Module:Citation/CS1/Date validation

local p = {}

--[[--< 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 days

Wikipedia 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 |accessdate= at time 00:00:00 UTC today 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 tomorrow

]]

local function is_valid_accessdate (accessdate) local lang = mw.getContentLanguage; local good1, good2; local access_ts, tomorrow_ts;												-- to hold unix time stamps representing the dates good1, access_ts = pcall( lang.formatDate, lang, 'U', accessdate );			-- convert accessdate value to unix timesatmp good2, tomorrow_ts = pcall( lang.formatDate, lang, 'U', 'today + 2 days' );	-- today midnight + 2 days is one second more than all day tomorrow if good1 and good2 then access_ts = tonumber (access_ts);										-- convert to numbers for the comparison tomorrow_ts = tonumber (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 end end

--[[--< 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) local long_months = {['January']=1, ['February']=2, ['March']=3, ['April']=4, ['May']=5, ['June']=6, ['July']=7, ['August']=8, ['September']=9, ['October']=10, ['November']=11, ['December']=12}; local short_months = {['Jan']=1, ['Feb']=2, ['Mar']=3, ['Apr']=4, ['May']=5, ['Jun']=6, ['Jul']=7, ['Aug']=8, ['Sep']=9, ['Oct']=10, ['Nov']=11, ['Dec']=12}; local temp; temp=long_months[month]; if temp then return temp; end				-- if month is the long-form name temp=short_months[month]; if temp then return temp; end				-- if month is the short-form name return 0;									-- misspelled, improper case, or not a month name end

--[[--< 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: 1 for Winter, etc. Capitalization and spelling must be correct. If not a valid season, returns 0

]]

local function get_season_number (season) local season_list = {['Winter']=21, ['Spring']=22, ['Summer']=23, ['Fall']=24, ['Autumn']=24};	-- make sure these numbers do not overlap month numbers local temp; temp=season_list[season]; if temp then return temp; end												-- if season is a valid name return its number return 0;																	-- misspelled, improper case, or not a season name end

--[[--< I S _ P R O P E R _ N A M E >--

returns a non-zero number if date contains a recognized proper name. Capitalization and spelling must be correct.

]]

local function is_proper_name (name) local name_list = {['Christmas']=31} local temp; temp=name_list[name]; if temp then return temp; end				-- if name is a valid name return its number return 0;									-- misspelled, improper case, or not a proper name end

--[[--< I S _ V A L I D _ M O N T H _ O R _ S E A S O N >--

--returns true if month or season is valid (properly spelled, capitalized, abbreviated)

]]

local function is_valid_month_or_season (month_season) if 0 == get_month_number (month_season) then		-- if month text isn't one of the twelve months, might be a season if 0 == get_season_number (month_season) then	-- not a month, is it a season? return false;								-- return false not a month or one of the five seasons end end return true; end

--[[--< 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 one year in the future are not acceptable.

]]

local function is_valid_year(year) 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 return tonumber(year) <= year_limit;				-- false if year is in the future more than one year 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 future than next year; else returns false.

Assumes Julian calendar prior to year 1582 and Gregorian calendar thereafter. Accounts for Julian calendar leap years before 1582 and Gregorian leap years after 1582. Where the two calendars overlap (1582 to approximately 1923) dates are assumed to be Gregorian.

]]

local function is_valid_date (year, month, day) 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) then												-- no farther into the future than next year 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 month_length = 29; 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. There is a special test for May because it can be either short or long form.

Returns true when style for both months is the same

]]

local function is_valid_month_range_style (month1, month2) local len1 = month1:len; local len2 = month2:len; if len1 == len2 then return true;															-- both months are short form so return true elseif 'May' == month1 or 'May'== month2 then 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 end end

--[[--< 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.

Similarly, seasons are also left to right, earliest to latest in time. There is an oddity with seasons: winter is assigned a value of 1, spring 2, ..., fall and autumn 4. Because winter can follow fall/autumn at the end of a calender year, a special test is made to see if |date=Fall-Winter yyyy (4-1) is the date.

