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 //   https://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 #include "absl/base/config.h"
24 
25 // Disable constexpr support unless we are in C++14 mode.
26 #if __cpp_constexpr >= 201304 || (defined(_MSC_VER) && _MSC_VER >= 1910)
27 #define CONSTEXPR_D constexpr  // data
28 #define CONSTEXPR_F constexpr  // function
29 #define CONSTEXPR_M constexpr  // member
30 #else
31 #define CONSTEXPR_D const
32 #define CONSTEXPR_F inline
33 #define CONSTEXPR_M
34 #endif
35 
36 namespace absl {
37 ABSL_NAMESPACE_BEGIN
38 namespace time_internal {
39 namespace cctz {
40 
41 // Support years that at least span the range of 64-bit time_t values.
42 using year_t = std::int_fast64_t;
43 
44 // Type alias that indicates an argument is not normalized (e.g., the
45 // constructor parameters and operands/results of addition/subtraction).
46 using diff_t = std::int_fast64_t;
47 
48 namespace detail {
49 
50 // Type aliases that indicate normalized argument values.
51 using month_t = std::int_fast8_t;   // [1:12]
52 using day_t = std::int_fast8_t;     // [1:31]
53 using hour_t = std::int_fast8_t;    // [0:23]
54 using minute_t = std::int_fast8_t;  // [0:59]
55 using second_t = std::int_fast8_t;  // [0:59]
56 
57 // Normalized civil-time fields: Y-M-D HH:MM:SS.
58 struct fields {
fieldsfields59   CONSTEXPR_M fields(year_t year, month_t month, day_t day, hour_t hour,
60                      minute_t minute, second_t second)
61       : y(year), m(month), d(day), hh(hour), mm(minute), ss(second) {}
62   std::int_least64_t y;
63   std::int_least8_t m;
64   std::int_least8_t d;
65   std::int_least8_t hh;
66   std::int_least8_t mm;
67   std::int_least8_t ss;
68 };
69 
70 struct second_tag {};
71 struct minute_tag : second_tag {};
72 struct hour_tag : minute_tag {};
73 struct day_tag : hour_tag {};
74 struct month_tag : day_tag {};
75 struct year_tag : month_tag {};
76 
77 ////////////////////////////////////////////////////////////////////////
78 
79 // Field normalization (without avoidable overflow).
80 
81 namespace impl {
82 
is_leap_year(year_t y)83 CONSTEXPR_F bool is_leap_year(year_t y) noexcept {
84   return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0);
85 }
year_index(year_t y,month_t m)86 CONSTEXPR_F int year_index(year_t y, month_t m) noexcept {
87   return (static_cast<int>((y + (m > 2)) % 400) + 400) % 400;
88 }
days_per_century(year_t y,month_t m)89 CONSTEXPR_F int days_per_century(year_t y, month_t m) noexcept {
90   const int yi = year_index(y, m);
91   return 36524 + (yi == 0 || yi > 300);
92 }
days_per_4years(year_t y,month_t m)93 CONSTEXPR_F int days_per_4years(year_t y, month_t m) noexcept {
94   const int yi = year_index(y, m);
95   return 1460 + (yi == 0 || yi > 300 || (yi - 1) % 100 < 96);
96 }
days_per_year(year_t y,month_t m)97 CONSTEXPR_F int days_per_year(year_t y, month_t m) noexcept {
98   return is_leap_year(y + (m > 2)) ? 366 : 365;
99 }
days_per_month(year_t y,month_t m)100 CONSTEXPR_F int days_per_month(year_t y, month_t m) noexcept {
101   CONSTEXPR_D int k_days_per_month[1 + 12] = {
102       -1, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31  // non leap year
103   };
104   return k_days_per_month[m] + (m == 2 && is_leap_year(y));
105 }
106 
n_day(year_t y,month_t m,diff_t d,diff_t cd,hour_t hh,minute_t mm,second_t ss)107 CONSTEXPR_F fields n_day(year_t y, month_t m, diff_t d, diff_t cd, hour_t hh,
108                          minute_t mm, second_t ss) noexcept {
109   year_t ey = y % 400;
110   const year_t oey = ey;
111   ey += (cd / 146097) * 400;
112   cd %= 146097;
113   if (cd < 0) {
114     ey -= 400;
115     cd += 146097;
116   }
117   ey += (d / 146097) * 400;
118   d = d % 146097 + cd;
119   if (d > 0) {
120     if (d > 146097) {
121       ey += 400;
122       d -= 146097;
123     }
124   } else {
125     if (d > -365) {
126       // We often hit the previous year when stepping a civil time backwards,
127       // so special case it to avoid counting up by 100/4/1-year chunks.
