Module:WPSHIPS utilities

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Add categories to the /doc subpage. Subpages of this module.

require('strict')
local get_args = require ('Module:Arguments').getArgs;
local styles = require ('Module:WPMILHIST Infobox style');						-- infobox css
local data = mw.loadData ('Module:WPSHIPS utilities/data');
local namespace = mw.title.getCurrentTitle().namespace;							-- used for categorization


--[[--------------------------< E R R O R _ M A P _ T >--------------------------------------------------------
]]

local error_map_t = {															-- [1] is error message; [2] is error category
	synonymous = {'has synonymous parameter', 'Category:Pages using infobox ship with synonymous parameters'};
	missing = {'missing required parameter: %s', 'Category:WPSHIPS: sclass and sclass2 errors'},
	format = {'invalid format code: %s. Should be 0–5, or blank', 'Category:WPSHIPS: sclass and sclass2 errors'},
	missing_name = {'missing name', 'Category:WPSHIPS: Template Ship parameter errors'},
	missing_dab = {'missing disambiguator', 'Category:WPSHIPS: Template Ship parameter errors'},
	missing_prefix = {'missing prefix', 'Category:WPSHIPS: Template Ship parameter errors'},
	invalid_control = {'invalid control parameter: %s', 'Category:WPSHIPS: Template Ship parameter errors'},
	}


--[[--------------------------< E R R O R _ M S G _ M A K E >--------------------------------------------------

assembles an error message from message text and category in <error_map_t>.  creates a help link to the category
page; categorizes only main and template namespaces.

<no_cat> disables categorization for those templates that support it; to disable categorization set <no_cat> true

]]

local function error_msg_make (msg_idx, template, detail, no_cat, link_template_name)
	local out = {};
	local category;
	
	table.insert (out, '<span style=\"font-size: 100%; font-style: normal;\" class=\"error\">Error: ');	--TODO: simplify?
	if template then
		if link_template_name then
			table.insert (out, table.concat ({'{{[[Template:', template, '|', template, ']]}} '}));
		else
			table.insert (out, table.concat ({'{{', template, '}} '}));				-- TODO: get template names for synonymous parameter errors
		end
	end
	table.insert (out, string.format (error_map_t[msg_idx][1], detail));		-- build error message from base + <detail>
	table.insert (out, table.concat ({' ([[:', error_map_t[msg_idx][2], '|help]])'}));	-- help text on category pages; TODO: help text on template pages also?
	table.insert (out, '</span>');
	
	if (0 == namespace or 10 == namespace) and not no_cat then					-- categorize in article space (and template space to take care of broken usages)
		table.insert (out, table.concat ({'[[', error_map_t[msg_idx][2], ']]'}));
	end

	return table.concat (out);													-- make a big string and done
end


--[[--------------------------< 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 == '');
end


--[[--------------------------< S I Z E O F _ S H I P _ T Y P E >----------------------------------------------

Returns the size in words of ship type.  Inputs are the fragment table, the number of elements in the fragment table,
and the number of words that make up nationality.

The number of fragments (words) in a ship name dictate the possible sizes of ship type.  If nationality takes one fragment,
and ship type takes four fragments, then the minimum number of fragments in a composite ship name is:
	5 = 1 (nationality) + 3 (ship type) + 1 (ship name) (same as 4 fragments (words) after nationality)

This function starts at the longest possible series of fragments that might be ship type.  This order is important becuase
some ship types might begin with similar fragments: 'ship' and 'ship of the line'.  Starting with the least possible
series of fragments (1) would find 'ship' and make 'of the line' part of the italicized name.

Returns 0 if there is no recognizable ship type.

]]

local function sizeof_ship_type (frag, frag_len, nat_len)
	local ship_type;
	
	if 5 <= (frag_len - nat_len) then											-- must have at least five fragments after nationality for four-word ship type
		ship_type = table.concat (frag, ' ', nat_len+1, nat_len+4);				-- four-word ship type
		if data.ship_type_t[ship_type] then
			return 4;
		end
	end
	if 4 <= (frag_len - nat_len) then											-- must have at least four fragments after nationality for three-word ship type
		ship_type = table.concat (frag, ' ', nat_len+1, nat_len+3);				-- three-word ship type
		if data.ship_type_t[ship_type] then
			return 3;
		end
	end
	if 3 <= (frag_len - nat_len) then											-- must have at least three fragments after nationality for two-word ship type
		ship_type = table.concat (frag, ' ', nat_len+1, nat_len+2);				-- two-word ship type
		if data.ship_type_t[ship_type] then
			return 2;
		end
	end	
	if 2 <= (frag_len - nat_len) then											-- must have at least two fragments after nationality for one-word ship type
		if data.ship_type_t[frag[nat_len+1]] then								-- one-word ship type
			return 1;
		end
	end
	return 0;																	-- no recognizable ship type
end

--[[--------------------------< S I Z E O F _ N A T I O N A L I T Y >------------------------------------------

This function the size (in words) of the nationality from the fragments table.  Nationality may be one or two
words that occupy the first one or two positions in the table.

Returns the number of words that identify the nationality:
	1 for French or German, etc.
	2 for United States;
	0 when table doesn't have a recognizable nationality

]]

local function sizeof_nationality (frag, frag_len)
	local nat = '';

	if not data.nationality_t [frag[1]] then									-- if not a one-word nationality
		if 2 <= frag_len - 2 then												-- must have at least two fragments after nationality for minimal ship type and name
			nat = table.concat (frag, ' ', 1, 2);
			if data.nationality_t [nat] then									-- is it a two-word nationality?
				return 2;														-- yes
			else
				return 0;														-- no
			end
		end
		return 0;																-- not one-word and not enough fragments for two-word
	end
	return 1;																	-- one-word nationality
end


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

This function applies correct styling to ship and ship-class names.  These names are, for example, ship-article titles
used by templates {{navsource}}, {{Infobox ship begin}}, where the article title is to be rendered with proper
styling.

This function requires one argument:
	|name= (required): a name is required; if missing or empty, this function returns an error message (may or may not be visible depending on where it is used)
		used in {{infobox ship begin}} to provide a value for {{DISPLAYTITLE:}} and to provide a value for |infobox caption=
			{{#invoke:WPSHIPS_utilities|ship_name_format|name={{PAGENAME}}}}
Optional arguments to support {{infobox ship begin}}:
	|dab=none – displays ship name without parenthetical disambiguator; use when |infobox caption=nodab
	|sclass=2 – for ship classes only; displays class name without italics (parameter name is loosely similar to {{slcass2}} which does the same thing); use when |infobox caption=class
	|adj=off – for ship classes only; displays class name as a noun (no hyphen, no ship type); use when |infobox caption=class

Arguments are passed in a table.

to call this function locally:
	do_ship_name_format ({['name=name'], ['dab']=dab, ['sclass']=sclass, ['adj']=adj, ['showerrs']=showerrs}) or
	args = {['name=name'], ['dab']=dab, ['sclass']=sclass, ['adj']=adj, ['showerrs']=showerrs};
	do_ship_name_format (args)

The function returns the formatted name or, if unable to format the name, the original name and an unformatted error message.

