Mô đun:Citation/CS1/Date validation

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Mô-đun này chứa các chương trình hỗ trợ định dạng cho trích dẫn Citation Style 1 trên Wikipedia. Đặc biệt, mô-đun này chứa một bộ các hàm xác nhận các định dạng và nội dung ngày cho nhiều tham số giữ ngày được liên kết với các trích dẫn CS1.

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--[[--------------------------< F O R W A R D   D E C L A R A T I O N S >--------------------------------------]]local add_prop_cat, is_set, in_array, set_message, substitute, wrap_style;		-- imported functions from selected Module:Citation/CS1/Utilitieslocal cfg;																		-- table of tables imported from selected Module:Citation/CS1/Configuration--[[--------------------------< F I L E - S C O P E   D E C L A R A T I O N S >--------------------------------File-scope variables are declared here]]local lang_object = mw.getContentLanguage();									-- used by is_valid_accessdate(), is_valid_year(), date_name_xlate(); TODO: move to ~/Configuration?local year_limit;																-- used by is_valid_year()--[=[-------------------------< I S _ V A L I D _ A C C E S S D A T E >----------------------------------------returns true if:	Wikipedia start date <= accessdate < today + 2 daysWikipedia start date is 2001-01-15T00:00:00 UTC which is 979516800 seconds after 1970-01-01T00:00:00 UTC (the start of Unix time)accessdate is the date provided in |access-date= at time 00:00:00 UTCtoday is the current date at time 00:00:00 UTC plus 48 hours	if today is 2015-01-01T00:00:00 then		adding 24 hours gives 2015-01-02T00:00:00 – one second more than today		adding 24 hours gives 2015-01-03T00:00:00 – one second more than tomorrowThis function does not work if it is fed month names for languages other than English.  Wikimedia #time: parserapparently doesn't understand non-English date month names. This function will always return false when the datecontains a non-English month name because good1 is false after the call to lang.formatDate().  To get around thatcall this function with YYYY-MM-DD format dates.]=]local function is_valid_accessdate (accessdate)	local good1, good2;	local access_ts, tomorrow_ts;												-- to hold Unix time stamps representing the dates	good1, access_ts = pcall (lang_object.formatDate, lang_object, 'U', accessdate );			-- convert accessdate value to Unix timestamp 	good2, tomorrow_ts = pcall (lang_object.formatDate, lang_object, 'U', 'today + 2 days' );	-- today midnight + 2 days is one second more than all day tomorrow		if good1 and good2 then														-- lang.formatDate() returns a timestamp in the local script which which tonumber() may not understand		access_ts = tonumber (access_ts) or lang_object:parseFormattedNumber (access_ts);		-- convert to numbers for the comparison;		tomorrow_ts = tonumber (tomorrow_ts) or lang_object:parseFormattedNumber (tomorrow_ts);	else		return false;															-- one or both failed to convert to Unix time stamp	end	if 979516800 <= access_ts and access_ts < tomorrow_ts then					-- Wikipedia start date <= accessdate < tomorrow's date		return true;	else		return false;															-- accessdate out of range	endend--[[--------------------------< G E T _ M O N T H _ N U M B E R >----------------------------------------------returns a number according to the month in a date: 1 for January, etc.  Capitalization and spelling must be correct.If not a valid month, returns 0]]local function get_month_number (month)	return cfg.date_names['local'].long[month] or cfg.date_names['local'].short[month] or	-- look for local names first			cfg.date_names['en'].long[month] or	cfg.date_names['en'].short[month] or		-- failing that, look for English names			0;																				-- not a recognized month nameend--[[--------------------------< G E T _ S E A S O N _ N U M B E R >--------------------------------------------returns a number according to the sequence of seasons in a year: 21 for Spring, etc.  Capitalization and spellingmust be correct. If not a valid season, returns 0.	21-24 = Spring, Summer, Autumn, Winter, independent of “Hemisphere”returns 0 when <param> is not |date=Season numbering is defined by Extended Date/Time Format (EDTF) specification (https://www.loc.gov/standards/datetime/)which became part of ISO 8601 in 2019.  See '§Sub-year groupings'.  The standard defines various divisions usingnumbers 21-41.  cs1|2 only supports generic seasons.  EDTF does support the distinction between north and southhemisphere seasons but cs1|2 has no way to make that distinction.These additional divisions not currently supported:	25-28 = Spring - Northern Hemisphere, Summer- Northern Hemisphere, Autumn - Northern Hemisphere, Winter - Northern Hemisphere	29-32 = Spring – Southern Hemisphere, Summer– Southern Hemisphere, Autumn – Southern Hemisphere, Winter - Southern Hemisphere	33-36 = Quarter 1, Quarter 2, Quarter 3, Quarter 4 (3 months each)	37-39 = Quadrimester 1, Quadrimester 2, Quadrimester 3 (4 months each)	40-41 = Semestral 1, Semestral-2 (6 months each)]]local function get_season_number (season, param)	if 'date' ~= param then		return 0;																-- season dates only supported by |date=	end	return cfg.date_names['local'].season[season] or							-- look for local names first			cfg.date_names['en'].season[season] or								-- failing that, look for English names			0;																	-- not a recognized season nameend--[[--------------------------< G E T _ Q U A R T E R _ N U M B E R >------------------------------------------returns a number according to the sequence of quarters in a year: 33 for first quarter, etc.  Capitalization and spellingmust be correct. If not a valid quarter, returns 0.	33-36 = Quarter 1, Quarter 2, Quarter 3, Quarter 4 (3 months each)returns 0 when <param> is not |date=Quarter numbering is defined by Extended Date/Time Format (EDTF) specification (https://www.loc.gov/standards/datetime/)which became part of ISO 8601 in 2019.  See '§Sub-year groupings'.  The standard defines various divisions usingnumbers 21-41.  cs1|2 only supports generic seasons and quarters.These additional divisions not currently supported:	37-39 = Quadrimester 1, Quadrimester 2, Quadrimester 3 (4 months each)	40-41 = Semestral 1, Semestral-2 (6 months each)]]local function get_quarter_number (quarter, param)	if 'date' ~= param then		return 0;																-- quarter dates only supported by |date=	end	quarter = mw.ustring.gsub (quarter, ' +', ' ');								-- special case replace multiple space chars with a single space char	return cfg.date_names['local'].quarter[quarter] or							-- look for local names first			cfg.date_names['en'].quarter[quarter] or							-- failing that, look for English names			0;																	-- not a recognized quarter nameend--[[--------------------------< G E T _ P R O P E R _ N A M E _ N U M B E R >----------------------------------returns a non-zero number if date contains a recognized proper-name.  Capitalization and spelling must be correct.returns 0 when <param> is not |date=]]local function get_proper_name_number (name, param)	if 'date' ~= param then		return 0;																-- proper-name dates only supported by |date=	end	return cfg.date_names['local'].named[name] or								-- look for local names dates first			cfg.date_names['en'].named[name] or									-- failing that, look for English names			0;																	-- not a recognized named dateend--[[--------------------------< G E T _ E L E M E N T _ N U M B E R <------------------------------------------returns true if month or season or quarter or proper name is valid (properly spelled, capitalized, abbreviated)]]local function get_element_number (element, param)	local num;		local funcs = {get_month_number, get_season_number, get_quarter_number, get_proper_name_number};	-- list of functions to execute in order		for _, func in ipairs (funcs) do											-- spin through the function list		num = func (element, param);											-- call the function and get the returned number		if 0 ~= num then														-- non-zero when valid month season quarter 			return num;															-- return that number		end	end	return nil;																	-- not validend--[[--------------------------< I S _ V A L I D _ Y E A R >----------------------------------------------------Function gets current year from the server and compares it to year from a citation parameter.  