Module:Age
Documentation for this module may be created at Module:Age/doc
-- Code to implement {{age in years and months}}.
-- This could be extended to handle the many other {{age}} templates.
-- However, calendar functions will be needed in many areas, so this may be
-- superseded by some other system, perhaps using functions from the PHP host.
local MINUS = '−' -- Unicode U+2212 MINUS SIGN (UTF-8: e2 88 92)
local function number_name(number, singular, plural, sep)
plural = plural or (singular .. 's')
sep = sep or ' '
return tostring(number) .. sep .. ((number == 1) and singular or plural)
end
local function strip(text)
-- If text is a string, return its content with no leading/trailing
-- whitespace. Otherwise return nil (a nil argument gives a nil result).
if type(text) == 'string' then
return text:match("^%s*(.-)%s*$")
end
end
local function is_leap_year(year)
-- Return true if year is a leap year, assuming Gregorian calendar.
return (year % 4 == 0 and year % 100 ~= 0) or year % 400 == 0
end
local function days_in_month(year, month)
-- Return number of days (1..31) in given month (1..12).
local month_days = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
if month == 2 and is_leap_year(year) then
return 29
end
return month_days[month]
end
local Date = {
-- A naive date that assumes the Gregorian calendar always applied.
year = 0, -- 1 to 9999 (0 if never set)
month = 1, -- 1 to 12
day = 1, -- 1 to 31
isvalid = false,
new = function (self, o)
o = o or {}
setmetatable(o, self)
self.__index = self
return o
end
}
function Date:set_current()
-- Set date from current time (UTC) and return self.
local d = os.date('!*t')
self.year = d.year
self.month = d.month
self.day = d.day
self.isvalid = true
return self
end
function Date:set_ymd(y, m, d)
-- Set date from year, month, day (strings or numbers) and return self.
-- LATER: If m is a name like "March" or "mar", translate it to a month.
y = tonumber(y)
m = tonumber(m)
d = tonumber(d)
if type(y) == 'number' and type(m) == 'number' and type(d) == 'number' then
self.year = y
self.month = m
self.day = d
self.isvalid = (1 <= y and y <= 9999 and 1 <= m and m <= 12 and
1 <= d and d <= days_in_month(y, m))
end
return self
end
function Date:less_than(rhs)
-- Set true if self < rhs.
if self.year < rhs.year then
return true
end
if self.year == rhs.year then
if self.month < rhs.month then
return true
end
if self.month == rhs.month then
return self.day < rhs.day
end
end
return false
end
local DateDiff = {
-- Simple difference between two dates, assuming Gregorian calendar.
isnegative = false, -- true if second date is before first
years = 0,
months = 0,
days = 0,
new = function (self, o)
o = o or {}
setmetatable(o, self)
self.__index = self
return o
end
}
function DateDiff:set(date1, date2)
-- Set difference between the two dates, and return self.
-- Difference is negative if the second date is older than the first.
local isnegative
if date2:less_than(date1) then
isnegative = true
date1, date2 = date2, date1
else
isnegative = false
end
-- It is known that date1 <= date2.
local y1, m1, d1 = date1.year, date1.month, date1.day
local y2, m2, d2 = date2.year, date2.month, date2.day
local years, months, days = y2 - y1, m2 - m1, d2 - d1
if days < 0 then
days = days + days_in_month(y1, m1)
months = months - 1
end
if months < 0 then
months = months + 12
years = years - 1
end
self.years, self.months, self.days, self.isnegative = years, months, days, isnegative
return self
end
function DateDiff:age_ym()
-- Return text specifying difference in years, months.
local sign = self.isnegative and MINUS or ''
local mtext = number_name(self.months, 'month')
local result
if self.years > 0 then
local ytext = number_name(self.years, 'year')
if self.months == 0 then
result = ytext
else
result = ytext .. ', ' .. mtext
end
else
if self.months == 0 then
sign = ''
end
result = mtext
end
return sign .. result
end
local function error_wikitext(text)
-- Return message for display when template parameters are invalid.
-- TODO Get opinions on whether the prefix and category are suitable.
local prefix = '[[Module talk:Age|Module error]]:'
local cat = '[[Category:Age error]]'
return '<span style="color:black; background-color:pink;">' ..
prefix .. ' ' .. text .. cat .. '</span>'
end
local function get_parms(pframe)
-- Return date1, date2 from parameters to template.
-- If date1 is missing or invalid, the returned date1 is nil.
-- If date2 is missing, the returned date2 is the current date.
-- If date2 is invalid, the returned date2 is nil.
local args = {} -- arguments passed to template
for i = 1, 6 do
args[i] = strip(pframe.args[i])
end
local date1, date2
if args[1] and args[2] and args[3] then
date1 = Date:new():set_ymd(args[1], args[2], args[3])
if not date1.isvalid then
date1 = nil
end
end
if args[4] and args[5] and args[6] then
date2 = Date:new():set_ymd(args[4], args[5], args[6])
if not date2.isvalid then
date2 = nil
end
else
date2 = Date:new():set_current()
end
return date1, date2
end
local function age_ym(frame)
local date1, date2 = get_parms(frame:getParent())
if date1 then
if not date2 then
return error_wikitext('Second date should be year, month, day')
end
local diff = DateDiff:new():set(date1, date2)
return diff:age_ym()
end
return error_wikitext('Need date: year, month, day')
end
return { age_ym = age_ym }