]]

local function is_valid_month_season_range(range_start, range_end) local range_start_number = get_month_number (range_start); if 0 == range_start_number then												-- is this a month range? local range_start_number = get_season_number (range_start);				-- not a month; is it a season? get start season number local range_end_number = get_season_number (range_end);					-- get end season number

if 0 ~= range_start_number then											-- is start of range a season? if range_start_number < range_end_number then						-- range_start is a season return true;													-- return true when range_end is also a season and follows start season; else false end if 24 == range_start_number and 21 == range_end_number then			-- special case when season range is Fall-Winter or Autumn-Winter return true; end end return false;		-- range_start is not a month or a season; or range_start is a season and range_end is not; or improper season sequence end

local range_end_number = get_month_number (range_end);						-- get end month number if range_start_number < range_end_number then								-- range_start is a month; does range_start precede range_end? if is_valid_month_range_style (range_start, range_end) then				-- do months have the same style? return true;														-- proper order and same style end end return false;																-- range_start month number is greater than or equal to range end number; or range end isn't a month end

--[[--< 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 in Module:Citation/CS1. The function is called only for |date= parameters and only if the |date= 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/yyyy

Dates in the Julian calendar are reduced to year or year/year so that we don't have to do calendar conversion from Julian 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; 31– proper name dates day, day2 – 0 if not provided, 1-31 for days the output table receives: rftdate:	an IS8601 formatted date rftchron:	a free-form version of the date, usually without year which is in rftdate (season ranges and propername dates) rftssn:		one of four season keywords: winter, spring, summer, fall (lowercase)

]]

local function make_COinS_date (input, tCOinS_date) local date;																	-- one date or first date in a range local date2 = '';															-- end of range date if 1582 > tonumber(input.year) or 20 < tonumber(input.month) then			-- Julian calendar or season so &rft.date gets year only date = input.year; 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', tonumber(input.year), tonumber(input.year2))		-- assemble the date range end if 20 < tonumber(input.month) then										-- if season or propername date local season = {[21]='winter', [22]='spring', [23]='summer', [24]='fall', [31]='Christmas'};	-- seasons lowercase, no autumn; proper names use title case if 0 == input.month2 then											-- single season date if 30 <tonumber(input.month) then tCOinS_date.rftchron = season[input.month];					-- proper name dates else tCOinS_date.rftssn = season[input.month];					-- seasons end else																-- season range with a second season specified if input.year ~= input.year2 then								-- season year – season year range or season year–year tCOinS_date.rftssn = season[input.month];					-- start of range season; keep this? if 0~= month2 then tCOinS_date.rftchron = string.format ('%s %s – %s %s', season[input.month], input.year, season[input.month2], input.year2); end else															-- season–season year range tCOinS_date.rftssn = season[input.month];					-- start of range season; keep this? tCOinS_date.rftchron = season[input.month] .. '–' .. season[input.month2];	-- season–season year range end end end tCOinS_date.rftdate = date; return;																	-- done end 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

--[[--< 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: only allowed range separator is endash. Additionally, check the date to see that it is a real date: no 31 in 30-day months; no 29 February when not a leap year. Months, both long-form and three character abbreviations, and seasons must 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 and COinS_date. When this happens, the date parameter is used in the COinS metadata and the CITEREF identifier gets its 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, accessdate, embargo, archivedate, etc.)

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, 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;

if date_string:match("^%d%d%d%d%-%d%d%-%d%d$") then										-- year-initial numerical year month day format year, month, day=string.match(date_string, "(%d%d%d%d)%-(%d%d)%-(%d%d)"); if 12 < tonumber(month) or 1 > tonumber(month) or 1583 > tonumber(year) then return false; end			-- month number not valid or not Gregorian calendar anchor_year = year;

