# मोड्युल:मिति

Documentation for this module may be created at मोड्युल:मिति/doc

```-- Date functions for use by other modules.
-- I18N and time zones are not supported.

local MINUS = '−'  -- Unicode U+2212 MINUS SIGN
local floor = math.floor

local Date, DateDiff, diffmt  -- forward declarations
local uniq = { 'unique identifier' }

local function is_date(t)
-- The system used to make a date read-only means there is no unique
-- metatable that is conveniently accessible to check.
return type(t) == 'table' and t._id == uniq
end

local function is_diff(t)
return type(t) == 'table' and getmetatable(t) == diffmt
end

local function _list_join(list, sep)
return table.concat(list, sep)
end

local function collection()
-- Return a table to hold items.
return {
n = 0,
self.n = self.n + 1
self[self.n] = item
end,
join = _list_join,
}
end

local function strip_to_nil(text)
-- If text is a string, return its trimmed content, or nil if empty.
-- Otherwise return text (convenient when Date fields are provided from
-- another module which may pass a string, a number, or another type).
if type(text) == 'string' then
text = text:match('(%S.-)%s*\$')
end
return text
end

local function is_leap_year(year, calname)
-- Return true if year is a leap year.
if calname == 'Julian' then
return year % 4 == 0
end
return (year % 4 == 0 and year % 100 ~= 0) or year % 400 == 0
end

local function days_in_month(year, month, calname)
-- Return number of days (1..31) in given month (1..12).
if month == 2 and is_leap_year(year, calname) then
return 29
end
return ({ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 })[month]
end

local function h_m_s(time)
-- Return hour, minute, second extracted from fraction of a day.
time = floor(time * 24 * 3600 + 0.5)  -- number of seconds
local second = time % 60
time = floor(time / 60)
return floor(time / 60), time % 60, second
end

local function hms(date)
-- Return fraction of a day from date's time, where (0 <= fraction < 1)
-- if the values are valid, but could be anything if outside range.
return (date.hour + (date.minute + date.second / 60) / 60) / 24
end

local function julian_date(date)
-- Return jd, jdz from a Julian or Gregorian calendar date where
--   jd = Julian date and its fractional part is zero at noon
--   jdz = same, but assume time is 00:00:00 if no time given
-- http://www.tondering.dk/claus/cal/julperiod.php#formula
-- Testing shows this works for all dates from year -9999 to 9999!
-- JDN 0 is the 24-hour period starting at noon UTC on Monday
--    1 January 4713 BC  = (-4712, 1, 1)   Julian calendar
--   24 November 4714 BC = (-4713, 11, 24) Gregorian calendar
local offset
local a = floor((14 - date.month)/12)
local y = date.year + 4800 - a
if date.calendar == 'Julian' then
offset = floor(y/4) - 32083
else
offset = floor(y/4) - floor(y/100) + floor(y/400) - 32045
end
local m = date.month + 12*a - 3
local jd = date.day + floor((153*m + 2)/5) + 365*y + offset
if date.hastime then
jd = jd + hms(date) - 0.5
return jd, jd
end
return jd, jd - 0.5
end

local function set_date_from_jd(date)
-- Set the fields of table date from its Julian date field.
-- Return true if date is valid.
-- http://www.tondering.dk/claus/cal/julperiod.php#formula
-- This handles the proleptic Julian and Gregorian calendars.
-- Negative Julian dates are not defined but they work.
local calname = date.calendar
local low, high  -- min/max limits for date ranges −9999-01-01 to 9999-12-31
if calname == 'Gregorian' then
low, high = -1930999.5, 5373484.49999
elseif calname == 'Julian' then
low, high = -1931076.5, 5373557.49999
else
return
end
local jd = date.jd
if not (type(jd) == 'number' and low <= jd and jd <= high) then
return
end
local jdn = floor(jd)
if date.hastime then
local time = jd - jdn  -- 0 <= time < 1
if time >= 0.5 then    -- if at or after midnight of next day
jdn = jdn + 1
time = time - 0.5
else
time = time + 0.5
end
date.hour, date.minute, date.second = h_m_s(time)
else
date.second = 0
date.minute = 0
date.hour = 0
end
local b, c
if calname == 'Julian' then
b = 0
c = jdn + 32082
else  -- Gregorian
local a = jdn + 32044
b = floor((4*a + 3)/146097)
c = a - floor(146097*b/4)
end
local d = floor((4*c + 3)/1461)
local e = c - floor(1461*d/4)
local m = floor((5*e + 2)/153)
date.day = e - floor((153*m + 2)/5) + 1
date.month = m + 3 - 12*floor(m/10)
date.year = 100*b + d - 4800 + floor(m/10)
return true
end

local function fix_numbers(numbers, y, m, d, H, M, S, partial, hastime, calendar)
-- Put the result of normalizing the given values in table numbers.
-- The result will have valid m, d values if y is valid; caller checks y.
-- The logic of PHP mktime is followed where m or d can be zero to mean
-- the previous unit, and -1 is the one before that, etc.
-- Positive values carry forward.
local date
if not (1 <= m and m <= 12) then
date = Date(y, 1, 1)
if not date then return end
date = date + ((m - 1) .. 'm')
y, m = date.year, date.month
end
local days_hms
if not partial then
if hastime and H and M and S then
if not (0 <= H and H <= 23 and
0 <= M and M <= 59 and
0 <= S and S <= 59) then
days_hms = hms({ hour = H, minute = M, second = S })
end
end
if days_hms or not (1 <= d and d <= days_in_month(y, m, calendar)) then
date = date or Date(y, m, 1)
if not date then return end
date = date + (d - 1 + (days_hms or 0))
y, m, d = date.year, date.month, date.day
if days_hms then
H, M, S = date.hour, date.minute, date.second
end
end
end
numbers.year = y
numbers.month = m
numbers.day = d
if days_hms then
-- Don't set H unless it was valid because a valid H will set hastime.
numbers.hour = H
numbers.minute = M
numbers.second = S
end
end

local function set_date_from_numbers(date, numbers, options)
-- Set the fields of table date from numeric values.
