Module: CalendariumRomanum::Temporale::Dates

Defined in:
lib/calendarium-romanum/temporale/dates.rb

Overview

dates of movable feasts

Constant Summary collapse

WEEKDAYS =
%w{sunday monday tuesday wednesday thursday friday saturday}

Class Method Summary collapse

Class Method Details

.ascension(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 83

def self.ascension(year)
  pentecost(year) - 10
end

.ash_wednesday(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 34

def self.ash_wednesday(year)
  easter_sunday(year) - (6 * Temporale::WEEK + 4)
end

.baptism_of_lord(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 30

def self.baptism_of_lord(year)
  sunday_after epiphany(year)
end

.body_blood(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 95

def self.body_blood(year)
  holy_trinity(year) + 4
end

.christ_king(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 107

def self.christ_king(year)
  first_advent_sunday(year + 1) - 7
end

.easter_sunday(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 38

def self.easter_sunday(year)
  year += 1

  # algorithm below taken from the 'easter' gem:
  # https://github.com/jrobertson/easter

  golden_number = (year % 19) + 1
  if year <= 1752 then
    # Julian calendar
    dominical_number = (year + (year / 4) + 5) % 7
    paschal_full_moon = (3 - (11 * golden_number) - 7) % 30
  else
    # Gregorian calendar
    dominical_number = (year + (year / 4) - (year / 100) + (year / 400)) % 7
    solar_correction = (year - 1600) / 100 - (year - 1600) / 400
    lunar_correction = (((year - 1400) / 100) * 8) / 25
    paschal_full_moon = (3 - 11 * golden_number + solar_correction - lunar_correction) % 30
  end
  dominical_number += 7 until dominical_number > 0
  paschal_full_moon += 30 until paschal_full_moon > 0
  paschal_full_moon -= 1 if paschal_full_moon == 29 or (paschal_full_moon == 28 and golden_number > 11)
  difference = (4 - paschal_full_moon - dominical_number) % 7
  difference += 7 if difference < 0
  day_easter = paschal_full_moon + difference + 1
  if day_easter < 11 then
    # Easter occurs in March.
    return Date.new(y=year, m=3, d=day_easter + 21)
  else
    # Easter occurs in April.
    return Date.new(y=year, m=4, d=day_easter - 10)
  end
end

.epiphany(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 26

def self.epiphany(year)
  Date.new(year+1, 1, 6)
end

.first_advent_sunday(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 5

def self.first_advent_sunday(year)
  sunday_before(nativity(year)) - 3 * Temporale::WEEK
end

.good_friday(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 75

def self.good_friday(year)
  easter_sunday(year) - 2
end

.holy_family(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 13

def self.holy_family(year)
  xmas = nativity(year)
  if xmas.sunday?
    return Date.new(year, 12, 30)
  else
    sunday_after(xmas)
  end
end

.holy_saturday(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 79

def self.holy_saturday(year)
  easter_sunday(year) - 1
end

.holy_trinity(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 91

def self.holy_trinity(year)
  octave_of(pentecost(year))
end

.immaculate_heart(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 103

def self.immaculate_heart(year)
  pentecost(year) + 20
end

.mother_of_god(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 22

def self.mother_of_god(year)
  octave_of(nativity(year))
end

.nativity(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 9

def self.nativity(year)
  Date.new(year, 12, 25)
end

.octave_of(date) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 133

def self.octave_of(date)
  date + Temporale::WEEK
end

.palm_sunday(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 71

def self.palm_sunday(year)
  easter_sunday(year) - 7
end

.pentecost(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 87

def self.pentecost(year)
  easter_sunday(year) + 7 * Temporale::WEEK
end

.sacred_heart(year) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 99

def self.sacred_heart(year)
  body_blood(year) + 8
end

.weekday_after(weekday, date) ⇒ Object


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 123

def self.weekday_after(weekday, date)
  if date.wday == weekday then
    return date + Temporale::WEEK
  elsif weekday > date.wday
    return date + (weekday - date.wday)
  else
    return date + (Temporale::WEEK - date.wday + weekday)
  end
end

.weekday_before(weekday, date) ⇒ Object

utility methods


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# File 'lib/calendarium-romanum/temporale/dates.rb', line 113

def self.weekday_before(weekday, date)
  if date.wday == weekday then
    return date - Temporale::WEEK
  elsif weekday < date.wday
    return date - (date.wday - weekday)
  else
    return date - (date.wday + Temporale::WEEK - weekday)
  end
end