So far I've come up with:
module LazyEnumerable
extend Enumerable
def select(&block)
lazily_enumerate { |enum, value| enum.yield(value) if
block.call(value) }
end
def map(&block)
lazily_enumerate {|enum, value| enum.yield(block.call(value))}
end
def collect(&block)
map(&block)
end
private
def lazily_enumerate(&block)
Enumerator.new do |enum|
self.each do |value|
block.call(enum, value)
end
end
end
end
class LazyInfiniteDays
include LazyEnumerable
attr_reader :day
def self.day_of_week
dow = { :sundays => 0, :mondays => 1, :tuesdays => 2, :wednesdays =>
3, :thursdays => 4, :fridays => 5, :saturdays => 6, :sundays => 7 }
dow.default = -10
dow
end
DAY_OF_WEEK = day_of_week()
def advance_to_midnight_of_next_specified_day(day_sym)
year = DateTime.now.year
month = DateTime.now.month
day_of_month = DateTime.now.day
output_day = DateTime.civil(year, month, day_of_month)
output_day += 1 until output_day.wday == DAY_OF_WEEK[day_sym]
output_day
end
def initialize(day_sym)
@day = advance_to_midnight_of_next_specified_day(day_sym)
end
def each
day = @day.dup
while true
yield day
day += 7
end
end
def ==(other)
return false unless other.kind_of? LazyInfiniteDays
@day.wday == other.day.wday
end
end
···
--
Posted via http://www.ruby-forum.com/.