nd, nhh, nmm, nss);
201 }
202 return n_mon(y, m, d, 0, nhh, nmm, nss);
203 }
204 return n_hour(y, m, d, hh / 24, hh % 24, nmm, nss);
205 }
206 return n_min(y, m, d, hh, mm / 60, mm % 60, nss);
207 }
208 diff_t cm = ss / 60;
209 ss %= 60;
210 if (ss < 0) {
211 cm -= 1;
212 ss += 60;
213 }
214 return n_min(y, m, d, hh, mm / 60 + cm / 60, mm % 60 + cm % 60,
215 static_cast<second_t>(ss));
216 }
217
218 } // namespace impl
219
220 ////////////////////////////////////////////////////////////////////////
221
222 // Increments the indicated (normalized) field by "n".
step(second_tag,fields f,diff_t n)223 CONSTEXPR_F fields step(second_tag, fields f, diff_t n) noexcept {
224 return impl::n_sec(f.y, f.m, f.d, f.hh, f.mm + n / 60, f.ss + n % 60);
225 }
step(minute_tag,fields f,diff_t n)226 CONSTEXPR_F fields step(minute_tag, fields f, diff_t n) noexcept {
227 return impl::n_min(f.y, f.m, f.d, f.hh + n / 60, 0, f.mm + n % 60, f.ss);
228 }
step(hour_tag,fields f,diff_t n)229 CONSTEXPR_F fields step(hour_tag, fields f, diff_t n) noexcept {
230 return impl::n_hour(f.y, f.m, f.d + n / 24, 0, f.hh + n % 24, f.mm, f.ss);
231 }
step(day_tag,fields f,diff_t n)232 CONSTEXPR_F fields step(day_tag, fields f, diff_t n) noexcept {
233 return impl::n_day(f.y, f.m, f.d, n, f.hh, f.mm, f.ss);
234 }
step(month_tag,fields f,diff_t n)235 CONSTEXPR_F fields step(month_tag, fields f, diff_t n) noexcept {
236 return impl::n_mon(f.y + n / 12, f.m + n % 12, f.d, 0, f.hh, f.mm, f.ss);
237 }
step(year_tag,fields f,diff_t n)238 CONSTEXPR_F fields step(year_tag, fields f, diff_t n) noexcept {
239 return fields(f.y + n, f.m, f.d, f.hh, f.mm, f.ss);
240 }
241
242 ////////////////////////////////////////////////////////////////////////
243
244 namespace impl {
245
246 // Returns (v * f + a) but avoiding intermediate overflow when possible.
scale_add(diff_t v,diff_t f,diff_t a)247 CONSTEXPR_F diff_t scale_add(diff_t v, diff_t f, diff_t a) noexcept {
248 return (v < 0) ? ((v + 1) * f + a) - f : ((v - 1) * f + a) + f;
249 }
250
251 // Map a (normalized) Y/M/D to the number of days before/after 1970-01-01.
252 // Probably overflows for years outside [-292277022656:292277026595].
ymd_ord(year_t y,month_t m,day_t d)253 CONSTEXPR_F diff_t ymd_ord(year_t y, month_t m, day_t d) noexcept {
254 const diff_t eyear = (m <= 2) ? y - 1 : y;
255 const diff_t era = (eyear >= 0 ? eyear : eyear - 399) / 400;
256 const diff_t yoe = eyear - era * 400;
257 const diff_t doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1;
258 const diff_t doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
259 return era * 146097 + doe - 719468;
260 }
261
262 // Returns the difference in days between two normalized Y-M-D tuples.
263 // ymd_ord() will encounter integer overflow given extreme year values,
264 // yet the difference between two such extreme values may actually be
265 // small, so we take a little care to avoid overflow when possible by
266 // exploiting the 146097-day cycle.
day_difference(year_t y1,month_t m1,day_t d1,year_t y2,month_t m2,day_t d2)267 CONSTEXPR_F diff_t day_difference(year_t y1, month_t m1, day_t d1,
268 year_t y2, month_t m2, day_t d2) noexcept {
269 const diff_t a_c4_off = y1 % 400;
270 const diff_t b_c4_off = y2 % 400;
271 diff_t c4_diff = (y1 - a_c4_off) - (y2 - b_c4_off);
272 diff_t delta = ymd_ord(a_c4_off, m1, d1) - ymd_ord(b_c4_off, m2, d2);
273 if (c4_diff > 0 && delta < 0) {
274 delta += 2 * 146097;
275 c4_diff -= 2 * 400;
276 } else if (c4_diff < 0 && delta > 0) {
277 delta -= 2 * 146097;
278 c4_diff += 2 * 400;
279 }
280 return (c4_diff / 400 * 146097) + delta;
281 }
282
283 } // namespace impl
284
285 // Returns the difference between fields structs using the indicated unit.
