holidays/lib/holidays.rb
2009-11-17 20:46:36 +01:00

404 lines
13 KiB
Ruby

$:.unshift File.dirname(__FILE__)
require 'digest/md5'
require 'date'
# == Region options
# Holidays can be defined as belonging to one or more regions and sub regions.
# The Holidays#on, Holidays#between, Date#holidays and Date#holiday? methods
# each allow you to specify a specific region.
#
# There are several different ways that you can specify a region:
#
# [<tt>:region</tt>]
# By region. For example, return holidays in the Canada with <tt>:ca</tt>.
# [<tt>:region_</tt>]
# By region and sub regions. For example, return holidays in Germany
# and all its sub regions with <tt>:de_</tt>.
# [<tt>:region_sub</tt>]
# By sub region. Return national holidays in Spain plus holidays in Spain's
# Valencia region with <tt>:es_v</tt>.
# [<tt>:any</tt>]
# Any region. Return holidays from any loaded region.
#
# == Other options
# [<tt>:observed</tt>] Return holidays on the day they are observed (e.g. on a Monday if they fall on a Sunday).
# [<tt>:informal</tt>] Include informal holidays (e.g. Valentine's Day)
#
# == Examples
# Return all holidays in the <tt>:ca</tt> and <tt>:us</tt> regions on the day that they are
# observed.
#
# Holidays.between(from, to, :ca, :us, :observed)
#
# Return all holidays in <tt>:ca</tt> and any <tt>:ca</tt> sub-region.
#
# Holidays.between(from, to, :ca_)
#
# Return all holidays in <tt>:ca_bc</tt> sub-region (which includes the <tt>:ca</tt>), including informal holidays.
#
# Holidays.between(from, to, :ca_bc, :informal)
module Holidays
# Exception thrown when an unknown region is requested.
class UnkownRegionError < ArgumentError; end
VERSION = '0.9.2'
@@regions = []
@@holidays_by_month = {}
@@proc_cache = {}
WEEKS = {:first => 1, :second => 2, :third => 3, :fourth => 4, :fifth => 5, :last => -1}
MONTH_LENGTHS = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
DAY_SYMBOLS = Date::DAYNAMES.collect { |n| n.downcase.intern }
# Get all holidays on a given date.
#
# [<tt>date</tt>] A Date object.
# [<tt>:options</tt>] One or more region symbols, <tt>:informal</tt> and/or <tt>:observed</tt>.
#
# Returns an array of hashes or nil. See Holidays#between for the output
# format.
#
# Also available via Date#holidays.
def self.on(date, *options)
self.between(date, date, options)
end
# Get all holidays occuring between two dates, inclusively.
#
# Returns an array of hashes or nil.
#
# Each holiday is returned as a hash with the following fields:
# [<tt>start_date</tt>] Ruby Date object.
# [<tt>end_date</tt>] Ruby Date object.
# [<tt>options</tt>] One or more region symbols, <tt>:informal</tt> and/or <tt>:observed</tt>.
#
# ==== Example
# from = Date.civil(2008,7,1)
# to = Date.civil(2008,7,31)
#
# Holidays.between(from, to, :ca, :us)
# => [{:name => 'Canada Day', :regions => [:ca]...}
# {:name => 'Independence Day'', :regions => [:us], ...}]
def self.between(start_date, end_date, *options)
regions, observed, informal = parse_options(options)
holidays = []
dates = {}
(start_date..end_date).each do |date|
# Always include month '0' for variable-month holidays
dates[date.year] = [0] unless dates[date.year]
# TODO: test this, maybe should push then flatten
dates[date.year] << date.month unless dates[date.year].include?(date.month)
end
dates.each do |year, months|
months.each do |month|
next unless hbm = @@holidays_by_month[month]
hbm.each do |h|
next unless in_region?(regions, h[:regions])
# Skip informal holidays unless they have been requested
next if h[:type] == :informal and not informal
if h[:function]
# Holiday definition requires a calculation
result = call_proc(h[:function], year)
# Procs may return either Date or an integer representing mday
if result.kind_of?(Date)
month = result.month
mday = result.mday
else
mday = result
end
else
# Calculate the mday
mday = h[:mday] || Date.calculate_mday(year, month, h[:week], h[:wday])
end
# Silently skip bad mdays
begin
date = Date.civil(year, month, mday)
rescue; next; end
# If the :observed option is set, calculate the date when the holiday
# is observed.
if observed and h[:observed]
date = call_proc(h[:observed], date)
end
if date.between?(start_date, end_date)
holidays << {:date => date, :name => h[:name], :regions => h[:regions]}
end
end
end
end
holidays
end
# Merge a new set of definitions into the Holidays module.
#
# This method is automatically called when including holiday definition
# files.
def self.merge_defs(regions, holidays) # :nodoc:
@@regions = @@regions | regions
@@regions.uniq!
