Module:Age: Difference between revisions

    From Nonbinary Wiki
    mNo edit summary
    (update from Module:Age/sandbox: date handling moved to Module:Date, many more features)
    Line 1: Line 1:
    --[[ Code for some date functions, including implementations of:
    -- Implement various "age of" and other date-related templates.
            {{Age in days}}                age_days
            {{Age in years and months}}    age_ym
            {{Gregorian serial date}}      gsd_ymd
    Calendar functions will be needed in many areas, so this may be superseded
    by some other system, perhaps using PHP functions accessed via mediawiki.
    ]]


    local MINUS = '' -- Unicode U+2212 MINUS SIGN
    local _Date, _current_date
    local function get_exports(frame)
    -- Return objects exported from the date module or its sandbox.
    if not _Date then
    local sandbox = frame:getTitle():find('sandbox', 1, true) and '/sandbox' or ''
    local datemod = require('Module:Date' .. sandbox)
    _Date = datemod._Date
    _current_date = datemod._current
    end
    return _Date, _current_date
    end


    local function number_name(number, singular, plural, sep)
    local function collection()
        -- Return the given number, converted to a string, with the
    -- Return a table to hold items.
        -- separator (default space) and singular or plural name appended.
    return {
        plural = plural or (singular .. 's')
    n = 0,
        sep = sep or ' '
    add = function (self, item)
        return tostring(number) .. sep .. ((number == 1) and singular or plural)
    self.n = self.n + 1
        -- this uses an interesting trick of Lua:
    self[self.n] = item
        --  * and returns false if the first argument is false, and the second otherwise, so (number==1) and singular returns singular if its 1, returns false if it is only 1
    end,
        --  * or returns the first argument if it is not false, and the second argument if the first is false
    join = function (self, sep)
        --  * so, if number is 1, and evaluates (true and singular) returning (singular); or evaluates (singular or plural), finds singular non-false, and returns singular
    return table.concat(self, sep)
        --  * but, if number is not 1, and evaluates (false and singular) returning (false); or evaluates (false or plural), and is forced to return plural
    end,
    }
    end
    end


    local function strip_to_nil(text)
    local function strip_to_nil(text)
        -- If text is a non-blank string, return its content with no leading
    -- If text is a string, return its trimmed content, or nil if empty.
        -- or trailing whitespace.
    -- Otherwise return text (which may, for example, be nil).
        -- Otherwise return nil (a nil or empty string argument gives a nil
    if type(text) == 'string' then
        -- result, as does a string argument of only whitespace).
    text = text:match('(%S.-)%s*$')
        if type(text) == 'string' then
    end
            local result = text:match("^%s*(.-)%s*$")
    return text
            if result ~= '' then
                return result
            end
        end
        return nil
    end
    end


    local function is_leap_year(year)
    local function yes(parameter)
        -- Return true if year is a leap year, assuming Gregorian calendar.
    -- Return true if parameter should be interpreted as "yes".
        return year % 4 == 0 and (year % 100 ~= 0 or year % 400 == 0)
    -- 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
    end


    local function days_in_month(year, month)
    local function message(msg, nocat)
        -- Return number of days (1..31) in given month (1..12).
    -- Return formatted message text for an error.
        local month_days = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
    -- Can append "#FormattingError" to URL of a page with a problem to find it.
        if month == 2 and is_leap_year(year) then
    local anchor = '<span id="FormattingError" />'
            return 29
    local category
        end
    if not nocat and mw.title.getCurrentTitle():inNamespaces(0, 10) then
        return month_days[month]
    -- Category only in namespaces: 0=article, 10=template.
    category = '[[Category:Age error]]'
    else
    category = ''
    end
    return anchor ..
    '<strong class="error">Error: ' ..
    mw.text.nowiki(msg) ..
    '</strong>' ..
    category
    end
    end


    -- A table to get current year/month/day (UTC), but only if needed.
    local function formatnumber(number)
    local current = setmetatable({}, {
    -- Return the given number formatted with commas as group separators,
            __index = function (self, key)
    -- given that the number is an integer.
                local d = os.date('!*t')
    local numstr = tostring(number)
                self.year = d.year
    local length = #numstr
                self.month = d.month
    local places = collection()
                self.day = d.day
    local pos = 0
                return rawget(self, key)
    repeat
            end
    places:add(pos)
        })
    pos = pos + 3
     