difference(year_tag,fields f1,fields f2)286 CONSTEXPR_F diff_t difference(year_tag, fields f1, fields f2) noexcept {
287 return f1.y - f2.y;
288 }
difference(month_tag,fields f1,fields f2)289 CONSTEXPR_F diff_t difference(month_tag, fields f1, fields f2) noexcept {
290 return impl::scale_add(difference(year_tag{}, f1, f2), 12, (f1.m - f2.m));
291 }
difference(day_tag,fields f1,fields f2)292 CONSTEXPR_F diff_t difference(day_tag, fields f1, fields f2) noexcept {
293 return impl::day_difference(f1.y, f1.m, f1.d, f2.y, f2.m, f2.d);
294 }
difference(hour_tag,fields f1,fields f2)295 CONSTEXPR_F diff_t difference(hour_tag, fields f1, fields f2) noexcept {
296 return impl::scale_add(difference(day_tag{}, f1, f2), 24, (f1.hh - f2.hh));
297 }
difference(minute_tag,fields f1,fields f2)298 CONSTEXPR_F diff_t difference(minute_tag, fields f1, fields f2) noexcept {
299 return impl::scale_add(difference(hour_tag{}, f1, f2), 60, (f1.mm - f2.mm));
300 }
difference(second_tag,fields f1,fields f2)301 CONSTEXPR_F diff_t difference(second_tag, fields f1, fields f2) noexcept {
302 return impl::scale_add(difference(minute_tag{}, f1, f2), 60, f1.ss - f2.ss);
303 }
304
305 ////////////////////////////////////////////////////////////////////////
306
307 // Aligns the (normalized) fields struct to the indicated field.
align(second_tag,fields f)308 CONSTEXPR_F fields align(second_tag, fields f) noexcept {
309 return f;
310 }
align(minute_tag,fields f)311 CONSTEXPR_F fields align(minute_tag, fields f) noexcept {
312 return fields{f.y, f.m, f.d, f.hh, f.mm, 0};
313 }
align(hour_tag,fields f)314 CONSTEXPR_F fields align(hour_tag, fields f) noexcept {
315 return fields{f.y, f.m, f.d, f.hh, 0, 0};
316 }
align(day_tag,fields f)317 CONSTEXPR_F fields align(day_tag, fields f) noexcept {
318 return fields{f.y, f.m, f.d, 0, 0, 0};
319 }
align(month_tag,fields f)320 CONSTEXPR_F fields align(month_tag, fields f) noexcept {
321 return fields{f.y, f.m, 1, 0, 0, 0};
322 }
align(year_tag,fields f)323 CONSTEXPR_F fields align(year_tag, fields f) noexcept {
324 return fields{f.y, 1, 1, 0, 0, 0};
325 }
326
327 ////////////////////////////////////////////////////////////////////////
328
329 template <typename T>
330 class civil_time {
331 public:
332 explicit CONSTEXPR_M civil_time(year_t y, diff_t m = 1, diff_t d = 1,
333 diff_t hh = 0, diff_t mm = 0,
334 diff_t ss = 0) noexcept
civil_time(impl::n_sec (y,m,d,hh,mm,ss))335 : civil_time(impl::n_sec(y, m, d, hh, mm, ss)) {}
336
civil_time()337 CONSTEXPR_M civil_time() noexcept : f_{1970, 1, 1, 0, 0, 0} {}
338 civil_time(const civil_time&) = default;
339 civil_time& operator=(const civil_time&) = default;
340
341 // Conversion between civil times of different alignment. Conversion to
342 // a more precise alignment is allowed implicitly (e.g., day -> hour),
343 // but conversion where information is discarded must be explicit
344 // (e.g., second -> minute).
