Module:Age: Difference between revisions

    From Nonbinary Wiki
    (update from sandbox: Template:Death date and age now gives an error if the death date is in future by more than one day)
    m (29 revisions imported from wikipedia:Module:Age: see Topic:Vtixlm0q28eo6jtf)
     
    (4 intermediate revisions by one other user not shown)
    Line 3: Line 3:
    local mtext = {
    local mtext = {
    -- Message and other text that should be localized.
    -- Message and other text that should be localized.
    -- Also need to localize text in table names in function dateDifference.
    ['mt-bad-param1'] =            'Invalid parameter $1',
    ['mt-bad-param1'] =            'Invalid parameter $1',
    ['mt-bad-param2'] =            'Parameter $1=$2 is invalid',
    ['mt-bad-param2'] =            'Parameter $1=$2 is invalid',
    Line 25: Line 26:
    ['mt-template-bad-name'] =      'The specified template name is not valid',
    ['mt-template-bad-name'] =      'The specified template name is not valid',
    ['mt-template-x'] =            'The template invoking this must have "|template=x" where x is the wanted operation',
    ['mt-template-x'] =            'The template invoking this must have "|template=x" where x is the wanted operation',
    ['txt-age'] =                  '(age ',
    ['txt-aged'] =                  ' (aged ',
    ['txt-and'] =                  ' and ',
    ['txt-and'] =                  ' and ',
    ['txt-or'] =                    ' or ',
    ['txt-category'] =              'Category:Age error',
    ['txt-comma-and'] =            ', and ',
    ['txt-comma-and'] =            ', and ',
    ['txt-error'] =                'Error: ',
    ['txt-error'] =                'Error: ',
    ['txt-or'] =                   ' or ',
    ['txt-format-default'] =        'mf',  -- 'df' (day first = dmy) or 'mf' (month first = mdy)
    ['txt-module-convertnumeric'] = 'Module:ConvertNumeric',
    ['txt-module-date'] =          'Module:Date',
    ['txt-sandbox'] =              'sandbox',
    ['txt-bda'] = '<span style="display:none"> (<span class="bday">$1</span>) </span>$2<span class="noprint ForceAgeToShow"> (age&nbsp;$3)</span>',
    ['txt-dda'] = '$2<span style="display:none">($1)</span> (aged&nbsp;$3)',
    ['txt-bda-disp'] = 'disp_raw',  -- disp_raw → age is a number only; disp_age → age is a number and unit (normally years but months or days if very young)
    ['txt-dda-disp'] = 'disp_raw',
    ['txt-dmy'] = '%-d %B %-Y',
    ['txt-mdy'] = '%B %-d, %-Y',
    }
     
    local isWarning = {
    ['mt-bad-param1'] = true,
    }
    }


    Line 50: Line 64:
    -- Return objects exported from the date module or its sandbox.
    -- Return objects exported from the date module or its sandbox.
    if not _Date then
    if not _Date then
    local sandbox = frame:getTitle():find('sandbox', 1, true) and '/sandbox' or ''
    local sandbox = frame:getTitle():find(mtext['txt-sandbox'], 1, true) and ('/' .. mtext['txt-sandbox']) or ''
    local datemod = require('Module:Date' .. sandbox)
    local datemod = require(mtext['txt-module-date'] .. sandbox)
    local realDate = datemod._Date
    local realDate = datemod._Date
    _currentDate = datemod._current
    _currentDate = datemod._current
    Line 102: Line 116:
    end
    end
    return text
    return text
    end
    local function dateFormat(args)
    -- Return string for wanted date format.
    local default = mtext['txt-format-default']
    local other = default == 'df' and 'mf' or 'df'
    local wanted = stripToNil(args[other]) and other or default
    return wanted == 'df' and mtext['txt-dmy'] or mtext['txt-mdy']
    end
    local function substituteParameters(text, ...)
    -- Return text after substituting any given parameters for $1, $2, etc.
    return mw.message.newRawMessage(text, ...):plain()
    end
    end


    Line 111: Line 138:
    end
    end


    local function message(msg, id)
    local function message(msg, ...)
    -- Return formatted message text for an error or warning.
    -- Return formatted message text for an error or warning.
    local function getText(msg)
    local function getText(msg)
    return mtext[msg] or error('Bug: message "' .. tostring(msg) .. '" not defined')
    return mtext[msg] or error('Bug: message "' .. tostring(msg) .. '" not defined')
    end
    local text
    if type(msg) == 'table' then
    text = getText(msg[1])
    local rep = {}
    for i, v in ipairs(msg) do
    if i > 1 then
    rep['$' .. (i - 1)] = v
    end
    end
    text = text:gsub('$%d+', rep)
    else
    text = getText(msg)
    end
    end
    local categories = {
    local categories = {
    error = '[[Category:Age error]]',
    error = mtext['txt-category'],
    warning = '[[Category:Age error]]',  -- same as error until determine whether 'Age warning' would be worthwhile
    warning = mtext['txt-category'],
    }
    }
    local a, b, category
    local a, b, k, category
    if id == 'warning' then
    local text = substituteParameters(getText(msg), ...)
    if isWarning[msg] then
    a = '<sup>[<i>'
    a = '<sup>[<i>'
    b = '</i>]</sup>'
    b = '</i>]</sup>'
    k = 'warning'
    else
    else
    a = '<strong class="error">' .. getText('txt-error')
    a = '<strong class="error">' .. getText('txt-error')
    b = '</strong>'
    b = '</strong>'
    k = 'error'
    end
    end
    if mw.title.getCurrentTitle():inNamespaces(0) then
    if mw.title.getCurrentTitle():inNamespaces(0) then
    -- Category only in namespaces: 0=article.
    -- Category only in namespaces: 0=article.
    category = categories[id or 'error']
    category = '[[' .. categories[k] .. ']]'
    end
    end
    return
    return
    Line 178: Line 195:
    -- i == 1 for the first number which can optionally start with an uppercase letter.
    -- i == 1 for the first number which can optionally start with an uppercase letter.
    number = tostring(number)
    number = tostring(number)
    return require('Module:ConvertNumeric').spell_number(
    return require(mtext['txt-module-convertnumeric']).spell_number(
    number,
    number,
    nil,                      -- fraction numerator
    nil,                      -- fraction numerator
    Line 195: Line 212:
    if mw.ustring.len(extra) > 1 then
    if mw.ustring.len(extra) > 1 then
    -- Parameter "~" gives "~3" whereas "over" gives "over 3".
    -- Parameter "~" gives "~3" whereas "over" gives "over 3".
    extra = extra .. ' '
    if extra:sub(-6, -1) ~= '&nbsp;' then
    extra = extra .. ' '
    end
    end
    end
    if flagCurrent then
    if flagCurrent then
    Line 220: Line 239:
    sortKey = string.format('%d', sortKey) .. string.format('%015.0f', math.floor(value * 10^(14-mag)))
    sortKey = string.format('%d', sortKey) .. string.format('%015.0f', math.floor(value * 10^(14-mag)))
    end
    end
    local lhs, rhs
    local result
    if sortable == 'sortable_table' then
    if sortable == 'sortable_table' then
    lhs = 'data-sort-value="'
    result = 'data-sort-value="_SORTKEY_"|'
    rhs = '"|'
    elseif sortable == 'sortable_debug' then
    result = '<span data-sort-value="_SORTKEY_♠"><span style="border:1px solid">_SORTKEY_♠</span></span>'
    else
    else
    lhs = sortable == 'sortable_debug' and
    result = '<span data-sort-value="_SORTKEY_♠"></span>'
    '<span style="border:1px solid;display:inline;" class="sortkey">' or
    '<span style="display:none" class="sortkey">'
    rhs = '♠</span>'
    end
    end
    return lhs .. sortKey .. rhs
    return (result:gsub('_SORTKEY_', sortKey))
    end
    end
    end
    end
    Line 276: Line 293:
    hm = { 'H', 'M', id = 'hm' },
    hm = { 'H', 'M', id = 'hm' },
    hms = { 'H', 'M', 'S', id = 'hms' },
    hms = { 'H', 'M', 'S', id = 'hms' },
    M = { 'M', id = 'M' },
    s = { 'S', id = 's' },
    d = { 'd', id = 'd' },
    d = { 'd', id = 'd' },
    dh = { 'd', 'H', id = 'dh' },
    dh = { 'd', 'H', id = 'dh' },
    Line 331: Line 350:
    date = date + item
    date = date + item
    if not date then
    if not date then
    return message({ 'mt-cannot-add', item })
    return message('mt-cannot-add', item)
    end
    end
    end
    end
    Line 351: Line 370:
    end
    end
    end
    end
    return (sortKey or '') .. (result or '')
    return (sortKey or '') .. makeExtra(args) .. (result or '')
    end
    end