-- Return true if date is valid.
if type(numbers) ~= 'table' then
return
end
local y = numbers.year   or date.year
local m = numbers.month  or date.month
local d = numbers.day    or date.day
local H = numbers.hour
local M = numbers.minute or date.minute or 0
local S = numbers.second or date.second or 0
local need_fix
if y and m and d then
date.partial = nil
if not (-9999 <= y and y <= 9999 and
1 <= m and m <= 12 and
1 <= d and d <= days_in_month(y, m, date.calendar)) then
if not date.want_fix then
return
end
need_fix = true
end
elseif y and date.partial then
if d or not (-9999 <= y and y <= 9999) then
return
end
if m and not (1 <= m and m <= 12) then
if not date.want_fix then
return
end
need_fix = true
end
else
return
end
if date.partial then
H = nil  -- ignore any time
M = nil
S = nil
else
if H then
-- It is not possible to set M or S without also setting H.
date.hastime = true
else
H = 0
end
if not (0 <= H and H <= 23 and
0 <= M and M <= 59 and
0 <= S and S <= 59) then
if date.want_fix then
need_fix = true
else
return
end
end
end
date.want_fix = nil
if need_fix then
fix_numbers(numbers, y, m, d, H, M, S, date.partial, date.hastime, date.calendar)
return set_date_from_numbers(date, numbers, options)
end
date.year = y    -- -9999 to 9999 ('n BC' → year = 1 - n)
date.month = m   -- 1 to 12 (may be nil if partial)
date.day = d     -- 1 to 31 (* = nil if partial)
date.hour = H    -- 0 to 59 (*)
date.minute = M  -- 0 to 59 (*)
date.second = S  -- 0 to 59 (*)
if type(options) == 'table' then
for _, k in ipairs({ 'am', 'era', 'format' }) do
if options[k] then
date.options[k] = options[k]
end
end
end
return true
end

local function make_option_table(options1, options2)
-- If options1 is a string, return a table with its settings, or
-- if it is a table, use its settings.
-- Missing options are set from table options2 or defaults.
-- If a default is used, a flag is set so caller knows the value was not intentionally set.
-- Valid option settings are:
-- am: 'am', 'a.m.', 'AM', 'A.M.'
--     'pm', 'p.m.', 'PM', 'P.M.' (each has same meaning as corresponding item above)
-- era: 'BCMINUS', 'BCNEGATIVE', 'BC', 'B.C.', 'BCE', 'B.C.E.', 'AD', 'A.D.', 'CE', 'C.E.'
-- Option am = 'am' does not mean the hour is AM; it means 'am' or 'pm' is used, depending on the hour,
--    and am = 'pm' has the same meaning.
-- Similarly, era = 'BC' means 'BC' is used if year <= 0.
-- BCMINUS displays a MINUS if year < 0 and the display format does not include %{era}.
-- BCNEGATIVE is similar but displays a hyphen.
local result = { bydefault = {} }
if type(options1) == 'table' then
result.am = options1.am
result.era = options1.era
elseif type(options1) == 'string' then
-- Example: 'am:AM era:BC' or 'am=AM era=BC'.
for item in options1:gmatch('%S+') do
local lhs, rhs = item:match('^(%w+)[:=](.+)\$')
if lhs then
result[lhs] = rhs
end
end
end
options2 = type(options2) == 'table' and options2 or {}
local defaults = { am = 'am', era = 'BC' }
for k, v in pairs(defaults) do
if not result[k] then
if options2[k] then
result[k] = options2[k]
else
result[k] = v
result.bydefault[k] = true
end
end
end
return result
end

local ampm_options = {
-- lhs = input text accepted as an am/pm option
-- rhs = code used internally
['am']   = 'am',
['AM']   = 'AM',
['a.m.'] = 'a.m.',
['A.M.'] = 'A.M.',
['pm']   = 'am',  -- same as am
['PM']   = 'AM',
['p.m.'] = 'a.m.',
['P.M.'] = 'A.M.',
}

local era_text = {
-- Text for displaying an era with a positive year (after adjusting
-- by replacing year with 1 - year if date.year <= 0).
-- options.era = { year<=0 , year>0 }
['BCMINUS']    = { 'BC'    , ''    , isbc = true, sign = MINUS },
['BCNEGATIVE'] = { 'BC'    , ''    , isbc = true, sign = '-'   },
['BC']         = { 'BC'    , ''    , isbc = true },
['B.C.']       = { 'B.C.'  , ''    , isbc = true },
['BCE']        = { 'BCE'   , ''    , isbc = true },
['B.C.E.']     = { 'B.C.E.', ''    , isbc = true },
['A.D.']       = { 'B.C.'  , 'A.D.' },
['CE']         = { 'BCE'   , 'CE'   },
['C.E.']       = { 'B.C.E.', 'C.E.' },
}

local function get_era_for_year(era, year)
return (era_text[era] or era_text['BC'])[year > 0 and 2 or 1] or ''
end

local function strftime(date, format, options)
-- Return date formatted as a string using codes similar to those
-- in the C strftime library function.