holidays.each do |month, holiday_defs|
@@holidays_by_month[month] = [] unless @@holidays_by_month[month]
holiday_defs.each do |holiday_def|
exists = false
@@holidays_by_month[month].each do |ex|
# TODO: gross.
if ex[:name] == holiday_def[:name] and ex[:wday] == holiday_def[:wday] and ex[:mday] == holiday_def[:mday] and ex[:week] == holiday_def[:week] and ex[:function_id] == holiday_def[:function_id] and ex[:type] == holiday_def[:type] and ex[:observed_id] == holiday_def[:observed_id]
# append regions
ex[:regions] << holiday_def[:regions]
# Should do this once we're done
ex[:regions].flatten!
ex[:regions].uniq!
exists = true
end
end
@@holidays_by_month[month] << holiday_def unless exists
end
end
end
# Get the date of Easter Sunday in a given year. From Easter Sunday, it is
# possible to calculate many traditional holidays in Western countries.
# Returns a Date object.
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
# Move date to Monday if it occurs on a Sunday.
# Used as a callback function.
def self.to_monday_if_sunday(date)
date += 1 if date.wday == 0
date
end
# Move date to Monday if it occurs on a Saturday on Sunday.
# Used as a callback function.
def self.to_monday_if_weekend(date)
date += 1 if date.wday == 0
date += 2 if date.wday == 6
date
end
# Move Boxing Day if it falls on a weekend, leaving room for Christmas.
# Used as a callback function.
def self.to_weekday_if_boxing_weekend(date)
date += 2 if date.wday == 6 or date.wday == 0
date
end
# Move date to Monday if it occurs on a Sunday or to Friday if it occurs on a
# Saturday.
# Used as a callback function.
def self.to_weekday_if_weekend(date)
date += 1 if date.wday == 0
date -= 1 if date.wday == 6
date
end
private
# Returns [(arr)regions, (bool)observed, (bool)informal]
def self.parse_options(*options) # :nodoc:
options.flatten!
observed = options.delete(:observed) ? true : false
informal = options.delete(:informal) ? true : false
regions = parse_regions(options)
return regions, observed, informal
end
# Check regions against list of supported regions and return an array of
# symbols.
#
# If a wildcard region is found (e.g. <tt>:ca_</tt>) it is expanded into all
# of its available sub regions.
def self.parse_regions(regions) # :nodoc:
regions = [regions] unless regions.kind_of?(Array)
return [:any] if regions.empty?
regions = regions.collect { |r| r.to_sym }
# Found sub region wild-card
regions.delete_if do |reg|
if reg.to_s =~ /_$/
regions << @@regions.select { |dr| dr.to_s =~ Regexp.new("^#{reg}") }
true
end
end
regions.flatten!
raise UnkownRegionError unless regions.all? { |r| r == :any or @@regions.include?(r) }
regions
end
# Check sub regions.
#
# When request :any, all holidays should be returned.
# When requesting :ca_bc, holidays in :ca or :ca_bc should be returned.
# When requesting :ca, holidays in :ca but not its subregions should be returned.
def self.in_region?(requested, available) # :nodoc:
return true if requested.include?(:any)