Years more than oneyear in the future are not acceptable.Special case for |pmc-embargo-date=: years more than two years in the future are not acceptable]]local function is_valid_year (year, param)	if not is_set (year_limit) then		year_limit = tonumber(os.date("%Y"))+1;									-- global variable so we only have to fetch it once	end	year = tonumber (year) or lang_object:parseFormattedNumber (year);			-- convert to number for the comparison	if year and (100 > year) then												-- years less than 100 not supported		return false;	end		if 'pmc-embargo-date' == param then											-- special case for |pmc-embargo-date=		return year and (year <= tonumber(os.date("%Y"))+2) or false;			-- years more than two years in the future are not accepted	end		return year and (year <= year_limit) or false;end--[[--------------------------< I S _ V A L I D _ D A T E >----------------------------------------------------Returns true if day is less than or equal to the number of days in month and year is no farther into the futurethan next year; else returns false.Assumes Julian calendar prior to year 1582 and Gregorian calendar thereafter. Accounts for Julian calendar leapyears before 1582 and Gregorian leap years after 1582. Where the two calendars overlap (1582 to approximately1923) dates are assumed to be Gregorian.]]local function is_valid_date (year, month, day, param)local days_in_month = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};local month_length;	if not is_valid_year (year, param) then										-- no farther into the future than next year except |pmc-embargo-date= no more than two years in the future		return false;	end		month = tonumber (month);													-- required for YYYY-MM-DD dates		if (2 == month) then														-- if February		month_length = 28;														-- then 28 days unless		if 1582 > tonumber(year) then											-- Julian calendar			if 0 == (year%4) then												-- is a leap year?				month_length = 29;												-- if leap year then 29 days in February			end		else																	-- Gregorian calendar			if (0 == (year%4) and (0 ~= (year%100) or 0 == (year%400))) then	-- is a leap year?				month_length = 29;												-- if leap year then 29 days in February			end		end	else		month_length = days_in_month[month];	end	if tonumber (day) > month_length then		return false;	end	return true;end--[[--------------------------< I S _ V A L I D _ M O N T H _ R A N G E _ S T Y L E >--------------------------Months in a range are expected to have the same style: Jan–Mar or October–December but not February–Mar or Jul–August. This function looks in cfg.date_names{} to see if both month names are listed in the long subtable or both arelisted in the short subtable.  When both have the same style (both are listed in the same table), returns true; false else]]local function is_valid_month_range_style (month1, month2)local len1 = month1:len();local len2 = month2:len();local viet1 = mw.ustring.match(month1, "[Tt]háng (.*)")local viet2 = mw.ustring.match(month2, "[Tt]háng (.*)")	if tonumber(viet1) and tonumber(viet2) then		return true;	elseif viet1 and viet2 and not tonumber(viet1) and not tonumber(viet2) then		return true;	elseif viet1 or viet2 then		return false;	elseif len1 == len2 then		return true;															-- both months are short form so return true	elseif 'May' == month1 or 'May'== month2 then -- ToDo: I18N		return true;															-- both months are long form so return true	elseif 3 == len1 or 3 == len2 then		return false;															-- months are mixed form so return false	else		return true;															-- both months are long form so return true	endend--[[--------------------------< I S _ V A L I D _ M O N T H _ S E A S O N _ R A N G E >------------------------Check a pair of months or seasons to see if both are valid members of a month or season pair.Month pairs are expected to be left to right, earliest to latest in time.All season ranges are accepted as valid because there are publishers out there who have published a Summer–Spring YYYY issue, hence treat as ok]]local function is_valid_month_season_range(range_start, range_end, param)	local range_start_number = get_month_number (range_start);	local range_end_number;	if 0 == range_start_number then												-- is this a month range?		range_start_number = get_season_number (range_start, param);			-- not a month; is it a season? get start season number		range_end_number = get_season_number (range_end, param);				-- get end season number		if (0 ~= range_start_number) and (0 ~= range_end_number) and (range_start_number ~= range_end_number) then			return true;														-- any season pairing is accepted except when both are the same		end		return false;															-- range_start and/or range_end is not a season	end																				-- here when range_start is a month	range_end_number = get_month_number (range_end);							-- get end month number	if range_start_number < range_end_number and								-- range_start is a month; does range_start precede range_end?		is_valid_month_range_style (range_start, range_end) then				-- do months have the same style?			return true;														-- proper order and same style	end	return false;																-- range_start month number is greater than or equal to range end number; or range end isn't a monthend--[[--------------------------< M A K E _ C O I N S _ D A T E >------------------------------------------------This function receives a table of date parts for one or two dates and an empty table reference declared inModule:Citation/CS1.  The function is called only for |date= parameters and only if the |date=<value> is determined to be a valid date format.  The question of what to do with invalid date formats is not answered here.The date parts in the input table are converted to an ISO 8601 conforming date string:	single whole dates:		yyyy-mm-dd	month and year dates:	yyyy-mm	year dates:				yyyy	ranges:					yyyy-mm-dd/yyyy-mm-dd							yyyy-mm/yyyy-mm							yyyy/yyyyDates in the Julian calendar are reduced to year or year/year so that we don't have to do calendar conversion fromJulian to Proleptic Gregorian.The input table has:	year, year2 – always present; if before 1582, ignore months and days if present	month, month2 – 0 if not provided, 1-12 for months, 21-24 for seasons; 99 Christmas	day, day2 –  0 if not provided, 1-31 for days	the output table receives:	rftdate:	an ISO 8601 formatted date	rftchron:	a free-form version of the date, usually without year which is in rftdate (season ranges and proper-name dates)	rftssn:		one of four season keywords: winter, spring, summer, fall (lowercase)	rftquarter:	one of four values: 1, 2, 3, 4]]local function make_COinS_date (input, tCOinS_date)	local date;																	-- one date or first date in a range	local date2 = '';															-- end of range date	input.year = tonumber (input.year) or lang_object:parseFormattedNumber (input.year);	-- language-aware tonumber()	input.year2 = tonumber (input.year2) or lang_object:parseFormattedNumber (input.year2);	-- COinS dates are pseudo-ISO 8601 so convert to Arabic numerals	if ((1582 == input.year) and (10 > tonumber(input.month))) or (1582 > input.year) then	-- if a Julian calendar date		tCOinS_date.rftdate = tostring (input.year);							-- &rft.date gets year only		return;																	-- done	end																				-- here for all forms of Gregorian dates	if 20 < tonumber (input.month) then											-- if season, quarter, or proper-name date		date = input.year;														-- &rft.date gets year only		if 0 ~= input.year2 and input.year ~= input.year2 then					-- if a range, only the second year portion when not the same as range start year			date = string.format ('%.4d/%.4d', input.year, input.year2)			-- assemble the date range		end		local season = {[24] = 'winter', [21] = 'spring', [22] = 'summer', [23] = 'fall', [33] = '1', [34] = '2', [35] = '3', [36] = '4', [98] = 'Easter', [99] = 'Christmas'};	-- seasons lowercase, no autumn; proper-names use title case		if 0 == input.month2 then												-- single season, quarter, or proper-name date			if 40 < tonumber(input.month) then				tCOinS_date.rftchron = season[input.month];						-- proper-name date; used in journal metadata only			elseif 30 < tonumber(input.month) then				tCOinS_date.rftquarter = season[input.month];					-- quarter date; used in journal metadata only			else				tCOinS_date.rftssn = season[input.month];						-- season date; used in journal metadata only			end		else																	-- season ranges are lumped into &rft.chron; &rft.ssn and &rft.quarter are left blank			if input.year ~= input.year2 then									-- season year – season year range or season year–year				if 0 ~= input.month2 then					tCOinS_date.rftchron = string.format ('%s %s – %s %s', season[input.month], input.year, season[input.month2], input.year2);	-- used in journal metadata only				end			else																-- season–season year range				tCOinS_date.rftchron = season[input.month] .. '–' .. season[input.month2];	-- season–season year range; used in journal metadata only			end		end		tCOinS_date.rftdate = tostring (date);		return;																	-- done	end																				-- here for gregorian calendar dates	if 0 ~= input.day then		date = string.format ('%s-%.2d-%.2d', input.year, tonumber(input.month), tonumber(input.day));	-- whole date	elseif 0 ~= input.month then		date = string.format ('%s-%.2d', input.year, tonumber(input.month));	-- year and month	else		date = string.format ('%s', input.year);								-- just year	end	if 0 ~= input.year2 then		if 0 ~= input.day2 then			date2 = string.format ('/%s-%.2d-%.2d', input.year2, tonumber(input.month2), tonumber(input.day2));		-- whole date		elseif 0 ~= input.month2 then			date2 = string.format ('/%s-%.2d', input.year2, tonumber(input.month2));	-- year and month		else			date2 = string.format ('/%s', input.year2);							-- just year		end	end		tCOinS_date.rftdate = date .. date2;										-- date2 has the '/' separator	return;end--[[--------------------------< P A T T E R N S _ T >----------------------------------------------------------this is the list of patterns for date formats that this module recognizes.  