local sformat = string.format
local shortcuts = {
['%c'] = '%-I:%M %p %-d %B %-Y %{era}',  -- date and time: 2:30 pm 1 April 2016
['%x'] = '%-d %B %-Y %{era}',            -- date:          1 April 2016
['%X'] = '%-I:%M %p',                    -- time:          2:30 pm
}
if shortcuts[format] then
format = shortcuts[format]
end
local codes = {
a = { field = 'dayabbr' },
A = { field = 'dayname' },
b = { field = 'monthabbr' },
B = { field = 'monthname' },
u = { fmt = '%d'  , field = 'dowiso' },
w = { fmt = '%d'  , field = 'dow' },
d = { fmt = '%02d', fmt2 = '%d', field = 'day' },
m = { fmt = '%02d', fmt2 = '%d', field = 'month' },
Y = { fmt = '%04d', fmt2 = '%d', field = 'year' },
H = { fmt = '%02d', fmt2 = '%d', field = 'hour' },
M = { fmt = '%02d', fmt2 = '%d', field = 'minute' },
S = { fmt = '%02d', fmt2 = '%d', field = 'second' },
j = { fmt = '%03d', fmt2 = '%d', field = 'dayofyear' },
I = { fmt = '%02d', fmt2 = '%d', field = 'hour', special = 'hour12' },
p = { field = 'hour', special = 'am' },
}
options = make_option_table(options, date.options)
local amopt = options.am
local eraopt = options.era
local function replace_code(spaces, modifier, id)
local code = codes[id]
if code then
local fmt = code.fmt
if modifier == '-' and code.fmt2 then
fmt = code.fmt2
end
local value = date[code.field]
if not value then
return nil  -- an undefined field in a partial date
end
local special = code.special
if special then
if special == 'hour12' then
value = value % 12
value = value == 0 and 12 or value
elseif special == 'am' then
local ap = ({
['a.m.'] = { 'a.m.', 'p.m.' },
['AM'] = { 'AM', 'PM' },
['A.M.'] = { 'A.M.', 'P.M.' },
})[ampm_options[amopt]] or { 'am', 'pm' }
return (spaces == '' and '' or '&nbsp;') .. (value < 12 and ap[1] or ap[2])
end
end
if code.field == 'year' then
local sign = (era_text[eraopt] or {}).sign
if not sign or format:find('%{era}', 1, true) then
sign = ''
if value <= 0 then
value = 1 - value
end
else
if value >= 0 then
sign = ''
else
value = -value
end
end
return spaces .. sign .. sformat(fmt, value)
end
return spaces .. (fmt and sformat(fmt, value) or value)
end
end
local function replace_property(spaces, id)
if id == 'era' then
-- Special case so can use local era option.
local result = get_era_for_year(eraopt, date.year)
if result == '' then
return ''
end
return (spaces == '' and '' or '&nbsp;') .. result
end
local result = date[id]
if type(result) == 'string' then
return spaces .. result
end
if type(result) == 'number' then
return  spaces .. tostring(result)
end
if type(result) == 'boolean' then
return  spaces .. (result and '1' or '0')
end
-- This occurs if id is an undefined field in a partial date, or is the name of a function.
return nil
end
local PERCENT = '\127PERCENT\127'
return (format
:gsub('%%%%', PERCENT)
:gsub('(%s*)%%{(%w+)}', replace_property)
:gsub('(%s*)%%(%-?)(%a)', replace_code)
:gsub(PERCENT, '%%')
)
end

local function _date_text(date, fmt, options)
-- Return a formatted string representing the given date.
if not is_date(date) then
error('date:text: need a date (use "date:text()" with a colon)', 2)
end
if type(fmt) == 'string' and fmt:match('%S') then
if fmt:find('%', 1, true) then
return strftime(date, fmt, options)
end
elseif date.partial then
fmt = date.month and 'my' or 'y'
else
fmt = 'dmy'
if date.hastime then
fmt = (date.second > 0 and 'hms ' or 'hm ') .. fmt
end
end
-- For consistency with other format processing, return given format
-- (or cleaned format if original was not a string) if invalid.
return mw.text.nowiki(fmt)
end
if date.partial then
-- Ignore days in standard formats like 'ymd'.
if fmt == 'ym' or fmt == 'ymd' then
fmt = date.month and '%Y-%m %{era}' or '%Y %{era}'
elseif fmt == 'my' or fmt == 'dmy' or fmt == 'mdy' then
fmt = date.month and '%B %-Y %{era}' or '%-Y %{era}'
elseif fmt == 'y' then
fmt = date.month and '%-Y %{era}' or '%-Y %{era}'
else
end
return strftime(date, fmt, options)
end
local function hm_fmt()
local plain = make_option_table(options, date.options).bydefault.am
return plain and '%H:%M' or '%-I:%M %p'
end
local need_time = date.hastime
local t = collection()
for item in fmt:gmatch('%S+') do
local f
if item == 'hm' then
f = hm_fmt()
need_time = false
elseif item == 'hms' then
f = '%H:%M:%S'
need_time = false
elseif item == 'ymd' then
f = '%Y-%m-%d %{era}'
elseif item == 'mdy' then
f = '%B %-d, %-Y %{era}'
elseif item == 'dmy' then
f = '%-d %B %-Y %{era}'
else
end
end
fmt = t:join(' ')
if need_time then
fmt = hm_fmt() .. ' ' .. fmt
end
return strftime(date, fmt, options)
end

local day_info = {
-- 0=Sun to 6=Sat
[0] = { 'Sun', 'Sunday' },
{ 'Mon', 'Monday' },
{ 'Tue', 'Tuesday' },
{ 'Wed', 'Wednesday' },
{ 'Thu', 'Thursday' },
{ 'Fri', 'Friday' },
{ 'Sat', 'Saturday' },
}

local month_info = {
-- 1=Jan to 12=Dec
{ 'Jan', 'January' },
{ 'Feb', 'February' },
{ 'Mar', 'March' },
{ 'Apr', 'April' },
{ 'May', 'May' },
{ 'Jun', 'June' },
{ 'Jul', 'July' },
{ 'Aug', 'August' },
{ 'Sep', 'September' },
{ 'Oct', 'October' },
{ 'Nov', 'November' },
{ 'Dec', 'December' },
}

local function name_to_number(text, translate)
if type(text) == 'string' then
return translate[text:lower()]
end
end

local function day_number(text)
return name_to_number(text, {
sun = 0, sunday = 0,
mon = 1, monday = 1,
tue = 2, tuesday = 2,
wed = 3, wednesday = 3,
thu = 4, thursday = 4,
fri = 5, friday = 5,
sat = 6, saturday = 6,
})
end

local function month_number(text)
return name_to_number(text, {
jan = 1, january = 1,
feb = 2, february = 2,
mar = 3, march = 3,
apr = 4, april = 4,
may = 5,
jun = 6, june = 6,
jul = 7, july = 7,
aug = 8, august = 8,
sep = 9, september = 9, sept = 9,
oct = 10, october = 10,
nov = 11, november = 11,
dec = 12, december = 12,
})
end

local function _list_text(list, fmt)
-- Return a list of formatted strings from a list of dates.
if not type(list) == 'table' then
error('date:list:text: need "list:text()" with a colon', 2)
end
local result = { join = _list_join }
for i, date in ipairs(list) do
result[i] = date:text(fmt)
end
return result
end

local function _date_list(date, spec)
-- Return a possibly empty numbered table of dates meeting the specification.