    Line 388: Line 407:
    local name = names[components[i]]
    local name = names[components[i]]
    if name then
    if name then
    local plural = names.plural
    if type(name) == 'table' then
    if not plural or (islist and v[2] or v) == 1 then
    name = mw.getContentLanguage():plural(islist and v[2] or v, name)
    plural = ''
    end
    end
    text:add(vstr .. sep .. name .. plural)
    text:add(vstr .. sep .. name)
    else
    else
    text:add(vstr)
    text:add(vstr)
    Line 440: Line 458:
    -- which have been validated.
    -- which have been validated.
    local names = {
    local names = {
    -- Each name is:
    -- * a string if no plural form of the name is used; or
    -- * a table of strings, one of which is selected using the rules at
    --  https://translatewiki.net/wiki/Plural/Mediawiki_plural_rules
    abbr_off = {
    abbr_off = {
    plural = 's',
    sep = '&nbsp;',
    sep = '&nbsp;',
    y = 'year',
    y = {'year', 'years'},
    m = 'month',
    m = {'month', 'months'},
    w = 'week',
    w = {'week', 'weeks'},
    d = 'day',
    d = {'day', 'days'},
    H = 'hour',
    H = {'hour', 'hours'},
    M = 'minute',
    M = {'minute', 'minutes'},
    S = 'second',
    S = {'second', 'seconds'},
    },
    },
    abbr_on = {
    abbr_on = {
    Line 461: Line 482:
    },
    },
    abbr_infant = {      -- for {{age for infant}}
    abbr_infant = {      -- for {{age for infant}}
    plural = 's',
    sep = '&nbsp;',
    sep = '&nbsp;',
    y = 'yr',
    y = {'yr', 'yrs'},
    m = 'mo',
    m = {'mo', 'mos'},
    w = 'wk',
    w = {'wk', 'wks'},
    d = 'day',
    d = {'day', 'days'},
    H = 'hr',
    H = {'hr', 'hrs'},
    M = 'min',
    M = {'min', 'mins'},
    S = 'sec',
    S = {'sec', 'secs'},
    },
    },
    abbr_raw = {},
    abbr_raw = {},
    Line 550: Line 570:
    (textOptions.suffix or '')
    (textOptions.suffix or '')
    end
    end
    return message({ 'mt-bad-show', show.id })
    return message('mt-bad-show', show.id)
    end
    end


    Line 624: Line 644:
    for i = 1, nrDates do
    for i = 1, nrDates do
    local index = i == 1 and 1 or 4
    local index = i == 1 and 1 or 4
    dates[i] = Date(fields[index], fields[index+1], fields[index+2])
    local y, m, d = fields[index], fields[index+1], fields[index+2]
    if (m == 2 or m == '2') and (d == 29 or d == '29') then
    -- Workaround error with following which attempt to use invalid date 2001-02-29.
    -- {{age_ymwd|year1=2001|year2=2004|month2=2|day2=29}}
    -- {{age_ymwd|year1=2001|month1=2|year2=2004|month2=1|day2=29}}
    -- TODO Get rid of wantMixture because even this ugly code does not handle
    -- 'Feb' or 'February' or 'feb' or 'february'.
    if not ((y % 4 == 0 and y % 100 ~= 0) or y % 400 == 0) then
    d = 28
    end
    end
    dates[i] = Date(y, m, d)
    end
    end
    else
    else
    Line 850: Line 881:
    return message('mt-invalid-bd-age')
    return message('mt-invalid-bd-age')
    end
    end
    local disp, show = 'disp_raw', 'y'
    local disp = mtext['txt-bda-disp']
    local show = 'y'
    if diff.years < 2 then
    if diff.years < 2 then
    disp = 'disp_age'
    disp = 'disp_age'
    Line 859: Line 891:
    end
    end
    end
    end
    local df = stripToNil(args.df)  -- day first (dmy); default is month first (mdy)
    local result = substituteParameters(
    local result = '(<span class="bday">%-Y-%m-%d</span>) </span>' ..
    mtext['txt-bda'],
    (df and '%-d %B %-Y' or '%B %-d, %-Y')
    date:text('%-Y-%m-%d'),
    result = from_en('<span style="display:none"> ' ..
    from_en(date:text(dateFormat(args))),
    date:text(result) ..
    from_en(dateDifference({
    '<span class="noprint ForceAgeToShow"> ' ..
    mtext['txt-age'] ..
    dateDifference({
    diff = diff,
    diff = diff,
    show = show,
    show = show,
    Line 872: Line 901:
    disp = disp,
    disp = disp,
    sep = 'sep_space',
    sep = 'sep_space',
    }) ..
    }))
    ')</span>')
    )
    local warnings = tonumber(frame.args.warnings)
    local warnings = tonumber(frame.args.warnings)
    if warnings and warnings > 0 then
    if warnings and warnings > 0 then
    Line 902: Line 931:
    end
    end
    if invalid then
    if invalid then
    result = result .. message({ 'mt-bad-param1', invalid }, 'warning')
    result = result .. message('mt-bad-param1', invalid)
    end
    end
    end
    end
    Line 940: Line 969:
    return message('mt-invalid-dates-age')
    return message('mt-invalid-dates-age')
    end
    end
    local df = stripToNil(args.df)  -- day first (dmy); default is month first (mdy)
    local fmt_date, fmt_ymd
    local result
    if date1.day then  -- y, m, d known
    if date1.day then  -- y, m, d known
    result = (df and
    fmt_date = dateFormat(args)
    '%-d %B %-Y' or
    fmt_ymd = '%-Y-%m-%d'
    '%B %-d, %-Y') ..
    '<span style="display:none">(%-Y-%m-%d)</span>'
    elseif date1.month then  -- y, m known; d unknown
    elseif date1.month then  -- y, m known; d unknown
    result =
    fmt_date = '%B %-Y'
    '%B %-Y' ..
    fmt_ymd = '%-Y-%m-00'
    '<span style="display:none">(%-Y-%m-00)</span>'
    else  -- y known; m, d unknown
    else  -- y known; m, d unknown
    result =
    fmt_date = '%-Y'
    '%-Y' ..
    fmt_ymd = '%-Y-00-00'
    '<span style="display:none">(%-Y-00-00)</span>'
    end
    end
    result = from_en(date1:text(result) ..
    local result = substituteParameters(
    mtext['txt-aged'] ..
    mtext['txt-dda'],
    dateDifference({
    date1:text(fmt_ymd),
    from_en(date1:text(fmt_date)),
    from_en(dateDifference({
    diff = diff,
    diff = diff,
    show = 'y',
    show = 'y',
    abbr = 'abbr_off',
    abbr = 'abbr_off',
    disp = 'disp_raw',
    disp = mtext['txt-dda-disp'],
    range = 'dash',
    range = 'dash',
    sep = 'sep_space',
    sep = 'sep_space',
    }) ..
    }))
    ')')
    )
    local warnings = tonumber(frame.args.warnings)
    local warnings = tonumber(frame.args.warnings)
    if warnings and warnings > 0 then
    if warnings and warnings > 0 then
    Line 989: Line 1,015:
    end
    end
    if invalid then
    if invalid then
    result = result .. message({ 'mt-bad-param1', invalid }, 'warning')
    result = result .. message('mt-bad-param1', invalid)
    end
    end
    end
    end
    Line 1,061: Line 1,087:
    parm = translate[parm]
    parm = translate[parm]
    if parm == nil then  -- test for nil because false is a valid setting
    if parm == nil then  -- test for nil because false is a valid setting
    return message({ 'mt-bad-param2', argname, args[argname] })
    return message('mt-bad-param2', argname, args[argname])
    end
    end
    parms[argname] = parm
    parms[argname] = parm
    Line 1,072: Line 1,098:
    if show then
    if show then
    if show.id ~= round then
    if show.id ~= round then
    return message({ 'mt-conflicting-show', args.show, args.round })
    return message('mt-conflicting-show', args.show, args.round)
    end
    end
    else
    else