Approximately the first half of thesepatterns represent formats that might be reformatted into another format.  Those that might be reformatted have'indicator' letters that identify the content of the matching capture: 'd' (day), 'm' (month), 'a' (anchor year),'y' (year); second day, month, year have a '2' suffix.These patterns are used for both date validation and for reformatting.  This table should not be moved to ~/Configurationbecause changes to this table require changes to check_date() and to reformatter() and reformat_date()]]local patterns_t = {	 																			-- year-initial numerical year-month-day	['ymd'] = {'^(%d%d%d%d)%-(%d%d)%-(%d%d)$', 'y', 'm', 'd'},																				-- month-initial: month day, year	['Mdy'] = {'^(%D-) +([1-9]%d?), +((%d%d%d%d?)%a?)$', 'm', 'd', 'a', 'y'},																				-- month-initial day range: month day–day, year; days are separated by endash	['Md-dy'] = {'^(%D-) +([1-9]%d?)[%-–]([1-9]%d?), +((%d%d%d%d)%a?)$', 'm', 'd', 'd2', 'a', 'y'},																				-- day-initial: day month year	['dMy'] = {'^([1-9]%d?) +(%D-) +((%d%d%d%d?)%a?)$', 'd', 'm', 'a', 'y'},	['dMy_v1'] = {'^([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d?)%a?)$', 'd', 'm', 'a', 'y'},	['dMy_v2'] = {'^([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d?)%a?)$', 'd', 'm', 'a', 'y'},																				-- year-initial: year month day; day: 1 or 2 two digits, leading zero allowed; not supported at en.wiki	--	['yMd'] = {'^((%d%d%d%d?)%a?) +(%D-) +(%d%d?)$', 'a', 'y', 'm', 'd'},																				-- day-range-initial: day–day month year; days are separated by endash	['d-dMy'] = {'^([1-9]%d?)[%-–]([1-9]%d?) +(%D-) +((%d%d%d%d)%a?)$', 'd', 'd2', 'm', 'a', 'y'},	['d-dMy_v1'] = {'^([1-9]%d?)[%-–]([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'd', 'd2', 'm', 'a', 'y'},	['d-dMy_v2'] = {'^([1-9]%d?)[%-–]([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d)%a?)$', 'd', 'd2', 'm', 'a', 'y'},																				-- day initial month-day-range: day month - day month year; uses spaced endash	['dM-dMy'] = {'^([1-9]%d?) +(%D-) +[%-–] +([1-9]%d?) +(%D-) +((%d%d%d%d)%a?)$', 'd', 'm', 'd2', 'm2', 'a', 'y'},	['dM-dMy_v1'] = {'^([1-9]%d?) +(%a+ +[1-9]%d?) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'd', 'm', 'd2', 'm2', 'a', 'y'},	['dM-dMy_v2'] = {'^([1-9]%d?) +(%a+ +[1-9]%d?) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d)%a?)$', 'd', 'm', 'd2', 'm2', 'a', 'y'},																				-- month initial month-day-range: month day – month day, year;  uses spaced endash	['Md-Mdy'] = {'^(%D-) +([1-9]%d?) +[%-–] +(%D-) +([1-9]%d?), +((%d%d%d%d)%a?)$','m', 'd', 'm2', 'd2', 'a', 'y'},																				-- day initial month-day-year-range: day month year - day month year; uses spaced endash	['dMy-dMy'] = {'^([1-9]%d?) +(%D-) +(%d%d%d%d) +[%-–] +([1-9]%d?) +(%D-) +((%d%d%d%d)%a?)$', 'd', 'm', 'y', 'd2', 'm2', 'a', 'y2'},	['dMy-dMy_v1'] = {'^([1-9]%d?) +(%a+ +[%a%d]+) +năm +(%d%d%d%d) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'd', 'm', 'y', 'd2', 'm2', 'a', 'y2'},	['dMy-dMy_v2'] = {'^([1-9]%d?) +(%a+ +[%a%d]+), +(%d%d%d%d) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d)%a?)$', 'd', 'm', 'y', 'd2', 'm2', 'a', 'y2'},																				-- month initial month-day-year-range: month day, year – month day, year;  uses spaced endash	['Mdy-Mdy'] = {'^(%D-) +([1-9]%d?), +(%d%d%d%d) +[%-–] +(%D-) +([1-9]%d?), +((%d%d%d%d)%a?)$', 'm', 'd', 'y', 'm2', 'd2', 'a', 'y2'},																				-- these date formats cannot be converted, per se, but month name can be rendered short or long																				-- month/season year - month/season year; separated by spaced endash	['My-My'] = {'^(%D-) +(%d%d%d%d) +[%-–] +(%D-) +((%d%d%d%d)%a?)$', 'm', 'y', 'm2', 'a', 'y2'},	['My-My_v1'] = {'^(%a+ +[%a%d]+) +năm +(%d%d%d%d) +[%-–] +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'm', 'y', 'm2', 'a', 'y2'},																				-- month/season range year; months separated by endash	['M-My'] = {'^(%D-)[%-–](%D-) +((%d%d%d%d)%a?)$', 'm', 'm2', 'a', 'y'},	['M-My_v1'] = {'^([Tt]háng +[%a%d]+)[%-–]([%a%d]+) +năm +((%d%d%d%d)%a?)$', 'm', 'm2', 'a', 'y'},	['M-My_v2'] = {'^([Tt]háng +[%a%d]+)[%-–]([%a%d]+), +((%d%d%d%d)%a?)$', 'm', 'm2', 'a', 'y'},																				-- month/season year or proper-name year; quarter year when First Quarter YYYY etc.	['My'] = {'^([^%d–]-) +((%d%d%d%d)%a?)$', 'm', 'a', 'y'},					-- this way because endash is a member of %D; %D- will match January–March 2019 when it shouldn't	['My_v1'] = {'^(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'm', 'a', 'y'},																				-- these date formats cannot be converted	['Sy4-y2'] = {'^(%D-) +((%d%d)%d%d)[%-–]((%d%d)%a?)$'},						-- special case Winter/Summer year-year (YYYY-YY); year separated with unspaced endash	['Sy4-y2_v1'] = {'^(%a+ +%a+) +năm +((%d%d)%d%d)[%-–]((%d%d)%a?)$'},	['Sy-y'] = {'^(%D-) +(%d%d%d%d)[%-–]((%d%d%d%d)%a?)$'},						-- special case Winter/Summer year-year; year separated with unspaced endash	['Sy-y_v1'] = {'^(%a+ +%a+) +năm +(%d%d%d%d)[%-–]((%d%d%d%d)%a?)$'},	['y-y'] = {'^(%d%d%d%d?)[%-–]((%d%d%d%d?)%a?)$'},							-- year range: YYY-YYY or YYY-YYYY or YYYY–YYYY; separated by unspaced endash; 100-9999	['y4-y2'] = {'^((%d%d)%d%d)[%-–]((%d%d)%a?)$'},								-- year range: YYYY–YY; separated by unspaced endash	['ymx'] = {'^(%d%d%d%d)%-(%d%d)%-XX$', 'y', 'm'},							-- edtf year-initial numerical year-month-XX	['y'] = {'^((%d%d%d%d?)%a?)$'},												-- year; here accept either YYY or YYYY	}--[[--------------------------< I S _ V A L I D _ E M B A R G O _ D A T E >------------------------------------returns true and date value if that value has proper dmy, mdy, ymd format.returns false and 9999 (embargoed forever) when date value is not proper format; assumes that when |pmc-embargo-date= isset, the editor intended to embargo a PMC but |pmc-embargo-date= does not hold a single date.]]local function is_valid_embargo_date (v)	if v:match (patterns_t['ymd'][1]) or										-- ymd		v:match (patterns_t['Mdy'][1]) or										-- dmy		v:match (patterns_t['dMy'][1]) then										-- mdy			return true, v;	end	return false, '9999';														-- if here not good date so return false and set embargo date to long time in futureend--[[--------------------------< C H E C K _ D A T E >----------------------------------------------------------Check date format to see that it is one of the formats approved by WP:DATESNO or WP:DATERANGE. Exception: onlyallowed range separator is endash.  Additionally, check the date to see that it is a real date: no 31 in 30-daymonths; no 29 February when not a leap year.  Months, both long-form and three character abbreviations, and seasonsmust be spelled correctly.  Future years beyond next year are not allowed.If the date fails the format tests, this function returns false and does not return values for anchor_year andCOinS_date.  When this happens, the date parameter is (DEBUG: not?) used in the COinS metadata and the CITEREF identifier getsits year from the year parameter if present otherwise CITEREF does not get a date value.Inputs:	date_string - date string from date-holding parameters (date, year, publication-date, access-date, pmc-embargo-date, archive-date, lay-date)Returns:	false if date string is not a real date; else	true, anchor_year, COinS_date		anchor_year can be used in CITEREF anchors		COinS_date is ISO 8601 format date; see make_COInS_date()]]local function check_date (date_string, param, tCOinS_date)	local year;																	-- assume that year2, months, and days are not used;	local year2 = 0;															-- second year in a year range	local month = 0;	local month2 = 0;															-- second month in a month range	local day = 0;	local day2 = 0;																-- second day in a day range	local anchor_year;	local coins_date;	local iso_date;		date_string = mw.ustring.gsub(date_string, "Tháng", "tháng", 1)	date_string = mw.ustring.gsub(date_string, "^[Nn]gày ", "", 1)	if date_string:match (patterns_t['ymd'][1]) then								-- year-initial numerical year month day format		year, month, day = date_string:match (patterns_t['ymd'][1]);		if 12 < tonumber(month) or 1 > tonumber(month) or 1582 > tonumber(year) or 0 == tonumber(day) then return false; end	-- month or day number not valid or not Gregorian calendar		