]]

local function do_ship_name_format (args)
	local name_sans_dab;														-- the ship or class name without a trailing parenthetical dab
	local dab;																	-- the dab stripped from the name
	local fragments = {};														-- a table of words that make up name_sans_dab
	local ship_type;															-- a word or phrase that describes a ship
	local type_len;																-- the number of words that describe a ship
	local nat_len;																-- the number of words used to specify a ship's nationality
	local name = '';															-- the reassembles and formatted ship name
	local error_msg = '';														-- a repository for error messages if any

--	args.name = mw.text.decode (args.name);										-- replace html entities in title with their characters; doesn't work for &amp; and &#38; in prefix
	args.name = args.name:gsub ("&#39;", "\'");									-- replace html appostrophe with the character
--	args.name = args.name:gsub ("&amp;", "&");
--	args.name = args.name:gsub ("&#38;", "&");
--	args.name = args.name:gsub ("&amp;", "&#38;");


	if args.name:match ('.+%-class%s+%a+') then									-- if a ship-class
		fragments = mw.text.split (args.name, '-class' );						-- split at -class
		if '2' == args.sclass then												-- for DISPLAYTITLE and infobox caption when class not named for a member of the class
			if 'off' == args.adj then
				return fragments[1] .. ' class';								-- for infobox caption do noun form <name> class (no hyphen, no ship type)
			end
			return args.name;													-- nothing to do so return original unformatted name
		end
		if 'off' == args.adj then
			return "''" .. fragments[1] .. "'' class";							-- for infobox caption do noun form <name> class (no hyphen, no ship type)
		end
		return "''" .. fragments[1] .. "''-class" .. fragments[2];				-- and return formatted adjectival name
	end
																				-- not a ship class so try to format a ship name
	name_sans_dab, dab = args.name:match('^(.+)%s+(%b())%s*$');					-- split name into name_sans_dab and dab
	if is_set (dab) then
		dab = ' ' .. dab;														-- insert a space for later reassembly
	else
		name_sans_dab = args.name;												-- because without a dab, the string.match returns nil
		dab = '';																-- empty string for concatenation
	end
	
	fragments = mw.text.split (name_sans_dab, '%s' );							-- split into a table of separate words

	nat_len = sizeof_nationality (fragments, #fragments);						-- get the number of words in the ship's nationality
	if 0 < nat_len then															-- if not zero we have a valid nationality
		type_len = sizeof_ship_type (fragments, #fragments, nat_len);			-- get the number of words in the ship type
		if 0 < type_len then													-- if not zero, ship type is valid; nationality and type not italics, the rest is name
			name = "''" .. table.concat (fragments, ' ', nat_len + type_len + 1) .. "''";	-- format name
			if 'none' == args.dab then											-- for |infobox caption=nodab
				return name;													-- return the formatted name without the nationality or ship type or dab
			end
			name = table.concat (fragments, ' ', 1, nat_len + type_len) .. " " .. name;	-- assemble everything but dab
		else
			error_msg = ' unrecognized ship type;';								-- valid nationality, invalid ship type
		end
	elseif data.ship_prefix_t[fragments[1]] then								-- if the first fragment is a ship prefix
		name = table.remove (fragments, 1);										-- fetch it from the table
		name = name .. " ''" .. table.concat (fragments, ' ') .. "''";			-- assemble formatted name
	else
		error_msg = ' no nationality or prefix;';								-- invalid nationality and first word in ship name not a valid prefix
	end

	if is_set (name) then														-- name will be set if we were able to format it
		if 'none' == args.dab then												-- for |infobox caption=nodab
			return name;														-- return the formatted name without the dab
		end
		return name .. dab;														-- return the formatted name with the dab
	end
	
	if is_set (dab) then
		if dab:match ('%(%u+[%- ]?%d+%)') or									-- one or more uppercase letters, optional space or hyphen, one or more digits
			dab:match ('%(%d+[%- ]?%u+%)') or									-- one or more digits, optional space or hyphen, one or more uppercase letters
			dab:match ('%(%u[%u%-]*%-%d+%)') or									-- one or more uppercase letters with hyphens, a hyphen, one or more digits (e.g., T-AO-157)
			dab:match ('%([12]%d%d%d%)') then									-- four digits representing year in the range 1000–2999
				name = "''" .. table.concat (fragments, ' ') .. "''";			-- format the name
				if 'none' == args.dab then										-- for |infobox caption=nodab
					return name;												-- return the formatted name without the dab
				end
			return name .. dab;													-- return the formatted name with the dab
		end
																				-- last chance, is there a ship type in the dab?
		for key, _ in pairs (data.ship_type_t) do								-- spin through the ship type list and see if there is a ship type (key) in the dab
	    	if dab:find ('%f[%a]' .. key .. '%f[^%a]') then						-- avoid matches that are not whole word
	    		name = "''" .. table.concat (fragments, ' ') .. "''";			-- format the name
				if 'none' == args.dab then										-- for |infobox caption=nodab
					return name;												-- return the formatted name without the dab
				end
				return name .. dab;												-- return the formatted name with the dab
	    	end
		end
		error_msg = error_msg .. ' no ship type in dab;';
		
		if 'none' == args.dab then												-- for |infobox caption=nodab
			return table.concat (fragments, ' '), error_msg;					-- return the unformatted name without the dab, and an error message
		end
	end

	return args.name, error_msg;												-- return original un-formatted name with unformatted error message if any
end


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

This function is the external interface to do_ship_name_format().

The function requires one parameter:
	|name= (required): a name is required; if missing or empty, this function returns an error message (may or may not be visible depending on where it is used)
		used in {{infobox ship begin}} to provide a value for {{DISPLAYTITLE:}} and to provide a value for |infobox caption=
			{{#invoke:WPSHIPS_utilities|ship_name_format|name={{PAGENAME}}}}
Optional parameters to support {{infobox ship begin}}:
	|dab=none – displays ship name without parenthetical disambiguator; use when |infobox caption=nodab
	|sclass=2 – for ship classes only; displays class name without italics (parameter name is loosely similar to {{slcass2}} which does the same thing); use when |infobox caption=class
	|adj=off – for ship classes only; displays class name as a noun (no hyphen, no ship type); use when |infobox caption=class
Other optional parameters:
	|showerrs=yes – marginally useful; can display error messages if the module invocation is not buried in a template
	
Values from the above parameters are placed in a table and that table passed as an argument in the call to do_ship_name_format().

do_ship_name_format() returns two strings: a name and an error message.  If do_ship_name_format() could format the name, it returns the formatted name and 
an empty string for the error message.  If it could not format the name, do_ship_name_format() returns the original name and an error message.