345 template <typename U, typename S>
346 using preserves_data =
347 typename std::enable_if<std::is_base_of<U, S>::value>::type;
348 template <typename U>
349 CONSTEXPR_M civil_time(const civil_time<U>& ct,
350 preserves_data<T, U>* = nullptr) noexcept
351 : civil_time(ct.f_) {}
352 template <typename U>
353 explicit CONSTEXPR_M civil_time(const civil_time<U>& ct,
354 preserves_data<U, T>* = nullptr) noexcept
355 : civil_time(ct.f_) {}
356
357 // Factories for the maximum/minimum representable civil_time.
max()358 static civil_time max() {
359 const auto max_year = std::numeric_limits<std::int_least64_t>::max();
360 return civil_time(max_year, 12, 31, 23, 59, 59);
361 }
min()362 static civil_time min() {
363 const auto min_year = std::numeric_limits<std::int_least64_t>::min();
364 return civil_time(min_year, 1, 1, 0, 0, 0);
365 }
366
367 // Field accessors. Note: All but year() return an int.
year()368 CONSTEXPR_M year_t year() const noexcept { return f_.y; }
month()369 CONSTEXPR_M int month() const noexcept { return f_.m; }
day()370 CONSTEXPR_M int day() const noexcept { return f_.d; }
hour()371 CONSTEXPR_M int hour() const noexcept { return f_.hh; }
minute()372 CONSTEXPR_M int minute() const noexcept { return f_.mm; }
second()373 CONSTEXPR_M int second() const noexcept { return f_.ss; }
374
375 // Assigning arithmetic.
376 CONSTEXPR_M civil_time& operator+=(diff_t n) noexcept {
377 f_ = step(T{}, f_, n);
378 return *this;
379 }
380 CONSTEXPR_M civil_time& operator-=(diff_t n) noexcept {
381 if (n != std::numeric_limits<diff_t>::min()) {
382 f_ = step(T{}, f_, -n);
383 } else {
384 f_ = step(T{}, step(T{}, f_, -(n + 1)), 1);
385 }
386 return *this;
387 }
388 CONSTEXPR_M civil_time& operator++() noexcept {
389 return *this += 1;
390 }
391 CONSTEXPR_M civil_time operator++(int) noexcept {
392 const civil_time a = *this;
393 ++*this;
394 return a;
395 }
396 CONSTEXPR_M civil_time& operator--() noexcept {
397 return *this -= 1;
398 }
399 CONSTEXPR_M civil_time operator--(int) noexcept {
400 const civil_time a = *this;
401 --*this;
402 return a;
403 }
404
405 // Binary arithmetic operators.
406 friend CONSTEXPR_F civil_time operator+(civil_time a, diff_t n) noexcept {
407 return a += n;
408 }
409 friend CONSTEXPR_F civil_time operator+(diff_t n, civil_time a) noexcept {
410 return a += n;
411 }
412 friend CONSTEXPR_F civil_time operator-(civil_time a, diff_t n) noexcept {
413 return a -= n;
414 }
415 friend CONSTEXPR_F diff_t operator-(civil_time lhs, civil_time rhs) noexcept {
416 return difference(T{}, lhs.f_, rhs.f_);
417 }
418
419 private:
420 // All instantiations of this template are allowed to call the following
421 // private constructor and access the private fields member.
422 template <typename U>
423 friend class civil_time;
424
425 // The designated constructor that all others eventually call.
civil_time(fields f)426 explicit CONSTEXPR_M civil_time(fields f) noexcept : f_(align(T{}, f)) {}
427
428 fields f_;
429 };
430
431 // Disallows difference between differently aligned types.
432 // auto n = civil_day(...) - civil_hour(...); // would be confusing.
433 template <typename T, typename U>
434 CONSTEXPR_F diff_t operator-(civil_time<T>, civil_time<U>) = delete;
435
436 using civil_year = civil_time<year_tag>;
437 using civil_month = civil_time<month_tag>;
438 using civil_day = civil_time<day_tag>;
439 using civil_hour = civil_time<hour_tag>;
440 using civil_minute = civil_time<minute_tag>;
441 using civil_second = civil_time<second_tag>;
442
443 ////////////////////////////////////////////////////////////////////////
444
445 // Relational operators that work with differently aligned objects.
446 // Always compares all six fields.