128       ey -= 1;
129       d += days_per_year(ey, m);
130     } else {
131       ey -= 400;
132       d += 146097;
133     }
134   }
135   if (d > 365) {
136     for (;;) {
137       int n = days_per_century(ey, m);
138       if (d <= n) break;
139       d -= n;
140       ey += 100;
141     }
142     for (;;) {
143       int n = days_per_4years(ey, m);
144       if (d <= n) break;
145       d -= n;
146       ey += 4;
147     }
148     for (;;) {
149       int n = days_per_year(ey, m);
150       if (d <= n) break;
151       d -= n;
152       ++ey;
153     }
154   }
155   if (d > 28) {
156     for (;;) {
157       int n = days_per_month(ey, m);
158       if (d <= n) break;
159       d -= n;
160       if (++m > 12) {
161         ++ey;
162         m = 1;
163       }
164     }
165   }
166   return fields(y + (ey - oey), m, static_cast<day_t>(d), hh, mm, ss);
167 }
n_mon(year_t y,diff_t m,diff_t d,diff_t cd,hour_t hh,minute_t mm,second_t ss)168 CONSTEXPR_F fields n_mon(year_t y, diff_t m, diff_t d, diff_t cd, hour_t hh,
169                          minute_t mm, second_t ss) noexcept {
170   if (m != 12) {
171     y += m / 12;
172     m %= 12;
173     if (m <= 0) {
174       y -= 1;
175       m += 12;
176     }
177   }
178   return n_day(y, static_cast<month_t>(m), d, cd, hh, mm, ss);
179 }
n_hour(year_t y,diff_t m,diff_t d,diff_t cd,diff_t hh,minute_t mm,second_t ss)180 CONSTEXPR_F fields n_hour(year_t y, diff_t m, diff_t d, diff_t cd, diff_t hh,
181                           minute_t mm, second_t ss) noexcept {
182   cd += hh / 24;
183   hh %= 24;
184   if (hh < 0) {
185     cd -= 1;
186     hh += 24;
187   }
188   return n_mon(y, m, d, cd, static_cast<hour_t>(hh), mm, ss);
189 }
n_min(year_t y,diff_t m,diff_t d,diff_t hh,diff_t ch,diff_t mm,second_t ss)190 CONSTEXPR_F fields n_min(year_t y, diff_t m, diff_t d, diff_t hh, diff_t ch,
191                          diff_t mm, second_t ss) noexcept {
192   ch += mm / 60;
193   mm %= 60;
194   if (mm < 0) {
195     ch -= 1;
196     mm += 60;
197   }
198   return n_hour(y, m, d, hh / 24 + ch / 24, hh % 24 + ch % 24,
199                 static_cast<minute_t>(mm), ss);
200 }
n_sec(year_t y,diff_t m,diff_t d,diff_t hh,diff_t mm,diff_t ss)201 CONSTEXPR_F fields n_sec(year_t y, diff_t m, diff_t d, diff_t hh, diff_t mm,
202                          diff_t ss) noexcept {
203   // Optimization for when (non-constexpr) fields are already normalized.