    until pos >= length
    local function date_component(named, positional, component)
    places:add(length)
        -- Return the first of the two arguments that is not nil and is not empty.
    local groups = collection()
        -- If both are nil, return the current date component, if specified.
    for i = places.n, 2, -1 do
        -- The returned value is nil or is a number.
    local p1 = length - places[i] + 1
        -- This translates empty arguments passed to the template to nil, and
    local p2 = length - places[i - 1]
        -- optionally replaces a nil argument with a value from the current date.
    groups:add(numstr:sub(p1, p2))
        named = strip_to_nil(named)
    end
        if named then
    return groups:join(',')
            return tonumber(named)
        end
        positional = strip_to_nil(positional)
        if positional then
            return tonumber(positional)
        end
        if component then
            return current[component]
        end
        return nil
    end
    end


    local function gsd(year, month, day)
    local function make_sort(value, sortable)
        -- Return the Gregorian serial day (an integer >= 1) for the given date,
    -- Return a sort key in a span if specified.
        -- or return nil if the date is invalid (only check that year >= 1).
    -- Assume value is a valid number which has not overflowed.
        -- This is the number of days from the start of 1 AD (there is no year 0).
    if sortable == 'sortable_on' or sortable == 'sortable_debug' then
        -- This code implements the logic in [[Template:Gregorian serial date]].
    local sortkey
        if year < 1 then
    if value == 0 then
            return nil
    sortkey = '5000000000000000000'
        end
    else
        local floor = math.floor
    local mag = math.floor(math.log10(math.abs(value)) + 1e-14)
        local days_this_year = (month - 1) * 30.5 + day
    local prefix
        if month > 2 then
    if value > 0 then
            if is_leap_year(year) then
    prefix = 7000 + mag
                days_this_year = days_this_year - 1
    else
            else
    prefix = 2999 - mag
                days_this_year = days_this_year - 2
    value = value + 10^(mag+1)
            end
    end
            if month > 8 then
    sortkey = string.format('%d', prefix) .. string.format('%015.0f', math.floor(value * 10^(14-mag)))
                days_this_year = days_this_year + 0.9
    end
            end
    local lhs = sortable == 'sortable_debug' and
        end
    '<span style="border:1px solid;display:inline;" class="sortkey">' or
        days_this_year = floor(days_this_year + 0.5)
    '<span style="display:none" class="sortkey">'
        year = year - 1
    return lhs .. sortkey .. '♠</span>'
        local days_from_past_years = year * 365
    end
            + floor(year / 4)
            - floor(year / 100)
            + floor(year / 400)
        return days_from_past_years + days_this_year
    end
    end


    local Date = {
    local translate_parameters = {
        -- A naive date that assumes the Gregorian calendar always applied.
    abbr = {
        year = 0,   -- 1 to 9999 (0 if never set)
    off = 'abbr_off',
        month = 1, -- 1 to 12
    on = 'abbr_on',
        day = 1,   -- 1 to 31
    },
        isvalid = false,
    disp = {
        new = function (self, o)
    age = 'disp_age',
            o = o or {}
    raw = 'disp_raw',
            setmetatable(o, self)
    },
            self.__index = self
    format = {
            return o
    raw = 'format_raw',
        end
    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' },
    d = { 'd', id = 'd' },
    dh = { 'd', 'H', id = 'dh' },
    dhm = { 'd', 'H', 'M', id = 'dhm' },
    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',
    debug = 'sortable_debug',
    },
    }
    }


    function Date:__lt(rhs)
    local function date_extract(frame)
        -- Return true if self < rhs.
    -- Return part of a date after performing an optional operation.
        if self.year < rhs.year then
    local Date = get_exports(frame)
            return true
    local args = frame:getParent().args
        elseif self.year == rhs.year then
    local parms = {}
            if self.month < rhs.month then
    for i, v in ipairs(args) do
                return true
    parms[i] = v
            elseif self.month == rhs.month then
    end
                return self.day < rhs.day
    if yes(args.fix) then
            end
    table.insert(parms, 'fix')
        end
    end
        return false
    if yes(args.partial) then
        -- probably simplify to return (self.year < rhs.year) or ((self.year == rhs.year) and ((self.month < rhs.month) or ((self.month == rhs.month) and (self.day < rhs.day))))
    table.insert(parms, 'partial')
        -- would be just as efficient, as lua does not evaluate second argument of (true or second_argument)
    end
        -- or similarly return self.year < rhs.year ? true : self.year > rhs.year ? false : self.month < rhs.month ? true : self.month > rhs.month ? false : self.day < rhs.day
    local date = Date(unpack(parms))
    if not date then
    return message('Need valid date')
    end
    local add = strip_to_nil(args.add)
    if add then
    for item in add:gmatch('%S+') do
    date = date + item
    if not date then
    return message('Cannot add "' .. item .. '"')
    end
    end
    end
    local prefix, result
    local sortable = translate_parameters.sortable[args.sortable]
    if sortable then
    local value = (date.partial and date.partial.first or date).jdz
    prefix = make_sort(value, sortable)
    end
    local show = strip_to_nil(args.show) or 'dmy'
    if show ~= 'hide' then
    result = date[show]
    if result == nil then
    result = date:text(show)
    elseif type(result) == 'boolean' then
    result = result and '1' or '0'
    else
    result = tostring(result)
    end
    end
    return (prefix or '') .. (result or '')
    end
    end