elseif date_string:match("^%a+ +[1-9]%d?, +[1-9]%d%d%d%a?$") then						-- month-initial: month day, year month, day, anchor_year, year=string.match(date_string, "(%a+)%s*(%d%d?),%s*((%d%d%d%d)%a?)"); month = get_month_number (month); if 0 == month then return false; end												-- return false if month text isn't one of the twelve months elseif date_string:match("^%a+ +[1-9]%d?–[1-9]%d?, +[1-9]%d%d%d%a?$") then				-- month-initial day range: month day–day, year; days are separated by endash month, day, day2, anchor_year, year=string.match(date_string, "(%a+) +(%d%d?)–(%d%d?), +((%d%d%d%d)%a?)"); 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 date_string:match("^[1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then						-- day-initial: day month year day, month, anchor_year, year=string.match(date_string, "(%d%d*)%s*(%a+)%s*((%d%d%d%d)%a?)"); 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 date_string:match("^[1-9]%d?–[1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then				-- day-range-initial: day–day month year; days are separated by endash day, day2, month, anchor_year, year=string.match(date_string, "(%d%d?)–(%d%d?) +(%a+) +((%d%d%d%d)%a?)"); 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 date_string:match("^[1-9]%d? +%a+ – [1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then		-- day initial month-day-range: day month - day month year; uses spaced endash day, month, day2, month2, anchor_year, year=date_string:match("(%d%d?) +(%a+) – (%d%d?) +(%a+) +((%d%d%d%d)%a?)"); 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 date_string:match("^%a+ +[1-9]%d? – %a+ +[1-9]%d?, +[1-9]%d%d%d?%a?$") then		-- month initial month-day-range: month day – month day, year; uses spaced endash month, day, month2, day2, anchor_year, year=date_string:match("(%a+) +(%d%d?) – (%a+) +(%d%d?), +((%d%d%d%d)%a?)"); if (not is_valid_month_season_range(month, month2)) 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 date_string:match("^[1-9]%d? +%a+ +[1-9]%d%d%d – [1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then		-- day initial month-day-year-range: day month year - day month year; uses spaced endash day, month, year, day2, month2, anchor_year, year2=date_string:match("(%d%d?) +(%a+) +(%d%d%d%d?) – (%d%d?) +(%a+) +((%d%d%d%d?)%a?)"); 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);

elseif date_string:match("^%a+ +[1-9]%d?, +[1-9]%d%d%d – %a+ +[1-9]%d?, +[1-9]%d%d%d%a?$") then		-- month initial month-day-year-range: month day, year – month day, year; uses spaced endash month, day, year, month2, day2, anchor_year, year2=date_string:match("(%a+) +(%d%d?), +(%d%d%d%d) – (%a+) +(%d%d?), +((%d%d%d%d)%a?)"); 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);

elseif date_string:match("^%a+ +[1-9]%d%d%d–%d%d%a?$") then								-- special case Winter/Summer year-year (YYYY-YY); year separated with unspaced endash local century; month, year, century, anchor_year, year2=date_string:match("(%a+) +((%d%d)%d%d)–((%d%d)%a?)"); if 'Winter' ~= month and 'Summer' ~= month 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);

elseif date_string:match("^%a+ +[1-9]%d%d%d–[1-9]%d%d%d%a?$") then						-- special case Winter/Summer year-year; year separated with unspaced endash month, year, anchor_year, year2=date_string:match("(%a+) +(%d%d%d%d)–((%d%d%d%d)%a?)"); if 'Winter' ~= month and 'Summer' ~= month 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);													-- for metadata

elseif date_string:match("^%a+ +[1-9]%d%d%d% – %a+ +[1-9]%d%d%d%a?$") then				-- month/season year - month/season year; separated by spaced endash month, year, month2, anchor_year, year2=date_string:match("(%a+) +(%d%d%d%d) – (%a+) +((%d%d%d%d)%a?)"); 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) and 0 ~= get_season_number(month2) then		-- both must be or season year, not mixed month = get_season_number(month); month2 = get_season_number(month2); else return false; end