204   if (0 <= ss && ss < 60) {
205     const second_t nss = static_cast<second_t>(ss);
206     if (0 <= mm && mm < 60) {
207       const minute_t nmm = static_cast<minute_t>(mm);
208       if (0 <= hh && hh < 24) {
209         const hour_t nhh = static_cast<hour_t>(hh);
210         if (1 <= d && d <= 28 && 1 <= m && m <= 12) {
211           const day_t nd = static_cast<day_t>(d);
212           const month_t nm = static_cast<month_t>(m);
213           return fields(y, nm, nd, nhh, nmm, nss);
214         }
215         return n_mon(y, m, d, 0, nhh, nmm, nss);
216       }
217       return n_hour(y, m, d, hh / 24, hh % 24, nmm, nss);
218     }
219     return n_min(y, m, d, hh, mm / 60, mm % 60, nss);
220   }
221   diff_t cm = ss / 60;
222   ss %= 60;
223   if (ss < 0) {
224     cm -= 1;
225     ss += 60;
226   }
227   return n_min(y, m, d, hh, mm / 60 + cm / 60, mm % 60 + cm % 60,
228                static_cast<second_t>(ss));
229 }
230 
231 }  // namespace impl
232 
233 ////////////////////////////////////////////////////////////////////////
234 
235 // Increments the indicated (normalized) field by "n".
step(second_tag,fields f,diff_t n)236 CONSTEXPR_F fields step(second_tag, fields f, diff_t n) noexcept {
237   return impl::n_sec(f.y, f.m, f.d, f.hh, f.mm + n / 60, f.ss + n % 60);
238 }
step(minute_tag,fields f,diff_t n)239 CONSTEXPR_F fields step(minute_tag, fields f, diff_t n) noexcept {
240   return impl::n_min(f.y, f.m, f.d, f.hh + n / 60, 0, f.mm + n % 60, f.ss);
241 }
step(hour_tag,fields f,diff_t n)242 CONSTEXPR_F fields step(hour_tag, fields f, diff_t n) noexcept {
243   return impl::n_hour(f.y, f.m, f.d + n / 24, 0, f.hh + n % 24, f.mm, f.ss);
244 }
step(day_tag,fields f,diff_t n)245 CONSTEXPR_F fields step(day_tag, fields f, diff_t n) noexcept {
246   return impl::n_day(f.y, f.m, f.d, n, f.hh, f.mm, f.ss);
247 }
step(month_tag,fields f,diff_t n)248 CONSTEXPR_F fields step(month_tag, fields f, diff_t n) noexcept {
249   return impl::n_mon(f.y + n / 12, f.m + n % 12, f.d, 0, f.hh, f.mm, f.ss);
250 }
step(year_tag,fields f,diff_t n)251 CONSTEXPR_F fields step(year_tag, fields f, diff_t n) noexcept {
252   return fields(f.y + n, f.m, f.d, f.hh, f.mm, f.ss);
253 }
254 
255 ////////////////////////////////////////////////////////////////////////
256 
257 namespace impl {
258 
259 // Returns (v * f + a) but avoiding intermediate overflow when possible.
scale_add(diff_t v,diff_t f,diff_t a)260 CONSTEXPR_F diff_t scale_add(diff_t v, diff_t f, diff_t a) noexcept {
261   return (v < 0) ? ((v + 1) * f + a) - f : ((v - 1) * f + a) + f;
262 }
263 
264 // Map a (normalized) Y/M/D to the number of days before/after 1970-01-01.
265 // Probably overflows for years outside [-292277022656:292277026595].
ymd_ord(year_t y,month_t m,day_t d)266 CONSTEXPR_F diff_t ymd_ord(year_t y, month_t m, day_t d) noexcept {
267   const diff_t eyear = (m <= 2) ? y - 1 : y;
268   const diff_t era = (eyear >= 0 ? eyear : eyear - 399) / 400;
269   const diff_t yoe = eyear - era * 400;
270   const diff_t doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1;
271   const diff_t doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
272   return era * 146097 + doe - 719468;
273 }
274 
275 // Returns the difference in days between two normalized Y-M-D tuples.
276 // ymd_ord() will encounter integer overflow given extreme year values,
277 // yet the difference between two such extreme values may actually be
278 // small, so we take a little care to avoid overflow when possible by
279 // 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)280 CONSTEXPR_F diff_t day_difference(year_t y1, month_t m1, day_t d1, year_t y2,
281                                   month_t m2, day_t d2) noexcept {
282   const diff_t a_c4_off = y1 % 400;
283   const diff_t b_c4_off = y2 % 400;
284   diff_t c4_diff = (y1 - a_c4_off) - (y2 - b_c4_off);
285   diff_t delta = ymd_ord(a_c4_off, m1, d1) - ymd_ord(b_c4_off, m2, d2);
286   if (c4_diff > 0 && delta < 0) {
287     delta += 2 * 146097;
288     c4_diff -= 2 * 400;
289   } else if (c4_diff < 0 && delta > 0) {
290     delta -= 2 * 146097;
291     c4_diff += 2 * 400;
292   }
293   return (c4_diff / 400 * 146097) + delta;
294 }
295 
296 }  // namespace impl
297 
298 // Returns the difference between fields structs using the indicated unit.
