text: // Copyright 2016 Google Inc. All Rights Reserved.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //   https://www.apache.org/licenses/LICENSE-2.0
  //
  //   Unless required by applicable law or agreed to in writing, software
  //   distributed under the License is distributed on an "AS IS" BASIS,
  //   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  //   See the License for the specific language governing permissions and
  //   limitations under the License.
  
  #ifndef ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_
  #define ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_
  
  #include <cstdint>
  #include <limits>
  #include <ostream>
  #include <type_traits>
  
  #include "absl/base/config.h"
  
  // Disable constexpr support unless we are in C++14 mode.
  #if __cpp_constexpr >= 201304 || (defined(_MSC_VER) && _MSC_VER >= 1910)
  #define CONSTEXPR_D constexpr  // data
  #define CONSTEXPR_F constexpr  // function
  #define CONSTEXPR_M constexpr  // member
  #else
  #define CONSTEXPR_D const
  #define CONSTEXPR_F inline
  #define CONSTEXPR_M
  #endif
  
  namespace absl {
  ABSL_NAMESPACE_BEGIN
  namespace time_internal {
  namespace cctz {
  
  // Support years that at least span the range of 64-bit time_t values.
  using year_t = std::int_fast64_t;
  
  // Type alias that indicates an argument is not normalized (e.g., the
  // constructor parameters and operands/results of addition/subtraction).
  using diff_t = std::int_fast64_t;
  
  namespace detail {
  
  // Type aliases that indicate normalized argument values.
  using month_t = std::int_fast8_t;   // [1:12]
  using day_t = std::int_fast8_t;     // [1:31]
  using hour_t = std::int_fast8_t;    // [0:23]
  using minute_t = std::int_fast8_t;  // [0:59]
  using second_t = std::int_fast8_t;  // [0:59]
  
  // Normalized civil-time fields: Y-M-D HH:MM:SS.
  struct fields {
    CONSTEXPR_M fields(year_t year, month_t month, day_t day, hour_t hour,
                       minute_t minute, second_t second)
        : y(year), m(month), d(day), hh(hour), mm(minute), ss(second) {}
    std::int_least64_t y;
    std::int_least8_t m;
    std::int_least8_t d;
    std::int_least8_t hh;
    std::int_least8_t mm;
    std::int_least8_t ss;
  };
  
  struct second_tag {};
  struct minute_tag : second_tag {};
  struct hour_tag : minute_tag {};
  struct day_tag : hour_tag {};
  struct month_tag : day_tag {};
  struct year_tag : month_tag {};
  
  ////////////////////////////////////////////////////////////////////////
  
  // Field normalization (without avoidable overflow).
  
  namespace impl {
  
  CONSTEXPR_F bool is_leap_year(year_t y) noexcept {
    return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0);
  }
  CONSTEXPR_F int year_index(year_t y, month_t m) noexcept {
    return (static_cast<int>((y + (m > 2)) % 400) + 400) % 400;
  }
  CONSTEXPR_F int days_per_century(year_t y, month_t m) noexcept {
    const int yi = year_index(y, m);
    return 36524 + (yi == 0 || yi > 300);
  }
  CONSTEXPR_F int days_per_4years(year_t y, month_t m) noexcept {
    const int yi = year_index(y, m);
    return 1460 + (yi == 0 || yi > 300 || (yi - 1) % 100 < 96);
  }
  CONSTEXPR_F int days_per_year(year_t y, month_t m) noexcept {
    return is_leap_year(y + (m > 2)) ? 366 : 365;
  }
  CONSTEXPR_F int days_per_month(year_t y, month_t m) noexcept {
    CONSTEXPR_D int k_days_per_month[1 + 12] = {
        -1, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31  // non leap year
    };
    return k_days_per_month[m] + (m == 2 && is_leap_year(y));
  }
  