Formatting of the error message, in response to |showerrs=yes is the responsibility of the calling function.

]]

local function ship_name_format(frame)
	local name = '';															-- destination of the formatted ship name
	local error_msg = '';														-- destination of any error message

	if not is_set (frame.args.name) then										-- if a ship name not provided
		if 'yes' == frame.args.showerrs then									-- and we're supposed to show errors
			error_msg = '<span style="font-size:100%; font-weight:normal" class="error">Empty name</span>';	-- return an empty string error message if there is no name
		end
	else
		name, error_msg = do_ship_name_format (frame.args);						-- get formatted name and error message
		if is_set (error_msg) and 'yes' == frame.args.showerrs then				-- if appropriate, show error message
			error_msg = '<span style="font-size:100%; font-weight:normal" class="error">' .. error_msg .. '</span>';
		else
			error_msg = '';														-- for concatenation
		end
	end

	return name .. error_msg;													-- return name and error message
end


--[[--------------------------< H N S A >----------------------------------------------------------------------

Similar to {{navsource}}, this code supports {{hnsa}} by attempting to construct a link to a ship article at the
the Historic Nava Ships Association website.

The template has the form:
	{{hnsa|<page>|<name>}}
where:
	<page> is the name of the page at http://hnsa.org/hnsa-ships/<page>
	<name> (optional) is the name of the ship; if left blank, the template uses the current page title; if a ship name, it is formatted
from which this code produces:
	[http://hnsa.org/hnsa-ships/<page> <name>] at Historic Naval Ships Association

]]

local function hnsa (frame)
	local pframe = frame:getParent()											-- get arguments from calling template frame
	local ship_name = '';
	local error_msg = '';
	local article_title = mw.title.getCurrentTitle().text;						-- fetch the article title
	
	if not is_set (pframe.args[1]) then
		return '<span style="font-size:100%; font-weight:normal" class="error">missing hsna page</span>';
	end
	
	local fmt_params = {['name']='', ['showerrs']=nil};

	if is_set (pframe.args.showerrs) then										-- if showerrs set in template, override showerrs in #invoke:
		fmt_params.showerrs = pframe.args.showerrs;								-- template value
	else
		fmt_params.showerrs = frame.args.showerrs;								-- invoke value
	end

	if is_set (pframe.args[2]) then
		fmt_params.name = pframe.args[2];
	else
		fmt_params.name = article_title;										-- use article title
	end

	ship_name, error_msg = do_ship_name_format (fmt_params);
	
	if is_set (error_msg) and is_set (pframe.args[2]) then						-- if unable to format the name
		local escaped_name = pframe.args[2]:gsub("([%(%)%.%-])", "%%%1");		-- escape some of the Lua magic characters
		if pframe.args[2] == article_title or									-- is name same as article title?
			nil ~= article_title:find ('%f[%a]' .. escaped_name .. '%f[%s]') or	-- is name a word or words substring of article title?
			nil ~= article_title:find ('%f[%a]' .. escaped_name .. '$') then	-- is name a word or words substring that ends article title?
				ship_name = "''" .. pframe.args[2] .. "''";						-- non-standard 'name'; perhaps just the name without prefix and dab;
				error_msg = '';													-- unset because we think we have a name
		end
	end
	if is_set (error_msg) and 'yes' == fmt_params.showerrs then
		error_msg = '<span style="font-size:100%; font-weight:normal" class="error">' .. error_msg .. '</span>';
	else
		error_msg = '';															-- unset so it doesn't diplay
	end
	
	local output = {
		'[http://www.hnsa.org/hnsa-ships/',
		pframe.args[1],
		'/ ',
		ship_name,
		'] at Historic Naval Ships Association',
		error_msg,
		}

	return table.concat (output);
end


--[[--------------------------< N A V S O U R C E >------------------------------------------------------------

This version of the template {{navsource}} was added as a test vehicle for do_ship_name_format().

]]

local function navsource (frame)
	local pframe = frame:getParent()											-- get arguments from calling template frame
	local ship_name = '';
	local error_msg = '';
	local article_title = mw.title.getCurrentTitle().text;						-- fetch the article title
	
	if not is_set (pframe.args[1]) then
		return '<span style="font-size:100%; font-weight:normal" class="error">missing navsource URLcode</span>';
	end
	
	local fmt_params = {['name']='', ['showerrs']=nil};

	if is_set (pframe.args.showerrs) then										-- if showerrs set in template, override showerrs in #invoke:
		fmt_params.showerrs = pframe.args.showerrs;								-- template value
	else
		fmt_params.showerrs = frame.args.showerrs;								-- invoke value
	end

	if is_set (pframe.args[2]) then
		fmt_params.name = pframe.args[2];
	else
		fmt_params.name = article_title;										-- use article title
	end

	ship_name, error_msg = do_ship_name_format (fmt_params);
	
	if is_set (error_msg) and is_set (pframe.args[2]) then						-- if unable to format the name
		local escaped_name = pframe.args[2]:gsub("([%(%)%.%-])", "%%%1");		-- escape some of the Lua magic characters
		if pframe.args[2] == article_title or									-- is name same as article title?
			nil ~= article_title:find ('%f[%a]' .. escaped_name .. '%f[%s]') or	-- is name a word or words substring of article title?
			nil ~= article_title:find ('%f[%a]' .. escaped_name .. '$') then	-- is name a word or words substring that ends article title?
				ship_name = "''" .. pframe.args[2] .. "''";						-- non-standard 'name'; perhaps just the name without prefix and dab;
				error_msg = '';													-- unset because we think we have a name
		end
	end
	if is_set (error_msg) and 'yes' == fmt_params.showerrs then
		error_msg = '<span style="font-size:100%; font-weight:normal" class="error">' .. error_msg .. '</span>';
	else
		error_msg = '';															-- unset so it doesn't diplay
	end
	
	local output = {
		'[http://www.navsource.org/archives/',
		pframe.args[1],
		'.htm Photo gallery] of ',
		ship_name,
		' at NavSource Naval History',
		error_msg,
		}

	return table.concat (output);
end


--[[--------------------------< _ S H I P >--------------------------------------------------------------------

This is a possible replacement for the template {{ship}}.  It has better error detection and handling.