difference(year_tag,fields f1,fields f2)299 CONSTEXPR_F diff_t difference(year_tag, fields f1, fields f2) noexcept {
300   return f1.y - f2.y;
301 }
difference(month_tag,fields f1,fields f2)302 CONSTEXPR_F diff_t difference(month_tag, fields f1, fields f2) noexcept {
303   return impl::scale_add(difference(year_tag{}, f1, f2), 12, (f1.m - f2.m));
304 }
difference(day_tag,fields f1,fields f2)305 CONSTEXPR_F diff_t difference(day_tag, fields f1, fields f2) noexcept {
306   return impl::day_difference(f1.y, f1.m, f1.d, f2.y, f2.m, f2.d);
307 }
difference(hour_tag,fields f1,fields f2)308 CONSTEXPR_F diff_t difference(hour_tag, fields f1, fields f2) noexcept {
309   return impl::scale_add(difference(day_tag{}, f1, f2), 24, (f1.hh - f2.hh));
310 }
difference(minute_tag,fields f1,fields f2)311 CONSTEXPR_F diff_t difference(minute_tag, fields f1, fields f2) noexcept {
312   return impl::scale_add(difference(hour_tag{}, f1, f2), 60, (f1.mm - f2.mm));
313 }
difference(second_tag,fields f1,fields f2)314 CONSTEXPR_F diff_t difference(second_tag, fields f1, fields f2) noexcept {
315   return impl::scale_add(difference(minute_tag{}, f1, f2), 60, f1.ss - f2.ss);
316 }
317 
318 ////////////////////////////////////////////////////////////////////////
319 
320 // Aligns the (normalized) fields struct to the indicated field.
align(second_tag,fields f)321 CONSTEXPR_F fields align(second_tag, fields f) noexcept { return f; }
align(minute_tag,fields f)322 CONSTEXPR_F fields align(minute_tag, fields f) noexcept {
323   return fields{f.y, f.m, f.d, f.hh, f.mm, 0};
324 }
align(hour_tag,fields f)325 CONSTEXPR_F fields align(hour_tag, fields f) noexcept {
326   return fields{f.y, f.m, f.d, f.hh, 0, 0};
327 }
align(day_tag,fields f)328 CONSTEXPR_F fields align(day_tag, fields f) noexcept {
329   return fields{f.y, f.m, f.d, 0, 0, 0};
330 }
align(month_tag,fields f)331 CONSTEXPR_F fields align(month_tag, fields f) noexcept {
332   return fields{f.y, f.m, 1, 0, 0, 0};
333 }
align(year_tag,fields f)334 CONSTEXPR_F fields align(year_tag, fields f) noexcept {
335   return fields{f.y, 1, 1, 0, 0, 0};
336 }
337 
338 ////////////////////////////////////////////////////////////////////////
339 
340 namespace impl {
341 
342 template <typename H>
AbslHashValueImpl(second_tag,H h,fields f)343 H AbslHashValueImpl(second_tag, H h, fields f) {
344   return H::combine(std::move(h), f.y, f.m, f.d, f.hh, f.mm, f.ss);
345 }
346 template <typename H>
AbslHashValueImpl(minute_tag,H h,fields f)347 H AbslHashValueImpl(minute_tag, H h, fields f) {
348   return H::combine(std::move(h), f.y, f.m, f.d, f.hh, f.mm);
349 }
350 template <typename H>
AbslHashValueImpl(hour_tag,H h,fields f)351 H AbslHashValueImpl(hour_tag, H h, fields f) {
352   return H::combine(std::move(h), f.y, f.m, f.d, f.hh);
353 }
354 template <typename H>
AbslHashValueImpl(day_tag,H h,fields f)355 H AbslHashValueImpl(day_tag, H h, fields f) {
356   return H::combine(std::move(h), f.y, f.m, f.d);
357 }
358 template <typename H>
AbslHashValueImpl(month_tag,H h,fields f)359 H AbslHashValueImpl(month_tag, H h, fields f) {
360   return H::combine(std::move(h), f.y, f.m);
361 }
362 template <typename H>
AbslHashValueImpl(year_tag,H h,fields f)363 H AbslHashValueImpl(year_tag, H h, fields f) {
