From TestWiki

    Documentation for this module may be created at Module:Citation/CS1/Utilities/doc

    local z = {
    	error_categories = {};														-- for categorizing citations that contain errors
    	error_ids = {};
    	message_tail = {};
    	maintenance_cats = {};														-- for categorizing citations that aren't erroneous per se, but could use a little work
    	properties_cats = {};														-- for categorizing citations based on certain properties, language of source for instance
    --[[--------------------------< F O R W A R D   D E C L A R A T I O N S >--------------------------------------
    local cfg;																		-- table of tables imported from selected Module:Citation/CS1/Configuration
    --[[--------------------------< H A S _ A C C E P T _ A S _ W R I T T E N >------------------------------------
    When <str> is wholly wrapped in accept-as-written markup, return <str> without markup and true; return <str> and false else
    with allow_empty = false, <str> must have at least one character inside the markup
    with allow_empty = true, <str> the markup frame can be empty like (()) to distinguish an empty template parameter from the specific condition "has no applicable value" in citation-context.
    After further evaluation the two cases might be merged at a later stage, but should be kept separated for now.
    local function has_accept_as_written (str, allow_empty)
    	local count;
    	if true == allow_empty then
    		str, count = str:gsub ('^%(%((.*)%)%)$', '%1'); 						-- allows (()) to be an empty set
    		str, count = str:gsub ('^%(%((.+)%)%)$', '%1');
    	return str, 0 ~= count;
    --[[--------------------------< I S _ S E T >------------------------------------------------------------------
    Returns true if argument is set; false otherwise. Argument is 'set' when it exists (not nil) or when it is not an empty string.
    local function is_set (var)
    	return not (var == nil or var == '');
    --[[--------------------------< I N _ A R R A Y >--------------------------------------------------------------
    Whether needle is in haystack
    local function in_array (needle, haystack)
    	if needle == nil then
    		return false;
    	for n, v in ipairs (haystack) do
    		if v == needle then
    			return n;
    	return false;
    --[[--------------------------< S U B S T I T U T E >----------------------------------------------------------
    Populates numbered arguments in a message string using an argument table.
    local function substitute (msg, args)
    	return args and mw.message.newRawMessage (msg, args):plain() or msg;
    --[[--------------------------< E R R O R _ C O M M E N T >----------------------------------------------------
    Wraps error messages with CSS markup according to the state of hidden.
    local function error_comment (content, hidden)
    	return substitute (hidden and cfg.presentation['hidden-error'] or cfg.presentation['visible-error'], content);
    --[=[-------------------------< M A K E _ W I K I L I N K >----------------------------------------------------
    Makes a wikilink; when both link and display text is provided, returns a wikilink in the form [[L|D]]; if only
    link is provided (or link and display are the same), returns a wikilink in the form [[L]]; if neither are
    provided or link is omitted, returns an empty string.
    local function make_wikilink (link, display)
    	if not is_set (link) then return '' end
    	if is_set (display) and link ~= display then			
    		return table.concat ({'[[', link, '|', display, ']]'});			
    		return table.concat ({'[[', link, ']]'});
    --[[--------------------------< S E T _ M E S S A G E >----------------------------------------------------------
    Sets an error condition and returns the appropriate error message.  The actual placement of the error message in the output is
    the responsibility of the calling function.
    TODO: change z.error_categories and z.maintenance_cats to have the form cat_name = true; to avoid dups without having to have an extra cat
    local added_maint_cats = {}														-- list of maintenance categories that have been added to z.maintenance_cats; TODO: figure out how to delete this table
    local function set_message (error_id, arguments, raw, prefix, suffix)
    	local error_state = cfg.error_conditions[error_id];
    	prefix = prefix or '';
    	suffix = suffix or '';
    	if error_state == nil then
    		error (cfg.messages['undefined_error'] .. ': ' .. error_id);			-- because missing error handler in Module:Citation/CS1/Configuration
    	elseif is_set (error_state.category) then
    		if error_state.message then												-- when error_state.message defined, this is an error message
    			table.insert (z.error_categories, error_state.category);
    			if not added_maint_cats[error_id] then
    				added_maint_cats[error_id] = true;								-- note that we've added this category
    				table.insert (z.maintenance_cats, substitute (error_state.category, arguments));	-- make cat name then add to table
    			return;																-- because no message, nothing more to do
    	local message = substitute (error_state.message, arguments);
    	message = table.concat (
    		' (',
    		make_wikilink (
    			table.concat (
    				cfg.messages['help page link'],
    			cfg.messages['help page label']),
    	z.error_ids[error_id] = true;
    	if z.error_ids['err_citation_missing_title'] and							-- if missing-title error already noted
    		in_array (error_id, {'err_bare_url_missing_title', 'err_trans_missing_title'}) then		-- and this error is one of these
    			return '', false;													-- don't bother because one flavor of missing title is sufficient
    	message = table.concat ({prefix, message, suffix});
    	if raw == true then
    		return message, error_state.hidden;
    	return error_comment (message, error_state.hidden);
    --[[-------------------------< I S _ A L I A S _ U S E D >-----------------------------------------------------
    This function is used by select_one() to determine if one of a list of alias parameters is in the argument list
    provided by the template.