]]

local function _ship (prefix, name, dab, control, unlinked_prefix, unlinked_whole, template, no_cat)
	local error_msg = '';
	local category = '';
	
	if not is_set (control) then
		control = '';															-- if not provided, ensure that control is empty string for comparisons
	elseif control:find ('%-') then												-- shortcut for |link=no when using a format control parameter ...|SSBN-659|-6}} same as ...|SSBN-659|6|link=no}}
		unlinked_whole = true;													-- set the unlinked flag
		control = control:match ('%d');											-- strip out the hyphen
	end

																				-- dispose of error conditions straight away
	if not is_set (name) then													-- this is the only required parameter
		error_msg = error_msg_make ('missing_name', template, '', no_cat, true);
	elseif not is_set (dab) and ('1' == control or '3' == control or '5' == control) then	-- dab required when control value set to expect it
		error_msg = error_msg_make ('missing_dab', template, '', no_cat, true);
	elseif not is_set (prefix) and ('5' == control or '6' == control) then		-- prefix required when control value set to expect it
		error_msg = error_msg_make ('missing_prefix', template, '', no_cat, true);
	elseif '4' == control then													-- displaying only the prefix
		error_msg = error_msg_make ('invalid_control', template, control, no_cat, true);
	elseif is_set (control) then
		if ('number' ~= type (tonumber (control))) or (1 ~= control:len()) or (1 > tonumber (control) or 6 < tonumber (control)) then	-- control must be a single-digit number 1 through 6
			error_msg = error_msg_make ('invalid_control', template, control, no_cat, true);
		end
	elseif not is_set (prefix) and unlinked_prefix then							-- prefix required when |up=yes
		error_msg = error_msg_make ('missing_prefix', template, '', no_cat, true);
	end

	if is_set (error_msg) then
		return error_msg;
	end

	local link_name;
	local link = '';

	if is_set (prefix) then
		link = prefix .. ' ' .. name;											-- begin assembling the article name (link) portion of the wikilink
	else
		link = name;
	end

	if is_set (dab) then
		link = link .. ' (' .. dab .. ')';										-- wrap dab in parentheses
	end

	local target_object = mw.title.new (link).redirectTarget;					-- if <link> points to a redirect
	if target_object then
		link = target_object.fullText;											-- get the target title to avoid linking through the redirect
	end

	name = "''" .. name .. "''";												-- name is always italicized so do it now

	if '1' == control then
		link_name = dab;														-- special case when displaying only the dab, don't wrap in parentheses
	end
	
	if is_set (dab) then														-- for all other cases that display dab
		if '5' == control then
			dab = "&nbsp;\'\'" .. dab .. "\'\'";								-- for prefix with dab display HMS A1. italicize the dab
		else
			dab = '&nbsp;(' .. dab .. ')';										-- except for dab-only, all others display with parentheses 
		end
	end
		
	if not is_set (control) then												-- when control not set: prefix, name, and dab
		if is_set (prefix) then
			link_name = prefix .. '&nbsp;' .. name .. dab;
		else
			link_name = name .. dab;
		end
	else																		-- when control is not 1 or none
		if '2' == control then													-- name only
			link_name = name;
		elseif '3' == control then												-- name and dab
			link_name = name .. dab;
		elseif '5' == control then												-- prefix and dab
				link_name = prefix .. dab;
		elseif '6' == control then												-- prefix and name
				link_name = prefix .. '&nbsp;' .. name;
		end
	end

	if '5' ~= control and'6' ~= control and is_set (control) then
		unlinked_prefix = false;												-- no prefix so don't try to unlink it
	end

	if unlinked_whole then
		return link_name;														-- no linking desired so done
	elseif unlinked_prefix and is_set (prefix) then								-- when there is a prefix to unlink
		link_name = link_name:gsub ('^.-&nbsp;', '', 1);						-- remove the prefix and nbsp
		return prefix ..  '&nbsp;[[' .. link .. '|' .. link_name .. ']]';		-- add prefix and nbsp to front and done
	else
		return '[[' .. link .. '|' .. link_name .. ']]';						-- construct the wikilink and done
	end
end


--[[--------------------------< S H I P >----------------------------------------------------------------------

This is a possible replacement for the template {{ship}}.  It has better error detection and handling.

This function is the externally accessible entry point for template {{ship}}, {{HMS}}, {{USS}}, etc

{{#invoke:WPSHIPS_utilities|ship|_template=<template name>}}

{{#invoke:WPSHIPS_utilities|ship_pre|prefix=<prefix>|_template=<template name>}}

Parameters in the module frame are:
	there are no module frame parameters
	
Parameters in the template frame are:
	{{{1|}}} – prefix (HMS, USS, Japanese submarine, etc)
	{{{2|}}} – ship's name (required)
	{{{3|}}} – disambiguator (year, hull or pennant number, etc)
	{{{4|}}} – format control (1, 2, 3, 5, 6; 4 not allowed)
	|wl= – when set to 'no', rendering is not wikilinked
	|up= – when set to 'yes' prefix (if rendered) is not linked

]]

local function ship (frame)														-- this version not supported from the template yet
	local args_t = get_args (frame);

	local prefix = args_t[1] or '';												-- fetch positional parameters into named variables for readability
	local name = args_t[2] or '';												-- stripped of leading and trailing whitespace 
	local dab = args_t[3] or '';												-- empty positional parameters are nil so convert nil to empty string
	local control = args_t[4];
	local unlinked_prefix = 'yes' == args_t.up;									-- make boolean: true when |up=yes
	local unlinked_whole = 'no' == args_t.wl;									-- make boolean: true when |wl=no
	local no_cat = 'yes' == args_t['no-tracking'];								-- make boolean: true when |no-tracking=yes

	return _ship (prefix, name, dab, control, unlinked_prefix, unlinked_whole, 'Ship', no_cat);
end


--[[--------------------------< S H I P _ P R E F I X _ T E M P L A T E S >------------------------------------

This is a possible replacement for the template prefix templates {{USS}}, {{HMS}}, etc.  It has better error
detection and handling.