anchor_year = year;		elseif date_string:match (patterns_t['ymx'][1]) then							-- year-initial numerical year month edtf format		year, month = date_string:match (patterns_t['ymx'][1]);		if 12 < tonumber(month) or 1 > tonumber(month) or 1582 > tonumber(year) or not is_valid_year(year) then return false; end	-- month number not valid or not Gregorian calendar or future year		anchor_year = year;	elseif mw.ustring.match(date_string, patterns_t['Mdy'][1]) then				-- month-initial: month day, year		month, day, anchor_year, year = mw.ustring.match(date_string, patterns_t['Mdy'][1]);		month = get_month_number (month);		if 0 == month then return false; end									-- return false if month text isn't one of the twelve months					elseif mw.ustring.match(date_string, patterns_t['Md-dy'][1]) then				-- month-initial day range: month day–day, year; days are separated by endash		month, day, day2, anchor_year, year = mw.ustring.match(date_string, patterns_t['Md-dy'][1]);		if tonumber(day) >= tonumber(day2) then return false; end				-- date range order is left to right: earlier to later; dates may not be the same;		month = get_month_number (month);		if 0 == month then return false; end									-- return false if month text isn't one of the twelve months		month2=month;															-- for metadata		year2 = year;	elseif (mw.ustring.match(date_string, patterns_t['dMy'][1]) or			mw.ustring.match(date_string, patterns_t['dMy_v1'][1]) or			mw.ustring.match(date_string, patterns_t['dMy_v2'][1])) then				-- day-initial: day month year		day, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['dMy'][1]);		if day == nil then day, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['dMy_v1'][1]) end		if day == nil then day, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['dMy_v2'][1]) end		month = get_month_number (month);		if 0 == month then return false; end									-- return false if month text isn't one of the twelve months--[[ NOT supported at en.wiki	elseif mw.ustring.match(date_string, patterns_t['yMd'][1]) then				-- year-initial: year month day; day: 1 or 2 two digits, leading zero allowed		anchor_year, year, month, day = mw.ustring.match(date_string, patterns_t['yMd'][1]);		month = get_month_number (month);		if 0 == month then return false; end									-- return false if month text isn't one of the twelve months-- end NOT supported at en.wiki ]]	elseif (mw.ustring.match(date_string, patterns_t['d-dMy'][1]) or			mw.ustring.match(date_string, patterns_t['d-dMy_v1'][1]) or			mw.ustring.match(date_string, patterns_t['d-dMy_v2'][1])) then				-- day-range-initial: day–day month year; days are separated by endash		day, day2, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['d-dMy'][1]);		if day == nil then day, day2, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['d-dMy_v1'][1]) end		if day == nil then day, day2, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['d-dMy_v2'][1]) end		if tonumber(day) >= tonumber(day2) then return false; end				-- date range order is left to right: earlier to later; dates may not be the same;		month = get_month_number (month);		if 0 == month then return false; end									-- return false if month text isn't one of the twelve months		month2 = month;															-- for metadata		year2 = year;	elseif (mw.ustring.match(date_string, patterns_t['dM-dMy'][1]) or			mw.ustring.match(date_string, patterns_t['dM-dMy_v1'][1]) or			mw.ustring.match(date_string, patterns_t['dM-dMy_v2'][1])) then			-- day initial month-day-range: day month - day month year; uses spaced endash		day, month, day2, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['dM-dMy'][1]);		if day == nil then day, month, day2, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['dM-dMy_v1'][1]) end		if day == nil then day, month, day2, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['dM-dMy_v2'][1]) end		if (not is_valid_month_season_range(month, month2)) or not is_valid_year(year) then return false; end	-- date range order is left to right: earlier to later;		month = get_month_number (month);										-- for metadata		month2 = get_month_number (month2);		year2 = year;	elseif mw.ustring.match(date_string, patterns_t['Md-Mdy'][1]) then			-- month initial month-day-range: month day – month day, year; uses spaced endash		month, day, month2, day2, anchor_year, year = mw.ustring.match(date_string, patterns_t['Md-Mdy'][1]);		if (not is_valid_month_season_range(month, month2, param)) or not is_valid_year(year) then return false; end		month = get_month_number (month);										-- for metadata		month2 = get_month_number (month2);		year2 = year;	elseif (mw.ustring.match(date_string, patterns_t['dMy-dMy'][1]) or			mw.ustring.match(date_string, patterns_t['dMy-dMy_v1'][1]) or			mw.ustring.match(date_string, patterns_t['dMy-dMy_v2'][1])) then			-- day initial month-day-year-range: day month year - day month year; uses spaced endash		day, month, year, day2, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['dMy-dMy'][1]);		if day == nil then day, month, year, day2, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['dMy-dMy_v1'][1]) end		if day == nil then day, month, year, day2, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['dMy-dMy_v2'][1]) end		if tonumber(year2) <= tonumber(year) then return false; end				-- must be sequential years, left to right, earlier to later		if not is_valid_year(year2) or not is_valid_month_range_style(month, month2) then return false; end		-- year2 no more than one year in the future; months same style		month = get_month_number (month);										-- for metadata		month2 = get_month_number (month2);		if 0 == month or 0 == month2 then return false; end						-- both must be valid	elseif mw.ustring.match(date_string, patterns_t['Mdy-Mdy'][1]) then			-- month initial month-day-year-range: month day, year – month day, year; uses spaced endash		month, day, year, month2, day2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['Mdy-Mdy'][1]);		if tonumber(year2) <= tonumber(year) then return false; end				-- must be sequential years, left to right, earlier to later		if not is_valid_year(year2) or not is_valid_month_range_style(month, month2) then return false; end		-- year2 no more than one year in the future; months same style		month = get_month_number (month);										-- for metadata		month2 = get_month_number(month2);		if 0 == month or 0 == month2 then return false; end						-- both must be valid	elseif (mw.ustring.match(date_string, patterns_t['Sy4-y2'][1]) or			mw.ustring.match(date_string, patterns_t['Sy4-y2_v1'][1])) then			-- special case Winter/Summer year-year (YYYY-YY); year separated with unspaced endash		local century;		month, year, century, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['Sy4-y2'][1]);		if month == nil then month, year, century, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['Sy4-y2_v1'][1]) end		if 'Winter' ~= month and 'Summer' ~= month and not mw.ustring.match(month, "^[Mm]ùa +[Đđ]ông$") and not mw.ustring.match(month, "^[Mm]ùa +[Hh][ạè]$") then return false end;	-- 'month' can only be Winter or Summer		anchor_year = year .. '–' .. anchor_year;								-- assemble anchor_year from both years		year2 = century..year2;													-- add the century to year2 for comparisons		if 1 ~= tonumber(year2) - tonumber(year) then return false; end			-- must be sequential years, left to right, earlier to later		if not is_valid_year(year2) then return false; end						-- no year farther in the future than next year		month = get_season_number(month, param);	elseif (mw.ustring.match(date_string, patterns_t['Sy-y'][1]) or			mw.ustring.match(date_string, patterns_t['Sy-y_v1'][1])) then				-- special case Winter/Summer year-year; year separated with unspaced endash		month, year, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['Sy-y'][1]);		if month == nil then month, year, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['Sy-y_v1'][1]) end		if 'Winter' ~= month and 'Summer' ~= month and not mw.ustring.match(month, "^[Mm]ùa +[Đđ]ông$") and not mw.ustring.match(month, "^[Mm]ùa +[Hh][ạè]$") then return false end;		-- 'month' can only be Winter or Summer		anchor_year = year .. '–' .. anchor_year;										-- assemble anchor_year from both years		if 1 ~= tonumber(year2) - tonumber(year) then return false; end			-- must be sequential years, left to right, earlier to later		if not is_valid_year(year2) then return false; end						-- no year farther in the future than next year		month = get_season_number (month, param);								-- for metadata	elseif (mw.ustring.match(date_string, patterns_t['My-My'][1]) or			mw.ustring.match(date_string, patterns_t['My-My_v1'][1])) then				-- month/season year - month/season year; separated by spaced endash		month, year, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['My-My'][1]);		if month == nil then month, year, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['My-My_v1'][1]) end		anchor_year = year .. '–' .. anchor_year;								