  CONSTEXPR_F fields n_day(year_t y, month_t m, diff_t d, diff_t cd, hour_t hh,
                           minute_t mm, second_t ss) noexcept {
    year_t ey = y % 400;
    const year_t oey = ey;
    ey += (cd / 146097) * 400;
    cd %= 146097;
    if (cd < 0) {
      ey -= 400;
      cd += 146097;
    }
    ey += (d / 146097) * 400;
    d = d % 146097 + cd;
    if (d > 0) {
      if (d > 146097) {
        ey += 400;
        d -= 146097;
      }
    } else {
      if (d > -365) {
        // We often hit the previous year when stepping a civil time backwards,
        // so special case it to avoid counting up by 100/4/1-year chunks.
        ey -= 1;
        d += days_per_year(ey, m);
      } else {
        ey -= 400;
        d += 146097;
      }
    }
    if (d > 365) {
      for (;;) {
        int n = days_per_century(ey, m);
        if (d <= n) break;
        d -= n;
        ey += 100;
      }
      for (;;) {
        int n = days_per_4years(ey, m);
        if (d <= n) break;
        d -= n;
        ey += 4;
      }
      for (;;) {
        int n = days_per_year(ey, m);
        if (d <= n) break;
        d -= n;
        ++ey;
      }
    }
    if (d > 28) {
      for (;;) {
        int n = days_per_month(ey, m);
        if (d <= n) break;
        d -= n;
        if (++m > 12) {
          ++ey;
          m = 1;
        }
      }
    }
    return fields(y + (ey - oey), m, static_cast<day_t>(d), hh, mm, ss);
  }
  CONSTEXPR_F fields n_mon(year_t y, diff_t m, diff_t d, diff_t cd, hour_t hh,
                           minute_t mm, second_t ss) noexcept {
    if (m != 12) {
      y += m / 12;
      m %= 12;
      if (m <= 0) {
        y -= 1;
        m += 12;
      }
    }
    return n_day(y, static_cast<month_t>(m), d, cd, hh, mm, ss);
  }
  CONSTEXPR_F fields n_hour(year_t y, diff_t m, diff_t d, diff_t cd, diff_t hh,
                            minute_t mm, second_t ss) noexcept {
    cd += hh / 24;
    hh %= 24;
    if (hh < 0) {
      cd -= 1;
      hh += 24;
    }
    return n_mon(y, m, d, cd, static_cast<hour_t>(hh), mm, ss);
  }
  CONSTEXPR_F fields n_min(year_t y, diff_t m, diff_t d, diff_t hh, diff_t ch,
                           diff_t mm, second_t ss) noexcept {
    ch += mm / 60;
    mm %= 60;
    if (mm < 0) {
      ch -= 1;
      mm += 60;
    }
    return n_hour(y, m, d, hh / 24 + ch / 24, hh % 24 + ch % 24,
                  static_cast<minute_t>(mm), ss);
  }
  CONSTEXPR_F fields n_sec(year_t y, diff_t m, diff_t d, diff_t hh, diff_t mm,
                           diff_t ss) noexcept {
    // Optimization for when (non-constexpr) fields are already normalized.
    if (0 <= ss && ss < 60) {
      const second_t nss = static_cast<second_t>(ss);
      if (0 <= mm && mm < 60) {
        const minute_t nmm = static_cast<minute_t>(mm);
        if (0 <= hh && hh < 24) {
          const hour_t nhh = static_cast<hour_t>(hh);
          if (1 <= d && d <= 28 && 1 <= m && m <= 12) {
            const day_t nd = static_cast<day_t>(d);
            const month_t nm = static_cast<month_t>(m);
            return fields(y, nm, nd, nhh, nmm, nss);
          }
          return n_mon(y, m, d, 0, nhh, nmm, nss);
        }
        return n_hour(y, m, d, hh / 24, hh % 24, nmm, nss);
      }
      return n_min(y, m, d, hh, mm / 60, mm % 60, nss);
    }
    diff_t cm = ss / 60;
    ss %= 60;
    if (ss < 0) {
      cm -= 1;
      ss += 60;
    }
    return n_min(y, m, d, hh, mm / 60 + cm / 60, mm % 60 + cm % 60,
                 static_cast<second_t>(ss));
  }
  