364   return H::combine(std::move(h), f.y);
365 }
366 
367 }  // namespace impl
368 
369 ////////////////////////////////////////////////////////////////////////
370 
371 template <typename T>
372 class civil_time {
373  public:
374   explicit CONSTEXPR_M civil_time(year_t y, diff_t m = 1, diff_t d = 1,
375                                   diff_t hh = 0, diff_t mm = 0,
376                                   diff_t ss = 0) noexcept
civil_time(impl::n_sec (y,m,d,hh,mm,ss))377       : civil_time(impl::n_sec(y, m, d, hh, mm, ss)) {}
378 
civil_time()379   CONSTEXPR_M civil_time() noexcept : f_{1970, 1, 1, 0, 0, 0} {}
380   civil_time(const civil_time&) = default;
381   civil_time& operator=(const civil_time&) = default;
382 
383   // Conversion between civil times of different alignment. Conversion to
384   // a more precise alignment is allowed implicitly (e.g., day -> hour),
385   // but conversion where information is discarded must be explicit
386   // (e.g., second -> minute).
387   template <typename U, typename S>
388   using preserves_data =
389       typename std::enable_if<std::is_base_of<U, S>::value>::type;
390   template <typename U>
391   CONSTEXPR_M civil_time(const civil_time<U>& ct,
392                          preserves_data<T, U>* = nullptr) noexcept
393       : civil_time(ct.f_) {}
394   template <typename U>
395   explicit CONSTEXPR_M civil_time(const civil_time<U>& ct,
396                                   preserves_data<U, T>* = nullptr) noexcept
397       : civil_time(ct.f_) {}
398 
399   // Factories for the maximum/minimum representable civil_time.
civil_time(max)400   static CONSTEXPR_F civil_time(max)() {
401     const auto max_year = (std::numeric_limits<std::int_least64_t>::max)();
402     return civil_time(max_year, 12, 31, 23, 59, 59);
403   }
civil_time(min)404   static CONSTEXPR_F civil_time(min)() {
405     const auto min_year = (std::numeric_limits<std::int_least64_t>::min)();
406     return civil_time(min_year, 1, 1, 0, 0, 0);
407   }
408 
409   // Field accessors.  Note: All but year() return an int.
year()410   CONSTEXPR_M year_t year() const noexcept { return f_.y; }
month()411   CONSTEXPR_M int month() const noexcept { return f_.m; }
day()412   CONSTEXPR_M int day() const noexcept { return f_.d; }
hour()413   CONSTEXPR_M int hour() const noexcept { return f_.hh; }
minute()414   CONSTEXPR_M int minute() const noexcept { return f_.mm; }
second()415   CONSTEXPR_M int second() const noexcept { return f_.ss; }
416 
417   // Assigning arithmetic.
418   CONSTEXPR_M civil_time& operator+=(diff_t n) noexcept {
419     return *this = *this + n;
420   }
421   CONSTEXPR_M civil_time& operator-=(diff_t n) noexcept {
422     return *this = *this - n;
423   }
424   CONSTEXPR_M civil_time& operator++() noexcept { return *this += 1; }
425   CONSTEXPR_M civil_time operator++(int) noexcept {
426     const civil_time a = *this;
427     ++*this;
428     return a;
429   }
430   CONSTEXPR_M civil_time& operator--() noexcept { return *this -= 1; }
431   CONSTEXPR_M civil_time operator--(int) noexcept {
432     const civil_time a = *this;
433     --*this;
434     return a;
435   }
436 
437   // Binary arithmetic operators.