    	args – pointer to the arguments table from calling template
    	alias – one of the list of possible aliases in the aliases lists from Module:Citation/CS1/Configuration
    	index – for enumerated parameters, identifies which one
    	enumerated – true/false flag used to choose how enumerated aliases are examined
    	value – value associated with an alias that has previously been selected; nil if not yet selected
    	selected – the alias that has previously been selected; nil if not yet selected
    	error_list – list of aliases that are duplicates of the alias already selected
    	value – value associated with alias we selected or that was previously selected or nil if an alias not yet selected
    	selected – the alias we selected or the alias that was previously selected or nil if an alias not yet selected
    local function is_alias_used (args, alias, index, enumerated, value, selected, error_list)
    	if enumerated then															-- is this a test for an enumerated parameters?
    		alias = alias:gsub ('#', index);										-- replace '#' with the value in index
    		alias = alias:gsub ('#', '');											-- remove '#' if it exists
    	if is_set (args[alias]) then													-- alias is in the template's argument list
    		if value ~= nil and selected ~= alias then								-- if we have already selected one of the aliases
    			local skip;
    			for _, v in ipairs (error_list) do									-- spin through the error list to see if we've added this alias
    				if v == alias then
    					skip = true;
    					break;														-- has been added so stop looking 
    			if not skip then													-- has not been added so
    				table.insert (error_list, alias);								-- add error alias to the error list
    			value = args[alias];												-- not yet selected an alias, so select this one
    			selected = alias;
    	return value, selected;														-- return newly selected alias, or previously selected alias
    --[[--------------------------< A D D _ M A I N T _ C A T >------------------------------------------------------
    Adds a category to z.maintenance_cats using names from the configuration file with additional text if any.
    To prevent duplication, the added_maint_cats table lists the categories by key that have been added to z.maintenance_cats.
    local function add_maint_cat (key, arguments)
    	if not added_maint_cats [key] then
    		added_maint_cats [key] = true;											-- note that we've added this category
    		table.insert (z.maintenance_cats, substitute (cfg.maint_cats [key], arguments));	-- make name then add to table
    --[[--------------------------< A D D _ P R O P _ C A T >--------------------------------------------------------
    Adds a category to z.properties_cats using names from the configuration file with additional text if any.
    foreign_lang_source and foreign_lang_source_2 keys have a language code appended to them so that multiple languages
    may be categorized but multiples of the same language are not categorized.
    added_prop_cats is a table declared in page scope variables above
    local added_prop_cats = {};														-- list of property categories that have been added to z.properties_cats
    local function add_prop_cat (key, arguments)
    	if not added_prop_cats [key] then
    		added_prop_cats [key] = true;											-- note that we've added this category
    		key = key:gsub ('(foreign_lang_source_?2?)%a%a%a?[%a%-]*', '%1');		-- strip lang code from keyname
    		table.insert (z.properties_cats, substitute (cfg.prop_cats [key], arguments));	-- make name then add to table
    --[[--------------------------< S A F E _ F O R _ I T A L I C S >----------------------------------------------
    Protects a string that will be wrapped in wiki italic markup '' ... ''
    Note: We cannot use <i> for italics, as the expected behavior for italics specified by ''...'' in the title is that
    they will be inverted (i.e. unitalicized) in the resulting references.  In addition, <i> and '' tend to interact
    poorly under Mediawiki's HTML tidy.
    local function safe_for_italics (str)
    	if not is_set (str) then return str end
    	if str:sub (1, 1) == "'" then str = "<span></span>" .. str; end
    	if str:sub (-1, -1) == "'" then str = str .. "<span></span>"; end
    	-- Remove newlines as they break italics.