-- Dates in the list are in ascending order (oldest date first).
-- The spec should be a string of form "<count> <day> <op>"
-- where each item is optional and
--   count = number of items wanted in list
--   day = abbreviation or name such as Mon or Monday
--   op = >, >=, <, <= (default is > meaning after date)
-- If no count is given, the list is for the specified days in date's month.
-- The default day is date's day.
-- The spec can also be a positive or negative number:
--   -5 is equivalent to '5 <'
--   5  is equivalent to '5' which is '5 >'
if not is_date(date) then
error('date:list: need a date (use "date:list()" with a colon)', 2)
end
local list = { text = _list_text }
if date.partial then
return list
end
local count, offset, operation
local ops = {
['>='] = { before = false, include = true  },
['>']  = { before = false, include = false },
['<='] = { before = true , include = true  },
['<']  = { before = true , include = false },
}
if spec then
if type(spec) == 'number' then
count = floor(spec + 0.5)
if count < 0 then
count = -count
operation = ops['<']
end
elseif type(spec) == 'string' then
local num, day, op = spec:match('^%s*(%d*)%s*(%a*)%s*([<>=]*)%s*\$')
if not num then
return list
end
if num ~= '' then
count = tonumber(num)
end
if day ~= '' then
local dow = day_number(day:gsub('[sS]\$', ''))  -- accept plural days
if not dow then
return list
end
offset = dow - date.dow
end
operation = ops[op]
else
return list
end
end
offset = offset or 0
operation = operation or ops['>']
local datefrom, dayfirst, daylast
if operation.before then
if offset > 0 or (offset == 0 and not operation.include) then
offset = offset - 7
end
if count then
if count > 1 then
offset = offset - 7*(count - 1)
end
datefrom = date + offset
else
daylast = date.day + offset
dayfirst = daylast % 7
if dayfirst == 0 then
dayfirst = 7
end
end
else
if offset < 0 or (offset == 0 and not operation.include) then
offset = offset + 7
end
if count then
datefrom = date + offset
else
dayfirst = date.day + offset
daylast = date.monthdays
end
end
if not count then
if daylast < dayfirst then
return list
end
count = floor((daylast - dayfirst)/7) + 1
datefrom = Date(date, {day = dayfirst})
end
for i = 1, count do
if not datefrom then break end  -- exceeds date limits
list[i] = datefrom
datefrom = datefrom + 7
end
return list
end

-- A table to get the current date/time (UTC), but only if needed.
local current = setmetatable({}, {
__index = function (self, key)
local d = os.date('!*t')
self.year = d.year
self.month = d.month
self.day = d.day
self.hour = d.hour
self.minute = d.min
self.second = d.sec
return rawget(self, key)
end })

local function extract_date(newdate, text)
-- Parse the date/time in text and return n, o where
--   n = table of numbers with date/time fields
--   o = table of options for AM/PM or AD/BC or format, if any
-- or return nothing if date is known to be invalid.
-- Caller determines if the values in n are valid.
-- A year must be positive ('1' to '9999'); use 'BC' for BC.
-- In a y-m-d string, the year must be four digits to avoid ambiguity
-- ('0001' to '9999'). The only way to enter year <= 0 is by specifying
-- the date as three numeric parameters like ymd Date(-1, 1, 1).
-- Dates of form d/m/y, m/d/y, y/m/d are rejected as potentially ambiguous.
local date, options = {}, {}
if text:sub(-1) == 'Z' then
-- Extract date/time from a Wikidata timestamp.
-- The year can be 1 to 16 digits but this module handles 1 to 4 digits only.
-- Examples: '+2016-06-21T14:30:00Z', '-0000000180-00-00T00:00:00Z'.
local sign, y, m, d, H, M, S = text:match('^([+%-])(%d+)%-(%d%d)%-(%d%d)T(%d%d):(%d%d):(%d%d)Z\$')
if sign then
y = tonumber(y)
if sign == '-' and y > 0 then
y = -y
end
if y <= 0 then
options.era = 'BCE'
end
date.year = y
m = tonumber(m)
d = tonumber(d)
H = tonumber(H)
M = tonumber(M)
S = tonumber(S)
if m == 0 then
newdate.partial = true
return date, options
end
date.month = m
if d == 0 then
newdate.partial = true
return date, options
end
date.day = d
if H > 0 or M > 0 or S > 0 then
date.hour = H
date.minute = M
date.second = S
end
return date, options
end
return
end
local function extract_ymd(item)
-- Called when no day or month has been set.
local y, m, d = item:match('^(%d%d%d%d)%-(%w+)%-(%d%d?)\$')
if y then
if date.year then
return
end
if m:match('^%d%d?\$') then
m = tonumber(m)
else
m = month_number(m)
end
if m then
date.year = tonumber(y)
date.month = m
date.day = tonumber(d)
return true
end
end
end
local function extract_day_or_year(item)
-- Called when a day would be valid, or
-- when a year would be valid if no year has been set and partial is set.
local number, suffix = item:match('^(%d%d?%d?%d?)(.*)\$')
if number then
local n = tonumber(number)
if #number <= 2 and n <= 31 then
suffix = suffix:lower()
if suffix == '' or suffix == 'st' or suffix == 'nd' or suffix == 'rd' or suffix == 'th' then
date.day = n
return true
end
elseif suffix == '' and newdate.partial and not date.year then
date.year = n
return true
end
end
end
local function extract_month(item)
-- A month must be given as a name or abbreviation; a number could be ambiguous.