    function Date:set_current()
    local function make_text(values, components, names, options)
        -- Set date from current time (UTC) and return self.
    -- Return wikitext representing an age or duration.
        self.year = current.year
    local text = collection()
        self.month = current.month
    local count = #values
        self.day = current.day
    local sep = names.sep or ''
        self.isvalid = true
    for i, v in ipairs(values) do
        return self
    -- 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 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
    local join = options.range == 'dash' and '–' or '&nbsp;or '
    vstr = fmt(v[1]) .. join .. fmt(v[2])
    else
    vstr = fmt(v)
    end
    local name = names[components[i]]
    if name then
    local plural = names.plural
    if not plural or (islist and v[2] or v) == 1 then
    plural = ''
    end
    text:add(vstr .. sep .. name .. plural)
    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 = ', and '
    else
    first = ', '
    last = ' 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.prefix or '') ..
    sign ..
    text:join() ..
    (options.suffix or '')
    end
    end


    function Date:set_ymd(y, m, d)
    local function date_difference(parms)
        -- Set date from year, month, day (strings or numbers) and return self.
    -- Return a formatted date difference using the given parameters
        -- LATER: If m is a name like "March" or "mar", translate it to a month.
    -- which have been validated.
        y = tonumber(y)
    local names = {
        m = tonumber(m)
    abbr_off = {
        d = tonumber(d)
    plural = 's',
        if type(y) == 'number' and type(m) == 'number' and type(d) == 'number' then
    sep = '&nbsp;',
            self.year = y
    y = 'year',
            self.month = m
    m = 'month',
            self.day = d
    w = 'week',
            self.isvalid = (1 <= y and y <= 9999 and 1 <= m and m <= 12 and
    d = 'day',
                            1 <= d and d <= days_in_month(y, m))
    H = 'hour',
        end
    M = 'minute',
        return self
    },
    abbr_on = {
    y = 'y',
    m = 'm',
    w = 'w',
    d = 'd',
    H = 'h',
    M = 'm',
    },
    abbr_infant = {      -- for {{age for infant}}
    plural = 's',
    sep = '&nbsp;',
    y = 'yr',
    m = 'mo',
    w = 'wk',
    d = 'day',
    H = 'hr',
    M = 'min',
    },
    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 default_join
    if abbr ~= 'abbr_off' then
    default_join = 'sep_space'
    end
    if not show then
    show = 'ymd'
    if parms.disp == 'disp_age' then
    if diff.years < 3 then
    default_join = '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 = translate_parameters.show[show]
    end
    if parms.disp == 'disp_raw' then
    default_join = 'sep_space'
    abbr = 'abbr_raw'
    elseif parms.want_sc then
    default_join = 'sep_serialcomma'
    end
    local diff_options = {
    round = parms.round,
    duration = parms.want_duration,
    range = parms.range and true or nil,
    }
    local prefix
    if parms.sortable then
    local value = diff.age_days + (parms.want_duration and 1 or 0)  -- days and fraction of a day
    if diff.isnegative then
    value = -value
    end
    prefix = make_sort(value, parms.sortable)
    end
    local text_options = {
    prefix = prefix,
    suffix = parms.suffix,  -- not currently used
    format = parms.format,
    join = parms.sep or default_join,
    isnegative = diff.isnegative,
    range = parms.range,
    }
    if show.id == 'hide' then
    return prefix or ''
    end
    local values = { diff:age(show.id, diff_options) }
    return make_text(values, show, names[abbr], text_options)
    end
    end


    local DateDiff = {
    local function get_dates(frame, getopt)
        -- Simple difference between two dates, assuming Gregorian calendar.
    -- Parse template parameters and return one of:
        isnegative = false,  -- true if second date is before first
    -- * date        (a date table, if single)
        years = 0,
    -- * date1, date2 (two date tables, if not single)
        months = 0,
    -- * text        (a string error message)
        days = 0,
    -- A missing date is replaced with the current date.
        new = function (self, o)
    -- If want_mixture is true, a missing date component is replaced
            o = o or {}
    -- from the current date, so can get a bizarre mixture of
            setmetatable(o, self)
    -- specified/current y/m/d as has been done by some "age" templates.
            self.__index = self
    -- Some results may be placed in table getopt.
            return o
    local Date, current_date = get_exports(frame)
        end
    getopt = getopt or {}
    }
    local fix = getopt.fix and 'fix' or ''
     