    	return str:gsub ('\n', ' ');
    --[[--------------------------< W R A P _ S T Y L E >----------------------------------------------------------
    Applies styling to various parameters.  Supplied string is wrapped using a message_list configuration taking one
    argument; protects italic styled parameters.  Additional text taken from citation_config.presentation - the reason
    this function is similar to but separate from wrap_msg().
    local function wrap_style (key, str)
    	if not is_set (str) then
    		return "";
    	elseif in_array (key, {'italic-title', 'trans-italic-title'}) then
    		str = safe_for_italics (str);
    	return substitute (cfg.presentation[key], {str});
    --[[--------------------------< M A K E _ S E P _ L I S T >------------------------------------------------------------
    make a separated list of items using provided separators.
    	<sep_list> - typically '<comma><space>'
    	<sep_list_pair> - typically '<space>and<space>'
    	<sep_list_end> - typically '<comma><space>and<space>' or '<comma><space>&<space>'
    defaults to cfg.presentation['sep_list'], cfg.presentation['sep_list_pair'], and cfg.presentation['sep_list_end']
    if <sep_list_end> is specified, <sep_list> and <sep_list_pair> must also be supplied
    local function make_sep_list (count, list_seq, sep_list, sep_list_pair, sep_list_end)
    	local list = '';
    	if not sep_list then														-- set the defaults
    		sep_list = cfg.presentation['sep_list'];
    		sep_list_pair = cfg.presentation['sep_list_pair'];
    		sep_list_end = cfg.presentation['sep_list_end'];
    	if 2 >= count then
    		list = table.concat (list_seq, sep_list_pair);							-- insert separator between two items; returns list_seq[1] then only one item
    	elseif 2 < count then
    		list = table.concat (list_seq, sep_list, 1, count - 1);					-- concatenate all but last item with plain list separator
    		list = table.concat ({list, list_seq[count]}, sep_list_end);			-- concatenate last item onto end of <list> with final separator
    	return list;
    --[[--------------------------< S E L E C T _ O N E >----------------------------------------------------------
    Chooses one matching parameter from a list of parameters to consider.  The list of parameters to consider is just
    names.  For parameters that may be enumerated, the position of the numerator in the parameter name is identified
    by the '#' so |author-last1= and |author1-last= are represented as 'author-last#' and 'author#-last'.
    Because enumerated parameter |<param>1= is an alias of |<param>= we must test for both possibilities.
    Generates an error if more than one match is present.
    local function select_one (args, aliases_list, error_condition, index)
    	local value = nil;															-- the value assigned to the selected parameter
    	local selected = '';														-- the name of the parameter we have chosen
    	local error_list = {};
    	if index ~= nil then index = tostring(index); end
    	for _, alias in ipairs (aliases_list) do									-- for each alias in the aliases list
    		if alias:match ('#') then												-- if this alias can be enumerated
    			if '1' == index then												-- when index is 1 test for enumerated and non-enumerated aliases
    				value, selected = is_alias_used (args, alias, index, false, value, selected, error_list);	-- first test for non-enumerated alias
    			value, selected = is_alias_used (args, alias, index, true, value, selected, error_list);	-- test for enumerated alias
    			value, selected = is_alias_used (args, alias, index, false, value, selected, error_list);	-- test for non-enumerated alias
    	if #error_list > 0 and 'none' ~= error_condition then						-- for cases where this code is used outside of extract_names()
    		for i, v in ipairs (error_list) do
    			error_list[i] = wrap_style ('parameter', v);
    		table.insert (error_list, wrap_style ('parameter', selected));
    		table.insert (z.message_tail, {set_message (error_condition, {make_sep_list (#error_list, error_list)}, true)});
    	return value, selected;
    --[=[-------------------------< R E M O V E _ W I K I _ L I N K >----------------------------------------------
    Gets the display text from a wikilink like [[A|B]] or [[B]] gives B
    The str:gsub() returns either A|B froma [[A|B]] or B from [[B]] or B from B (no wikilink markup).