-- assemble anchor_year from both years		if tonumber(year) >= tonumber(year2) then return false; end				-- left to right, earlier to later, not the same		if not is_valid_year(year2) then return false; end						-- no year farther in the future than next year		if 0 ~= get_month_number(month) and 0 ~= get_month_number(month2) and is_valid_month_range_style(month, month2) then 	-- both must be month year, same month style			month = get_month_number(month);			month2 = get_month_number(month2);		elseif 0 ~= get_season_number(month, param) and 0 ~= get_season_number(month2, param) then	-- both must be season year, not mixed			month = get_season_number(month, param);			month2 = get_season_number(month2, param);		else			 return false;		end	elseif (mw.ustring.match(date_string, patterns_t['M-My'][1]) or			mw.ustring.match(date_string, patterns_t['M-My_v1'][1]) or			mw.ustring.match(date_string, patterns_t['M-My_v2'][1])) then				-- month/season range year; months separated by endash		month, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['M-My'][1]);		local monthNumber2		if month == nil then month, monthNumber2, anchor_year, year = mw.ustring.match(date_string, patterns_t['M-My_v1'][1]) end		if month == nil then month, monthNumber2, anchor_year, year = mw.ustring.match(date_string, patterns_t['M-My_v2'][1]) end        if monthNumber2 ~= nil then month2 = 'tháng ' .. monthNumber2 end -- the second “tháng” is implicit		if (not is_valid_month_season_range(month, month2, param)) or (not is_valid_year(year)) then return false; end		if 0 ~= get_month_number(month) then									-- determined to be a valid range so just check this one to know if month or season			month = get_month_number(month);			month2 = get_month_number(month2);			if 0 == month or 0 == month2 then return false; end		else			month = get_season_number(month, param);			month2 = get_season_number(month2, param);		end		year2 = year;			elseif (mw.ustring.match(date_string, patterns_t['My'][1]) or			mw.ustring.match(date_string, patterns_t['My_v1'][1])) then				-- month/season/quarter/proper-name year		month, anchor_year, year = mw.ustring.match(date_string, patterns_t['My'][1]);		if month == nil then month, anchor_year, year = mw.ustring.match(date_string, patterns_t['My_v1'][1]) end		if not is_valid_year(year) then return false; end		month = get_element_number(month, param);								-- get month season quarter proper-name number or nil		if not month then return false; end										-- not valid whatever it is	elseif mw.ustring.match(date_string, patterns_t['y-y'][1]) then				-- Year range: YYY-YYY or YYY-YYYY or YYYY–YYYY; separated by unspaced endash; 100-9999		year, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['y-y'][1]);		anchor_year = year .. '–' .. anchor_year;								-- assemble anchor year from both years		if tonumber(year) >= tonumber(year2) then return false; end				-- left to right, earlier to later, not the same		if not is_valid_year(year2) then return false; end						-- no year farther in the future than next year	elseif mw.ustring.match(date_string, patterns_t['y4-y2'][1]) then				-- Year range: YYYY–YY; separated by unspaced endash		local century;		year, century, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['y4-y2'][1]);		anchor_year = year .. '–' .. anchor_year;								-- assemble anchor year from both years		if in_array (param, {'date', 'publication-date', 'year'}) then			add_prop_cat ('year_range_abbreviated');		end		if 13 > tonumber(year2) then return false; end							-- don't allow 2003-05 which might be May 2003		year2 = century .. year2;													-- add the century to year2 for comparisons		if tonumber(year) >= tonumber(year2) then return false; end				-- left to right, earlier to later, not the same		if not is_valid_year(year2) then return false; end						-- no year farther in the future than next year	elseif mw.ustring.match(date_string, patterns_t['y'][1]) then					-- year; here accept either YYY or YYYY		anchor_year, year = mw.ustring.match(date_string, patterns_t['y'][1]);		if false == is_valid_year(year) then			return false;		end	else		return false;															-- date format not one of the MOS:DATE approved formats	end	if 'access-date' == param then												-- test accessdate here because we have numerical date parts		if 0 ~= year and 0 ~= month and 0 ~= day and 							-- all parts of a single date required			0 == year2 and 0 == month2 and 0 == day2 then						-- none of these; accessdate must not be a range				if not is_valid_accessdate(year .. '-' .. month .. '-' .. day) then						return false;												-- return false when accessdate out of bounds				end		else			return false;														-- return false when accessdate is a range of two dates		end	end	local result=true;															-- check whole dates for validity; assume true because not all dates will go through this test	if 0 ~= year and 0 ~= month and 0 ~= day and 0 == year2 and 0 == month2 and 0 == day2 then		-- YMD (simple whole date)		result = is_valid_date(year, month, day);	elseif 0 ~= year and 0 ~= month and 0 ~= day and 0 == year2 and 0 == month2 and 0 ~= day2 then	-- YMD-d (day range)		result = is_valid_date(year, month, day);		result = result and is_valid_date(year, month, day2);	elseif 0 ~= year and 0 ~= month and 0 ~= day and 0 == year2 and 0 ~= month2 and 0 ~= day2 then	-- YMD-md (day month range)		result = is_valid_date(year, month, day);		result = result and is_valid_date(year, month2, day2);	elseif 0 ~= year and 0 ~= month and 0 ~= day and 0 ~= year2 and 0 ~= month2 and 0 ~= day2 then	-- YMD-ymd (day month year range)		result = is_valid_date(year, month, day);		result = result and is_valid_date(year2, month2, day2);	end		if false == result then return false; end	if nil ~= tCOinS_date then													-- this table only passed into this function when testing |date= parameter values		make_COinS_date ({year = year, month = month, day = day, year2 = year2, month2 = month2, day2 = day2}, tCOinS_date);	-- make an ISO 8601 date string for COinS	end		return true, anchor_year;													-- format is good and date string represents a real dateend--[[--------------------------< D A T E S >--------------------------------------------------------------------Cycle the date-holding parameters in passed table date_parameters_list through check_date() to check compliance with MOS:DATE. For all valid dates, check_date() returnstrue. The |date= parameter test is unique, it is the only date holding parameter from which values for anchor_year (used in CITEREF identifiers) and COinS_date (used inthe COinS metadata) are derived.  The |date= parameter is the only date-holding parameter that is allowed to contain the no-date keywords "n.d." or "nd" (without quotes).Unlike most error messages created in this module, only one error message is created by this function. Because all of the date holding parameters are processed serially,parameters with errors are added to the <error_list> sequence table as the dates are tested.]]local function dates(date_parameters_list, tCOinS_date, error_list)	local anchor_year;															-- will return as nil if the date being tested is not |date=	local COinS_date;															-- will return as nil if the date being tested is not |date=	local embargo_date;															-- if embargo date is a good dmy, mdy, ymd date then holds original value else reset to 9999	local good_date = false;	for k, v in pairs(date_parameters_list) do									-- for each date-holding parameter in the list		if is_set(v.val) then													-- if the parameter has a value			v.val = mw.ustring.gsub(v.val, '%d', cfg.date_names.local_digits);	-- translate 'local' digits to Western 0-9			if v.val:match("^[ck]%. [1-9]%d%d%d?%a?$") then						-- special case for c. year or with or without CITEREF disambiguator - only |date= and |year=				local year = v.val:match("[ck]%. ([1-9]%d%d%d?)%a?");				-- get the year portion so it can be tested				if 'date' == k then					anchor_year, COinS_date = v.val:match("(([ck]%. [1-9]%d%d%d?)%a?)");	-- anchor year and COinS_date only from |date= parameter					good_date = is_valid_year(year);				elseif 'year' == k then					good_date = is_valid_year(year);				end			elseif 'date' == k then												-- if the parameter is |date=				if v.val:match("^n%.d%.%a?$") then -- ToDo: I18N								-- if |date=n.d. with or without a CITEREF disambiguator					good_date, anchor_year, COinS_date = true, v.val:match("((n%.d%.)%a?)"); -- ToDo: I18N	-- "n.d."; no error when date parameter is set to no date				elseif v.val:match("^nd%a?$") then -- ToDo: I18N								-- if |date=nd with or without a CITEREF disambiguator					good_date, anchor_year, COinS_date = true, v.val:match("((nd)%a?)"); -- ToDo: I18N	-- "nd";	no error when date parameter is set to no date				else					good_date, anchor_year, COinS_date = check_date (v.val, k, tCOinS_date);	-- go test the date				end			elseif 'year' == k then												-- if the parameter is |year= it should hold only a year value				if v.val:match("^[1-9]%d%d%d?