local m = month_number(item)
if m then
date.month = m
return true
end
end
local function extract_time(item)
local h, m, s = item:match('^(%d%d?):(%d%d)(:?%d*)\$')
if date.hour or not h then
return
end
if s ~= '' then
s = s:match('^:(%d%d)\$')
if not s then
return
end
end
date.hour = tonumber(h)
date.minute = tonumber(m)
date.second = tonumber(s)  -- nil if empty string
return true
end
local item_count = 0
local index_time
local function set_ampm(item)
local H = date.hour
if H and not options.am and index_time + 1 == item_count then
options.am = ampm_options[item]  -- caller checked this is not nil
if item:match('^[Aa]') then
if not (1 <= H and H <= 12) then
return
end
if H == 12 then
date.hour = 0
end
else
if not (1 <= H and H <= 23) then
return
end
if H <= 11 then
date.hour = H + 12
end
end
return true
end
end
for item in text:gsub(',', ' '):gsub('&nbsp;', ' '):gmatch('%S+') do
item_count = item_count + 1
if era_text[item] then
-- Era is accepted in peculiar places.
if options.era then
return
end
options.era = item
elseif ampm_options[item] then
if not set_ampm(item) then
return
end
elseif item:find(':', 1, true) then
if not extract_time(item) then
return
end
index_time = item_count
elseif date.day and date.month then
if date.year then
return  -- should be nothing more so item is invalid
end
if not item:match('^(%d%d?%d?%d?)\$') then
return
end
date.year = tonumber(item)
elseif date.day then
if not extract_month(item) then
return
end
elseif date.month then
if not extract_day_or_year(item) then
return
end
elseif extract_month(item) then
options.format = 'mdy'
elseif extract_ymd(item) then
options.format = 'ymd'
elseif extract_day_or_year(item) then
if date.day then
options.format = 'dmy'
end
else
return
end
end
if not date.year or date.year == 0 then
return
end
local era = era_text[options.era]
if era and era.isbc then
date.year = 1 - date.year
end
return date, options
end

local function autofill(date1, date2)
-- Fill any missing month or day in each date using the
-- corresponding component from the other date, if present,
-- or with 1 if both dates are missing the month or day.
-- This gives a good result for calculating the difference
-- between two partial dates when no range is wanted.
-- Return filled date1, date2 (two full dates).
local function filled(a, b)
local fillmonth, fillday
if not a.month then
fillmonth = b.month or 1
end
if not a.day then
fillday = b.day or 1
end
if fillmonth or fillday then  -- need to create a new date
a = Date(a, { month = fillmonth, day = fillday })
end
return a
end
return filled(date1, date2), filled(date2, date1)
end

-- Return a new date from calculating (lhs + rhs) or (lhs - rhs),
-- or return nothing if invalid.
-- The result is nil if the calculated date exceeds allowable limits.
-- Caller ensures that lhs is a date; its properties are copied for the new date.
if lhs.partial then
-- Adding to a partial is not supported.
-- Can subtract a date or partial from a partial, but this is not called for that.
return
end
local function is_prefix(text, word, minlen)
local n = #text
return (minlen or 1) <= n and n <= #word and text == word:sub(1, n)
end
local function do_days(n)
local forcetime, jd
if floor(n) == n then
jd = lhs.jd
else
forcetime = not lhs.hastime
jd = lhs.jdz
end
jd = jd + (is_sub and -n or n)
if forcetime then
jd = tostring(jd)
if not jd:find('.', 1, true) then
jd = jd .. '.0'
end
end
return Date(lhs, 'juliandate', jd)
end
if type(rhs) == 'number' then
-- Add/subtract days, including fractional days.
return do_days(rhs)
end
if type(rhs) == 'string' then
-- rhs is a single component like '26m' or '26 months' (with optional sign).
-- Fractions like '3.25d' are accepted for the units which are handled as days.
local sign, numstr, id = rhs:match('^%s*([+-]?)([%d%.]+)%s*(%a+)\$')
if sign then
if sign == '-' then
is_sub = not (is_sub and true or false)
end
local y, m, days
local num = tonumber(numstr)
if not num then
return
end
id = id:lower()
if is_prefix(id, 'years') then
y = num
m = 0
elseif is_prefix(id, 'months') then
y = floor(num / 12)
m = num % 12
elseif is_prefix(id, 'weeks') then
days = num * 7
elseif is_prefix(id, 'days') then
days = num
elseif is_prefix(id, 'hours') then
days = num / 24
elseif is_prefix(id, 'minutes', 3) then
days = num / (24 * 60)
elseif is_prefix(id, 'seconds') then
days = num / (24 * 3600)
else
return
end
if days then
return do_days(days)
end
if numstr:find('.', 1, true) then
return
end
if is_sub then
y = -y
m = -m
end
assert(-11 <= m and m <= 11)
y = lhs.year + y
m = lhs.month + m
if m > 12 then
y = y + 1
m = m - 12
elseif m < 1 then
y = y - 1
m = m + 12
end
local d = math.min(lhs.day, days_in_month(y, m, lhs.calendar))
return Date(lhs, y, m, d)
end
end
if is_diff(rhs) then
local days = rhs.age_days
if (is_sub or false) ~= (rhs.isnegative or false) then
days = -days
end
return lhs + days
end
end

local full_date_only = {
dayabbr = true,
dayname = true,
dow = true,
dayofweek = true,
dowiso = true,
dayofweekiso = true,
dayofyear = true,
gsd = true,
juliandate = true,
jd = true,
jdz = true,
jdnoon = true,
}

-- Metatable for a date's calculated fields.
local datemt = {
__index = function (self, key)
if rawget(self, 'partial') then
if full_date_only[key] then return end
if key == 'monthabbr' or key == 'monthdays' or key == 'monthname' then
if not self.month then return end
end
end
local value
if key == 'dayabbr' then
value = day_info[self.dow][1]
elseif key == 'dayname' then
value = day_info[self.dow][2]
elseif key == 'dow' then
value = (self.jdnoon + 1) % 7  -- day-of-week 0=Sun to 6=Sat
elseif key == 'dayofweek' then
value = self.dow
elseif key == 'dowiso' then
value = (self.jdnoon % 7) + 1  -- ISO day-of-week 1=Mon to 7=Sun
elseif key == 'dayofweekiso' then
value = self.dowiso
elseif key == 'dayofyear' then
local first = Date(self.year, 1, 1, self.calendar).jdnoon
value = self.jdnoon - first + 1  -- day-of-year 1 to 366
elseif key == 'era' then
-- Era text (never a negative sign) from year and options.