    Latest revision as of 11:41, 21 May 2021

    Documentation for this module may be created at Module:Age/doc

    -- Implement various "age of" and other date-related templates.
    
    local mtext = {
    	-- Message and other text that should be localized.
    	-- Also need to localize text in table names in function dateDifference.
    	['mt-bad-param1'] =             'Invalid parameter $1',
    	['mt-bad-param2'] =             'Parameter $1=$2 is invalid',
    	['mt-bad-show'] =               'Parameter show=$1 is not supported here',
    	['mt-cannot-add'] =             'Cannot add "$1"',
    	['mt-conflicting-show'] =       'Parameter show=$1 conflicts with round=$2',
    	['mt-date-wrong-order'] =       'The second date must be later in time than the first date',
    	['mt-dd-future'] =              'Death date (first date) must not be in the future',
    	['mt-dd-wrong-order'] =         'Death date (first date) must be later in time than the birth date (second date)',
    	['mt-invalid-bd-age'] =         'Invalid birth date for calculating age',
    	['mt-invalid-dates-age'] =      'Invalid dates for calculating age',
    	['mt-invalid-end'] =            'Invalid end date in second parameter',
    	['mt-invalid-start'] =          'Invalid start date in first parameter',
    	['mt-need-jdn'] =               'Need valid Julian date number',
    	['mt-need-valid-bd'] =          'Need valid birth date: year, month, day',
    	['mt-need-valid-bd2'] =         'Need valid birth date (second date): year, month, day',
    	['mt-need-valid-date'] =        'Need valid date',
    	['mt-need-valid-dd'] =          'Need valid death date (first date): year, month, day',
    	['mt-need-valid-ymd'] =         'Need valid year, month, day',
    	['mt-need-valid-ymd-current'] = 'Need valid year|month|day or "currentdate"',
    	['mt-need-valid-ymd2'] =        'Second date should be year, month, day',
    	['mt-template-bad-name'] =      'The specified template name is not valid',
    	['mt-template-x'] =             'The template invoking this must have "|template=x" where x is the wanted operation',
    	['txt-and'] =                   ' and ',
    	['txt-or'] =                    '&nbsp;or ',
    	['txt-category'] =              'Category:Age error',
    	['txt-comma-and'] =             ', and ',
    	['txt-error'] =                 'Error: ',
    	['txt-format-default'] =        'mf',  -- 'df' (day first = dmy) or 'mf' (month first = mdy)
    	['txt-module-convertnumeric'] = 'Module:ConvertNumeric',
    	['txt-module-date'] =           'Module:Date',
    	['txt-sandbox'] =               'sandbox',
    	['txt-bda'] = '<span style="display:none"> (<span class="bday">$1</span>) </span>$2<span class="noprint ForceAgeToShow"> (age&nbsp;$3)</span>',
    	['txt-dda'] = '$2<span style="display:none">($1)</span> (aged&nbsp;$3)',
    	['txt-bda-disp'] = 'disp_raw',  -- disp_raw → age is a number only; disp_age → age is a number and unit (normally years but months or days if very young)
    	['txt-dda-disp'] = 'disp_raw',
    	['txt-dmy'] = '%-d %B %-Y',
    	['txt-mdy'] = '%B %-d, %-Y',
    }
    
    local isWarning = {
    	['mt-bad-param1'] = true,
    }
    
    local translate, from_en, to_en, isZero
    if translate then
    	-- Functions to translate from en to local language and reverse go here.
    	-- See example at [[:bn:Module:বয়স]].
    else
    	from_en = function (text)
    		return text
    	end
    	isZero = function (text)
    		return tonumber(text) == 0
    	end
    end
    
    local _Date, _currentDate
    local function getExports(frame)
    	-- Return objects exported from the date module or its sandbox.
    	if not _Date then
    		local sandbox = frame:getTitle():find(mtext['txt-sandbox'], 1, true) and ('/' .. mtext['txt-sandbox']) or ''
    		local datemod = require(mtext['txt-module-date'] .. sandbox)
    		local realDate = datemod._Date
    		_currentDate = datemod._current
    		if to_en then
    			_Date = function (...)
    				local args = {}
    				for i, v in ipairs({...}) do
    					args[i] = to_en(v)
    				end
    				return realDate(unpack(args))
    			end
    		else
    			_Date = realDate
    		end
    	end
    	return _Date, _currentDate
    end
    