438   friend CONSTEXPR_F civil_time operator+(civil_time a, diff_t n) noexcept {
439     return civil_time(step(T{}, a.f_, n));
440   }
441   friend CONSTEXPR_F civil_time operator+(diff_t n, civil_time a) noexcept {
442     return a + n;
443   }
444   friend CONSTEXPR_F civil_time operator-(civil_time a, diff_t n) noexcept {
445     return n != (std::numeric_limits<diff_t>::min)()
446                ? civil_time(step(T{}, a.f_, -n))
447                : civil_time(step(T{}, step(T{}, a.f_, -(n + 1)), 1));
448   }
449   friend CONSTEXPR_F diff_t operator-(civil_time lhs, civil_time rhs) noexcept {
450     return difference(T{}, lhs.f_, rhs.f_);
451   }
452 
453   template <typename H>
AbslHashValue(H h,civil_time a)454   friend H AbslHashValue(H h, civil_time a) {
455     return impl::AbslHashValueImpl(T{}, std::move(h), a.f_);
456   }
457 
458  private:
459   // All instantiations of this template are allowed to call the following
460   // private constructor and access the private fields member.
461   template <typename U>
462   friend class civil_time;
463 
464   // The designated constructor that all others eventually call.
civil_time(fields f)465   explicit CONSTEXPR_M civil_time(fields f) noexcept : f_(align(T{}, f)) {}
466 
467   fields f_;
468 };
469 
470 // Disallows difference between differently aligned types.
471 // auto n = civil_day(...) - civil_hour(...);  // would be confusing.
472 template <typename T, typename U>
473 CONSTEXPR_F diff_t operator-(civil_time<T>, civil_time<U>) = delete;
474 
475 using civil_year = civil_time<year_tag>;
476 using civil_month = civil_time<month_tag>;
477 using civil_day = civil_time<day_tag>;
478 using civil_hour = civil_time<hour_tag>;
479 using civil_minute = civil_time<minute_tag>;
480 using civil_second = civil_time<second_tag>;
481 
482 ////////////////////////////////////////////////////////////////////////
483 
484 // Relational operators that work with differently aligned objects.
485 // Always compares all six fields.
486 template <typename T1, typename T2>
487 CONSTEXPR_F bool operator<(const civil_time<T1>& lhs,
488                            const civil_time<T2>& rhs) noexcept {
489   return (
490       lhs.year() < rhs.year() ||
491       (lhs.year() == rhs.year() &&
492        (lhs.month() < rhs.month() ||
493         (lhs.month() == rhs.month() &&
494          (lhs.day() < rhs.day() || (lhs.day() == rhs.day() &&
495                                     (lhs.hour() < rhs.hour() ||
496                                      (lhs.hour() == rhs.hour() &&
497                                       (lhs.minute() < rhs.minute() ||
498                                        (lhs.minute() == rhs.minute() &&
499                                         (lhs.second() < rhs.second())))))))))));
500 }
501 template <typename T1, typename T2>
502 CONSTEXPR_F bool operator<=(const civil_time<T1>& lhs,
503                             const civil_time<T2>& rhs) noexcept {
504   return !(rhs < lhs);
505 }
506 template <typename T1, typename T2>
507 CONSTEXPR_F bool operator>=(const civil_time<T1>& lhs,
508                             const civil_time<T2>& rhs) noexcept {
509   return !(lhs < rhs);
510 }
511 template <typename T1, typename T2>
512 CONSTEXPR_F bool operator>(const civil_time<T1>& lhs,
513                            const civil_time<T2>& rhs) noexcept {
514   return rhs < lhs;
515 }
516 template <typename T1, typename T2>
517 CONSTEXPR_F bool operator==(const civil_time<T1>& lhs,
518                             const civil_time<T2>& rhs) noexcept {
519   return lhs.year() == rhs.year() && lhs.month() == rhs.month() &&
520          lhs.day() == rhs.day() && lhs.hour() == rhs.hour() &&
521          lhs.minute() == rhs.minute() && lhs.second() == rhs.second();
522 }
523 template <typename T1, typename T2>
524 CONSTEXPR_F bool operator!=(const civil_time<T1>& lhs,
525                             const civil_time<T2>& rhs) noexcept {