value = get_era_for_year(self.options.era, self.year)
elseif key == 'format' then
value = self.options.format or 'dmy'
elseif key == 'gsd' then
-- GSD = 1 from 00:00:00 to 23:59:59 on 1 January 1 AD Gregorian calendar,
-- which is from jd 1721425.5 to 1721426.49999.
value = floor(self.jd - 1721424.5)
elseif key == 'juliandate' or key == 'jd' or key == 'jdz' then
local jd, jdz = julian_date(self)
rawset(self, 'juliandate', jd)
rawset(self, 'jd', jd)
rawset(self, 'jdz', jdz)
return key == 'jdz' and jdz or jd
elseif key == 'jdnoon' then
-- Julian date at noon (an integer) on the calendar day when jd occurs.
value = floor(self.jd + 0.5)
elseif key == 'isleapyear' then
value = is_leap_year(self.year, self.calendar)
elseif key == 'monthabbr' then
value = month_info[self.month][1]
elseif key == 'monthdays' then
value = days_in_month(self.year, self.month, self.calendar)
elseif key == 'monthname' then
value = month_info[self.month][2]
end
if value ~= nil then
rawset(self, key, value)
return value
end
end,
}

-- Date operators.
if not is_date(lhs) then
lhs, rhs = rhs, lhs  -- put date on left (it must be a date for this to have been called)
end
end

local function mt_date_sub(lhs, rhs)
if is_date(lhs) then
if is_date(rhs) then
return DateDiff(lhs, rhs)
end
end
end

local function mt_date_concat(lhs, rhs)
end

local function mt_date_tostring(self)
return self:text()
end

local function mt_date_eq(lhs, rhs)
-- Return true if dates identify same date/time where, for example,
-- Date(-4712, 1, 1, 'Julian') == Date(-4713, 11, 24, 'Gregorian') is true.
-- This is called only if lhs and rhs have the same type and the same metamethod.
if lhs.partial or rhs.partial then
-- One date is partial; the other is a partial or a full date.
-- The months may both be nil, but must be the same.
return lhs.year == rhs.year and lhs.month == rhs.month and lhs.calendar == rhs.calendar
end
return lhs.jdz == rhs.jdz
end

local function mt_date_lt(lhs, rhs)
-- Return true if lhs < rhs, for example,
-- Date('1 Jan 2016') < Date('06:00 1 Jan 2016') is true.
-- This is called only if lhs and rhs have the same type and the same metamethod.
if lhs.partial or rhs.partial then
-- One date is partial; the other is a partial or a full date.
if lhs.calendar ~= rhs.calendar then
return lhs.calendar == 'Julian'
end
if lhs.partial then
lhs = lhs.partial.first
end
if rhs.partial then
rhs = rhs.partial.first
end
end
return lhs.jdz < rhs.jdz
end

--[[ Examples of syntax to construct a date:
Date(y, m, d, 'julian')             default calendar is 'gregorian'
Date(y, m, d, H, M, S, 'julian')
Date('juliandate', jd, 'julian')    if jd contains "." text output includes H:M:S
Date('currentdate')
Date('currentdatetime')
Date('1 April 1995', 'julian')      parse date from text
Date('1 April 1995 AD', 'julian')   using an era sets a flag to do the same for output
Date('04:30:59 1 April 1995', 'julian')
Date(date)                          copy of an existing date
Date(date, t)                       same, updated with y,m,d,H,M,S fields from table t
Date(t)                       		date with y,m,d,H,M,S fields from table t
]]
function Date(...)  -- for forward declaration above
-- Return a table holding a date assuming a uniform calendar always applies
-- (proleptic Gregorian calendar or proleptic Julian calendar), or
-- return nothing if date is invalid.
-- A partial date has a valid year, however its month may be nil, and
-- its day and time fields are nil.
-- Field partial is set to false (if a full date) or a table (if a partial date).
local calendars = { julian = 'Julian', gregorian = 'Gregorian' }
local newdate = {
_id = uniq,
calendar = 'Gregorian',  -- default is Gregorian calendar
hastime = false,  -- true if input sets a time
hour = 0,  -- always set hour/minute/second so don't have to handle nil
minute = 0,
second = 0,
options = {},
list = _date_list,
subtract = function (self, rhs, options)
return DateDiff(self, rhs, options)
end,
text = _date_text,
}
local argtype, datetext, is_copy, jd_number, tnums
local numindex = 0
local numfields = { 'year', 'month', 'day', 'hour', 'minute', 'second' }
local numbers = {}
for _, v in ipairs({...}) do
v = strip_to_nil(v)
local vlower = type(v) == 'string' and v:lower() or nil
if v == nil then
-- Ignore empty arguments after stripping so modules can directly pass template parameters.
elseif calendars[vlower] then
newdate.calendar = calendars[vlower]
elseif vlower == 'partial' then
newdate.partial = true
elseif vlower == 'fix' then
newdate.want_fix = true
elseif is_date(v) then
-- Copy existing date (items can be overridden by other arguments).
if is_copy or tnums then
return
end
is_copy = true
newdate.calendar = v.calendar
newdate.partial = v.partial
newdate.hastime = v.hastime
newdate.options = v.options
newdate.year = v.year
newdate.month = v.month
newdate.day = v.day
newdate.hour = v.hour
newdate.minute = v.minute
newdate.second = v.second
elseif type(v) == 'table' then
if tnums then
return
end
tnums = {}
local tfields = { year=1, month=1, day=1, hour=2, minute=2, second=2 }
for tk, tv in pairs(v) do
if tfields[tk] then
tnums[tk] = tonumber(tv)
end
if tfields[tk] == 2 then
newdate.hastime = true
end
end
else
local num = tonumber(v)
if not num and argtype == 'setdate' and numindex == 1 then
num = month_number(v)
end
if num then
if not argtype then
argtype = 'setdate'
end
if argtype == 'setdate' and numindex < 6 then
numindex = numindex + 1
numbers[numfields[numindex]] = num
elseif argtype == 'juliandate' and not jd_number then
jd_number = num
if type(v) == 'string' then
if v:find('.', 1, true) then
newdate.hastime = true
end
elseif num ~= floor(num) then
-- The given value was a number. The time will be used
-- if the fractional part is nonzero.