    local Collection  -- a table to hold items
    Collection = {
    	add = function (self, item)
    		if item ~= nil then
    			self.n = self.n + 1
    			self[self.n] = item
    		end
    	end,
    	join = function (self, sep)
    		return table.concat(self, sep)
    	end,
    	remove = function (self, pos)
    		if self.n > 0 and (pos == nil or (0 < pos and pos <= self.n)) then
    			self.n = self.n - 1
    			return table.remove(self, pos)
    		end
    	end,
    	sort = function (self, comp)
    		table.sort(self, comp)
    	end,
    	new = function ()
    		return setmetatable({n = 0}, Collection)
    	end
    }
    Collection.__index = Collection
    
    local function stripToNil(text)
    	-- If text is a string, return its trimmed content, or nil if empty.
    	-- Otherwise return text (which may, for example, be nil).
    	if type(text) == 'string' then
    		text = text:match('(%S.-)%s*$')
    	end
    	return text
    end
    
    local function dateFormat(args)
    	-- Return string for wanted date format.
    	local default = mtext['txt-format-default']
    	local other = default == 'df' and 'mf' or 'df'
    	local wanted = stripToNil(args[other]) and other or default
    	return wanted == 'df' and mtext['txt-dmy'] or mtext['txt-mdy']
    end
    
    local function substituteParameters(text, ...)
    	-- Return text after substituting any given parameters for $1, $2, etc.
    	return mw.message.newRawMessage(text, ...):plain()
    end
    
    local function yes(parameter)
    	-- Return true if parameter should be interpreted as "yes".
    	-- Do not want to accept mixed upper/lowercase unless done by current templates.
    	-- Need to accept "on" because "round=on" is wanted.
    	return ({ y = true, yes = true, on = true })[parameter]
    end
    
    local function message(msg, ...)
    	-- Return formatted message text for an error or warning.
    	local function getText(msg)
    		return mtext[msg] or error('Bug: message "' .. tostring(msg) .. '" not defined')
    	end
    	local categories = {
    		error = mtext['txt-category'],
    		warning = mtext['txt-category'],
    	}
    	local a, b, k, category
    	local text = substituteParameters(getText(msg), ...)
    	if isWarning[msg] then
    		a = '<sup>[<i>'
    		b = '</i>]</sup>'
    		k = 'warning'
    	else
    		a = '<strong class="error">' .. getText('txt-error')
    		b = '</strong>'
    		k = 'error'
    	end
    	if mw.title.getCurrentTitle():inNamespaces(0) then
    		-- Category only in namespaces: 0=article.
    		category = '[[' .. categories[k] .. ']]'
    	end
    	return
    		a ..
    		mw.text.nowiki(text) ..
    		b ..
    		(category or '')
    end
    
    local function formatNumber(number)
    	-- Return the given number formatted with commas as group separators,
    	-- given that the number is an integer.
    	local numstr = tostring(number)
    	local length = #numstr
    	local places = Collection.new()
    	local pos = 0
    	repeat
    		places:add(pos)
    		pos = pos + 3
    	until pos >= length
    	places:add(length)
    	local groups = Collection.new()
    	for i = places.n, 2, -1 do
    		local p1 = length - places[i] + 1
    		local p2 = length - places[i - 1]
    		groups:add(numstr:sub(p1, p2))
    	end
    	return groups:join(',')
    end
    
    local function spellNumber(number, options, i)
    	-- Return result of spelling number, or
    	-- return number (as a string) if cannot spell it.
    	-- i == 1 for the first number which can optionally start with an uppercase letter.
    	number = tostring(number)
    	return require(mtext['txt-module-convertnumeric']).spell_number(
    		number,
    		nil,                       -- fraction numerator
    		nil,                       -- fraction denominator
    		i == 1 and options.upper,  -- true: 'One' instead of 'one'
    		not options.us,            -- true: use 'and' between tens/ones etc
    		options.adj,               -- true: hyphenated
    		options.ordinal            -- true: 'first' instead of 'one'
    	) or number
    end
    
    local function makeExtra(args, flagCurrent)
    	-- Return extra text that will be inserted before the visible result
    	-- but after any sort key.
    	local extra = args.prefix or ''
    	if mw.ustring.len(extra) > 1 then
    		-- Parameter "~" gives "~3" whereas "over" gives "over 3".
    		if extra:sub(-6, -1) ~= '&nbsp;' then
    			extra = extra .. ' '
    		end
    	end
    	if flagCurrent then
    		extra = '<span class="currentage"></span>' .. extra
    	end
    	return extra
    end
    
    local function makeSort(value, sortable)
    	-- Return a sort key if requested.
    	-- Assume value is a valid number which has not overflowed.
    	if sortable == 'sortable_table' or sortable == 'sortable_on' or sortable == 'sortable_debug' then
    		local sortKey
    		if value == 0 then
    			sortKey = '5000000000000000000'
    		else
    			local mag = math.floor(math.log10(math.abs(value)) + 1e-14)
    			if value > 0 then
    				sortKey = 7000 + mag
    			else
    				sortKey = 2999 - mag
    				value = value + 10^(mag+1)
    			end
    			sortKey = string.format('%d', sortKey) .. string.format('%015.0f', math.floor(value * 10^(14-mag)))
    		end
    		local result
    		if sortable == 'sortable_table' then
    			result = 'data-sort-value="_SORTKEY_"|'
    		elseif sortable == 'sortable_debug' then
    			result = '<span data-sort-value="_SORTKEY_♠"><span style="border:1px solid">_SORTKEY_♠</span></span>'
    		else
    			result = '<span data-sort-value="_SORTKEY_♠"></span>'
    		end
    		return (result:gsub('_SORTKEY_', sortKey))
    	end
    end
    
    local translateParameters = {
    	abbr = {
    		off = 'abbr_off',
    		on = 'abbr_on',
    	},
    	disp = {
    		age = 'disp_age',
    		raw = 'disp_raw',
    	},
    	format = {
    		raw = 'format_raw',
    		commas = 'format_commas',
    	},
    	round = {
    		on = 'on',
    		yes = 'on',
    		months = 'ym',
    		weeks = 'ymw',
    		days = 'ymd',
    		hours = 'ymdh',
    	},
    	sep = {
    		comma = 'sep_comma',
    		[','] = 'sep_comma',
    		serialcomma = 'sep_serialcomma',
    		space = 'sep_space',
    	},
    	show = {
    		hide = { id = 'hide' },
    		y = { 'y', id = 'y' },
    		ym = { 'y', 'm', id = 'ym' },
    		ymd = { 'y', 'm', 'd', id = 'ymd' },
    		ymw = { 'y', 'm', 'w', id = 'ymw' },
    		ymwd = { 'y', 'm', 'w', 'd', id = 'ymwd' },
    		yd = { 'y', 'd', id = 'yd', keepZero = true },
    		m = { 'm', id = 'm' },
    		md = { 'm', 'd', id = 'md' },
    		w = { 'w', id = 'w' },
    		wd = { 'w', 'd', id = 'wd' },
    		h = { 'H', id = 'h' },
    		hm = { 'H', 'M', id = 'hm' },
    		hms = { 'H', 'M', 'S', id = 'hms' },
    		M = { 'M', id = 'M' },
    		s = { 'S', id = 's' },
    		d = { 'd', id = 'd' },
    		dh = { 'd', 'H', id = 'dh' },
    		dhm = { 'd', 'H', 'M', id = 'dhm' },
    		dhms = { 'd', 'H', 'M', 'S', id = 'dhms' },
    		ymdh = { 'y', 'm', 'd', 'H', id = 'ymdh' },
    		ymdhm = { 'y', 'm', 'd', 'H', 'M', id = 'ymdhm' },
    		ymwdh = { 'y', 'm', 'w', 'd', 'H', id = 'ymwdh' },
    		ymwdhm = { 'y', 'm', 'w', 'd', 'H', 'M', id = 'ymwdhm' },
    	},
    	sortable = {
    		off = false,
    		on = 'sortable_on',
    		table = 'sortable_table',
    		debug = 'sortable_debug',
    	},
    }
    