  }  // namespace impl
  
  ////////////////////////////////////////////////////////////////////////
  
  // Increments the indicated (normalized) field by "n".
  CONSTEXPR_F fields step(second_tag, fields f, diff_t n) noexcept {
    return impl::n_sec(f.y, f.m, f.d, f.hh, f.mm + n / 60, f.ss + n % 60);
  }
  CONSTEXPR_F fields step(minute_tag, fields f, diff_t n) noexcept {
    return impl::n_min(f.y, f.m, f.d, f.hh + n / 60, 0, f.mm + n % 60, f.ss);
  }
  CONSTEXPR_F fields step(hour_tag, fields f, diff_t n) noexcept {
    return impl::n_hour(f.y, f.m, f.d + n / 24, 0, f.hh + n % 24, f.mm, f.ss);
  }
  CONSTEXPR_F fields step(day_tag, fields f, diff_t n) noexcept {
    return impl::n_day(f.y, f.m, f.d, n, f.hh, f.mm, f.ss);
  }
  CONSTEXPR_F fields step(month_tag, fields f, diff_t n) noexcept {
    return impl::n_mon(f.y + n / 12, f.m + n % 12, f.d, 0, f.hh, f.mm, f.ss);
  }
  CONSTEXPR_F fields step(year_tag, fields f, diff_t n) noexcept {
    return fields(f.y + n, f.m, f.d, f.hh, f.mm, f.ss);
  }
  
  ////////////////////////////////////////////////////////////////////////
  
  namespace impl {
  
  // Returns (v * f + a) but avoiding intermediate overflow when possible.
  CONSTEXPR_F diff_t scale_add(diff_t v, diff_t f, diff_t a) noexcept {
    return (v < 0) ? ((v + 1) * f + a) - f : ((v - 1) * f + a) + f;
  }
  
  // Map a (normalized) Y/M/D to the number of days before/after 1970-01-01.
  // Probably overflows for years outside [-292277022656:292277026595].
  CONSTEXPR_F diff_t ymd_ord(year_t y, month_t m, day_t d) noexcept {
    const diff_t eyear = (m <= 2) ? y - 1 : y;
    const diff_t era = (eyear >= 0 ? eyear : eyear - 399) / 400;
    const diff_t yoe = eyear - era * 400;
    const diff_t doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1;
    const diff_t doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
    return era * 146097 + doe - 719468;
  }
  
  // Returns the difference in days between two normalized Y-M-D tuples.
  // ymd_ord() will encounter integer overflow given extreme year values,
  // yet the difference between two such extreme values may actually be
  // small, so we take a little care to avoid overflow when possible by
  // exploiting the 146097-day cycle.
  CONSTEXPR_F diff_t day_difference(year_t y1, month_t m1, day_t d1, year_t y2,
                                    month_t m2, day_t d2) noexcept {
    const diff_t a_c4_off = y1 % 400;
    const diff_t b_c4_off = y2 % 400;
    diff_t c4_diff = (y1 - a_c4_off) - (y2 - b_c4_off);
    diff_t delta = ymd_ord(a_c4_off, m1, d1) - ymd_ord(b_c4_off, m2, d2);
    if (c4_diff > 0 && delta < 0) {
      delta += 2 * 146097;
      c4_diff -= 2 * 400;
    } else if (c4_diff < 0 && delta > 0) {
      delta -= 2 * 146097;
      c4_diff += 2 * 400;
    }
    return (c4_diff / 400 * 146097) + delta;
  }
  
  }  // namespace impl
  
  // Returns the difference between fields structs using the indicated unit.
  CONSTEXPR_F diff_t difference(year_tag, fields f1, fields f2) noexcept {
    return f1.y - f2.y;
  }
  CONSTEXPR_F diff_t difference(month_tag, fields f1, fields f2) noexcept {
    return impl::scale_add(difference(year_tag{}, f1, f2), 12, (f1.m - f2.m));
  }
  CONSTEXPR_F diff_t difference(day_tag, fields f1, fields f2) noexcept {
    return impl::day_difference(f1.y, f1.m, f1.d, f2.y, f2.m, f2.d);
  }
  CONSTEXPR_F diff_t difference(hour_tag, fields f1, fields f2) noexcept {
    return impl::scale_add(difference(day_tag{}, f1, f2), 24, (f1.hh - f2.hh));
  }
  CONSTEXPR_F diff_t difference(minute_tag, fields f1, fields f2) noexcept {
    return impl::scale_add(difference(hour_tag{}, f1, f2), 60, (f1.mm - f2.mm));
  }
  CONSTEXPR_F diff_t difference(second_tag, fields f1, fields f2) noexcept {
    return impl::scale_add(difference(minute_tag{}, f1, f2), 60, f1.ss - f2.ss);
  }
  