    local partial = getopt.range and 'partial' or ''
    function DateDiff:set(date1, date2)
    local args = frame:getParent().args
        -- Set difference between the two dates, and return self.
    local fields = {}
        -- Difference is negative if the second date is older than the first.
    local is_named = args.year or args.year1 or args.year2 or
        local isnegative
    args.month or args.month1 or args.month2 or
        if date2 < date1 then
    args.day or args.day1 or args.day2
            isnegative = true
    if is_named then
            date1, date2 = date2, date1
    fields[1] = args.year1 or args.year
        else
    fields[2] = args.month1 or args.month
            isnegative = false
    fields[3] = args.day1 or args.day
        end
    fields[4] = args.year2
        -- It is known that date1 <= date2.
    fields[5] = args.month2
        local y1, m1, d1 = date1.year, date1.month, date1.day
    fields[6] = args.day2
        local y2, m2, d2 = date2.year, date2.month, date2.day
    else
        local years, months, days = y2 - y1, m2 - m1, d2 - d1
    for i = 1, 6 do
        if days < 0 then
    fields[i] = args[i]
            days = days + days_in_month(y1, m1)
    end
            months = months - 1
    end
        end
    local imax = 0
        if months < 0 then
    for i = 1, 6 do
            months = months + 12
    fields[i] = strip_to_nil(fields[i])
            years = years - 1
    if fields[i] then
        end
    imax = i
        self.years, self.months, self.days, self.isnegative = years, months, days, isnegative
    end
        return self
    end
    local single = getopt.single
    local dates = {}
    if is_named or imax > 2 then
    local nr_dates = single and 1 or 2
    if getopt.want_mixture then
    -- Cannot be partial since empty fields are set from current.
    local components = { 'year', 'month', 'day' }
    for i = 1, nr_dates * 3 do
    fields[i] = fields[i] or current_date[components[i > 3 and i - 3 or i]]
    end
    for i = 1, nr_dates do
    local index = i == 1 and 1 or 4
    dates[i] = Date(fields[index], fields[index+1], fields[index+2])
    end
    else
    for i = 1, nr_dates do
    local index = i == 1 and 1 or 4
    local y, m, d = fields[index], fields[index+1], fields[index+2]
    if (partial and y) or (y and m and d) then
    dates[i] = Date(fix, partial, y, m, d)
    elseif not (y or m or d) then
    dates[i] = Date('currentdate')
    end
    end
    end
    else
    getopt.textdates = true
    dates[1] = Date(fix, partial, fields[1] or 'currentdate')
    if not single then
    dates[2] = Date(fix, partial, fields[2] or 'currentdate')
    end
    end
    if not dates[1] then
    return message('Need valid year, month, day')
    end
    if single then
    return dates[1]
    end
    if not dates[2] then
    return message('Second date should be year, month, day')
    end
    return dates[1], dates[2]
    end
    end


    function DateDiff:age_ym()
    local function age_generic(frame)
        -- Return text specifying difference in years, months.
    -- Return the result required by the specified template.
        local sign = self.isnegative and MINUS or ''
    -- Can use sortable=x where x = on/off/debug in any supported template.
        local mtext = number_name(self.months, 'month')
    -- Some templates default to sortable=on but can be overridden with sortable=off.
        local result
    local name = frame.args.template
        if self.years > 0 then
    if not name then
            local ytext = number_name(self.years, 'year')
    return message('The template invoking this must have "|template=x" where x is the wanted operation')
            if self.months == 0 then
    end
                result = ytext
    local args = frame:getParent().args
            else
    local specs = {
                result = ytext .. ',&nbsp;' .. mtext
    age_days = {                -- {{age in days}}
            end
    show = 'd',
        else
    disp = 'disp_raw',
            if self.months == 0 then
    },
                sign = ''
    age_days_nts = {            -- {{age in days nts}}
            end
    show = 'd',
            result = mtext
    disp = 'disp_raw',
        end
    format = 'format_commas',
        return sign .. result
    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',
    },
    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',
    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',
    want_mixture = true,
    },
    }
    local spec = specs[name]
    if not spec then
    return message('The specified template name is not valid')
    end
    if name == 'age_days' then
    local su = strip_to_nil(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 range = spec.range or yes(args.range) or (args.range == 'dash' and 'dash' or nil)
    local getopt = {
    fix = yes(args.fix),
    range = range,
    want_mixture = spec.want_mixture,
    }
    local date1, date2 = get_dates(frame, getopt)
    if type(date1) == 'string' then
    return date1
    end
    local format = strip_to_nil(args.format)
    if format then
    format = 'format_' .. format
    elseif name == 'age_days' and getopt.textdates then
    format = 'format_commas'
    end
    local parms = {
    diff = date2 - date1,
    want_duration = spec.duration or yes(args.duration),
    range = range,
    want_sc = yes(args.sc),
    show = args.show == 'hide' and 'hide' or spec.show,
    abbr = spec.abbr,
    disp = spec.disp,
    format = format or spec.format,
    round = yes(args.round),
    sep = spec.sep,
    sortable = translate_parameters.sortable[args.sortable or spec.sortable],
    }
    if (spec.negative or frame.args.negative) == 'error' and parms.diff.isnegative then
    return message('The second date should not be before the first date')
    end
    return date_difference(parms)
    end
    end