elseif date_string:match ("^%a+–%a+ +[1-9]%d%d%d%a?$") then					-- month/season range year; months separated by endash month, month2, anchor_year, year=date_string:match ("(%a+)–(%a+)%s*((%d%d%d%d)%a?)"); if (not is_valid_month_season_range(month, month2)) or (not is_valid_year(year)) then return false; end if 0 ~= get_month_number(month) then									-- determined to be a valid range so just check this one to know if month or season month = get_month_number(month); month2 = get_month_number(month2); else month = get_season_number(month); month2 = get_season_number(month2); end year2=year; elseif date_string:match("^%a+ +%d%d%d%d%a?$") then							-- month/season year or proper-name year month, anchor_year, year=date_string:match("(%a+)%s*((%d%d%d%d)%a?)"); if not is_valid_year(year) then return false; end if not is_valid_month_or_season (month) and 0 == is_proper_name (month) 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); elseif 0 ~= get_season_number(month) then month = get_season_number(month); else month = is_proper_name (month);										-- must be proper name; not supported in COinS end

elseif date_string:match("^[1-9]%d%d%d?–[1-9]%d%d%d?%a?$") then				-- Year range: YYY-YYY or YYY-YYYY or YYYY–YYYY; separated by unspaced endash; 100-9999 year, anchor_year, year2=date_string:match("(%d%d%d%d?)–((%d%d%d%d?)%a?)"); 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 date_string:match("^[1-9]%d%d%d–%d%d%a?$") then						-- Year range: YYYY–YY; separated by unspaced endash local century; year, century, anchor_year, year2=date_string:match("((%d%d)%d%d)–((%d%d)%a?)"); anchor_year=year..'–'..anchor_year;										-- assemble anchor year from both years 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 date_string:match("^[1-9]%d%d%d?%a?$") then							-- year; here accept either YYY or YYYY anchor_year, year=date_string:match("((%d%d%d%d?)%a?)"); if false == is_valid_year(year) then return false; end

else return false;															-- date format not one of the MOS:DATE approved formats 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 date end

--[[--< 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 returns true. 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 in the 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, a single error message is created as the dates are tested.

]]

local function dates(date_parameters_list, tCOinS_date) 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 error_message = ""; 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) then														-- if the parameter has a value if v:match("^c%. [1-9]%d%d%d?%a?$") then							-- special case for c. year or with or without CITEREF disambiguator - only |date= and |year= local year = v:match("c%. ([1-9]%d%d%d?)%a?");					-- get the year portion so it can be tested if 'date'==k then anchor_year, COinS_date = v:match("((c%. [1-9]%d%d%d?)%a?)");	-- anchor year and COinS_date only from |date= parameter good_date = is_valid_year(year); elseif 'year'==k then good_date = is_valid_year(year); end elseif 'date'==k then												-- if the parameter is |date= if v:match("^n%.d%.%a?") then									-- if |date=n.d. with or without a CITEREF disambiguator good_date, anchor_year, COinS_date = true, v:match("((n%.d%.)%a?)");	--"n.d."; no error when date parameter is set to no date elseif v:match("^nd%a?$") then									-- if |date=nd with or without a CITEREF disambiguator good_date, anchor_year, COinS_date = true, v:match("((nd)%a?)");	--"nd";	no error when date parameter is set to no date else good_date, anchor_year, COinS_date = check_date (v, tCOinS_date);	-- go test the date end elseif 'access-date'==k then										-- if the parameter is |date= good_date = check_date (v);										-- go test the date if true == good_date then										-- if the date is a valid date good_date = is_valid_accessdate (v);						-- is Wikipedia start date < accessdate < tomorrow's date? end else																-- any other date-holding parameter good_date = check_date (v);										-- go test the date end if false==good_date then											-- assemble one error message so we don't add the tracking category multiple times if is_set(error_message) then									-- once we've added the first portion of the error message ... error_message=error_message .. ", ";						-- ... add a comma space separator end error_message=error_message .. "&#124;" .. k .. "=";			-- add the failed parameter end end end return anchor_year, error_message;											-- and done end

--[[--< 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 returns a 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)

]]

local function year_date_check (year_string, date_string) 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 date and year 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 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 date_string:match ("%d%d%d%d[%s%-–]+%d%d") then						-- YYYY-YY date ranges local century; date1, century, date2 = date_string:match ("((%d%d)%d%d)[%s%-–]+(%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 end return result; end

return {dates = dates, year_date_check = year_date_check}						-- return exported functions