447 template <typename T1, typename T2>
448 CONSTEXPR_F bool operator<(const civil_time<T1>& lhs,
449 const civil_time<T2>& rhs) noexcept {
450 return (lhs.year() < rhs.year() ||
451 (lhs.year() == rhs.year() &&
452 (lhs.month() < rhs.month() ||
453 (lhs.month() == rhs.month() &&
454 (lhs.day() < rhs.day() ||
455 (lhs.day() == rhs.day() &&
456 (lhs.hour() < rhs.hour() ||
457 (lhs.hour() == rhs.hour() &&
458 (lhs.minute() < rhs.minute() ||
459 (lhs.minute() == rhs.minute() &&
460 (lhs.second() < rhs.second())))))))))));
461 }
462 template <typename T1, typename T2>
463 CONSTEXPR_F bool operator<=(const civil_time<T1>& lhs,
464 const civil_time<T2>& rhs) noexcept {
465 return !(rhs < lhs);
466 }
467 template <typename T1, typename T2>
468 CONSTEXPR_F bool operator>=(const civil_time<T1>& lhs,
469 const civil_time<T2>& rhs) noexcept {
470 return !(lhs < rhs);
471 }
472 template <typename T1, typename T2>
473 CONSTEXPR_F bool operator>(const civil_time<T1>& lhs,
474 const civil_time<T2>& rhs) noexcept {
475 return rhs < lhs;
476 }
477 template <typename T1, typename T2>
478 CONSTEXPR_F bool operator==(const civil_time<T1>& lhs,
479 const civil_time<T2>& rhs) noexcept {
480 return lhs.year() == rhs.year() && lhs.month() == rhs.month() &&
481 lhs.day() == rhs.day() && lhs.hour() == rhs.hour() &&
482 lhs.minute() == rhs.minute() && lhs.second() == rhs.second();
483 }
484 template <typename T1, typename T2>
485 CONSTEXPR_F bool operator!=(const civil_time<T1>& lhs,
486 const civil_time<T2>& rhs) noexcept {
487 return !(lhs == rhs);
488 }
489
490 ////////////////////////////////////////////////////////////////////////
491
492 enum class weekday {
493 monday,
494 tuesday,
495 wednesday,
496 thursday,
497 friday,
498 saturday,
499 sunday,
500 };
501
get_weekday(const civil_day & cd)502 CONSTEXPR_F weekday get_weekday(const civil_day& cd) noexcept {
503 CONSTEXPR_D weekday k_weekday_by_sun_off[7] = {
504 weekday::sunday, weekday::monday, weekday::tuesday,
505 weekday::wednesday, weekday::thursday, weekday::friday,
506 weekday::saturday,
507 };
508 CONSTEXPR_D int k_weekday_offsets[1 + 12] = {
509 -1, 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4,
510 };
511 year_t wd = cd.year() - (cd.month() < 3);
512 if (wd >= 0) {
513 wd += wd / 4 - wd / 100 + wd / 400;
514 } else {
515 wd += (wd - 3) / 4 - (wd - 99) / 100 + (wd - 399) / 400;
516 }
517 wd += k_weekday_offsets[cd.month()] + cd.day();
518 return k_weekday_by_sun_off[(wd % 7 + 7) % 7];
519 }
520
521 ////////////////////////////////////////////////////////////////////////
522
next_weekday(civil_day cd,weekday wd)523 CONSTEXPR_F civil_day next_weekday(civil_day cd, weekday wd) noexcept {
524 do { cd += 1; } while (get_weekday(cd) != wd);
525 return cd;
526 }
527
prev_weekday(civil_day cd,weekday wd)528 CONSTEXPR_F civil_day prev_weekday(civil_day cd, weekday wd) noexcept {
529 do { cd -= 1; } while (get_weekday(cd) != wd);
530 return cd;
531 }
532
get_yearday(const civil_day & cd)533 CONSTEXPR_F int get_yearday(const civil_day& cd) noexcept {
534 CONSTEXPR_D int k_month_offsets[1 + 12] = {
535 -1, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,
536 };
537 const int feb29 = (cd.month() > 2 && impl::is_leap_year(cd.year()));
538 return k_month_offsets[cd.month()] + feb29 + cd.day();
539 }
540
541 ////////////////////////////////////////////////////////////////////////
542
543 std::ostream& operator<<(std::ostream& os, const civil_year& y);
544 std::ostream& operator<<(std::ostream& os, const civil_month& m);
545 std::ostream& operator<<(std::ostream& os, const civil_day& d);
546 std::ostream& operator<<(std::ostream& os, const civil_hour& h);
547 std::ostream& operator<<(std::ostream& os, const civil_minute& m);
548 std::ostream& operator<<(std::ostream& os, const civil_second& s);
549 std::ostream& operator<<(std::ostream& os, weekday wd);
550
551 } // namespace detail
552 } // namespace cctz
553 } // namespace time_internal
554 } // namespace absl
555
556 #undef CONSTEXPR_M
557 #undef CONSTEXPR_F
558 #undef CONSTEXPR_D
559
560 #endif // ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_
561