    In l(), l:gsub() removes the link and pipe (if they exist); the second :gsub() trims whitespace from the label
    if str was wrapped in wikilink markup.  Presumably, this is because without wikimarkup in str, there is no match
    in the initial gsub, the replacement function l() doesn't get called.
    local function remove_wiki_link (str)
    	return (str:gsub ("%[%[([^%[%]]*)%]%]", function(l)
    		return l:gsub ("^[^|]*|(.*)$", "%1" ):gsub ("^%s*(.-)%s*$", "%1");
    --[=[-------------------------< I S _ W I K I L I N K >--------------------------------------------------------
    Determines if str is a wikilink, extracts, and returns the wikilink type, link text, and display text parts.
    If str is a complex wikilink ([[L|D]]):
    	returns wl_type 2 and D and L from [[L|D]];
    if str is a simple wikilink ([[D]])
    	returns wl_type 1 and D from [[D]] and L as empty string;
    if not a wikilink:
    	returns wl_type 0, str as D, and L as empty string.
    trims leading and trailing whitespace and pipes from L and D ([[L|]] and [[|D]] are accepted by MediaWiki and
    treated like [[D]]; while [[|D|]] is not accepted by MediaWiki, here, we accept it and return D without the pipes).
    local function is_wikilink (str)
    	local D, L
    	local wl_type = 2;															-- assume that str is a complex wikilink [[L|D]]
    	if not str:match ('^%[%[[^%]]+%]%]$') then									-- is str some sort of a wikilink (must have some sort of content)
    		return 0, str, '';														-- not a wikilink; return wl_type as 0, str as D, and empty string as L
    	L, D = str:match ('^%[%[([^|]+)|([^%]]+)%]%]$');							-- get L and D from [[L|D]] 
    	if not is_set (D) then														-- if no separate display
    		D = str:match ('^%[%[([^%]]*)|*%]%]$');									-- get D from [[D]] or [[D|]]
    		wl_type = 1; 
    	D = mw.text.trim (D, '%s|');												-- trim white space and pipe characters 
    	return wl_type, D, L or '';
    --[[--------------------------< S T R I P _ A P O S T R O P H E _ M A R K U P >--------------------------------
    Strip wiki italic and bold markup from argument so that it doesn't contaminate COinS metadata.
    This function strips common patterns of apostrophe markup.  We presume that editors who have taken the time to
    markup a title have, as a result, provided valid markup. When they don't, some single apostrophes are left behind.
    Returns the argument without wiki markup and a number; the number is more-or-less meaningless except as a flag
    to indicate that markup was replaced; do not rely on it as an indicator of how many of any kind of markup was
    removed; returns the argument and nil when no markup removed
    local function strip_apostrophe_markup (argument)
    	if not is_set (argument) then
    		return argument, nil;													-- no argument, nothing to do
    	if nil == argument:find ( "''", 1, true ) then								-- Is there at least one double apostrophe?  If not, exit.
    		return argument, nil;
    	local flag;
    	while true do
    		if argument:find ("'''''", 1, true) then								-- bold italic (5)
    			argument, flag = argument:gsub ("%'%'%'%'%'", "");						-- remove all instances of it
    		elseif argument:find ("''''", 1, true) then							-- italic start and end without content (4)
    			argument, flag=argument:gsub ("%'%'%'%'", "");
    		elseif argument:find ("'''", 1, true) then							-- bold (3)
    			argument, flag=argument:gsub ("%'%'%'", "");
    		elseif argument:find ("''", 1, true) then								-- italic (2)
    			argument, flag = argument:gsub ("%'%'", "");
    	return argument, flag;														-- done
    --[[--------------------------< S E T _ S E L E C T E D _ M O D U L E S >--------------------------------------
    Sets local cfg table to same (live or sandbox) as that used by the other modules.
    local function set_selected_modules (cfg_table_ptr)
    	cfg = cfg_table_ptr;
    --[[--------------------------< E X P O R T S >----------------------------------------------------------------
    return {
    	add_maint_cat = add_maint_cat,												-- exported functions
    	add_prop_cat = add_prop_cat,
    	error_comment = error_comment,
    	has_accept_as_written = has_accept_as_written,
    	in_array = in_array,
    	is_set = is_set,
    	is_wikilink = is_wikilink,
    	make_sep_list = make_sep_list,
    	make_wikilink = make_wikilink,
    	remove_wiki_link = remove_wiki_link,
    	safe_for_italics = safe_for_italics,
    	select_one = select_one,
    	set_message = set_message,
    	set_selected_modules = set_selected_modules,
    	strip_apostrophe_markup = strip_apostrophe_markup,
    	substitute = substitute,
    	wrap_style = wrap_style,
    	z = z,																		-- exported table