  ////////////////////////////////////////////////////////////////////////
  
  // Aligns the (normalized) fields struct to the indicated field.
  CONSTEXPR_F fields align(second_tag, fields f) noexcept { return f; }
  CONSTEXPR_F fields align(minute_tag, fields f) noexcept {
    return fields{f.y, f.m, f.d, f.hh, f.mm, 0};
  }
  CONSTEXPR_F fields align(hour_tag, fields f) noexcept {
    return fields{f.y, f.m, f.d, f.hh, 0, 0};
  }
  CONSTEXPR_F fields align(day_tag, fields f) noexcept {
    return fields{f.y, f.m, f.d, 0, 0, 0};
  }
  CONSTEXPR_F fields align(month_tag, fields f) noexcept {
    return fields{f.y, f.m, 1, 0, 0, 0};
  }
  CONSTEXPR_F fields align(year_tag, fields f) noexcept {
    return fields{f.y, 1, 1, 0, 0, 0};
  }
  
  ////////////////////////////////////////////////////////////////////////
  
  namespace impl {
  
  template <typename H>
  H AbslHashValueImpl(second_tag, H h, fields f) {
    return H::combine(std::move(h), f.y, f.m, f.d, f.hh, f.mm, f.ss);
  }
  template <typename H>
  H AbslHashValueImpl(minute_tag, H h, fields f) {
    return H::combine(std::move(h), f.y, f.m, f.d, f.hh, f.mm);
  }
  template <typename H>
  H AbslHashValueImpl(hour_tag, H h, fields f) {
    return H::combine(std::move(h), f.y, f.m, f.d, f.hh);
  }
  template <typename H>
  H AbslHashValueImpl(day_tag, H h, fields f) {
    return H::combine(std::move(h), f.y, f.m, f.d);
  }
  template <typename H>
  H AbslHashValueImpl(month_tag, H h, fields f) {
    return H::combine(std::move(h), f.y, f.m);
  }
  template <typename H>
  H AbslHashValueImpl(year_tag, H h, fields f) {
    return H::combine(std::move(h), f.y);
  }
  
  }  // namespace impl
  
  ////////////////////////////////////////////////////////////////////////
  
  template <typename T>
  class civil_time {
   public:
    explicit CONSTEXPR_M civil_time(year_t y, diff_t m = 1, diff_t d = 1,
                                    diff_t hh = 0, diff_t mm = 0,
                                    diff_t ss = 0) noexcept
        : civil_time(impl::n_sec(y, m, d, hh, mm, ss)) {}
  
    CONSTEXPR_M civil_time() noexcept : f_{1970, 1, 1, 0, 0, 0} {}
    civil_time(const civil_time&) = default;
    civil_time& operator=(const civil_time&) = default;
  
    // Conversion between civil times of different alignment. Conversion to
    // a more precise alignment is allowed implicitly (e.g., day -> hour),
    // but conversion where information is discarded must be explicit
    // (e.g., second -> minute).
    template <typename U, typename S>
    using preserves_data =
        typename std::enable_if<std::is_base_of<U, S>::value>::type;
    template <typename U>
    CONSTEXPR_M civil_time(const civil_time<U>& ct,
                           preserves_data<T, U>* = nullptr) noexcept
        : civil_time(ct.f_) {}
    template <typename U>
    explicit CONSTEXPR_M civil_time(const civil_time<U>& ct,
                                    preserves_data<U, T>* = nullptr) noexcept
        : civil_time(ct.f_) {}
  
    // Factories for the maximum/minimum representable civil_time.
    static CONSTEXPR_F civil_time(max)() {
      const auto max_year = (std::numeric_limits<std::int_least64_t>::max)();
      return civil_time(max_year, 12, 31, 23, 59, 59);
    }
    static CONSTEXPR_F civil_time(min)() {
      const auto min_year = (std::numeric_limits<std::int_least64_t>::min)();
      return civil_time(min_year, 1, 1, 0, 0, 0);
    }
  
    // Field accessors.  Note: All but year() return an int.
    CONSTEXPR_M year_t year() const noexcept { return f_.y; }
    CONSTEXPR_M int month() const noexcept { return f_.m; }
    CONSTEXPR_M int day() const noexcept { return f_.d; }
    CONSTEXPR_M int hour() const noexcept { return f_.hh; }
    CONSTEXPR_M int minute() const noexcept { return f_.mm; }
    CONSTEXPR_M int second() const noexcept { return f_.ss; }
  