%a?$") then						-- if |year = 3 or 4 digits only with or without a CITEREF disambiguator					good_date, anchor_year, COinS_date = true, v.val:match("((%d+)%a?)");				end			elseif 'pmc-embargo-date' == k then									-- if the parameter is |pmc-embargo-date=				good_date = check_date (v.val, k);								-- go test the date				if true == good_date then										-- if the date is a valid date					good_date, embargo_date = is_valid_embargo_date (v.val);	-- is |pmc-embargo-date= date a single dmy, mdy, or ymd formatted date? yes: returns embargo date; no: returns 9999				end			else																-- any other date-holding parameter				good_date = check_date (v.val, k);								-- go test the date			end			if false == good_date then											-- assemble one error message so we don't add the tracking category multiple times				table.insert (error_list, wrap_style ('parameter', v.name));	-- make parameter name suitable for error message list			end		end	end	return anchor_year, embargo_date;											-- and doneend--[[--------------------------< Y E A R _ C H E C K >----------------------------------------------------------Temporary function to test |year= for acceptable values:	YYY, YYYY, year-only ranges, their circa forms, with or without CITEREF disambiguators.When |year= holds some form of date that is not one of these year-only dates, emit a maintenance message.This function necessary because many non-cs1|2 templates have a |year= parameter so cirrus searches are more-or-less useless]]local function year_check (year)	year = year:gsub ('[ck]%. *', '');											-- remove circa annotation (if present) before testing <year>		for _, index in ipairs ({'y-y', 'y4-y2', 'y'}) do							-- spin through these indexes into patterns_t		if mw.ustring.match (year, patterns_t[index][1]) then			return;																-- if a match then |year= holds a valid 'year'		end	end	set_message ('maint_year');													-- if here, |year= value is not an accepted value; add a maint catend--[[--------------------------< Y E A R _ D A T E _ C H E C K >------------------------------------------------Compare the value provided in |year= with the year value(s) provided in |date=.  This function sets a local numeric value:	0 - year value does not match the year value in date	1 - (default) year value matches the year value in date or one of the year values when date contains two years	2 - year value matches the year value in date when date is in the form YYYY-MM-DD and year is disambiguated (|year=YYYYx)the numeric value in <result> determines the 'output' if any from this function:	0 – adds error message to error_list sequence table	1 – adds maint cat	2 – does nothing]]local function year_date_check (year_string, year_origin, date_string, date_origin, error_list)	local year;	local date1;	local date2;	local result = 1;															-- result of the test; assume that the test passes	year = year_string:match ('(%d%d%d%d?)');	if date_string:match ('%d%d%d%d%-%d%d%-%d%d') and year_string:match ('%d%d%d%d%a') then	--special case where both date and year are required YYYY-MM-DD and YYYYx		date1 = date_string:match ('(%d%d%d%d)');		year = year_string:match ('(%d%d%d%d)');		if year ~= date1 then			result = 0;															-- years don't match		else			result = 2;															-- years match; but because disambiguated, don't add to maint cat		end			elseif date_string:match ("%d%d%d%d?.-%d%d%d%d?") then						-- any of the standard range formats of date with two three- or four-digit years		date1, date2 = date_string:match ("(%d%d%d%d?).-(%d%d%d%d?)");		if year ~= date1 and year ~= date2 then			result = 0;		end	elseif mw.ustring.match(date_string, "%d%d%d%d[%-–]%d%d") then				-- YYYY-YY date ranges		local century;		date1, century, date2 = mw.ustring.match(date_string, "((%d%d)%d%d)[%-–]+(%d%d)");		date2 = century..date2;													-- convert YY to YYYY		if year ~= date1 and year ~= date2 then			result = 0;		end	elseif date_string:match ("%d%d%d%d?") then									-- any of the standard formats of date with one year		date1 = date_string:match ("(%d%d%d%d?)");		if year ~= date1 then			result = 0;		end	else																		-- should never get here; this function called only when no other date errors		result = 0;																-- no recognizable year in date	end	if 0 == result then															-- year / date mismatch		table.insert (error_list, substitute (cfg.messages['mismatch'], {year_origin, date_origin}));	-- add error message to error_list sequence table	elseif 1 == result then														-- redundant year / date		set_message ('maint_date_year');										-- add a maint cat	endend--[[--------------------------< R E F O R M A T T E R >--------------------------------------------------------reformat 'date' into new format specified by format_param if pattern_idx (the current format of 'date') can bereformatted.  Does the grunt work for reformat_dates().The table re_formats maps pattern_idx (current format) and format_param (desired format) to a table that holds:	format string used by string.format()	identifier letters ('d', 'm', 'y', 'd2', 'm2', 'y2') that serve as indexes into a table t{} that holds captures		from mw.ustring.match() for the various date parts specified by  patterns_t[pattern_idx][1]Items in patterns_t{} have the general form:	['ymd'] = {'^(%d%d%d%d)%-(%d%d)%-(%d%d)$', 'y', 'm', 'd'}, where:		['ymd'] is pattern_idx		patterns_t['ymd'][1] is the match pattern with captures for mw.ustring.match()		patterns_t['ymd'][2] is an indicator letter identifying the content of the first capture		patterns_t['ymd'][3] ... the second capture etc.when a pattern matches a date, the captures are loaded into table t{} in capture order using the idemtifiercharacters as indexes into t{}  For the above, a ymd date is in t{} as:	t.y = first capture (year), t.m = second capture (month), t.d = third capture (day)To reformat, this function is called with the pattern_idx that matches the current format of the date and withformat_param set to the desired format.  This function loads table t{} as described and then calls string.format()with the format string specified by re_format[pattern_idx][format_param][1] using values taken from t{} accordingto the capture identifier letters specified by patterns_t[pattern_idx][format_param][n] where n is 2..]]local re_formats = {	['ymd'] = {																	-- date format is ymd; reformat to:		['mdy'] = {'%s %s, %s', 'm', 'd', 'y'},									-- |df=mdy		['dmy'] = {'%s %s %s', 'd', 'm', 'y'},									-- |df=dmy	--		['yMd'] = {'%s %s %s', 'y', 'm', 'd'},								-- |df=yMd; not supported at en.wiki		},	['Mdy'] = {																	-- date format is Mdy; reformat to:		['mdy'] = {'%s %s, %s', 'm', 'd', 'y'},									-- for long/short reformatting		['dmy'] = {'%s %s %s', 'd', 'm', 'y'},									-- |df=dmy		['ymd'] = {'%s-%s-%s', 'y', 'm', 'd'},									-- |df=ymd	--		['yMd'] = {'%s %s %s', 'y', 'm', 'd'},								-- |df=yMd; not supported at en.wiki		},	['dMy'] = {																	-- date format is dMy; reformat to:		['dmy'] = {'%s %s %s', 'd', 'm', 'y'},									-- for long/short reformatting		['mdy'] = {'%s %s, %s', 'm', 'd', 'y'},									-- |df=mdy		['ymd'] = {'%s-%s-%s', 'y', 'm', 'd'},									-- |df=ymd	--		['yMd'] = {'%s %s %s', 'y', 'm', 'd'},								-- |df=yMd; not supported at en.wiki		},	['Md-dy'] = {																-- date format is Md-dy; reformat to:		['mdy'] = {'%s %s–%s, %s', 'm', 'd', 'd2', 'y'},						-- for long/short reformatting		['dmy'] = {'%s–%s %s %s', 'd', 'd2', 'm', 'y'},							-- |df=dmy -> d-dMy 		},	['d-dMy'] = {																-- date format is d-d>y; reformat to:		['dmy'] = {'%s–%s %s %s', 'd', 'd2', 'm', 'y'},							-- for long/short reformatting		['mdy'] = {'%s %s–%s, %s', 'm', 'd', 'd2', 'y'},						-- |df=mdy -> Md-dy 		},	['dM-dMy'] = {																-- date format is dM-dMy; reformat to:		['dmy'] = {'%s %s – %s %s %s', 'd', 'm', 'd2', 'm2', 'y'},				-- for long/short reformatting		['mdy'] = {'%s %s – %s %s, %s', 'm', 'd', 'm2', 'd2', 'y'},				-- |df=mdy -> Md-Mdy 		},	['Md-Mdy'] = {																-- date format is Md-Mdy; reformat to:		['mdy'] = {'%s %s – %s %s, %s', 'm', 'd',  'm2', 'd2', 'y'},			-- for long/short reformatting		['dmy'] = {'%s %s – %s %s %s', 'd', 'm', 'd2', 'm2', 'y'},				-- |df=dmy -> dM-dMy 		},	['dMy-dMy'] = {																-- date format is dMy-dMy; reformat to:		['dmy'] = {'%s %s %s – %s %s %s', 'd', 'm', 'y', 'd2', 'm2', 'y2'},		-- for long/short reformatting		['mdy'] = {'%s %s, %s – %s %s, %s', 'm', 'd', 'y', 'm2', 'd2', 'y2'},	-- |df=mdy -> Mdy-Mdy 		},	['Mdy-Mdy'] = {																-- date format is Mdy-Mdy; reformat to:		['mdy'] = {'%s %s, %s – %s %s, %s', 'm', 'd', 'y', 'm2', 'd2', 'y2'},	-- for long/short reformatting		['dmy'] = {'%s %s %s – %s %s %s', 'd', 'm', 'y', 'd2', 'm2', 'y2'},		-- |df=dmy -> dMy-dMy 		},	['My-My'] = {																-- these for long/short reformatting		['any'] = {'%s %s – %s %s', 'm', 'y', 'm2', 'y2'},						-- dmy/mdy agnostic		},	['M-My'] = {																-- these for long/short reformatting		['any'] = {'%s–%s %s', 'm', 'm2', 'y'},									-- dmy/mdy agnostic		},	['My'] = {																	-- these for long/short reformatting		['any'] = {'%s %s', 'm', 'y'},											-- dmy/mdy agnostic		},	--	['yMd'] = {																-- not supported at en.wiki	--		['mdy'] = {'%s %s, %s', 'm', 'd', 'y'},								-- |df=mdy	--		['dmy'] = {'%s %s %s', 'd', 'm', 'y'},								-- |df=dmy	--		['ymd'] = {'%s-%s-%s', 'y', 'm', 'd'},								-- |df=ymd	--		},	}local function reformatter (date, pattern_idx, format_param, mon_len)	if not in_array (pattern_idx, {'ymd', 'Mdy', 'Md-dy', 'dMy', 'yMd', 'd-dMy', 'dM-dMy', 'Md-Mdy', 'dMy-dMy', 'Mdy-Mdy', 'My-My', 'M-My', 'My'}) then		return;																	-- not in this set of date format patterns_t then not a reformattable date	end		if 'ymd' == format_param and in_array (pattern_idx, {'ymd', 'Md-dy', 'd-dMy', 'dM-dMy', 'Md-Mdy', 'dMy-dMy', 'Mdy-Mdy', 'My-My', 'M-My', 'My'}) then		return;																	-- ymd date ranges not supported at en.wiki; no point in reformatting ymd to ymd	end	if in_array (pattern_idx, {'My', 'M-My', 'My-My'}) then						-- these are not dmy/mdy so can't be 'reformatted' into either		format_param = 'any';													-- so format-agnostic 	end																				-- yMd is not supported at en.wiki; when yMd is supported at your wiki, uncomment the next line	--	if 'yMd' == format_param and in_array (pattern_idx, {'yMd', 'Md-dy', 'd-dMy', 'dM-dMy', 'Md-Mdy', 'dMy-dMy', 'Mdy-Mdy'}) then	-- these formats not convertable; yMd not supported at en.wiki	if 'yMd' == format_param then												-- yMd not supported at en.wiki; when yMd is supported at your wiki, remove or comment-out this line		return;																	-- not a reformattable date	end		local c1, c2, c3, c4, c5, c6, c7;											-- these hold the captures specified in patterns_t[pattern_idx][1]	c1, c2, c3, c4, c5, c6, c7 = mw.ustring.match (date, patterns_t[pattern_idx][1]);	-- get the captures	local t = {																	-- table that holds k/v pairs of date parts from the captures and patterns_t[pattern_idx][2..]		[patterns_t[pattern_idx][2]] = c1;										-- at minimum there is always one capture with a matching indicator letter		[patterns_t[pattern_idx][3] or 'x'] = c2;								-- patterns_t can have a variable number of captures; each capture requires an indicator letter;		[patterns_t[pattern_idx][4] or 'x'] = c3;								-- where there is no capture, there is no indicator letter so n in patterns_t[pattern_idx][n] will be nil;		[patterns_t[pattern_idx][5] or 'x'] = c4;								-- the 'x' here spoofs an indicator letter to prevent 'table index is nil' error		[patterns_t[pattern_idx][6] or 'x'] = c5;		[patterns_t[pattern_idx][7] or 'x'] = c6;		[patterns_t[pattern_idx][8] or 'x'] = c7;		};	if t.a then																	-- if this date has an anchor year capture (all convertable date formats except ymd)		if t.y2 then															-- for year range date formats																	t.y2 = t.a;															-- use the anchor year capture when reassembling the date		else																	-- here for single date formats (except ymd)			t.y = t.a;															-- use the anchor year capture when reassembling the date		end	end	if tonumber(t.m) then														-- if raw month is a number (converting from ymd)		if 's' == mon_len then													-- if we are to use abbreviated month names			t.m = cfg.date_names['inv_local_short'][tonumber(t.m)];					-- convert it to a month name		else			t.m = cfg.date_names['inv_local_long'][tonumber(t.m)];					-- convert it to a month name		end		t.d = t.d:gsub ('0(%d)', '%1');											-- strip leading '0' from day if present	elseif 'ymd' == format_param then											-- when converting to ymd		t.y = t.y:gsub ('%a', '');												-- strip CITREF disambiguator if present; anchor year already known so process can proceed; TODO: maint message?		if 1582 > tonumber (t.y) then											-- ymd format dates not allowed before 1582			return;		end		t.m = string.format ('%02d', get_month_number (t.m));					-- make sure that month and day are two digits		t.d = string.format ('%02d', t.d);	elseif mon_len then															-- if mon_len is set to either 'short' or 'long'		for _, mon in ipairs ({'m', 'm2'}) do									-- because there can be two month names, check both 			if t[mon] then				t[mon] = get_month_number (t[mon]);								-- get the month number for this month (is length agnostic)				if 0 == t[mon] then return; end									-- seasons and named dates can't be converted				t[mon] = (('s' == mon_len) and cfg.date_names['inv_local_short'][t[mon]]) or cfg.date_names['inv_local_long'][t[mon]];	-- fetch month name according to length			end		end	end	local new_date = string.format (re_formats[pattern_idx][format_param][1],	-- format string		t[re_formats[pattern_idx][format_param][2]],							-- named captures from t{}		t[re_formats[pattern_idx][format_param][3]],		t[re_formats[pattern_idx][format_param][4]],		t[re_formats[pattern_idx][format_param][5]],		t[re_formats[pattern_idx][format_param][6]],		t[re_formats[pattern_idx][format_param][7]],		t[re_formats[pattern_idx][format_param][8]]		);	return new_date;end--[[-------------------------< R E F O R M A T _ D A T E S >--------------------------------------------------Reformats existing dates into the format specified by format.format is one of several manual keywords: dmy, dmy-all, mdy, mdy-all, ymd, ymd-all.  The -all version includesaccess- and archive-dates; otherwise these dates are not reformatted.This function allows automatic date formatting.  In ~/Configuration, the article source is searched for one ofthe {{use xxx dates}} templates.  If found, xxx becomes the global date format as xxx-all.  If |cs1-dates= in{{use xxx dates}} has legitimate value then that value determines how cs1|2 dates will be rendered.  Legitimatevalues for |cs1-dates= are:	l - all dates are rendered with long month names	ls - publication dates use long month names; access-/archive-dates use abbreviated month names	ly - publication dates use long month names; access-/archive-dates rendered in ymd format	s - all dates are rendered with abbreviated (short) month names	sy - publication dates use abbreviated month names; access-/archive-dates rendered in ymd format	y - all dates are rendered in ymd formatthe format argument for automatic date formatting will be the format specified by {{use xxx dates}} with thevalue supplied by |cs1-dates so one of: xxx-l, xxx-ls, xxx-ly, xxx-s, xxx-sy, xxx-y, or simply xxx (|cs1-dates=empty, omitted, or invalid) where xxx shall be either of dmy or mdy.dates are extracted from date_parameters_list, reformatted (if appropriate), and then written back into thelist in the new format.  Dates in date_parameters_list are presumed here to be valid (no errors).  This functionreturns true when a date has been reformatted, false else.  Actual reformatting is done by reformatter().]]local function reformat_dates (date_parameters_list, format)	local all = false;															-- set to false to skip access- and archive-dates	local len_p = 'l';															-- default publication date length shall be long	local len_a = 'l';															-- default access-/archive-date length shall be long	local result = false;	local new_date;																		if format:match('%a+%-all') then											-- manual df keyword; auto df keyword when length not specified in {{use xxx dates}}; 		format = format:match('(%a+)%-all');									-- extract the format		all = true;																-- all dates are long format dates because this keyword doesn't specify length	elseif format:match('%a+%-[lsy][sy]?') then									-- auto df keywords; internal only		all = true;																-- auto df applies to all dates; use length specified by capture len_p for all dates		format, len_p, len_a = format:match('(%a+)%-([lsy])([sy]?)');			-- extract the format and length keywords		if 'y' == len_p then													-- because allowed by MOS:DATEUNIFY (sort of) range dates and My dates not reformatted			format = 'ymd';														-- override {{use xxx dates}}		elseif (not is_set(len_a)) or (len_p == len_a) then						-- no access-/archive-date length specified or same length as publication dates then			len_a = len_p;														-- in case len_a not set		end	end																			-- else only publication dates and they are long	for param_name, param_val in pairs (date_parameters_list) do				-- for each date-holding parameter in the list		if is_set (param_val.val) then											-- if the parameter has a value			if not (not all and in_array (param_name, {'access-date', 'archive-date'})) then	-- skip access- or archive-date unless format is xxx-all; yeah, ugly; TODO: find a better way				for pattern_idx, pattern in pairs (patterns_t) do					if mw.ustring.match (param_val.val, pattern[1]) then						if all and in_array (param_name, {'access-date', 'archive-date'}) then	-- if this date is an access- or archive-date							new_date = reformatter (param_val.val, pattern_idx, (('y' == len_a) and 'ymd') or format, len_a);	-- choose ymd or dmy/mdy according to len_a setting						else													-- all other dates							new_date = reformatter (param_val.val, pattern_idx, format, len_p);						end												if new_date then										-- set when date was reformatted							date_parameters_list[param_name].val = new_date;	-- update date in date list							result = true;										-- and announce that changes have been made							break;						end					end	-- if				end		-- for			end			-- if		end				-- if	end					-- for	return result;																-- declare boolean result and doneend--[[--------------------------< D A T E _ H Y P H E N _ T O _ D A S H >----------------------------------------Loops through the list of date-holding parameters and converts any hyphen to an ndash.  