newdate.hastime = true
end
else
return
end
elseif argtype then
return
elseif type(v) == 'string' then
if v == 'currentdate' or v == 'currentdatetime' or v == 'juliandate' then
argtype = v
else
argtype = 'datetext'
datetext = v
end
else
return
end
end
end
if argtype == 'datetext' then
if tnums or not set_date_from_numbers(newdate, extract_date(newdate, datetext)) then
return
end
elseif argtype == 'juliandate' then
newdate.partial = nil
newdate.jd = jd_number
if not set_date_from_jd(newdate) then
return
end
elseif argtype == 'currentdate' or argtype == 'currentdatetime' then
newdate.partial = nil
newdate.year = current.year
newdate.month = current.month
newdate.day = current.day
if argtype == 'currentdatetime' then
newdate.hour = current.hour
newdate.minute = current.minute
newdate.second = current.second
newdate.hastime = true
end
newdate.calendar = 'Gregorian'  -- ignore any given calendar name
elseif argtype == 'setdate' then
if tnums or not set_date_from_numbers(newdate, numbers) then
return
end
elseif not (is_copy or tnums) then
return
end
if tnums then
newdate.jd = nil  -- force recalculation in case jd was set before changes from tnums
if not set_date_from_numbers(newdate, tnums) then
return
end
end
if newdate.partial then
local year = newdate.year
local month = newdate.month
local first = Date(year, month or 1, 1, newdate.calendar)
month = month or 12
local last = Date(year, month, days_in_month(year, month), newdate.calendar)
newdate.partial = { first = first, last = last }
else
newdate.partial = false  -- avoid index lookup
end
setmetatable(newdate, datemt)
local mt = {
__index = newdate,
__newindex = function(t, k, v) error('date.' .. tostring(k) .. ' is read-only', 2) end,
__sub = mt_date_sub,
__concat = mt_date_concat,
__tostring = mt_date_tostring,
__eq = mt_date_eq,
__lt = mt_date_lt,
}
end

local function _diff_age(diff, code, options)
-- Return a tuple of integer values from diff as specified by code, except that
-- each integer may be a list of two integers for a diff with a partial date, or
-- return nil if the code is not supported.
-- If want round, the least significant unit is rounded to nearest whole unit.
-- For a duration, an extra day is added.
local wantround, wantduration, wantrange
if type(options) == 'table' then
wantround = options.round
wantduration = options.duration
wantrange = options.range
else
wantround = options
end
if not is_diff(diff) then
local f = wantduration and 'duration' or 'age'
error(f .. ': need a date difference (use "diff:' .. f .. '()" with a colon)', 2)
end
if diff.partial then
-- Ignore wantround, wantduration.
local function choose(v)
if type(v) == 'table' then
if not wantrange or v[1] == v[2] then
-- Example: Date('partial', 2005) - Date('partial', 2001) gives
-- diff.years = { 3, 4 } to show the range of possible results.
-- If do not want a range, choose the second value as more expected.
return v[2]
end
end
return v
end
if code == 'ym' or code == 'ymd' then
if not wantrange and diff.iszero then
-- This avoids an unexpected result such as
-- Date('partial', 2001) - Date('partial', 2001)
-- giving diff = { years = 0, months = { 0, 11 } }
-- which would be reported as 0 years and 11 months.
return 0, 0
end
return choose(diff.partial.years), choose(diff.partial.months)
end
if code == 'y' then
return choose(diff.partial.years)
end
if code == 'm' or code == 'w' or code == 'd' then
return choose({ diff.partial.mindiff:age(code), diff.partial.maxdiff:age(code) })
end
return nil
end
local extra_days = wantduration and 1 or 0
if code == 'wd' or code == 'w' or code == 'd' then
local offset = wantround and 0.5 or 0
local days = diff.age_days + extra_days
if code == 'wd' or code == 'd' then
days = floor(days + offset)
if code == 'd' then
return days
end
return floor(days/7), days % 7
end
return floor(days/7 + offset)
end
local H, M, S = diff.hours, diff.minutes, diff.seconds
if code == 'dh' or code == 'dhm' or code == 'dhms' or code == 'h' or code == 'hm' or code == 'hms' then
local days = floor(diff.age_days + extra_days)
local inc_hour
if wantround then
if code == 'dh' or code == 'h' then
if M >= 30 then
inc_hour = true
end
elseif code == 'dhm' or code == 'hm' then
if S >= 30 then
M = M + 1
if M >= 60 then
M = 0
inc_hour = true
end
end
else
-- Nothing needed because S is an integer.
end
if inc_hour then
H = H + 1
if H >= 24 then
H = 0
days = days + 1
end
end
end
if code == 'dh' or code == 'dhm' or code == 'dhms' then
if code == 'dh' then
return days, H
elseif code == 'dhm' then
return days, H, M
else
return days, H, M, S
end
end
local hours = days * 24 + H
if code == 'h' then
return hours
elseif code == 'hm' then
return hours, M
end
return hours, M, S
end
if wantround then
local inc_hour
if code == 'ymdh' or code == 'ymwdh' then
if M >= 30 then
inc_hour = true
end
elseif code == 'ymdhm' or code == 'ymwdhm' then
if S >= 30 then
M = M + 1
if M >= 60 then
M = 0
inc_hour = true
end
end
elseif code == 'ymd' or code == 'ymwd' or code == 'yd' or code == 'md' then
if H >= 12 then
extra_days = extra_days + 1
end
end
if inc_hour then
H = H + 1
if H >= 24 then
H = 0
extra_days = extra_days + 1
end
end
end
local y, m, d = diff.years, diff.months, diff.days
if extra_days > 0 then
d = d + extra_days
if d > 28 or code == 'yd' then
-- Recalculate in case have passed a month.