# When an underscore is encountered, derive the parent regions
# symbol and include both in the requested array.
requested = requested.collect do |r|
r.to_s =~ /_/ ? [r, r.to_s.gsub(/_[\w]*$/, '').to_sym] : r
end
requested = requested.flatten.uniq
available.any? { |avail| requested.include?(avail) }
end
# Call a proc function defined in a holiday definition file.
#
# Procs are cached.
#
# ==== Benchmarks
#
# Lookup Easter Sunday, with caching, by number of iterations:
#
# user system total real
# 0001 0.000000 0.000000 0.000000 ( 0.000000)
# 0010 0.000000 0.000000 0.000000 ( 0.000000)
# 0100 0.078000 0.000000 0.078000 ( 0.078000)
# 1000 0.641000 0.000000 0.641000 ( 0.641000)
# 5000 3.172000 0.015000 3.187000 ( 3.219000)
#
# Lookup Easter Sunday, without caching, by number of iterations:
#
# user system total real
# 0001 0.000000 0.000000 0.000000 ( 0.000000)
# 0010 0.016000 0.000000 0.016000 ( 0.016000)
# 0100 0.125000 0.000000 0.125000 ( 0.125000)
# 1000 1.234000 0.000000 1.234000 ( 1.234000)
# 5000 6.094000 0.031000 6.125000 ( 6.141000)
def self.call_proc(function, year) # :nodoc:
proc_key = Digest::MD5.hexdigest("#{function.to_s}_#{year.to_s}")
@@proc_cache[proc_key] = function.call(year) unless @@proc_cache[proc_key]
@@proc_cache[proc_key]
end
end
# === Extending Ruby's Date class with the Holidays gem
# The Holidays gem automatically extends Ruby's Date class and gives you access
# to three new methods: holiday?, #holidays and #calculate_mday.
#
# ==== Examples
# Lookup Canada Day in the <tt>:ca</tt> region
# Date.civil(2008,7,1).holiday?(:ca)
# => true
#
# Lookup Canada Day in the <tt>:fr</tt> region
# Date.civil(2008,7,1).holiday?(:fr)
# => false
#
# Lookup holidays on North America in January 1.
# Date.civil(2008,1,1).holidays(:ca, :mx, :us, :informal, :observed)
# => [{:name => 'New Year\'s Day'...}]
class Date
include Holidays
# Get holidays on the current date.
#
# Returns an array of hashes or nil. See Holidays#between for options
# and the output format.
#
# Date.civil('2008-01-01').holidays(:ca_)
# => [{:name => 'New Year\'s Day',...}]
#
# Also available via Holidays#on.
def holidays(*options)
Holidays.on(self, options)
end
# Check if the current date is a holiday.
#
# Returns true or false.
#
# Date.civil('2008-01-01').holiday?(:ca)
# => true
def holiday?(*options)
holidays = self.holidays(options)
holidays && !holidays.empty?
end
# Calculate day of the month based on the week number and the day of the
# week.
#
# ==== Parameters
# [<tt>year</tt>] Integer.
# [<tt>month</tt>] Integer from 1-12.
# [<tt>week</tt>] One of <tt>:first</tt>, <tt>:second</tt>, <tt>:third</tt>,
# <tt>:fourth</tt>, <tt>:fifth</tt> or <tt>:last</tt>.
# [<tt>wday</tt>] Day of the week as an integer from 0 (Sunday) to 6
# (Saturday) or as a symbol (e.g. <tt>:monday</tt>).
#
# Returns an integer.
#
# ===== Examples
# First Monday of January, 2008:
# Date.calculate_mday(2008, 1, :first, :monday)
# => 7
#
# Third Thursday of December, 2008:
# Date.calculate_mday(2008, 12, :third, :thursday)
# => 18
#
# Last Monday of January, 2008:
# Date.calculate_mday(2008, 1, :last, 1)
# => 28
#--
# see http://www.irt.org/articles/js050/index.htm
def self.calculate_mday(year, month, week, wday)
raise ArgumentError, "Week parameter must be one of Holidays::WEEKS (provided #{week})." unless WEEKS.include?(week) or WEEKS.has_value?(week)
unless wday.kind_of?(Numeric) and wday.between?(0,6) or DAY_SYMBOLS.index(wday)
raise ArgumentError, "Wday parameter must be an integer between 0 and 6 or one of Date::DAY_SYMBOLS."
end
week = WEEKS[week] if week.kind_of?(Symbol)
wday = DAY_SYMBOLS.index(wday) if wday.kind_of?(Symbol)
# :first, :second, :third, :fourth or :fifth
if week > 0
return ((week - 1) * 7) + 1 + ((7 + wday - Date.civil(year, month,(week-1)*7 + 1).wday) % 7)
end
days = MONTH_LENGTHS[month-1]
days = 29 if month == 2 and Date.leap?(year)
return days - ((Date.civil(year, month, days).wday - wday + 7) % 7)
end
end