    local function error_wikitext(text)
    local function date_to_gsd(frame)
        -- Return message for display when template parameters are invalid.
    -- This implements {{gregorian serial date}}.
        local prefix = '[[Module talk:Age|Module error]]:'
    -- Return Gregorian serial date of the given date, or the current date.
        local cat = '[[Category:Age error]]'
    -- The returned value is negative for dates before 1 January 1 AD
        return '<span style="color:black; background-color:pink;">' ..
    -- despite the fact that GSD is not defined for such dates.
                prefix .. ' ' .. text .. cat .. '</span>'
    local date = get_dates(frame, { want_mixture=true, single=true })
    if type(date) == 'string' then
    return date
    end
    return tostring(date.gsd)
    end
    end


    local function age_days(frame)
    local function jd_to_date(frame)
        -- Return age in days between two given dates, or
    -- Return formatted date from a Julian date.
        -- between given date and current date.
    -- The result includes a time if the input includes a fraction.
        -- This code implements the logic in [[Template:Age in days]].
    -- The word 'Julian' is accepted for the Julian calendar.
        -- Like {{Age in days}}, a missing argument is replaced from the current
    local Date = get_exports(frame)
        -- date, so can get a bizarre mixture of specified/current y/m/d.
    local args = frame:getParent().args
        local args = frame:getParent().args
    local date = Date('juliandate', args[1], args[2])
        local year1  = date_component(args.year1 , args[1], 'year' )
    if date then
        local month1 = date_component(args.month1, args[2], 'month')
    return date:text()
        local day1  = date_component(args.day1  , args[3], 'day'  )
    end
        local year2  = date_component(args.year2 , args[4], 'year' )
    return message('Need valid Julian date number')
        local month2 = date_component(args.month2, args[5], 'month')
        local day2  = date_component(args.day2  , args[6], 'day'  )
        local gsd1 = gsd(year1, month1, day1)
        local gsd2 = gsd(year2, month2, day2)
        if gsd1 and gsd2 then
            local sign = ''
            local result = gsd2 - gsd1
            if result < 0 then
                sign = MINUS
                result = -result
            end
            return sign .. tostring(result)
        end
        return error_wikitext('Cannot handle dates before the year 1 AD')
    end
    end


    local function age_ym(frame)
    local function date_to_jd(frame)
        -- Return age in years and months between two given dates, or
    -- Return Julian date (a number) from a date which may include a time,
        -- between given date and current date.
    -- or the current date ('currentdate') or current date and time ('currentdatetime').
        local args = frame:getParent().args
    -- The word 'Julian' is accepted for the Julian calendar.
        local fields = {}
    local Date = get_exports(frame)
        for i = 1, 6 do
    local args = frame:getParent().args
            fields[i] = strip_to_nil(args[i])
    local date = Date(args[1], args[2], args[3], args[4], args[5], args[6], args[7])
        end
    if date then
        local date1, date2
    return tostring(date.jd)
        if fields[1] and fields[2] and fields[3] then
    end
            date1 = Date:new():set_ymd(fields[1], fields[2], fields[3])
    return message('Need valid year/month/day or "currentdate"')
        end
        if not (date1 and date1.isvalid) then
            return error_wikitext('Need date: year, month, day')
        end
        if fields[4] and fields[5] and fields[6] then
            date2 = Date:new():set_ymd(fields[4], fields[5], fields[6])
            if not date2.isvalid then
                return error_wikitext('Second date should be year, month, day')
            end
        else
            date2 = Date:new():set_current()
        end
        return DateDiff:new():set(date1, date2):age_ym()
    end
    end


