Which date range(s) must sanctorale of each Liturgia horarum volume cover?

lh_volume_sanctorale_ranges.rb

# Which date range(s) must sanctorale of each Liturgia horarum volume cover?

require 'calendarium-romanum/cr'

years = 1971 .. 3000

dates = CR::Temporale::Dates

xviii_sunday = lambda do |y|
  dates.first_advent_sunday(y + 1) -
    (1 + (34 - 18)) * 7
end

volume_ranges = {
  # First Advent Sunday and Ash Wednesday cannot be suppressed by an occurring
  # solemnity, so the first date relevant for sanctorale is the day after
  1 => [
    lambda {|y| dates.first_advent_sunday(y) + 1 },
    dates.method(:baptism_of_lord)
  ],
  2 => [
    lambda {|y| dates.ash_wednesday(y) + 1 },
    lambda {|y| dates.pentecost(y) - 1 }
  ],
  # volume III covers two ranges of dates - before and after Lent+Eastertide
  '3a' => [
    dates.method(:baptism_of_lord),
    lambda {|y| dates.ash_wednesday(y) - 1 }
  ],
  '3b' => [
    lambda {|y| dates.pentecost(y) + 1 },
    lambda {|y| xviii_sunday.call(y) - 1 }
  ],
  4 => [
    xviii_sunday,
    lambda {|y| dates.first_advent_sunday(y + 1) - 1 }
  ]
}

date_format = lambda {|date| date.month.to_s.rjust(2, '0') + '/' + date.day.to_s.rjust(2, '0') }

p years
puts
volume_ranges.each_pair do |number, (begin_proc, end_proc)|
  begin_date =
    years
      .collect {|y| CR::AbstractDate.from_date begin_proc.call(y) }
      .min
  end_date =
    years
      .collect {|y| CR::AbstractDate.from_date end_proc.call(y) }
      .max

  puts "#{number}: #{date_format.call(begin_date)} .. #{date_format.call(end_date)}"
end