This function is the externally accessible entry point for those templates

{{#invoke:WPSHIPS_utilities|ship_prefix_templates|prefix=<prefix>|template=<template name>}}

Parameters in the module frame are:
	|_prefix= – (required) _prefix (HMS, USS, Japanese submarine, etc)
	|_template= template name for error messages;  optional when |prefix= same as template name
	
Parameters in the template frame are:
	{{{1|}}} – ship's name (required)
	{{{2|}}} – disambiguator (year, hull or pennant number, etc)
	{{{3|}}} – format control (1, 2, 3, 5, 6; 4 not allowed)
	|wl= – when set to 'no', rendering is not wikilinked
	|up= – when set to 'yes' prefix (if rendered) is not linked

]]

local function ship_prefix_templates (frame)									-- this version not supported from the templates yet
	local args_t = get_args (frame);

	local prefix = args_t.prefix or '';										-- fetch positional parameters into named variables for readability
	local name = args_t[1] or '';												-- stripped of leading and trailing whitespace 
	local dab = args_t[2] or '';												-- empty positional parameters are nil so convert nil to empty string
	local control = args_t[3];
	local unlinked_prefix = 'yes' == args_t.up;									-- make boolean: true when |up=yes
	local unlinked_whole = 'no' == args_t.wl;									-- make boolean: true when |wl=no
	local no_cat = 'yes' == args_t['no-tracking'];								-- make boolean: true when |no-tracking=yes

	return _ship (prefix, name, dab, control, unlinked_prefix, unlinked_whole, args_t.template_name or prefix, no_cat);
end


--[[--------------------------< L I S T _ E R R O R >----------------------------------------------------------

Assembles an error message, the original parameter value and, if appropriate a category.  The error message precedes
the existing value of the parameter.  If the first non-whitespace character in the parameter is a '*', set prefix to
a '*' and sep to '\n'.  For line-break lists, set prefix to empty string and sep to '<br />'.

Category is appended to the end of the returned value only for pages in article space.

Inputs:
	prefix – a string of characters that precede the error message span; typically '' and '*'
	message – the error message to be displayed; goes inside the span
	sep – a string of characters that separates the span from the parameter value; typically '\n' and '<br />'
	param_val – the unmodified parameter value
	showerrs – a boolean, true to display the error message text

]]

local function list_error (prefix, message, sep, param_val, showerrs)
	local err_msg = '%s<span style="font-size:100%%" class="error">list error: %s ([[:Category:WPSHIPS:Infobox list errors|help]])</span>%s%s%s';
	local category = '';

	if 0 == mw.title.getCurrentTitle().namespace then							-- only categorize pages in article space
		category = '[[Category:WPSHIPS:Infobox list errors]]';
	end
	if true == showerrs then
		return string.format (err_msg, prefix, message, sep, param_val, category);			-- put it all together
	else
		return param_val .. category;
	end
end


--[[--------------------------< U N B U L L E T E D _ L I S T >------------------------------------------------

Mediawiki:Common.css imposes limitations on plain, unbulleted lists.  The template {{plainlist}} does not render this correctly:
{{plainlist|
*Item 1
*Item 2
**Item 2a
***Item 2a1
**Item 2b
*Item 3}}
The above renders without proper indents for items marked ** and ***.

If the list is not wrapped in {{plainlist}} then the above list is rendered with bullets which is contrary to the Infobox ship usage guide.

This code translates a bulleted list into an html unordered list:

<ul style="list-style:none; margin:0;"> 
 <li>Name 1</li>
 <li>Name 2</li>
 <ul style="list-style:none">
  <li>Subname 2a</li>
  <ul style="list-style:none">
   <li>Subname 2a1</li>
  </ul>
  <li>Subname 2b</li>
 </ul>
 <li>Name 3</li>
</ul>

There are rules:
	1. The parameter value must begin with a splat but may have leading and trailing whitespace.
	2. Each list item after the first must begin on a new line just as is required by normal bulleted lists.
	3. When adding a sublevel, the number of splats may increase by one and never more. This is illegal:
		*item
		***item
When any of these rules are violated, unbulleted_list() returns the original text and adds the article
to Category:WPSHIPS:Infobox list errors.  Error messaging in this function is somewhat sketchy so they are
disabled.  After initial adoption, better error messaging could/should be implemented.

This function receives the content of one parameter:
	{{#invoke:WPSHIPS utilities|unbulleted_list|{{{param|}}}}}

]]

local function _unbulleted_list (param)
	local showerrs = true;														-- set to false to hide error messages
	local List_item_otag = '<li style="padding-left: .4em; text-indent: -.4em;">';	-- hanging indent markup; everything moves right with padding-left; first line moved left by neg indent
	
	if nil == param:match ('^%s*%*') then										-- parameter value must begin with a splat (ignoring leading white space)
		if param:match ('<[%s/]*[Bb][Rr][%s/]*>') then							-- if the parameter value has a list using variants of <br /> tag
			return list_error ('', '&lt;br /> list', '<br />', param, showerrs);	-- return an error message with maintenance category
		elseif param:match ('<div style="clear:') then
			return list_error ('', '{{clear}} list', '<br />', param, showerrs);	-- return an error message with maintenance category
		elseif param:match ('.+\n%*') then										-- if the parameter value has text followed by an unordered list
			return list_error ('', 'mixed text and list', '<br />', param, showerrs);	-- return an error message with maintenance category
		end
		return param;															-- return the parameter as is
	end
	
	local item_table = mw.text.split (mw.text.trim (param), '\n');				-- trim white space from end then make a table of bulleted items by splitting on newlines
	if 1 == #item_table then													-- if only one bulleted item, no need for a list
		return (item_table[1]:gsub ('^%*%s*', ''));								-- trim off the splat and any following white space and done
	end
	
	if item_table[1]:match ('^%*%*+') then										-- if first list item uses more than one splat, that's an error
		return list_error ('*', 'too many * at start of list', '\n', param, showerrs);	-- return an error message with maintenance category
	end
	
	local html_table = {};														-- table to hold the html output
	local level = 1;															-- used to indicate when a new <ul> is required
	local splats = 0;															-- number of splats that start each item in the list
	local item = '';															-- the item text
	
	table.insert (html_table, '<ul style="list-style:none; margin:0;">')		-- this for first <ul> tag; sets no bullets and no indent
	
	for _,v in ipairs (item_table) do
		splats, item = v:match ('(%*+)%s*(.*)');								-- split the item into splats and item text
		if nil == splats then													-- nil if there is an extra line between items
			return list_error ('*', 'list item missing markup', '\n', param, showerrs);	-- return an error message with maintenance category
		elseif '' == item then
			return list_error ('*', 'empty list item', '\n', param, showerrs);	-- return an error message with maintenance category
		elseif item:match ('^[;:]') then										-- if the list item is mixed unordered list / description list markup (*:)
			return list_error ('*', 'mixed list type', '\n', param, showerrs);	-- return an error message with maintenance category
		end

		splats = splats:len();													-- change string of splats into a number indicating how many splats there are
		
		if splats == level then													-- if at the same level as previous item
			table.insert (html_table, List_item_otag .. item .. '</li>');
		elseif splats == level + 1 then											-- number of splats can only increase by one
			level = splats;														-- record the new level
			table.insert (html_table, '<ul style="list-style: none">');			-- add a new sublist
			table.insert (html_table, List_item_otag .. item .. '</li>');		-- and the item
		elseif splats < level then												-- from three splats to one splat for example
			while splats < level do
				table.insert (html_table, '</ul>');								-- close each sub <ul> until level and splats match
				level = level - 1;
			end
			table.insert (html_table, List_item_otag .. item .. '</li>');		-- add the item
		else																	-- jumping more than one level up – one splat to three splats for example – is an error
			return list_error ('*', 'too many asterisks', '\n', param, showerrs);	-- return an error message with maintenance category
		end
	end

	while 0 < level do
		table.insert (html_table, '</ul>');										-- close each <ul> until level counted down to zero
		level = level - 1;
	end

	return table.concat (html_table, '\n');										-- return the list as a string
end