    local function gsd_ymd(frame)
    local function time_interval(frame)
        -- Return Gregorian serial day of the given date, or the current date.
    -- This implements {{time interval}}.
        -- Like {{Gregorian serial date}}, a missing argument is replaced from the
    -- There are two positional arguments: date1, date2.
        -- current date, so can get a bizarre mixture of specified/current y/m/d.
    -- The default for each is the current date and time.
        -- This accepts positional arguments, although the original template does not.
    -- Result is date2 - date1 formatted.
        local args = frame:getParent().args
    local Date = get_exports(frame)
        local year  = date_component(args.year , args[1], 'year' )
    local args = frame:getParent().args
        local month = date_component(args.month, args[2], 'month')
    local parms = {
        local day  = date_component(args.day  , args[3], 'day' )
    want_duration = yes(args.duration),
        local result = gsd(year, month, day)
    range = yes(args.range) or (args.range == 'dash' and 'dash' or nil),
        if result then
    want_sc = yes(args.sc),
            return tostring(result)
    }
        end
    local fix = yes(args.fix) and 'fix' or ''
        return error_wikitext('Cannot handle dates before the year 1 AD')
    local date1 = Date(fix, 'partial', strip_to_nil(args[1]) or 'currentdatetime')
    if not date1 then
    return message('Invalid start date in first parameter')
    end
    local date2 = Date(fix, 'partial', strip_to_nil(args[2]) or 'currentdatetime')
    if not date2 then
    return message('Invalid end date in second parameter')
    end
    parms.diff = date2 - date1
    for argname, translate in pairs(translate_parameters) do
    local parm = strip_to_nil(args[argname])
    if parm then
    parm = translate[parm]
    if parm == nil then  -- test for nil because false is a valid setting
    return message('Parameter ' .. argname .. '=' .. args[argname] .. ' is invalid')
    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('Parameter show=' .. args.show .. ' conflicts with round=' .. args.round)
    end
    else
    parms.show = translate_parameters.show[round]
    end
    end
    parms.round = true
    end
    return date_difference(parms)
    end
    end


    return { age_days = age_days, age_ym = age_ym, gsd = gsd_ymd }
    return {
    age_generic = age_generic,         -- can emulate several age templates
    gsd = date_to_gsd,                 -- Template:Gregorian_serial_date
    extract = date_extract,            -- Template:Extract
    jd_to_date = jd_to_date,          -- Template:?
    JULIANDAY = date_to_jd,            -- Template:JULIANDAY
    time_interval = time_interval,    -- Template:Time_interval
    }

    Revision as of 01:19, 24 June 2016

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

    -- Implement various "age of" and other date-related templates.
    
    local _Date, _current_date
    local function get_exports(frame)
    	-- Return objects exported from the date module or its sandbox.
    	if not _Date then
    		local sandbox = frame:getTitle():find('sandbox', 1, true) and '/sandbox' or ''
    		local datemod = require('Module:Date' .. sandbox)
    		_Date = datemod._Date
    		_current_date = datemod._current
    	end
    	return _Date, _current_date
    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 = function (self, sep)
    			return table.concat(self, sep)
    		end,
    	}
    end
    
    local function strip_to_nil(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 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, nocat)
    	-- Return formatted message text for an error.
    	-- Can append "#FormattingError" to URL of a page with a problem to find it.
    	local anchor = '<span id="FormattingError" />'
    	local category
    	if not nocat and mw.title.getCurrentTitle():inNamespaces(0, 10) then
    		-- Category only in namespaces: 0=article, 10=template.
    		category = '[[Category:Age error]]'
    	else
    		category = ''
    	end
    	return anchor ..
    		'<strong class="error">Error: ' ..
    		mw.text.nowiki(msg) ..
    		'</strong>' ..
    		category
    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()
    	local pos = 0
    	repeat
    		places:add(pos)
    		pos = pos + 3
    	until pos >= length
    	places:add(length)
    	local groups = collection()
    	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 make_sort(value, sortable)
    	-- Return a sort key in a span if specified.
    	-- Assume value is a valid number which has not overflowed.
    	if 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)
    			local prefix
    			if value > 0 then
    				prefix = 7000 + mag
    			else
    				prefix = 2999 - mag
    				value = value + 10^(mag+1)
    			end
    			sortkey = string.format('%d', prefix) .. string.format('%015.0f', math.floor(value * 10^(14-mag)))
    		end
    		local lhs = sortable == 'sortable_debug' and
    			'<span style="border:1px solid;display:inline;" class="sortkey">' or
    			'<span style="display:none" class="sortkey">'
    		return lhs .. sortkey .. '♠</span>'
    	end
    end
    
    local translate_parameters = {
    	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' },
    		d = { 'd', id = 'd' },
    		dh = { 'd', 'H', id = 'dh' },
    		dhm = { 'd', 'H', 'M', id = 'dhm' },
    		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',
    		debug = 'sortable_debug',
    	},
    }
    