diff = diff.date1 + extra_days - diff.date2
y, m, d = diff.years, diff.months, diff.days
end
end
if code == 'ymd' then
return y, m, d
elseif code == 'yd' then
if y > 0 then
-- It is known that diff.date1 > diff.date2.
diff = diff.date1 - (diff.date2 + (y .. 'y'))
end
return y, floor(diff.age_days)
elseif code == 'md' then
return y * 12 + m, d
elseif code == 'ym' or code == 'm' then
if wantround then
if d >= 16 then
m = m + 1
if m >= 12 then
m = 0
y = y + 1
end
end
end
if code == 'ym' then
return y, m
end
return y * 12 + m
elseif code == 'ymw' then
local weeks = floor(d/7)
if wantround then
local days = d % 7
if days > 3 or (days == 3 and H >= 12) then
weeks = weeks + 1
end
end
return y, m, weeks
elseif code == 'ymwd' then
return y, m, floor(d/7), d % 7
elseif code == 'ymdh' then
return y, m, d, H
elseif code == 'ymwdh' then
return y, m, floor(d/7), d % 7, H
elseif code == 'ymdhm' then
return y, m, d, H, M
elseif code == 'ymwdhm' then
return y, m, floor(d/7), d % 7, H, M
end
if code == 'y' then
if wantround and m >= 6 then
y = y + 1
end
return y
end
return nil
end

local function _diff_duration(diff, code, options)
if type(options) ~= 'table' then
options = { round = options }
end
options.duration = true
return _diff_age(diff, code, options)
end

-- Metatable for some operations on date differences.
diffmt = {  -- for forward declaration above
__concat = function (lhs, rhs)
end,
__tostring = function (self)
end,
__index = function (self, key)
local value
if key == 'age_days' then
if rawget(self, 'partial') then
local function jdz(date)
return (date.partial and date.partial.first or date).jdz
end
value = jdz(self.date1) - jdz(self.date2)
else
value = self.date1.jdz - self.date2.jdz
end
end
if value ~= nil then
rawset(self, key, value)
return value
end
end,
}

function DateDiff(date1, date2, options)  -- for forward declaration above
-- Return a table with the difference between two dates (date1 - date2).
-- The difference is negative if date1 is older than date2.
-- Return nothing if invalid.
-- If d = date1 - date2 then
--     date1 = date2 + d
-- If date1 >= date2 and the dates have no H:M:S time specified then
--     date1 = date2 + (d.years..'y') + (d.months..'m') + d.days
-- where the larger time units are added first.
-- The result of Date(2015,1,x) + '1m' is Date(2015,2,28) for
-- x = 28, 29, 30, 31. That means, for example,
--     d = Date(2015,3,3) - Date(2015,1,31)
-- gives d.years, d.months, d.days = 0, 1, 3 (excluding date1).
if not (is_date(date1) and is_date(date2) and date1.calendar == date2.calendar) then
return
end
local wantfill
if type(options) == 'table' then
wantfill = options.fill
end
local isnegative = false
local iszero = false
if date1 < date2 then
isnegative = true
date1, date2 = date2, date1
elseif date1 == date2 then
iszero = true
end
-- It is known that date1 >= date2 (period is from date2 to date1).
if date1.partial or date2.partial then
-- Two partial dates might have timelines:
---------------------A=================B--- date1 is from A to B inclusive
--------C=======D-------------------------- date2 is from C to D inclusive
-- date1 > date2 iff A > C (date1.partial.first > date2.partial.first)
-- The periods can overlap ('April 2001' - '2001'):
-------------A===B------------------------- A=2001-04-01  B=2001-04-30
--------C=====================D------------ C=2001-01-01  D=2001-12-31
if wantfill then
date1, date2 = autofill(date1, date2)
else
local function zdiff(date1, date2)
local diff = date1 - date2
if diff.isnegative then
return date1 - date1  -- a valid diff in case we call its methods
end
return diff
end
local function getdate(date, which)
return date.partial and date.partial[which] or date
end
local maxdiff = zdiff(getdate(date1, 'last'), getdate(date2, 'first'))
local mindiff = zdiff(getdate(date1, 'first'), getdate(date2, 'last'))
local years, months
if maxdiff.years == mindiff.years then
years = maxdiff.years
if maxdiff.months == mindiff.months then
months = maxdiff.months
else
months = { mindiff.months, maxdiff.months }
end
else
years = { mindiff.years, maxdiff.years }
end
return setmetatable({
date1 = date1,
date2 = date2,
partial = {
years = years,
months = months,
maxdiff = maxdiff,
mindiff = mindiff,
},
isnegative = isnegative,
iszero = iszero,
age = _diff_age,
duration = _diff_duration,
}, diffmt)
end
end
local y1, m1 = date1.year, date1.month
local y2, m2 = date2.year, date2.month
local years = y1 - y2
local months = m1 - m2
local d1 = date1.day + hms(date1)
local d2 = date2.day + hms(date2)
local days, time
if d1 >= d2 then
days = d1 - d2
else
months = months - 1
-- Get days in previous month (before the "to" date) given December has 31 days.
local dpm = m1 > 1 and days_in_month(y1, m1 - 1, date1.calendar) or 31
if d2 >= dpm then
days = d1 - hms(date2)
else
days = dpm - d2 + d1
end
end
if months < 0 then
years = years - 1
months = months + 12
end
days, time = math.modf(days)
local H, M, S = h_m_s(time)
return setmetatable({
date1 = date1,
date2 = date2,
partial = false,  -- avoid index lookup
years = years,
months = months,
days = days,
hours = H,
minutes = M,
seconds = S,
isnegative = isnegative,
iszero = iszero,
age = _diff_age,
duration = _diff_duration,
}, diffmt)
end

return {
_current = current,
_Date = Date,
_days_in_month = days_in_month,
}
```
```"https://ne.wikipedia.org/w/index.php?title=मोड्युल:मिति&oldid=822089" बाट अनुप्रेषित
```