--[[--------------------------< U N B U L L E T E D _ L I S T >------------------------------------------------

external entry point

]]

local function unbulleted_list (frame)
	return _unbulleted_list (frame.args[1])
end


--[=[-------------------------< _I N F O B O X _ S H I P _ F L A G >--------------------------------------------

Output of {{shipboxflag|USA}}:
	[[File:Flag of the United States.svg|100x35px|alt=|link=]]
	
Image syntax:
	[[File:Name|Type|Border|Location|Alignment|Size|link=Link|alt=Alt|Caption]]

This function standardizes the size of flag images in the infobox ship career header by simply overwriting the Size
parameter value in the Image wikilink with |100x28px.  This size leave a 1px gap between the top and bottom of the flag image and
the header edge.  A similar left-side gap of 2px is supplied by {{infobox ship career}}.

]=]

local function _infobox_ship_flag (image)
	if image:match ('|[%s%dx]+px%s*') then										-- is there a size positional parameter?
		image = image:gsub('|[%s%dx]+px%s*', '%|100x28px');						-- overwrite it with |100x28px
	else
		return '<span style="font-size:100%" class="error">malformed flag image</span>'
	end
	return image;																-- return the modified image
end


--[=[-------------------------< I N F O B O X _ S H I P _ F L A G >--------------------------------------------

external entry point

]=]

local function infobox_ship_flag (frame)
	if not is_set (frame.args[1]) then											-- if |Ship flag= not set
		return '';																-- return empty string
	end
	
	return _infobox_ship_flag (frame.args[1]);									-- return the modified image
end


--[=[-------------------------< C I T E _ D A N F S _ T I T L E >----------------------------------------------

This function attempts to render a DANFS article title in more or less proper (per Wikipedia) format for the
template {{cite danfs}}.  DANFS titles typically take one of four forms:
	<ship name> <disambiguator> <hull number>
	<ship name> <hull number>
	<ship name> <disambiguator>
	<ship name>

Here, we extract the various parts, italicize the ship name and reassemble for use by the cite danfs |title= parameter.
To call this function:
	|title={{#invoke:WPSHIPS utilities|cite_danfs_title|{{{title}}}}}

]=]

local function cite_danfs_title (frame)
	local name;
	local disambiguator;
	local hullnum;
	
	if not is_set (frame.args[1]) then											-- if |title= not set
		return '';																-- return empty string
	end

	name, disambiguator, hullnum = frame.args[1]:match ('(.-)( [XVI]+)( %([^%)]+%))$');
	if not (name and disambiguator and hullnum) then
		disambiguator = '';														-- empty string for concatenation
		name, hullnum = frame.args[1]:match ('(.-)( %([^%)]+%))$');
		if not (name and hullnum) then
			hullnum = '';														-- empty string for concatenation
			name, disambiguator = frame.args[1]:match ('(.-)( [XVI]+)$');
			if not (name and disambiguator) then
				disambiguator = '';
				name = frame.args[1];											-- just a name or something we don't recognize
			end
		end
	end

	return table.concat ({"''", name, "''", disambiguator, hullnum});			-- reassemble and done
end


--[[--------------------------< S Y N O N Y M _ C H E C K >----------------------------------------------------

support function for infoboxen functions

there are a handful of infoboxen parameters that are synonymous pairs.  This function is called to see if both
of the parameters in a synonymous pair have been assigned a value.  When both have assigned values, each gets an
error message appended to it.  Most of the synonymous pairs are UK Emglish v US English so the variable names

<args_t> table of template parameters and values
<uk_param> UK English parameter name
<us_param> US English parameter name
<error_flag> boolean that this function sets true when both of a pair are set; controls addition of maint category

]]

local function synonym_check (args_t, uk_param, us_param, error_flag)
	if args_t[uk_param] and args_t[us_param] then

		args_t[uk_param] = args_t[uk_param] .. error_msg_make ('synonymous');		-- both are set so append error message with category
		args_t[us_param] = args_t[us_param] .. error_msg_make ('synonymous', nil, nil, true);	-- but append error message without category
		return true;															-- inform the calling function that it needs to emit maint category
	end
	return error_flag;															-- no match so return unmodified <error_flag>
end

--[[--------------------------< L I N E _ I T E M S >----------------------------------------------------------

support function for infoboxen functions

This function handles all infobox ship parameters that are 'line items' (label followed by value) because all
of these sorts of parameters are rendered with exacty the same formatting.

params_t{} is a table of tables where the params_t{} keys are the template's parameter names.  The params_t{}
values are sequences where [1] is an index number that defines where in the rendering the label/value pair is
positioned and [2] is the label that will be rendered when the parameter has a value.

This indexing is used because params_t{} is not a sequence and because pairs() does not necessarily return the
'next' k/v pair.

This function spins through params_t{} and writes html for parameters that have assigned values into temp_t{}
according to the 'index' value in the associated sequance table.  When parameters are missing or empty, this
function writes an empty string into the associated location in lines_t{} so that lines_t{} can be concatenated
into a string value that is returned to the calling function.

args_t is the arguments table from the template frame.

]]

local function line_items (args_t, params_t)
	local lines_t = {};															-- a sequence table of rendered label/value html lines; one for each key in params_t{}

	for k, v in pairs (params_t) do												-- k is templat e parameter name; v is a sequence table with index and associated label
		local temp_t = {}														-- initialize/reinitialize for next line item
		if not args_t[k] then													-- if no assigned value then
			lines_t[v[1]] = '';													-- set to empty string for concatenation
		else
			table.insert (temp_t, '<tr style="vertical-align:top;"><td style="font-weight: bold">');	-- open the line item row and cell
			table.insert (temp_t, v[2]);										-- add parameter's label text
			table.insert (temp_t, '</td><td>');									-- close that cell and open the parameter value cell
			table.insert (temp_t, _unbulleted_list (args_t[k]));				-- add the parameter's value; formatted as unordered list if appropriate
			table.insert (temp_t, '</td></tr>\n');								-- close that cell and this row
		end
		lines_t[v[1]] = table.concat (temp_t);									-- concatenate and put the line item in the lines sequence table at the index position
	end

