32 lines
795 B
YAML
32 lines
795 B
YAML
# Common method definitions for the Ruby Holiday gem.
|
|
# Updated 2008-11-21.
|
|
---
|
|
methods:
|
|
easter: |
|
|
# Get the date of Easter in a given year.
|
|
#
|
|
# +year+ must be a valid Gregorian year.
|
|
#
|
|
# Returns a Date object.
|
|
#--
|
|
# from http://snippets.dzone.com/posts/show/765
|
|
# TODO: check year to ensure Gregorian
|
|
def self.easter(year)
|
|
y = year
|
|
a = y % 19
|
|
b = y / 100
|
|
c = y % 100
|
|
d = b / 4
|
|
e = b % 4
|
|
f = (b + 8) / 25
|
|
g = (b - f + 1) / 3
|
|
h = (19 * a + b - d - g + 15) % 30
|
|
i = c / 4
|
|
k = c % 4
|
|
l = (32 + 2 * e + 2 * i - h - k) % 7
|
|
m = (a + 11 * h + 22 * l) / 451
|
|
month = (h + l - 7 * m + 114) / 31
|
|
day = ((h + l - 7 * m + 114) % 31) + 1
|
|
Date.civil(year, month, day)
|
|
end
|