Module:Date
This module provides date functions for use by other modules. Dates in the Gregorian calendar and the Julian calendar are supported, from 9999 BCE to 9999 CE. The calendars are proleptic—they are assumed to apply at all times with no irregularities.
A date, with an optional time, can be specified in a variety of formats, and can be converted for display using a variety of formats, for example, 1 April 2016 or April 1, 2016. The properties of a date include its Julian date and its Gregorian serial date, as well as the day-of-week and day-of-year.
Dates can be compared (for example, date1 <= date2), and can be used with add or subtract (for example, date + '3 months'). The difference between two dates can be determined with date1 - date2. These operations work with both Gregorian and Julian calendar dates, but date1 - date2 is nil if the two dates use different calendars.
The module provides the following items.
| Export | Description |
|---|---|
_current |
Table with the current year, month, day, hour, minute, second. |
_Date |
Function that returns a table for a specified date. |
_days_in_month |
Function that returns the number of days in a month. |
The following has examples of using the module:
- Module:Date/example • Demonstration showing how Module:Date may be used.
- Module talk:Date/example • Output from the demonstration.
Formatted output
A date can be formatted as text.
local Date = require('Module:Date')._Date
local text = Date(2016, 7, 1):text() -- result is '1 July 2016'
local text = Date(2016, 7, 1):text('%-d %B') -- result is '1 July'
local text = Date('1 July 2016'):text('mdy') -- result is 'July 1, 2016'
The following simplified formatting codes are available.
| Code | Result |
|---|---|
| hm | hour:minute, with "am" or "pm" or variant, if specified (14:30 or 2:30 pm or variant) |
| hms | hour:minute:second (14:30:45) |
| ymd | year-month-day (2016-07-01) |
| mdy | month day, year (July 1, 2016) |
| dmy | day month year (1 July 2016) |
The following formatting codes (similar to strftime) are available.
| Code | Result |
|---|---|
| %a | Day abbreviation: Mon, Tue, ... |
| %A | Day name: Monday, Tuesday, ... |
| %u | Day of week: 1 to 7 (Monday to Sunday) |
| %w | Day of week: 0 to 6 (Sunday to Saturday) |
| %d | Day of month zero-padded: 01 to 31 |
| %b | Month abbreviation: Jan to Dec |
| %B | Month name: January to December |
| %m | Month zero-padded: 01 to 12 |
| %Y | Year zero-padded: 0012, 0120, 1200 |
| %H | Hour 24-hour clock zero-padded: 00 to 23 |
| %I | Hour 12-hour clock zero-padded: 01 to 12 |
| %p | AM or PM or as in options |
| %M | Minute zero-padded: 00 to 59 |
| %S | Second zero-padded: 00 to 59 |
| %j | Day of year zero-padded: 001 to 366 |
| %-d | Day of month: 1 to 31 |
| %-m | Month: 1 to 12 |
| %-Y | Year: 12, 120, 1200 |
| %-H | Hour: 0 to 23 |
| %-M | Minute: 0 to 59 |
| %-S | Second: 0 to 59 |
| %-j | Day of year: 1 to 366 |
| %-I | Hour: 1 to 12 |
| %% | % |
In addition, %{property} (where property is any property of a date) can be used.
For example, Date('1 Feb 2015 14:30:45 A.D.') has the following properties.
| Code | Result |
|---|---|
| %{calendar} | Gregorian |
| %{year} | 2015 |
| %{month} | 2 |
| %{day} | 1 |
| %{hour} | 14 |
| %{minute} | 30 |
| %{second} | 45 |
| %{dayabbr} | Sun |
| %{dayname} | Sunday |
| %{dayofweek} | 0 |
| %{dow} | 0 (same as dayofweek) |
| %{dayofweekiso} | 7 |
| %{dowiso} | 7 (same as dayofweekiso) |
| %{dayofyear} | 32 |
| %{era} | A.D. |
| %{gsd} | 735630 (numbers of days from 1 January 1 CE; the first is day 1) |
| %{juliandate} | 2457055.1046875 (Julian day) |
| %{jd} | 2457055.1046875 (same as juliandate) |
| %{isleapyear} | false |
| %{monthdays} | 28 |
| %{monthabbr} | Feb |
| %{monthname} | February |
Some shortcuts are available. Given date = Date('1 Feb 2015 14:30'), the following results would occur.
| Code | Description | Example result | Equivalent format |
|---|---|---|---|
| date:text('%c') | date and time | 2:30 pm 1 February 2015 | %-I:%M %p %-d %B %-Y %{era} |
| date:text('%x') | date | 1 February 2015 | %-d %B %-Y %{era} |
| date:text('%X') | time | 2:30 pm | %-I:%M %p |
Julian date
The following has an example of converting a Julian date to a date, then obtaining information about the date.