Not called if the cs1|2template has any date errors.Modifies the date_parameters_list and returns true if hyphens are replaced, else returns false.]]local function date_hyphen_to_dash (date_parameters_list)	local result = false;	local n;	for param_name, param_val in pairs(date_parameters_list) do					-- for each date-holding parameter in the list		if is_set (param_val.val) and			not mw.ustring.match (param_val.val, patterns_t.ymd[1]) then		-- for those that are not ymd dates (ustring because here digits may not be Western)				param_val.val, n = param_val.val:gsub ('%-', '–');				-- replace any hyphen with ndash				if 0 ~= n then					date_parameters_list[param_name].val = param_val.val;		-- update the list					result = true;				end		end	end	return result;																-- so we know if any hyphens were replacedend--[[-------------------------< D A T E _ N A M E _ X L A T E >------------------------------------------------Attempts to translate English date names to local-language date names using names supplied by MediaWiki'sdate parser function.  This is simple name-for-name replacement and may not work for all languages.if xlat_dig is true, this function will also translate Western (English) digits to the local language's digits.This will also translate ymd dates.]]local function date_name_xlate (date_parameters_list, xlt_dig)	local xlate;	local mode;																	-- long or short month names	local modified = false;	local date;		local sources_t = {		{cfg.date_names.en.long, cfg.date_names.inv_local_long},				-- for translating long English month names to long local month names		{cfg.date_names.en.short, cfg.date_names.inv_local_short},				-- short month names		{cfg.date_names.en.quarter, cfg.date_names.inv_local_quarter},			-- quarter date names		{cfg.date_names.en.season, cfg.date_names.inv_local_season},			-- season date nam		{cfg.date_names.en.named, cfg.date_names.inv_local_named},				-- named dates		}	local function is_xlateable (month)											-- local function to get local date name that replaces existing English-language date name		for _, date_names_t in ipairs (sources_t) do							-- for each sequence table in date_names_t			if date_names_t[1][month] then										-- if date name is English month (long or short), quarter, season or named and				if date_names_t[2][date_names_t[1][month]] then					-- if there is a matching local date name					return date_names_t[2][date_names_t[1][month]];				-- return the local date name				end			end		end	end	for param_name, param_val in pairs(date_parameters_list) do					-- for each date-holding parameter in the list		if is_set(param_val.val) then											-- if the parameter has a value			date = param_val.val;			for month in mw.ustring.gmatch (date, '[%a ]+') do					-- iterate through all date names in the date (single date or date range)				month = mw.text.trim (month);									-- this because quarterly dates contain whitespace				xlate = is_xlateable (month);									-- get translate <month>; returns translation or nil								if xlate then							date = mw.ustring.gsub (date, month, xlate);				-- replace the English with the translation					date_parameters_list[param_name].val = date;				-- save the translated date					modified = true;				end			end			if xlt_dig then														-- shall we also translate digits?				date = date:gsub ('%d', cfg.date_names.xlate_digits);			-- translate digits from Western to 'local digits'				date_parameters_list[param_name].val = date;					-- save the translated date				modified = true;			end		end	end		return modified;end--[[--------------------------< S E T _ S E L E C T E D _ M O D U L E S >--------------------------------------Sets local imported functions table to same (live or sandbox) as that used by the other modules.]]local function set_selected_modules (cfg_table_ptr, utilities_page_ptr)	add_prop_cat = utilities_page_ptr.add_prop_cat ;							-- import functions from selected Module:Citation/CS1/Utilities module	is_set = utilities_page_ptr.is_set;	in_array = utilities_page_ptr.in_array;	set_message = utilities_page_ptr.set_message;	substitute = utilities_page_ptr.substitute;	wrap_style = utilities_page_ptr.wrap_style;	cfg = cfg_table_ptr;														-- import tables from selected Module:Citation/CS1/Configurationend--[[--------------------------< A R C H I V E _ D A T E _ C H E C K >------------------------------------------Compare value in |archive-date= with the timestamp in Wayback machine urls.  Emits an error message with suggesteddate from the |archive-url= timestamp in an appropriate format when the value in |archive-date= does not matchthe timestamp.this function never called when any date in a cs1|2 template has errorserror message suggests new |archive-date= value in an appropriate format specified by <df>.  <df> is either |df= or cfg.global_df in that order.  If <df> is nil, suggested date has format from |archive-date=.  There isa caveat: when |df=dmy or |df=mdy, the reformatter leaves |access-date= and |archive-date= formats as they are.The error message suggested date is passed to the formatter as YYYY-MM-DD so when |df=dmy or |df=mdy, the formatis not changed.]]local contentLanguage = mw.getContentLanguage()local function replace_vietnamese_date(date_str)	local replacements = {		["[Nn]gày "] = "",		["[Tt]háng 1"] = "January",		["[Tt]háng 2"] = "February",		["[Tt]háng 3"] = "March",		["[Tt]háng 4"] = "April",		["[Tt]háng 5"] = "May",		["[Tt]háng 6"] = "June",		["[Tt]háng 7"] = "July",		["[Tt]háng 8"] = "August",		["[Tt]háng 9"] = "September",		["[Tt]háng 10"] = "October",		["[Tt]háng 11"] = "November",		["[Tt]háng 12"] = "December",		["[Nn]ăm "] = "",	}		for k, v in pairs(replacements) do		date_str = mw.ustring.gsub(date_str, k, v)	end		return date_strendlocal vi_formatdate = require('Module:Ngày chuẩn').vi_formatdatelocal function archive_date_check (archive_date, archive_url_timestamp, df)	archive_date = replace_vietnamese_date(archive_date)						-- convert the input Vietnamese date from date_str before decoding, if it exists		local archive_date_format = 'dmy-y';										-- holds the date format of date in |archive-date; default to ymd; 'dmy' used here to spoof reformat_dates() 		for _, v_t in ipairs ({{'dMy', 'dmy-all'}, {'Mdy', 'mdy-all'}}) do			-- is |archive-date= format dmy or mdy?		if archive_date:match (patterns_t[v_t[1]][1]) then						-- does the pattern match?			archive_date_format = cfg.keywords_xlate[v_t[2]];					-- get appropriate |df= supported keyword from the i18n translator table			break;		end	end		local dates_t = {};	dates_t['archive-date'] = {val=archive_date, name=''};						-- setup to call reformat_dates(); never called when errors so <name> unset as not needed	reformat_dates (dates_t, 'dmy-y');											-- reformat |archive-date= to ymd; 'dmy' used here to spoof reformat_dates()	local archive_url_date = archive_url_timestamp:gsub ('(%d%d%d%d)(%d%d)(%d%d)%d*', '%1-%2-%3');	-- make ymd format date from timestamp	if dates_t['archive-date'].val == archive_url_date then						-- are the two dates the same		return;																	-- yes, done	else		dates_t['archive-date'] = {val=archive_url_date, name=''};				-- setup to call reformat_dates() with the timestamp date		reformat_dates (dates_t, df or archive_date_format);					-- reformat timestamp to format specified by <df> or format used in |archive-date= 		archive_url_date = vi_formatdate(archive_url_date, true);		set_message ('err_archive_date_url_ts_mismatch', archive_url_date);		-- emit an error message	endend--[[--------------------------< E X P O R T E D   F U N C T I O N S >------------------------------------------]]return {																		-- return exported functions	archive_date_check = archive_date_check,	date_hyphen_to_dash = date_hyphen_to_dash,	date_name_xlate = date_name_xlate,	dates = dates,	reformat_dates = reformat_dates,	replace_vietnamese_date = replace_vietnamese_date,	set_selected_modules = set_selected_modules,	vi_formatdate = vi_formatdate,	year_check = year_check,	year_date_check = year_date_check,	}