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module TZInfo
# A set of rules that define when transitions occur in time zones with
# annually occurring daylight savings time.
#
# @private
class AnnualRules #:nodoc:
# Returned by #transitions. #offset is the TimezoneOffset that applies
# from the UTC TimeOrDateTime #at. #previous_offset is the prior
# TimezoneOffset.
Transition = Struct.new(:offset, :previous_offset, :at)
# The standard offset that applies when daylight savings time is not in
# force.
attr_reader :std_offset
# The offset that applies when daylight savings time is in force.
attr_reader :dst_offset
# The rule that determines when daylight savings time starts.
attr_reader :dst_start_rule
# The rule that determines when daylight savings time ends.
attr_reader :dst_end_rule
# Initializes a new {AnnualRules} instance.
def initialize(std_offset, dst_offset, dst_start_rule, dst_end_rule)
@std_offset = std_offset
@dst_offset = dst_offset
@dst_start_rule = dst_start_rule
@dst_end_rule = dst_end_rule
end
# Returns the transitions between standard and daylight savings time for a
# given year. The results are ordered by time of occurrence (earliest to
# latest).
def transitions(year)
start_dst = apply_rule(@dst_start_rule, @std_offset, @dst_offset, year)
end_dst = apply_rule(@dst_end_rule, @dst_offset, @std_offset, year)
end_dst.at < start_dst.at ? [end_dst, start_dst] : [start_dst, end_dst]
end
private
# Applies a given rule between offsets on a year.
def apply_rule(rule, from_offset, to_offset, year)
at = rule.at(from_offset, year)
Transition.new(to_offset, from_offset, at)
end
end
end
Version data entries
7 entries across 7 versions & 2 rubygems