-- Code -- Result
Date = require('Module:Date')._Date
date = Date('juliandate', 320)
number = date.gsd -- -1721105
number = date.jd -- 320
text = date.dayname -- Saturday
text = date:text() -- 9 October 4713 BC
text = date:text('%Y-%m-%d') -- 4713-10-09
text = date:text('%{era} %Y-%m-%d') -- BC 4713-10-09
text = date:text('%Y-%m-%d %{era}') -- 4713-10-09 BC
text = date:text('%Y-%m-%d %{era}', 'era=B.C.E.') -- 4713-10-09 B.C.E.
text = date:text('%Y-%m-%d', 'era=BCNEGATIVE') -- -4712-10-09
text = date:text('%Y-%m-%d', 'era=BCMINUS') -- −4712-10-09 (uses Unicode MINUS SIGN U+2212)
text = Date('juliandate',320):text('%{gsd} %{jd}') -- -1721105 320
text = Date('Oct 9, 4713 B.C.E.'):text('%{gsd} %{jd}') -- -1721105 320
text = Date(-4712,10,9):text('%{gsd} %{jd}') -- -1721105 320
Date differences
The difference between two dates can be determined with date1 - date2. The result is valid if both dates use the Gregorian calendar or if both dates use the Julian calendar, otherwise the result is nil. An age and duration can be calculated from a date difference.
For example:
-- Code -- Result
Date = require('Module:Date')._Date
date1 = Date('21 Mar 2015')
date2 = Date('4 Dec 1999')
diff = date1 - date2
d = diff.age_days -- 5586
y, m, d = diff.years, diff.months, diff.days -- 15, 3, 17 (15 years + 3 months + 17 days)
y, m, d = diff:age('ymd') -- 15, 3, 17
y, m, w, d = diff:age('ymwd') -- 15, 3, 2, 3 (15 years + 3 months + 2 weeks + 3 days)
y, m, w, d = diff:duration('ymwd') -- 15, 3, 2, 4
d = diff:duration('d') -- 5587 (a duration includes the final day)
A date difference holds the original dates except they are swapped so diff.date1 >= diff.date2 (diff.date1 is the more recent date). This is shown in the following.
date1 = Date('21 Mar 2015')
date2 = Date('4 Dec 1999')
diff = date1 - date2
neg = diff.isnegative -- false
text = diff.date1:text() -- 21 March 2015
text = diff.date2:text() -- 4 December 1999
diff = date2 - date1
neg = diff.isnegative -- true (dates have been swapped)
text = diff.date1:text() -- 21 March 2015
text = diff.date2:text() -- 4 December 1999
A date difference also holds a time difference:
date1 = Date('8 Mar 2016 0:30:45')
date2 = Date('19 Jan 2014 22:55')
diff = date1 - date2
y, m, d = diff.years, diff.months, diff.days -- 2, 1, 17
H, M, S = diff.hours, diff.minutes, diff.seconds -- 1, 35, 45
A date difference can be added to a date, or subtracted from a date.
date1 = Date('8 Mar 2016 0:30:45')
date2 = Date('19 Jan 2014 22:55')
diff = date1 - date2
date3 = date2 + diff
date4 = date1 - diff
text = date3:text('ymd hms') -- 2016-03-08 00:30:45
text = date4:text('ymd hms') -- 2014-01-19 22:55:00
equal = (date1 == date3) -- true
equal = (date2 == date4) -- true
The age and duration methods of a date difference accept a code that identifies the components that should be returned. An extra day is included for the duration method because it includes the final day.
| Code | Returned values |
|---|---|
'ymwd' |
years, months, weeks, days |
'ymd' |
years, months, days |
'ym' |
years, months |
'y' |
years |
'm' |
months |
'wd' |
weeks, days |
'w' |
weeks |
'd' |
days |
-- 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,
add = function (self, item)
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 },
['AD'] = { 'BC' , 'AD' },
['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 ' ') .. (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 ' ') .. 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
local function bad_format()
-- 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
return bad_format()
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
return bad_format()
end
t:add(f)
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(' ', ' '):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
local function date_add_sub(lhs, rhs, is_sub)
-- 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.
local function mt_date_add(lhs, rhs)
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
return date_add_sub(lhs, rhs)
end
local function mt_date_sub(lhs, rhs)
if is_date(lhs) then
if is_date(rhs) then
return DateDiff(lhs, rhs)
end
return date_add_sub(lhs, rhs, true)
end
end
local function mt_date_concat(lhs, rhs)
return tostring(lhs) .. tostring(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 readonly = {}
local mt = {
__index = newdate,
__newindex = function(t, k, v) error('date.' .. tostring(k) .. ' is read-only', 2) end,
__add = mt_date_add,
__sub = mt_date_sub,
__concat = mt_date_concat,
__tostring = mt_date_tostring,
__eq = mt_date_eq,
__lt = mt_date_lt,
}
return setmetatable(readonly, mt)
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)
return tostring(lhs) .. tostring(rhs)
end,
__tostring = function (self)
return tostring(self.age_days)
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,
}