    local function date_extract(frame)
    	-- Return part of a date after performing an optional operation.
    	local Date = get_exports(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 date = Date(unpack(parms))
    	if not date then
    		return message('Need valid date')
    	end
    	local add = strip_to_nil(args.add)
    	if add then
    		for item in add:gmatch('%S+') do
    			date = date + item
    			if not date then
    				return message('Cannot add "' .. item .. '"')
    			end
    		end
    	end
    	local prefix, result
    	local sortable = translate_parameters.sortable[args.sortable]
    	if sortable then
    		local value = (date.partial and date.partial.first or date).jdz
    		prefix = make_sort(value, sortable)
    	end
    	local show = strip_to_nil(args.show) or 'dmy'
    	if show ~= 'hide' then
    		result = date[show]
    		if result == nil then
    			result = date:text(show)
    		elseif type(result) == 'boolean' then
    			result = result and '1' or '0'
    		else
    			result = tostring(result)
    		end
    	end
    	return (prefix or '') .. (result or '')
    end
    
    local function make_text(values, components, names, options)
    	-- Return wikitext representing an age or duration.
    	local text = collection()
    	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 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
    				local join = options.range == 'dash' and '–' or '&nbsp;or '
    				vstr = fmt(v[1]) .. join .. fmt(v[2])
    			else
    				vstr = fmt(v)
    			end
    			local name = names[components[i]]
    			if name then
    				local plural = names.plural
    				if not plural or (islist and v[2] or v) == 1 then
    					plural = ''
    				end
    				text:add(vstr .. sep .. name .. plural)
    			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 = ', and '
    	else
    		first = ', '
    		last = ' 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.prefix or '') ..
    		sign ..
    		text:join() ..
    		(options.suffix or '')
    end
    
    local function date_difference(parms)
    	-- Return a formatted date difference using the given parameters
    	-- which have been validated.
    	local names = {
    		abbr_off = {
    			plural = 's',
    			sep = '&nbsp;',
    			y = 'year',
    			m = 'month',
    			w = 'week',
    			d = 'day',
    			H = 'hour',
    			M = 'minute',
    		},
    		abbr_on = {
    			y = 'y',
    			m = 'm',
    			w = 'w',
    			d = 'd',
    			H = 'h',
    			M = 'm',
    		},
    		abbr_infant = {      -- for {{age for infant}}
    			plural = 's',
    			sep = '&nbsp;',
    			y = 'yr',
    			m = 'mo',
    			w = 'wk',
    			d = 'day',
    			H = 'hr',
    			M = 'min',
    		},
    		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 default_join
    	if abbr ~= 'abbr_off' then
    		default_join = 'sep_space'
    	end
    	if not show then
    		show = 'ymd'
    		if parms.disp == 'disp_age' then
    			if diff.years < 3 then
    				default_join = '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 = translate_parameters.show[show]
    	end
    	if parms.disp == 'disp_raw' then
    		default_join = 'sep_space'
    		abbr = 'abbr_raw'
    	elseif parms.want_sc then
    		default_join = 'sep_serialcomma'
    	end
    	local diff_options = {
    		round = parms.round,
    		duration = parms.want_duration,
    		range = parms.range and true or nil,
    	}
    	local prefix
    	if parms.sortable then
    		local value = diff.age_days + (parms.want_duration and 1 or 0)  -- days and fraction of a day
    		if diff.isnegative then
    			value = -value
    		end
    		prefix = make_sort(value, parms.sortable)
    	end
    	local text_options = {
    		prefix = prefix,
    		suffix = parms.suffix,  -- not currently used
    		format = parms.format,
    		join = parms.sep or default_join,
    		isnegative = diff.isnegative,
    		range = parms.range,
    	}
    	if show.id == 'hide' then
    		return prefix or ''
    	end
    	local values = { diff:age(show.id, diff_options) }
    	return make_text(values, show, names[abbr], text_options)
    end
    
    local function get_dates(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 replaced with the current date.
    	-- If want_mixture 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, current_date = get_exports(frame)
    	getopt = getopt or {}
    	local fix = getopt.fix and 'fix' or ''
    	local partial = getopt.range and 'partial' or ''
    	local args = frame:getParent().args
    	local fields = {}
    	local is_named = 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 is_named 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] = strip_to_nil(fields[i])
    		if fields[i] then
    			imax = i
    		end
    	end
    	local single = getopt.single
    	local dates = {}
    	if is_named or imax > 2 then
    		local nr_dates = single and 1 or 2
    		if getopt.want_mixture then
    			-- Cannot be partial since empty fields are set from current.
    			local components = { 'year', 'month', 'day' }
    			for i = 1, nr_dates * 3 do
    				fields[i] = fields[i] or current_date[components[i > 3 and i - 3 or i]]
    			end
    			for i = 1, nr_dates do
    				local index = i == 1 and 1 or 4
    				dates[i] = Date(fields[index], fields[index+1], fields[index+2])
    			end
    		else
    			for i = 1, nr_dates do
    				local index = i == 1 and 1 or 4
    				local y, m, d = fields[index], fields[index+1], fields[index+2]
    				if (partial and y) or (y and m and d) then
    					dates[i] = Date(fix, partial, y, m, d)
    				elseif not (y or m or d) then
    					dates[i] = Date('currentdate')
    				end
    			end
    		end
    	else
    		getopt.textdates = true
    		dates[1] = Date(fix, partial, fields[1] or 'currentdate')
    		if not single then
    			dates[2] = Date(fix, partial, fields[2] or 'currentdate')
    		end
    	end
    	if not dates[1] then
    		return message('Need valid year, month, day')
    	end
    	if single then
    		return dates[1]
    	end
    	if not dates[2] then
    		return message('Second date should be year, month, day')
    	end
    	return dates[1], dates[2]
    end
    
