Module:Catalog lookup link

--[[
|1=, |2=, |3=, |4=, |5=, |6=, |7=, |8=, |9=: Optional unnamed parameters for 0 to 9 items to be listed.
	Whitespace is trimmed off both ends and the strings are urlencoded as if they were query strings.
|article-link=: Optional Wikipedia article name to link to.
|article-name=: Optional alternative text to be displayed for |article-link= link in front of catalog link.
	If not specified, |article-link= is used for display as well. If both parameters are not specified, the prefix is omitted completely.
|article-postfix=: Optional symbol to be displayed after article name or link (f.e. ":"; omitted, if not defined).
|link-prefix=: Optional prefix portion of url to external catalog item(s).
|link-postfix=: Optional postfix portion of url to external catalog item(s).
|item-prefix=: Optional text displayed in front of each external link (omitted, if not defined)
|item-postfix=: Optional text displayed immediately after each external link (omitted, if not defined)
|list-separator=: Optional alternative separator displayed between list items (default: ", ", if not specified). Whitespace must be encoded.
|list-leadout=: Optional alternative leadout text displayed between the last two list items (f.e. "and", "or", "as well as", etc., default is the |list-separator= or ", ".)
|leadout-postfix=: Optional alternative postfix text of the leadout (see |list-leadout=) displayed between the last two list items.
	This gets added in front of the last list item instead of the default whitespace which is added without this parameter.
	This may be necessary if |list-separator= is used not only to define the list separator but also parts of the item prefix
	(except for the first one). (At present, this is used only to cope with format oddities of the {{MR}} template.)

]]

require('Module:No globals');
local getArgs = require ('Module:Arguments').getArgs;

local p = {};


--[[--------------------------< 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


--[=[-------------------------< 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, 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 is_set (link) then
		if is_set (display) then
			return table.concat ({'[[', link, '|', display, ']]'});
		else
			return table.concat ({'[[', link, ']]'});
		end
	else
		return '';
	end
end



--[[--------------------------< M A I N >----------------------------------------------------------------------


]]

function p.main (frame)
local args = getArgs (frame);
local result = {};

local article;

local article_postfix = args['article-postfix'] or '';
local link_prefix = args['link-prefix'] or '';
local link_postfix = args['link-postfix'] or '';
local item_prefix = args['item-prefix'] or '';
local item_postfix = args['item-postfix'] or '';
local list_separator = args['list-separator'] or ', ';
local list_leadout;

if is_set (args['list-leadout']) then
	list_leadout = table.concat ({' ', args['list-leadout'], ' '});
else
	list_leadout = '';
end
-- leadout-postfix?

	article = make_wikilink (args['article-link'], args['article-name']);
	if is_set (article) then
		article = table.concat ({article, article_postfix});
	elseif is_set (args['article-name']) then
		article = table.concat ({args['article-name'], article_postfix});
	end

	for k, item in ipairs (args) do												-- for each of the positional parameters
		item = mw.text.trim (item);												-- remove extraneous whitespace
		if is_set (link_prefix) then											-- if there is link prefix...
			item = table.concat ({												-- create an external link item
				'[',															-- open ext link markup
				link_prefix,													-- url prefix
				mw.uri.encode (item),											-- item is part of url
				link_postfix,													-- url postfix
				' ',															-- required space between url and label
				item_prefix,													-- label prefix
				item,															-- item as label
				item_postfix,													-- item postfix
				']'																-- close ext link markup
				});
		else
			item = table.concat ({												-- create an unlinked item
				item_prefix,													-- label prefix
				item,															-- item as label
				item_postfix,													-- item postfix
				});
		end

		table.insert (result, item);												-- add the item to the result list
	end

	if is_set (args['list-leadout']) then
		return table.concat ({article, mw.text.listToText (result, list_separator, list_leadout)}, ' ');
	else
		return table.concat ({article, table.concat (result, list_separator)}, ' ');
	end
end

return p;
Usage
