date/tz_private.h

#ifndef TZ_PRIVATE_H
#define TZ_PRIVATE_H

// Howard Hinnant
// This work is licensed under a Creative Commons Attribution 4.0 International License.
// http://creativecommons.org/licenses/by/4.0/

#include "tz.h"

namespace date
{

class MonthDayTime
{
private:
    struct pair
    {
        date::month_day month_day_;
        date::weekday   weekday_;
    };

    enum Type {month_day, month_last_dow, lteq, gteq};

    Type                         type_{month_day};
    union U
    {
        date::month_day          month_day_;
        date::month_weekday_last month_weekday_last_;
        pair                     month_day_weekday_;

        U() : month_day_{date::jan/1} {}
        U& operator=(const date::month_day& x);
        U& operator=(const date::month_weekday_last& x);
        U& operator=(const pair& x);
    } u;
    std::chrono::hours           h_{0};
    std::chrono::minutes         m_{0};
    std::chrono::seconds         s_{0};
    tz                           zone_{tz::local};

public:
    MonthDayTime() = default;
    MonthDayTime(seconds_point tp, tz timezone);
    MonthDayTime(const date::month_day& md, tz timezone);

    date::day day() const;
    date::month month() const;
    tz zone() const {return zone_;}

    void canonicalize(date::year y);

    seconds_point
       to_sys(date::year y, std::chrono::seconds offset, std::chrono::seconds save) const;
    date::day_point to_day_point(date::year y) const;

    seconds_point to_time_point(date::year y) const;
    int compare(date::year y, const MonthDayTime& x, date::year yx,
                std::chrono::seconds offset, std::chrono::minutes prev_save) const;

    friend std::istream& operator>>(std::istream& is, MonthDayTime& x);
    friend std::ostream& operator<<(std::ostream& os, const MonthDayTime& x);
};

// A Rule specifies one or more set of datetimes without using an offset.
// Multiple dates are specified with multiple years.  The years in effect
// go from starting_year_ to ending_year_, inclusive.  starting_year_ <=
// ending_year_. save_ is ineffect for times from the specified time
// onward, including the specified time. When the specified time is
// local, it uses the save_ from the chronologically previous Rule, or if
// there is none, 0.

class Rule
{
private:
    std::string          name_;
    date::year           starting_year_{0};
    date::year           ending_year_{0};
    MonthDayTime         starting_at_;
    std::chrono::minutes save_{0};
    std::string          abbrev_;

public:
    Rule() = default;
    explicit Rule(const std::string& s);
    Rule(const Rule& r, date::year starting_year, date::year ending_year);

    const std::string& name() const {return name_;}
    const std::string& abbrev() const {return abbrev_;}

    const MonthDayTime&         mdt()           const {return starting_at_;}
    const date::year&           starting_year() const {return starting_year_;}
    const date::year&           ending_year()   const {return ending_year_;}
    const std::chrono::minutes& save()          const {return save_;}

    static void split_overlaps(std::vector<Rule>& rules);

    friend bool operator==(const Rule& x, const Rule& y);
    friend bool operator<(const Rule& x, const Rule& y);
    friend bool operator==(const Rule& x, const date::year& y);
    friend bool operator<(const Rule& x, const date::year& y);
    friend bool operator==(const date::year& x, const Rule& y);
    friend bool operator<(const date::year& x, const Rule& y);
    friend bool operator==(const Rule& x, const std::string& y);
    friend bool operator<(const Rule& x, const std::string& y);
    friend bool operator==(const std::string& x, const Rule& y);
    friend bool operator<(const std::string& x, const Rule& y);

    friend std::ostream& operator<<(std::ostream& os, const Rule& r);

private:
    date::day day() const;
    date::month month() const;
    static void split_overlaps(std::vector<Rule>& rules, std::size_t i, std::size_t& e);
    static bool overlaps(const Rule& x, const Rule& y);
    static void split(std::vector<Rule>& rules, std::size_t i, std::size_t k,
                      std::size_t& e);
};

inline bool operator!=(const Rule& x, const Rule& y) {return !(x == y);}
inline bool operator> (const Rule& x, const Rule& y) {return   y < x;}
inline bool operator<=(const Rule& x, const Rule& y) {return !(y < x);}
inline bool operator>=(const Rule& x, const Rule& y) {return !(x < y);}

inline bool operator!=(const Rule& x, const date::year& y) {return !(x == y);}
inline bool operator> (const Rule& x, const date::year& y) {return   y < x;}
inline bool operator<=(const Rule& x, const date::year& y) {return !(y < x);}
inline bool operator>=(const Rule& x, const date::year& y) {return !(x < y);}

inline bool operator!=(const date::year& x, const Rule& y) {return !(x == y);}
inline bool operator> (const date::year& x, const Rule& y) {return   y < x;}
inline bool operator<=(const date::year& x, const Rule& y) {return !(y < x);}
inline bool operator>=(const date::year& x, const Rule& y) {return !(x < y);}

inline bool operator!=(const Rule& x, const std::string& y) {return !(x == y);}
inline bool operator> (const Rule& x, const std::string& y) {return   y < x;}
inline bool operator<=(const Rule& x, const std::string& y) {return !(y < x);}
inline bool operator>=(const Rule& x, const std::string& y) {return !(x < y);}

inline bool operator!=(const std::string& x, const Rule& y) {return !(x == y);}
inline bool operator> (const std::string& x, const Rule& y) {return   y < x;}
inline bool operator<=(const std::string& x, const Rule& y) {return !(y < x);}
inline bool operator>=(const std::string& x, const Rule& y) {return !(x < y);}

struct Zone::zonelet
{
    enum tag {has_rule, has_save, is_empty};

    std::chrono::seconds gmtoff_;
    tag tag_ = has_rule;
    union U
    {
        std::string          rule_;
        std::chrono::minutes save_;

        ~U() {}
        U() {}
        U(const U&) {}
        U& operator=(const U&) = delete;
    } u;
    std::string          format_;
    date::year           until_year_{0};
    MonthDayTime         until_date_;
    seconds_point        until_utc_;
    seconds_point        until_std_;
    seconds_point        until_loc_;
    std::chrono::minutes initial_save_{};
    std::string          initial_abrev_;
    std::pair<const Rule*, date::year> first_rule_{nullptr, date::year::min()};
    std::pair<const Rule*, date::year> last_rule_{nullptr, date::year::max()};

    ~zonelet();
    zonelet();
    zonelet(const zonelet& i);
    zonelet& operator=(const zonelet&) = delete;
};

}  // namespace date

#endif  // TZ_PRIVATE_H