	return table.concat (lines_t);												-- make a big string of line items and done

end


--[[--------------------------< I N F O B O X _ S H I P _ C A R E E R >----------------------------------------

implements {{Infobox ship career}}

{{#invoke:WPSHIPS utilities|infobox_ship_career}}

]]

local function infobox_ship_career (frame)
	local args_t = get_args (frame);											-- get a table of all parameters in the template call
	local html_out_t = {};														-- html table text goes here
	local error_flag = false;													-- controls emission of maint category when synonymous parameters are both set
	
	args_t['Hide header'] = args_t['Hide header'] and args_t['Hide header']:lower();	-- set to lowercase if set
	
	error_flag = synonym_check (args_t, 'Ship stricken', 'Ship struck', error_flag);	-- error if both synonymous parameters set
	error_flag = synonym_check (args_t, 'Ship honours', 'Ship honors', error_flag);
	
	if 'yes' ~= args_t['Hide header'] then										-- |Hide header=yes then no header
		if not ('title' == args_t['Hide header']) then							-- |Hide header=title then no title bar
			table.insert (html_out_t, '<tr><th colspan="2" ');
			table.insert (html_out_t, styles.header_bar);						-- style from WPMILHIST
			table.insert (html_out_t, '>History</th></tr>\n');
		end

		if args_t['Ship country'] and args_t['Ship flag'] then
			table.insert (html_out_t, '<tr><th height="30" colspan="2" style="background-color:#B0C4DE;text-align:left;padding-left:2px;vertical-align:middle;font-size:110%;">');
			table.insert (html_out_t, _infobox_ship_flag (args_t['Ship flag']));
			table.insert (html_out_t, '<span style="padding-left:1em">');
			table.insert (html_out_t, args_t['Ship country']);
			table.insert (html_out_t, '</span>');
			table.insert (html_out_t, '</th></tr>\n');
		elseif args_t['Ship country'] then
			table.insert (html_out_t, '<tr><th height="30" colspan="2" style="background-color:#B0C4DE;text-align:center;vertical-align:middle;font-size:110%;">');
			table.insert (html_out_t, args_t['Ship country']);
			table.insert (html_out_t, '</th></tr>\n');
		elseif args_t['Ship flag'] then
			table.insert (html_out_t, '<tr><th height="30" colspan="2" style="background-color:#B0C4DE;padding-left:2px;">');
			table.insert (html_out_t, _infobox_ship_flag (args_t['Ship flag']));
			table.insert (html_out_t, '</th></tr>\n');
		end
	end

	table.insert (html_out_t, line_items (args_t, data.infobox_career_params_t));	-- add all of the rest of the template's html

--mw.logObject (table.concat (html_out_t));
	return table.concat (html_out_t);											-- make a big string and done
end


--[[--------------------------< I N F O B O X _ S H I P _ C H A R A C T E R I S T I C S >----------------------

implements {{Infobox ship characteristics}}

{{#invoke:WPSHIPS utilities|infobox_ship_characteristics}}

]]

local function infobox_ship_characteristics (frame)
	local args_t = get_args (frame);											-- get a table of all parameters in the template call
	local html_out_t = {};														-- html table text goes here
	local error_flag = false;													-- controls emission of maint category when synonymous parameters are both set
	
	args_t['Hide header'] = args_t['Hide header'] and args_t['Hide header']:lower();	-- set to lowercase if set
	
	error_flag = synonym_check (args_t, 'Ship armour', 'Ship armor', error_flag);	-- error if both synonymous parameters set
	error_flag = synonym_check (args_t, 'Ship draught', 'Ship draft', error_flag);

	if 'yes' ~= args_t['Hide header'] then										-- |Hide header=yes then no header
		table.insert (html_out_t, '<tr><th colspan="2" ');
		table.insert (html_out_t, styles.header_bar);							-- style from WPMILHIST
		table.insert (html_out_t, '>General characteristics');
		if args_t['Header caption'] then
			table.insert (html_out_t, ' ');
			table.insert (html_out_t, args_t['Header caption']);
		end
		table.insert (html_out_t, '</th></tr>\n');
	end

	table.insert (html_out_t, line_items (args_t, data.infobox_characteristics_params_t));	-- add all of the rest of the template's html

--mw.logObject (table.concat (html_out_t));
	return table.concat (html_out_t);											-- make a big string and done
end


--[[--------------------------< I N F O B O X _ S H I P _ C L A S S _ O V E R V I E W >------------------------

implements {{Infobox ship class overview}}

{{#invoke:WPSHIPS utilities|infobox_ship_class_overview}}

]]

local function infobox_ship_class_overview (frame)
	local args_t = get_args (frame);											-- get a table of all parameters in the template call
	local html_out_t = {};														-- html table text goes here
	
	args_t['Hide header'] = args_t['Hide header'] and args_t['Hide header']:lower();
	
	if 'yes' ~= args_t['Hide header'] then										-- |Hide header=yes then no header
		table.insert (html_out_t, '<tr><th colspan="2" ');
		table.insert (html_out_t, styles.header_bar);							-- style from WPMILHIST
		table.insert (html_out_t, '>Class overview</th></tr>\n');
	end

	table.insert (html_out_t, line_items (args_t, data.infobox_class_overview_params_t));	-- add all of the rest of the template's html

--mw.logObject (table.concat (html_out_t));
	return table.concat (html_out_t);											-- make a big string and done
end


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

validate cite plimsoll |filename=<filename>

<filename> format is: YYvssss.pdf where
	YY - least significant two digits of four-digit first year in a two-year range
		30 -> 1930–1931
		allowed values are all integers between and including 30–45
	v - a single lowercase letter 'a' or 'b'
		'a' -> volume I
		'b' -> volume II
	ssss - scan number begins with 0001
		odd numbered scans have English headings
		even numbered scans have French headings

	{{#invoke:WPSHIPS utilities|is_plimsoll_filename|{{{filename}}}}}

]]

local function is_plimsoll_filename (frame)
	local args_t = get_args (frame);											-- get a table of all parameters in the invoke

	local year, volume, scan;
	if args_t[1] then															-- this to avoid script errors when args_t[1] missing
		year, volume, scan = args_t[1]:match ('(%d%d)(%l)(%d%d%d%d)%.[Pp][Dd][Ff]');	-- get the various parts
	end
	if not year then return nil end												-- nil when no match so we're done
	year = tonumber (year);
	scan = tonumber (scan);
	if (30 > year) or (45 < year) then return nil end
	if not (('a' == volume) or ('b' == volume)) then return nil end
	if (1 > scan) then return nil end

	return true;
end


--[[--------------------------< S E T _ P L I M S O L L _ D A T E >--------------------------------------------

create two-year range from first two digits in |filename=<filename>
	30 -> 1930–1931