    local function age_generic(frame)
    	-- Return the result required by the specified template.
    	-- Can use sortable=x where x = on/off/debug in any supported template.
    	-- Some templates default to sortable=on but can be overridden with sortable=off.
    	local name = frame.args.template
    	if not name then
    		return message('The template invoking this must have "|template=x" where x is the wanted operation')
    	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',
    		},
    		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',
    			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',
    			want_mixture = true,
    		},
    	}
    	local spec = specs[name]
    	if not spec then
    		return message('The specified template name is not valid')
    	end
    	if name == 'age_days' then
    		local su = strip_to_nil(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 range = spec.range or yes(args.range) or (args.range == 'dash' and 'dash' or nil)
    	local getopt = {
    		fix = yes(args.fix),
    		range = range,
    		want_mixture = spec.want_mixture,
    	}
    	local date1, date2 = get_dates(frame, getopt)
    	if type(date1) == 'string' then
    		return date1
    	end
    	local format = strip_to_nil(args.format)
    	if format then
    		format = 'format_' .. format
    	elseif name == 'age_days' and getopt.textdates then
    		format = 'format_commas'
    	end
    	local parms = {
    		diff = date2 - date1,
    		want_duration = spec.duration or yes(args.duration),
    		range = range,
    		want_sc = yes(args.sc),
    		show = args.show == 'hide' and 'hide' or spec.show,
    		abbr = spec.abbr,
    		disp = spec.disp,
    		format = format or spec.format,
    		round = yes(args.round),
    		sep = spec.sep,
    		sortable = translate_parameters.sortable[args.sortable or spec.sortable],
    	}
    	if (spec.negative or frame.args.negative) == 'error' and parms.diff.isnegative then
    		return message('The second date should not be before the first date')
    	end
    	return date_difference(parms)
    end
    
    local function date_to_gsd(frame)
    	-- This implements {{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 = get_dates(frame, { want_mixture=true, single=true })
    	if type(date) == 'string' then
    		return date
    	end
    	return tostring(date.gsd)
    end
    
    local function jd_to_date(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 = get_exports(frame)
    	local args = frame:getParent().args
    	local date = Date('juliandate', args[1], args[2])
    	if date then
    		return date:text()
    	end
    	return message('Need valid Julian date number')
    end
    
    local function date_to_jd(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 = get_exports(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('Need valid year/month/day or "currentdate"')
    end
    
    local function time_interval(frame)
    	-- This implements {{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 = get_exports(frame)
    	local args = frame:getParent().args
    	local parms = {
    		want_duration = yes(args.duration),
    		range = yes(args.range) or (args.range == 'dash' and 'dash' or nil),
    		want_sc = yes(args.sc),
    	}
    	local fix = yes(args.fix) and 'fix' or ''
    	local date1 = Date(fix, 'partial', strip_to_nil(args[1]) or 'currentdatetime')
    	if not date1 then
    		return message('Invalid start date in first parameter')
    	end
    	local date2 = Date(fix, 'partial', strip_to_nil(args[2]) or 'currentdatetime')
    	if not date2 then
    		return message('Invalid end date in second parameter')
    	end
    	parms.diff = date2 - date1
    	for argname, translate in pairs(translate_parameters) do
    		local parm = strip_to_nil(args[argname])
    		if parm then
    			parm = translate[parm]
    			if parm == nil then  -- test for nil because false is a valid setting
    				return message('Parameter ' .. argname .. '=' .. args[argname] .. ' is invalid')
    			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('Parameter show=' .. args.show .. ' conflicts with round=' .. args.round)
    				end
    			else
    				parms.show = translate_parameters.show[round]
    			end
    		end
    		parms.round = true
    	end
    	return date_difference(parms)
    end
    
    return {
    	age_generic = age_generic,         -- can emulate several age templates
    	gsd = date_to_gsd,                 -- Template:Gregorian_serial_date
    	extract = date_extract,            -- Template:Extract
    	jd_to_date = jd_to_date,           -- Template:?
    	JULIANDAY = date_to_jd,            -- Template:JULIANDAY
    	time_interval = time_interval,     -- Template:Time_interval
    }