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## Class template dst_calc_engine

boost::date_time::dst_calc_engine — Compile-time configurable daylight savings time calculation engine.

## Synopsis

    // In header: <boost/date_time/dst_rules.hpp>

    template<typename date_type, typename time_duration_type, typename dst_traits>
    class dst_calc_engine {
    public:
      // types
      typedef date_type::year_type                            year_type;
      typedef date_type::calendar_type                        calendar_type;
      typedef dst_calculator< date_type, time_duration_type > dstcalc;

      // public static functions
      static time_is_dst_result
      local_is_dst(const date_type &, const time_duration_type &);
      static bool is_dst_boundary_day(date_type);
      static time_duration_type dst_offset();
      static date_type local_dst_start_day(year_type);
      static date_type local_dst_end_day(year_type);
    };

## Description

### `dst_calc_engine` public static functions

1.     static time_is_dst_result
       local_is_dst(const date_type & d, const time_duration_type & td);

   Calculates if the given local time is dst or not.

   Determines if the time is really in DST or not. Also checks for invalid and ambiguous.

2.     static bool is_dst_boundary_day(date_type d);

3.     static time_duration_type dst_offset();

   The time of day for the dst transition (eg: typically 01:00:00 or 02:00:00)

4.     static date_type local_dst_start_day(year_type year);

5.     static date_type local_dst_end_day(year_type year);