    local spellOptions = {
    	cardinal = {},
    	Cardinal = { upper = true },
    	cardinal_us = { us = true },
    	Cardinal_us = { us = true, upper = true },
    	ordinal = { ordinal = true },
    	Ordinal = { ordinal = true, upper = true },
    	ordinal_us = { ordinal = true, us = true },
    	Ordinal_us = { ordinal = true, us = true, upper = true },
    }
    
    local function dateExtract(frame)
    	-- Return part of a date after performing an optional operation.
    	local Date = getExports(frame)
    	local args = frame:getParent().args
    	local parms = {}
    	for i, v in ipairs(args) do
    		parms[i] = v
    	end
    	if yes(args.fix) then
    		table.insert(parms, 'fix')
    	end
    	if yes(args.partial) then
    		table.insert(parms, 'partial')
    	end
    	local show = stripToNil(args.show) or 'dmy'
    	local date = Date(unpack(parms))
    	if not date then
    		if show == 'format' then
    			return 'error'
    		end
    		return message('mt-need-valid-date')
    	end
    	local add = stripToNil(args.add)
    	if add then
    		for item in add:gmatch('%S+') do
    			date = date + item
    			if not date then
    				return message('mt-cannot-add', item)
    			end
    		end
    	end
    	local sortKey, result
    	local sortable = translateParameters.sortable[args.sortable]
    	if sortable then
    		local value = (date.partial and date.partial.first or date).jdz
    		sortKey = makeSort(value, sortable)
    	end
    	if show ~= 'hide' then
    		result = date[show]
    		if result == nil then
    			result = from_en(date:text(show))
    		elseif type(result) == 'boolean' then
    			result = result and '1' or '0'
    		else
    			result = from_en(tostring(result))
    		end
    	end
    	return (sortKey or '') .. makeExtra(args) .. (result or '')
    end
    
    local function rangeJoin(range)
    	-- Return text to be used between a range of ages.
    	return range == 'dash' and '–' or mtext['txt-or']
    end
    
    local function makeText(values, components, names, options, noUpper)
    	-- Return wikitext representing an age or duration.
    	local text = Collection.new()
    	local count = #values
    	local sep = names.sep or ''
    	for i, v in ipairs(values) do
    		-- v is a number (say 4 for 4 years), or a table ({4,5} for 4 or 5 years).
    		local islist = type(v) == 'table'
    		if (islist or v > 0) or (text.n == 0 and i == count) or (text.n > 0 and components.keepZero) then
    			local fmt, vstr
    			if options.spell then
    				fmt = function(number)
    					return spellNumber(number, options.spell, noUpper or i)
    				end
    			elseif i == 1 and options.format == 'format_commas' then
    				-- Numbers after the first should be small and not need formatting.
    				fmt = formatNumber
    			else
    				fmt = tostring
    			end
    			if islist then
    				vstr = fmt(v[1]) .. rangeJoin(options.range)
    				noUpper = true
    				vstr = vstr .. fmt(v[2])
    			else
    				vstr = fmt(v)
    			end
    			local name = names[components[i]]
    			if name then
    				if type(name) == 'table' then
    					name = mw.getContentLanguage():plural(islist and v[2] or v, name)
    				end
    				text:add(vstr .. sep .. name)
    			else
    				text:add(vstr)
    			end
    		end
    	end
    	local first, last
    	if options.join == 'sep_space' then
    		first = ' '
    		last = ' '
    	elseif options.join == 'sep_comma' then
    		first = ', '
    		last = ', '
    	elseif options.join == 'sep_serialcomma' and text.n > 2 then
    		first = ', '
    		last = mtext['txt-comma-and']
    	else
    		first = ', '
    		last = mtext['txt-and']
    	end
    	for i, v in ipairs(text) do
    		if i < text.n then
    			text[i] = v .. (i + 1 < text.n and first or last)
    		end
    	end
    	local sign = ''
    	if options.isnegative then
    		-- Do not display negative zero.
    		if text.n > 1 or (text.n == 1 and text[1]:sub(1, 1) ~= '0' ) then
    			if options.format == 'format_raw' then
    				sign = '-'  -- plain hyphen so result can be used in a calculation
    			else
    				sign = '−'  -- Unicode U+2212 MINUS SIGN
    			end
    		end
    	end
    	return
    		(options.sortKey or '') ..
    		(options.extra or '') ..
    		sign ..
    		text:join() ..
    		(options.suffix or '')
    end
    