    // Assigning arithmetic.
    CONSTEXPR_M civil_time& operator+=(diff_t n) noexcept {
      f_ = step(T{}, f_, n);
      return *this;
    }
    CONSTEXPR_M civil_time& operator-=(diff_t n) noexcept {
      if (n != (std::numeric_limits<diff_t>::min)()) {
        f_ = step(T{}, f_, -n);
      } else {
        f_ = step(T{}, step(T{}, f_, -(n + 1)), 1);
      }
      return *this;
    }
    CONSTEXPR_M civil_time& operator++() noexcept { return *this += 1; }
    CONSTEXPR_M civil_time operator++(int) noexcept {
      const civil_time a = *this;
      ++*this;
      return a;
    }
    CONSTEXPR_M civil_time& operator--() noexcept { return *this -= 1; }
    CONSTEXPR_M civil_time operator--(int) noexcept {
      const civil_time a = *this;
      --*this;
      return a;
    }
  
    // Binary arithmetic operators.
    friend CONSTEXPR_F civil_time operator+(civil_time a, diff_t n) noexcept {
      return a += n;
    }
    friend CONSTEXPR_F civil_time operator+(diff_t n, civil_time a) noexcept {
      return a += n;
    }
    friend CONSTEXPR_F civil_time operator-(civil_time a, diff_t n) noexcept {
      return a -= n;
    }
    friend CONSTEXPR_F diff_t operator-(civil_time lhs, civil_time rhs) noexcept {
      return difference(T{}, lhs.f_, rhs.f_);
    }
  
    template <typename H>
    friend H AbslHashValue(H h, civil_time a) {
      return impl::AbslHashValueImpl(T{}, std::move(h), a.f_);
    }
  
   private:
    // All instantiations of this template are allowed to call the following
    // private constructor and access the private fields member.
    template <typename U>
    friend class civil_time;
  
    // The designated constructor that all others eventually call.
    explicit CONSTEXPR_M civil_time(fields f) noexcept : f_(align(T{}, f)) {}
  
    fields f_;
  };
  
  // Disallows difference between differently aligned types.
  // auto n = civil_day(...) - civil_hour(...);  // would be confusing.
  template <typename T, typename U>
  CONSTEXPR_F diff_t operator-(civil_time<T>, civil_time<U>) = delete;
  
  using civil_year = civil_time<year_tag>;
  using civil_month = civil_time<month_tag>;
  using civil_day = civil_time<day_tag>;
  using civil_hour = civil_time<hour_tag>;
  using civil_minute = civil_time<minute_tag>;
  using civil_second = civil_time<second_tag>;
  
  ////////////////////////////////////////////////////////////////////////
  
  // Relational operators that work with differently aligned objects.
  // Always compares all six fields.
  template <typename T1, typename T2>
  CONSTEXPR_F bool operator<(const civil_time<T1>& lhs,
                             const civil_time<T2>& rhs) noexcept {
    return (
        lhs.year() < rhs.year() ||
        (lhs.year() == rhs.year() &&
         (lhs.month() < rhs.month() ||
          (lhs.month() == rhs.month() &&
           (lhs.day() < rhs.day() || (lhs.day() == rhs.day() &&
                                      (lhs.hour() < rhs.hour() ||
                                       (lhs.hour() == rhs.hour() &&
                                        (lhs.minute() < rhs.minute() ||
                                         (lhs.minute() == rhs.minute() &&
                                          (lhs.second() < rhs.second())))))))))));
  }
  template <typename T1, typename T2>
  CONSTEXPR_F bool operator<=(const civil_time<T1>& lhs,
                              const civil_time<T2>& rhs) noexcept {
    return !(rhs < lhs);
  }
  template <typename T1, typename T2>
  CONSTEXPR_F bool operator>=(const civil_time<T1>& lhs,
                              const civil_time<T2>& rhs) noexcept {
    return !(lhs < rhs);
  }
  template <typename T1, typename T2>
  CONSTEXPR_F bool operator>(const civil_time<T1>& lhs,
                             const civil_time<T2>& rhs) noexcept {
    return rhs < lhs;
  }
  template <typename T1, typename T2>
  CONSTEXPR_F bool operator==(const civil_time<T1>& lhs,
                              const civil_time<T2>& rhs) noexcept {
    return lhs.year() == rhs.year() && lhs.month() == rhs.month() &&
           lhs.day() == rhs.day() && lhs.hour() == rhs.hour() &&
           lhs.minute() == rhs.minute() && lhs.second() == rhs.second();
  }
  template <typename T1, typename T2>
  CONSTEXPR_F bool operator!=(const civil_time<T1>& lhs,
                              const civil_time<T2>& rhs) noexcept {
    return !(lhs == rhs);
  }
  