	{{#invoke:WPSHIPS utilities|set_plimsoll_date|{{{filename}}}}}

]]

local function set_plimsoll_date (frame)
	local args_t = get_args (frame);											-- get a table of all parameters in the invoke

	if not args_t[1] then
		return nil;
	end

	local year = args_t[1]:match ('(%d%d)%l%d%d%d%d');							-- get the intial year
	
	year = 1900 + tonumber (year);												-- make it a four-digit year
	return string.format ('%d–%d', year, year + 1);								-- and then add one for the second year in the range
end


--[[--------------------------< S E T _ P L I M S O L L _ S U B T I T L E >-----------------------------------1

used in {{cite plimsoll}}

return appropriate subtitle string given |subtitle=<keyword>
		
	{{#invoke:WPSHIPS utilities|set_plimsoll_subtitle|{{{subtitle}}}}}

]]

local function set_plimsoll_subtitle (frame)
	local subtitle = get_args (frame)[1];										-- get the subtitle parameter
	
	if not subtitle then
		return nil;
	end
	
	if not data.subtitles_t[subtitle] then
		return '&#58; ' .. subtitle;											-- not predefined so return whatever |subtitle= holds with leading ': '
	end
	
	return '&#58; ' .. data.subtitles_t[subtitle];								-- return predefined subtitle with leading ': '
end


--[[--------------------------< S E T _ P L I M S O L L _ U R L >----------------------------------------------

create plimsoll url from |filename=<filename>

	{{#invoke:WPSHIPS utilities|set_plimsoll_url|{{{filename}}}}}

]]

local function set_plimsoll_url (frame)
	local args_t = get_args (frame);											-- get a table of all parameters in the invoke

	if args_t[1] then
		return string.format ('https://plimsoll.southampton.gov.uk/shipdata/pdfs/%s/%s',
			args_t[1]:match ('(%d%d)%l%d%d%d%d'),								-- get the year path portion from <filename>
			args_t[1]);															-- append <filename> onto the end, and done
	end
end


--[[--------------------------< S C L A S S >------------------------------------------------------------------

implements {{sclass}} and {{sclass2}}

{{#invoke:WPSHIPS utilities|sclass}}

]]

local function sclass (frame)
	local args_t = get_args (frame);
	local parent = frame:getParent();
	local template = parent:getTitle():gsub ('^Template:', ''):lower();			-- get the name of the template that called this module (includes namespace so strip that)
	
	local class_name = args_t[1];												-- names to make it easier to understand
	local ship_type = args_t[2];
	local format = args_t[3];
	local ship_type_dab = args_t[4];
	local class_name_dab = args_t[5];
	local no_cat = 'yes' == args_t['no-cat'];									-- make a boolean

	if not class_name then														-- when omitted, abandon with error message
		return error_msg_make ('missing', template, 'class name', no_cat);
	end

	if not ship_type then														-- when omitted, abandon with error message
		return error_msg_make ('missing', template, 'ship type', no_cat);
	end

	if format then
		if tonumber (format) then												-- if <format> has a value that is a number
			format = tonumber (format);											-- make it a number for comparisons
			if 5 < format then													-- is <format> outside of allowed range
				return error_msg_make ('format', template, format, no_cat);
			end
		else																	-- <format> could not be converted to a number
			return error_msg_make ('format', template, format, no_cat);
		end
	end
			
	local out_t = {};															-- output goes here
	table.insert (out_t, '[[');													-- open the wikilink
	table.insert (out_t, class_name);											-- build the wikilink to the class article
	table.insert (out_t, '-class ');
	table.insert (out_t, ship_type);											-- add ship type
	if class_name_dab then														-- when class article is disambiguated
		table.insert (out_t, ' (');												-- add the disambiguator
		table.insert (out_t, class_name_dab);
		table.insert (out_t, ')');
	end
	table.insert (out_t, '|');
	if 'sclass' == template:gsub ('/sandbox', '') then							-- strip '/sandbox' if present; class named for a member of the class
		table.insert (out_t, '\'\'');											-- class name is italicized
		table.insert (out_t, class_name);
		table.insert (out_t, '\'\'');
	else
		table.insert (out_t, class_name);										-- class name is a common attribute; plain text
	end

	if not format or (3 == format) then											-- when format is omitted, same as format #3
		table.insert (out_t, '-class]] [[');									-- open ship-type wikilink
		if ship_type_dab then													-- when ship-type article is disambiguated
			table.insert (out_t, ship_type);									-- add ship type
			table.insert (out_t, ' (');											-- and the disambiguator
			table.insert (out_t, ship_type_dab);
			table.insert (out_t, ')|');											-- dab is not displayed so insert a pipe and
		end
		table.insert (out_t, ship_type);										-- add ship type
		table.insert (out_t, ']]');												-- close ship-type wikilink
	end

	if 0 == format then															-- no separate ship-type wikilink
		table.insert (out_t, '-class]]');
	end
	
	if 1 == format then															-- no separate ship-type wikilink
		table.insert (out_t, '-class ');
		table.insert (out_t, ship_type);
		table.insert (out_t, ']]');
	end
	
	if 2 == format then															-- ship-type is not wikilinked
		table.insert (out_t, '-class]] ');
		table.insert (out_t, ship_type);
	end
	
	if 4 == format then															-- noun form; no ship type
		table.insert (out_t, ' class]]');
	end
	
	if 5 == format then															-- class name only; no '-class' annotation
		table.insert (out_t, ']]');
	end
	
	return table.concat (out_t);
end


--[[--------------------------< E X P O R T S >----------------------------------------------------------------
]]

return {
	cite_danfs_title = cite_danfs_title,										-- external entry points for templates and invokes
	hnsa = hnsa,
	infobox_ship_career = infobox_ship_career,
	infobox_ship_characteristics = infobox_ship_characteristics,
	infobox_ship_class_overview = infobox_ship_class_overview,
	infobox_ship_flag = infobox_ship_flag,
	is_plimsoll_filename = is_plimsoll_filename,
	navsource = navsource,
	sclass = sclass,
	set_plimsoll_subtitle = set_plimsoll_subtitle,
	set_plimsoll_date = set_plimsoll_date, 
	set_plimsoll_url = set_plimsoll_url,
	ship = ship,																-- experiment
	ship_prefix_templates = ship_prefix_templates,								-- experiment
	ship_name_format = ship_name_format,
	unbulleted_list = unbulleted_list,
	
	_infobox_ship_flag = _infobox_ship_flag,									-- external entry points from another module
	_ship_name_format = do_ship_name_format,
	_synonym_check = synonym_check,
	_unbulleted_list = _unbulleted_list,
	}