    local function dateDifference(parms)
    	-- Return a formatted date difference using the given parameters
    	-- which have been validated.
    	local names = {
    		-- Each name is:
    		-- * a string if no plural form of the name is used; or
    		-- * a table of strings, one of which is selected using the rules at
    		--   https://translatewiki.net/wiki/Plural/Mediawiki_plural_rules
    		abbr_off = {
    			sep = '&nbsp;',
    			y = {'year', 'years'},
    			m = {'month', 'months'},
    			w = {'week', 'weeks'},
    			d = {'day', 'days'},
    			H = {'hour', 'hours'},
    			M = {'minute', 'minutes'},
    			S = {'second', 'seconds'},
    		},
    		abbr_on = {
    			y = 'y',
    			m = 'm',
    			w = 'w',
    			d = 'd',
    			H = 'h',
    			M = 'm',
    			S = 's',
    		},
    		abbr_infant = {      -- for {{age for infant}}
    			sep = '&nbsp;',
    			y = {'yr', 'yrs'},
    			m = {'mo', 'mos'},
    			w = {'wk', 'wks'},
    			d = {'day', 'days'},
    			H = {'hr', 'hrs'},
    			M = {'min', 'mins'},
    			S = {'sec', 'secs'},
    		},
    		abbr_raw = {},
    	}
    	local diff = parms.diff  -- must be a valid date difference
    	local show = parms.show  -- may be nil; default is set below
    	local abbr = parms.abbr or 'abbr_off'
    	local defaultJoin
    	if abbr ~= 'abbr_off' then
    		defaultJoin = 'sep_space'
    	end
    	if not show then
    		show = 'ymd'
    		if parms.disp == 'disp_age' then
    			if diff.years < 3 then
    				defaultJoin = 'sep_space'
    				if diff.years >= 1 then
    					show = 'ym'
    				else
    					show = 'md'
    				end
    			else
    				show = 'y'
    			end
    		end
    	end
    	if type(show) ~= 'table' then
    		show = translateParameters.show[show]
    	end
    	if parms.disp == 'disp_raw' then
    		defaultJoin = 'sep_space'
    		abbr = 'abbr_raw'
    	elseif parms.wantSc then
    		defaultJoin = 'sep_serialcomma'
    	end
    	local diffOptions = {
    		round = parms.round,
    		duration = parms.wantDuration,
    		range = parms.range and true or nil,
    	}
    	local sortKey
    	if parms.sortable then
    		local value = diff.age_days + (parms.wantDuration and 1 or 0)  -- days and fraction of a day
    		if diff.isnegative then
    			value = -value
    		end
    		sortKey = makeSort(value, parms.sortable)
    	end
    	local textOptions = {
    		extra = parms.extra,
    		format = parms.format,
    		join = parms.sep or defaultJoin,
    		isnegative = diff.isnegative,
    		range = parms.range,
    		sortKey = sortKey,
    		spell = parms.spell,
    		suffix = parms.suffix,  -- not currently used
    	}
    	if show.id == 'hide' then
    		return sortKey or ''
    	end
    	local values = { diff:age(show.id, diffOptions) }
    	if values[1] then
    		return makeText(values, show, names[abbr], textOptions)
    	end
    	if diff.partial then
    		-- Handle a more complex range such as
    		-- {{age_yd|20 Dec 2001|2003|range=yes}} → 1 year, 12 days or 2 years, 11 days
    		local opt = {
    			format = textOptions.format,
    			join = textOptions.join,
    			isnegative = textOptions.isnegative,
    			spell = textOptions.spell,
    		}
    		return
    			(textOptions.sortKey or '') ..
    			makeText({ diff.partial.mindiff:age(show.id, diffOptions) }, show, names[abbr], opt) ..
    			rangeJoin(textOptions.range) ..
    			makeText({ diff.partial.maxdiff:age(show.id, diffOptions) }, show, names[abbr], opt, true) ..
    			(textOptions.suffix or '')
    	end
    	return message('mt-bad-show', show.id)
    end
    
    local function getDates(frame, getopt)
    	-- Parse template parameters and return one of:
    	-- * date         (a date table, if single)
    	-- * date1, date2 (two date tables, if not single)
    	-- * text         (a string error message)
    	-- A missing date is optionally replaced with the current date.
    	-- If wantMixture is true, a missing date component is replaced
    	-- from the current date, so can get a bizarre mixture of
    	-- specified/current y/m/d as has been done by some "age" templates.
    	-- Some results may be placed in table getopt.
    	local Date, currentDate = getExports(frame)
    	getopt = getopt or {}
    	local function flagCurrent(text)
    		-- This allows the calling template to detect if the current date has been used,
    		-- that is, whether both dates have been entered in a template expecting two.
    		-- For example, an infobox may want the age when an event occurred, not the current age.
    		-- Don't bother detecting if wantMixture is used because not needed and it is a poor option.
    		if not text then
    			if getopt.noMissing then
    				return nil  -- this gives a nil date which gives an error
    			end
    			text = 'currentdate'
    			if getopt.flag == 'usesCurrent' then
    				getopt.usesCurrent = true
    			end
    		end
    		return text
    	end
    	local args = frame:getParent().args
    	local fields = {}
    	local isNamed = args.year or args.year1 or args.year2 or
    		args.month or args.month1 or args.month2 or
    		args.day or args.day1 or args.day2
    	if isNamed then
    		fields[1] = args.year1 or args.year
    		fields[2] = args.month1 or args.month
    		fields[3] = args.day1 or args.day
    		fields[4] = args.year2
    		fields[5] = args.month2
    		fields[6] = args.day2
    	else
    		for i = 1, 6 do
    			fields[i] = args[i]
    		end
    	end
    	local imax = 0
    	for i = 1, 6 do
    		fields[i] = stripToNil(fields[i])
    		if fields[i] then
    			imax = i
    		end
    		if getopt.omitZero and i % 3 ~= 1 then  -- omit zero months and days as unknown values but keep year 0 which is 1 BCE
    			if isZero(fields[i]) then
    				fields[i] = nil
    				getopt.partial = true
    			end
    		end
    	end
    	local fix = getopt.fix and 'fix' or ''
    	local partialText = getopt.partial and 'partial' or ''
    	local dates = {}
    	if isNamed or imax >= 3 then
    		local nrDates = getopt.single and 1 or 2
    		if getopt.wantMixture then
    			-- Cannot be partial since empty fields are set from current.
    			local components = { 'year', 'month', 'day' }
    			for i = 1, nrDates * 3 do
    				fields[i] = fields[i] or currentDate[components[i > 3 and i - 3 or i]]
    			end
    			for i = 1, nrDates do
    				local index = i == 1 and 1 or 4
    				local y, m, d = fields[index], fields[index+1], fields[index+2]
    				if (m == 2 or m == '2') and (d == 29 or d == '29') then
    					-- Workaround error with following which attempt to use invalid date 2001-02-29.
    					-- {{age_ymwd|year1=2001|year2=2004|month2=2|day2=29}}
    					-- {{age_ymwd|year1=2001|month1=2|year2=2004|month2=1|day2=29}}
    					-- TODO Get rid of wantMixture because even this ugly code does not handle
    					-- 'Feb' or 'February' or 'feb' or 'february'.
    					if not ((y % 4 == 0 and y % 100 ~= 0) or y % 400 == 0) then
    						d = 28
    					end
    				end
    				dates[i] = Date(y, m, d)
    			end
    		else
    			-- If partial dates are allowed, accept
    			--     year only, or
    			--     year and month only
    			-- Do not accept year and day without a month because that makes no sense
    			-- (and because, for example, Date('partial', 2001, nil, 12) sets day = nil, not 12).
    			for i = 1, nrDates do
    				local index = i == 1 and 1 or 4
    				local y, m, d = fields[index], fields[index+1], fields[index+2]
    				if (getopt.partial and y and (m or not d)) or (y and m and d) then
    					dates[i] = Date(fix, partialText, y, m, d)
    				elseif not y and not m and not d then
    					dates[i] = Date(flagCurrent())
    				end
    			end
    		end
    	else
    		getopt.textdates = true  -- have parsed each date from a single text field
    		dates[1] = Date(fix, partialText, flagCurrent(fields[1]))
    		if not getopt.single then
    			dates[2] = Date(fix, partialText, flagCurrent(fields[2]))
    		end
    	end
    	if not dates[1] then
    		return message(getopt.missing1 or 'mt-need-valid-ymd')
    	end
    	if getopt.single then
    		return dates[1]
    	end
    	if not dates[2] then
    		return message(getopt.missing2 or 'mt-need-valid-ymd2')
    	end
    	return dates[1], dates[2]
    end
    