526   return !(lhs == rhs);
527 }
528 
529 ////////////////////////////////////////////////////////////////////////
530 
531 enum class weekday {
532   monday,
533   tuesday,
534   wednesday,
535   thursday,
536   friday,
537   saturday,
538   sunday,
539 };
540 
get_weekday(const civil_second & cs)541 CONSTEXPR_F weekday get_weekday(const civil_second& cs) noexcept {
542   CONSTEXPR_D weekday k_weekday_by_mon_off[13] = {
543       weekday::monday,    weekday::tuesday,  weekday::wednesday,
544       weekday::thursday,  weekday::friday,   weekday::saturday,
545       weekday::sunday,    weekday::monday,   weekday::tuesday,
546       weekday::wednesday, weekday::thursday, weekday::friday,
547       weekday::saturday,
548   };
549   CONSTEXPR_D int k_weekday_offsets[1 + 12] = {
550       -1, 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4,
551   };
552   year_t wd = 2400 + (cs.year() % 400) - (cs.month() < 3);
553   wd += wd / 4 - wd / 100 + wd / 400;
554   wd += k_weekday_offsets[cs.month()] + cs.day();
555   return k_weekday_by_mon_off[wd % 7 + 6];
556 }
557 
558 ////////////////////////////////////////////////////////////////////////
559 
next_weekday(civil_day cd,weekday wd)560 CONSTEXPR_F civil_day next_weekday(civil_day cd, weekday wd) noexcept {
561   CONSTEXPR_D weekday k_weekdays_forw[14] = {
562       weekday::monday,    weekday::tuesday,  weekday::wednesday,
563       weekday::thursday,  weekday::friday,   weekday::saturday,
564       weekday::sunday,    weekday::monday,   weekday::tuesday,
565       weekday::wednesday, weekday::thursday, weekday::friday,
566       weekday::saturday,  weekday::sunday,
567   };
568   weekday base = get_weekday(cd);
569   for (int i = 0;; ++i) {
570     if (base == k_weekdays_forw[i]) {
571       for (int j = i + 1;; ++j) {
572         if (wd == k_weekdays_forw[j]) {
573           return cd + (j - i);
574         }
575       }
576     }
577   }
578 }
579 
prev_weekday(civil_day cd,weekday wd)580 CONSTEXPR_F civil_day prev_weekday(civil_day cd, weekday wd) noexcept {
581   CONSTEXPR_D weekday k_weekdays_back[14] = {
582       weekday::sunday,   weekday::saturday,  weekday::friday,
583       weekday::thursday, weekday::wednesday, weekday::tuesday,
584       weekday::monday,   weekday::sunday,    weekday::saturday,
585       weekday::friday,   weekday::thursday,  weekday::wednesday,
586       weekday::tuesday,  weekday::monday,
587   };
588   weekday base = get_weekday(cd);
589   for (int i = 0;; ++i) {
590     if (base == k_weekdays_back[i]) {
591       for (int j = i + 1;; ++j) {
592         if (wd == k_weekdays_back[j]) {
593           return cd - (j - i);
594         }
595       }
596     }
597   }
598 }
599 
get_yearday(const civil_second & cs)600 CONSTEXPR_F int get_yearday(const civil_second& cs) noexcept {
601   CONSTEXPR_D int k_month_offsets[1 + 12] = {
602       -1, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,
603   };
604   const int feb29 = (cs.month() > 2 && impl::is_leap_year(cs.year()));
605   return k_month_offsets[cs.month()] + feb29 + cs.day();
606 }
607 
608 ////////////////////////////////////////////////////////////////////////
609 
610 std::ostream& operator<<(std::ostream& os, const civil_year& y);
611 std::ostream& operator<<(std::ostream& os, const civil_month& m);
612 std::ostream& operator<<(std::ostream& os, const civil_day& d);
613 std::ostream& operator<<(std::ostream& os, const civil_hour& h);
614 std::ostream& operator<<(std::ostream& os, const civil_minute& m);
615 std::ostream& operator<<(std::ostream& os, const civil_second& s);
616 std::ostream& operator<<(std::ostream& os, weekday wd);
617 
618 }  // namespace detail
619 }  // namespace cctz
620 }  // namespace time_internal
621 ABSL_NAMESPACE_END
622 }  // namespace absl
623 
624 #undef CONSTEXPR_M
625 #undef CONSTEXPR_F
626 #undef CONSTEXPR_D
627 
628 #endif  // ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_
629