  ////////////////////////////////////////////////////////////////////////
  
  enum class weekday {
    monday,
    tuesday,
    wednesday,
    thursday,
    friday,
    saturday,
    sunday,
  };
  
  CONSTEXPR_F weekday get_weekday(const civil_second& cs) noexcept {
    CONSTEXPR_D weekday k_weekday_by_mon_off[13] = {
        weekday::monday,    weekday::tuesday,  weekday::wednesday,
        weekday::thursday,  weekday::friday,   weekday::saturday,
        weekday::sunday,    weekday::monday,   weekday::tuesday,
        weekday::wednesday, weekday::thursday, weekday::friday,
        weekday::saturday,
    };
    CONSTEXPR_D int k_weekday_offsets[1 + 12] = {
        -1, 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4,
    };
    year_t wd = 2400 + (cs.year() % 400) - (cs.month() < 3);
    wd += wd / 4 - wd / 100 + wd / 400;
    wd += k_weekday_offsets[cs.month()] + cs.day();
    return k_weekday_by_mon_off[wd % 7 + 6];
  }
  
  ////////////////////////////////////////////////////////////////////////
  
  CONSTEXPR_F civil_day next_weekday(civil_day cd, weekday wd) noexcept {
    CONSTEXPR_D weekday k_weekdays_forw[14] = {
        weekday::monday,    weekday::tuesday,  weekday::wednesday,
        weekday::thursday,  weekday::friday,   weekday::saturday,
        weekday::sunday,    weekday::monday,   weekday::tuesday,
        weekday::wednesday, weekday::thursday, weekday::friday,
        weekday::saturday,  weekday::sunday,
    };
    weekday base = get_weekday(cd);
    for (int i = 0;; ++i) {
      if (base == k_weekdays_forw[i]) {
        for (int j = i + 1;; ++j) {
          if (wd == k_weekdays_forw[j]) {
            return cd + (j - i);
          }
        }
      }
    }
  }
  
  CONSTEXPR_F civil_day prev_weekday(civil_day cd, weekday wd) noexcept {
    CONSTEXPR_D weekday k_weekdays_back[14] = {
        weekday::sunday,   weekday::saturday,  weekday::friday,
        weekday::thursday, weekday::wednesday, weekday::tuesday,
        weekday::monday,   weekday::sunday,    weekday::saturday,
        weekday::friday,   weekday::thursday,  weekday::wednesday,
        weekday::tuesday,  weekday::monday,
    };
    weekday base = get_weekday(cd);
    for (int i = 0;; ++i) {
      if (base == k_weekdays_back[i]) {
        for (int j = i + 1;; ++j) {
          if (wd == k_weekdays_back[j]) {
            return cd - (j - i);
          }
        }
      }
    }
  }
  
  CONSTEXPR_F int get_yearday(const civil_second& cs) noexcept {
    CONSTEXPR_D int k_month_offsets[1 + 12] = {
        -1, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,
    };
    const int feb29 = (cs.month() > 2 && impl::is_leap_year(cs.year()));
    return k_month_offsets[cs.month()] + feb29 + cs.day();
  }
  
  ////////////////////////////////////////////////////////////////////////
  
  std::ostream& operator<<(std::ostream& os, const civil_year& y);
  std::ostream& operator<<(std::ostream& os, const civil_month& m);
  std::ostream& operator<<(std::ostream& os, const civil_day& d);
  std::ostream& operator<<(std::ostream& os, const civil_hour& h);
  std::ostream& operator<<(std::ostream& os, const civil_minute& m);
  std::ostream& operator<<(std::ostream& os, const civil_second& s);
  std::ostream& operator<<(std::ostream& os, weekday wd);
  
  }  // namespace detail
  }  // namespace cctz
  }  // namespace time_internal
  ABSL_NAMESPACE_END
  }  // namespace absl
  
  #undef CONSTEXPR_M
  #undef CONSTEXPR_F
  #undef CONSTEXPR_D
  
  #endif  // ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_
  