    local function ageGeneric(frame)
    	-- Return the result required by the specified template.
    	-- Can use sortable=x where x = on/table/off/debug in any supported template.
    	-- Some templates default to sortable=on but can be overridden.
    	local name = frame.args.template
    	if not name then
    		return message('mt-template-x')
    	end
    	local args = frame:getParent().args
    	local specs = {
    		age_days = {                -- {{age in days}}
    			show = 'd',
    			disp = 'disp_raw',
    		},
    		age_days_nts = {            -- {{age in days nts}}
    			show = 'd',
    			disp = 'disp_raw',
    			format = 'format_commas',
    			sortable = 'on',
    		},
    		duration_days = {           -- {{duration in days}}
    			show = 'd',
    			disp = 'disp_raw',
    			duration = true,
    		},
    		duration_days_nts = {       -- {{duration in days nts}}
    			show = 'd',
    			disp = 'disp_raw',
    			format = 'format_commas',
    			sortable = 'on',
    			duration = true,
    		},
    		age_full_years = {          -- {{age}}
    			show = 'y',
    			abbr = 'abbr_raw',
    			flag = 'usesCurrent',
    			omitZero = true,
    			range = 'no',
    		},
    		age_full_years_nts = {      -- {{age nts}}
    			show = 'y',
    			abbr = 'abbr_raw',
    			format = 'format_commas',
    			sortable = 'on',
    		},
    		age_in_years = {            -- {{age in years}}
    			show = 'y',
    			abbr = 'abbr_raw',
    			negative = 'error',
    			range = 'dash',
    		},
    		age_in_years_nts = {        -- {{age in years nts}}
    			show = 'y',
    			abbr = 'abbr_raw',
    			negative = 'error',
    			range = 'dash',
    			format = 'format_commas',
    			sortable = 'on',
    		},
    		age_infant = {              -- {{age for infant}}
    			-- Do not set show because special processing is done later.
    			abbr = yes(args.abbr) and 'abbr_infant' or 'abbr_off',
    			disp = 'disp_age',
    			sep = 'sep_space',
    			sortable = 'on',
    		},
    		age_m = {                   -- {{age in months}}
    			show = 'm',
    			disp = 'disp_raw',
    		},
    		age_w = {                   -- {{age in weeks}}
    			show = 'w',
    			disp = 'disp_raw',
    		},
    		age_wd = {                  -- {{age in weeks and days}}
    			show = 'wd',
    		},
    		age_yd = {                  -- {{age in years and days}}
    			show = 'yd',
    			format = 'format_commas',
    			sep = args.sep ~= 'and' and 'sep_comma' or nil,
    		},
    		age_yd_nts = {              -- {{age in years and days nts}}
    			show = 'yd',
    			format = 'format_commas',
    			sep = args.sep ~= 'and' and 'sep_comma' or nil,
    			sortable = 'on',
    		},
    		age_ym = {                  -- {{age in years and months}}
    			show = 'ym',
    			sep = 'sep_comma',
    		},
    		age_ymd = {                 -- {{age in years, months and days}}
    			show = 'ymd',
    			range = true,
    		},
    		age_ymwd = {                -- {{age in years, months, weeks and days}}
    			show = 'ymwd',
    			wantMixture = true,
    		},
    	}
    	local spec = specs[name]
    	if not spec then
    		return message('mt-template-bad-name')
    	end
    	if name == 'age_days' then
    		local su = stripToNil(args['show unit'])
    		if su then
    			if su == 'abbr' or su == 'full' then
    				spec.disp = nil
    				spec.abbr = su == 'abbr' and 'abbr_on' or nil
    			end
    		end
    	end
    	local partial, autofill
    	local range = stripToNil(args.range) or spec.range
    	if range then
    		-- Suppose partial dates are used and age could be 11 or 12 years.
    		-- "|range=" (empty value) has no effect (spec is used).
    		-- "|range=yes" or spec.range == true sets range = true (gives "11 or 12")
    		-- "|range=dash" or spec.range == 'dash' sets range = 'dash' (gives "11–12").
    		-- "|range=no" or spec.range == 'no' sets range = nil and fills each date in the diff (gives "12").
    		--     ("on" is equivalent to "yes", and "off" is equivalent to "no").
    		-- "|range=OTHER" sets range = nil and rejects partial dates.
    		range = ({ dash = 'dash', off = 'no', no = 'no', [true] = true })[range] or yes(range)
    		if range then
    			partial = true  -- accept partial dates with a possible age range for the result
    			if range == 'no' then
    				autofill = true  -- missing month/day in first or second date are filled from other date or 1
    				range = nil
    			end
    		end
    	end
    	local getopt = {
    		fix = yes(args.fix),
    		flag = stripToNil(args.flag) or spec.flag,
    		omitZero = spec.omitZero,
    		partial = partial,
    		wantMixture = spec.wantMixture,
    	}
    	local date1, date2 = getDates(frame, getopt)
    	if type(date1) == 'string' then
    		return date1
    	end
    	local format = stripToNil(args.format)
    	local spell = spellOptions[format]
    	if format then
    		format = 'format_' .. format
    	elseif name == 'age_days' and getopt.textdates then
    		format = 'format_commas'
    	end
    	local parms = {
    		diff = date2:subtract(date1, { fill = autofill }),
    		wantDuration = spec.duration or yes(args.duration),
    		range = range,
    		wantSc = yes(args.sc),
    		show = args.show == 'hide' and 'hide' or spec.show,
    		abbr = spec.abbr,
    		disp = spec.disp,
    		extra = makeExtra(args, getopt.usesCurrent and format ~= 'format_raw'),
    		format = format or spec.format,
    		round = yes(args.round),
    		sep = spec.sep,
    		sortable = translateParameters.sortable[args.sortable or spec.sortable],
    		spell = spell,
    	}
    	if (spec.negative or frame.args.negative) == 'error' and parms.diff.isnegative then
    		return message('mt-date-wrong-order')
    	end
    	return from_en(dateDifference(parms))
    end
    
    local function bda(frame)
    	-- Implement [[Template:Birth date and age]].
    	local args = frame:getParent().args
    	local options = {
    		missing1 = 'mt-need-valid-bd',
    		noMissing = true,
    		single = true,
    	}
    	local date = getDates(frame, options)
    	if type(date) == 'string' then
    		return date  -- error text
    	end
    	local Date = getExports(frame)
    	local diff = Date('currentdate') - date
    	if diff.isnegative or diff.years > 150 then
    		return message('mt-invalid-bd-age')
    	end
    	local disp = mtext['txt-bda-disp']
    	local show = 'y'
    	if diff.years < 2 then
    		disp = 'disp_age'
    		if diff.years == 0 and diff.months == 0 then
    			show = 'd'
    		else
    			show = 'm'
    		end
    	end
    	local result = substituteParameters(
    		mtext['txt-bda'],
    		date:text('%-Y-%m-%d'),
    		from_en(date:text(dateFormat(args))),
    		from_en(dateDifference({
    			diff = diff,
    			show = show,
    			abbr = 'abbr_off',
    			disp = disp,
    			sep = 'sep_space',
    		}))
    	)
    	local warnings = tonumber(frame.args.warnings)
    	if warnings and warnings > 0 then
    		local good = {
    			df = true,
    			mf = true,
    			day = true,
    			day1 = true,
    			month = true,
    			month1 = true,
    			year = true,
    			year1 = true,
    		}
    		local invalid
    		local imax = options.textdates and 1 or 3
    		for k, _ in pairs(args) do
    			if type(k) == 'number' then
    				if k > imax then
    					invalid = tostring(k)
    					break
    				end
    			else
    				if not good[k] then
    					invalid = k
    					break
    				end
    			end
    		end
    		if invalid then
    			result = result .. message('mt-bad-param1', invalid)
    		end
    	end
    	return result
    end
    
    local function dda(frame)
    	-- Implement [[Template:Death date and age]].
    	local args = frame:getParent().args
    	local options = {
    		missing1 = 'mt-need-valid-dd',
    		missing2 = 'mt-need-valid-bd2',
    		noMissing = true,
    		partial = true,
    	}
    	local date1, date2 = getDates(frame, options)
    	if type(date1) == 'string' then
    		return date1
    	end
    	local diff = date1 - date2
    	if diff.isnegative then
    		return message('mt-dd-wrong-order')
    	end
    	local Date = getExports(frame)
    	local today = Date('currentdate') + 1  -- one day in future allows for timezones
    	if date1 > today then
    		return message('mt-dd-future')
    	end
    	local years
    	if diff.partial then
    		years = diff.partial.years
    		years = type(years) == 'table' and years[2] or years
    	else
    		years = diff.years
    	end
    	if years > 150 then
    		return message('mt-invalid-dates-age')
    	end
    	local fmt_date, fmt_ymd
    	if date1.day then  -- y, m, d known
    		fmt_date = dateFormat(args)
    		fmt_ymd = '%-Y-%m-%d'
    	elseif date1.month then  -- y, m known; d unknown
    		fmt_date = '%B %-Y'
    		fmt_ymd = '%-Y-%m-00'
    	else  -- y known; m, d unknown
    		fmt_date = '%-Y'
    		fmt_ymd = '%-Y-00-00'
    	end
    	local result = substituteParameters(
    		mtext['txt-dda'],
    		date1:text(fmt_ymd),
    		from_en(date1:text(fmt_date)),
    		from_en(dateDifference({
    			diff = diff,
    			show = 'y',
    			abbr = 'abbr_off',
    			disp = mtext['txt-dda-disp'],
    			range = 'dash',
    			sep = 'sep_space',
    		}))
    	)
    	local warnings = tonumber(frame.args.warnings)
    	if warnings and warnings > 0 then
    		local good = {
    			df = true,
    			mf = true,
    		}
    		local invalid
    		local imax = options.textdates and 2 or 6
    		for k, _ in pairs(args) do
    			if type(k) == 'number' then
    				if k > imax then
    					invalid = tostring(k)
    					break
    				end
    			else
    				if not good[k] then
    					invalid = k
    					break
    				end
    			end
    		end
    		if invalid then
    			result = result .. message('mt-bad-param1', invalid)
    		end
    	end
    	return result
    end
    
    local function dateToGsd(frame)
    	-- Implement [[Template:Gregorian serial date]].
    	-- Return Gregorian serial date of the given date, or the current date.
    	-- The returned value is negative for dates before 1 January 1 AD
    	-- despite the fact that GSD is not defined for such dates.
    	local date = getDates(frame, { wantMixture=true, single=true })
    	if type(date) == 'string' then
    		return date
    	end
    	return tostring(date.gsd)
    end
    
    local function jdToDate(frame)
    	-- Return formatted date from a Julian date.
    	-- The result includes a time if the input includes a fraction.
    	-- The word 'Julian' is accepted for the Julian calendar.
    	local Date = getExports(frame)
    	local args = frame:getParent().args
    	local date = Date('juliandate', args[1], args[2])
    	if date then
    		return from_en(date:text())
    	end
    	return message('mt-need-jdn')
    end
    
    local function dateToJd(frame)
    	-- Return Julian date (a number) from a date which may include a time,
    	-- or the current date ('currentdate') or current date and time ('currentdatetime').
    	-- The word 'Julian' is accepted for the Julian calendar.
    	local Date = getExports(frame)
    	local args = frame:getParent().args
    	local date = Date(args[1], args[2], args[3], args[4], args[5], args[6], args[7])
    	if date then
    		return tostring(date.jd)
    	end
    	return message('mt-need-valid-ymd-current')
    end
    
    local function timeInterval(frame)
    	-- Implement [[Template:Time interval]].
    	-- There are two positional arguments: date1, date2.
    	-- The default for each is the current date and time.
    	-- Result is date2 - date1 formatted.
    	local Date = getExports(frame)
    	local args = frame:getParent().args
    	local parms = {
    		extra = makeExtra(args),
    		wantDuration = yes(args.duration),
    		range = yes(args.range) or (args.range == 'dash' and 'dash' or nil),
    		wantSc = yes(args.sc),
    	}
    	local fix = yes(args.fix) and 'fix' or ''
    	local date1 = Date(fix, 'partial', stripToNil(args[1]) or 'currentdatetime')
    	if not date1 then
    		return message('mt-invalid-start')
    	end
    	local date2 = Date(fix, 'partial', stripToNil(args[2]) or 'currentdatetime')
    	if not date2 then
    		return message('mt-invalid-end')
    	end
    	parms.diff = date2 - date1
    	for argname, translate in pairs(translateParameters) do
    		local parm = stripToNil(args[argname])
    		if parm then
    			parm = translate[parm]
    			if parm == nil then  -- test for nil because false is a valid setting
    				return message('mt-bad-param2', argname, args[argname])
    			end
    			parms[argname] = parm
    		end
    	end
    	if parms.round then
    		local round = parms.round
    		local show = parms.show
    		if round ~= 'on' then
    			if show then
    				if show.id ~= round then
    					return message('mt-conflicting-show', args.show, args.round)
    				end
    			else
    				parms.show = translateParameters.show[round]
    			end
    		end
    		parms.round = true
    	end
    	return from_en(dateDifference(parms))
    end
    
    return {
    	age_generic = ageGeneric,           -- can emulate several age templates
    	birth_date_and_age = bda,           -- Template:Birth_date_and_age
    	death_date_and_age = dda,           -- Template:Death_date_and_age
    	gsd = dateToGsd,                    -- Template:Gregorian_serial_date
    	extract = dateExtract,              -- Template:Extract
    	jd_to_date = jdToDate,              -- Template:?
    	JULIANDAY = dateToJd,               -- Template:JULIANDAY
    	time_interval = timeInterval,       -- Template:Time_interval
    }