Module:LangSwitch

Lua

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This module is rated as ready for general use. It has reached a mature form and is thought to be bug-free and ready for use wherever appropriate. To reduce server load and bad output, it should be improved by sandbox testing rather than repeated trial-and-error editing.

This module is subject to page protection. It is a highly visible module in use by a very large number of pages, or is substituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it is protected from editing.

Code for Template:LangSwitch.

Code

--[[
  __  __           _       _        _                      ____          _ _       _     
 |  \/  | ___   __| |_   _| | ___ _| |    __ _ _ __   __ _/ ___|_      _(_) |_ ___| |__  
 | |\/| |/ _ \ / _` | | | | |/ _ (_) |   / _` | '_ \ / _` \___ \ \ /\ / / | __/ __| '_ \ 
 | |  | | (_) | (_| | |_| | |  __/_| |__| (_| | | | | (_| |___) \ V  V /| | || (__| | | |
 |_|  |_|\___/ \__,_|\__,_|_|\___(_)_____\__,_|_| |_|\__, |____/ \_/\_/ |_|\__\___|_| |_|
                                                     |___/                               
 Authors and maintainers:
* User:Zolo   - original version in Module:Fallback
* User:Jarekt 
]]

-- add optional module 
-- used for debugging purposes as it detects cases of unintended global variables
require('strict')

local p = {}

local function add_labels(args)
	-- add invisible but machine readable labels to the files, which can be used to add titles to wikidata items
	local createTag = require('Module:TagQS').createTag -- lazy loading of the module: only for the files that need it
	local qsTable = {''}

	-- add text of invisible tag brodcasted by the template which allows creation of QuickStatements command used to add this info to Wikidata
	for lang, text in pairs( args ) do 
		if type(lang)=='string' and mw.language.isSupportedLanguage(lang)  then -- lang has to be a valid language 
			table.insert( qsTable, createTag('label', 'L'..lang, '"' .. text .. '"') )
		end
	end
	return table.concat( qsTable, '\n')
end

--[[
_langSwitch
 
This function is the core part of the LangSwitch template. 
 
Example usage from Lua:
text = _langSwitch({en='text in english', pl='tekst po polsku'}, lang)
 
Parameters:
  args - table with translations by language
  lang - desired language (often user's native language)

 Error Handling:

]]

function p._langSwitch(args, lang) -- args: table of translations
	-- Return error if there is not default and no english version
	if not args.en and not args.default then
		local err = '<b class="error">LangSwitch Error: no default</b>'
		if args.nocat == '1' then
			return err
		else
			return err .. '[[Category:LangSwitch template without default version]]'
		end
	end
	
	-- To improve performance try quick switch, and load fallback chain only if needed. 
	-- In the vast majority of cases fast switch is sufficient
	local val = args[lang]
	if val == '~' then 
		return ''
	elseif val and val ~= '' then 
		return val 
	elseif args.quick then
		return nil
	end
	
	-- get the list of accepetable language (lang + those in lang's fallback chain) and check their content
	assert(lang, 'LangSwitch Error: no lang')
	local langList = mw.language.getFallbacksFor(lang)
	table.insert(langList,1,lang)
	table.insert(langList,math.max(#langList,2),'default')
	for _, language in ipairs(langList) do 
		val = args[language]
		if val == '~' then 
			return ''
		elseif val and val ~= '' then 
			return val 
		end
	end
end

--[[
langSwitch
 
This function is the core part of the LangSwitch template. 
 
Example Usage from a template:
{{#invoke:fallback|langSwitch|en=text in english|pl=tekst po polsku|lang={{int:lang}} }}
 
Parameters:
  frame.args - table with translations by language
  frame.args.lang - desired language (often user's native language)

 Error Handling:

]]
function p.langSwitch(frame) -- version to be used from wikitext
	local args = frame.args
	-- if no expected args provided than check parent template/module args
	if args.en==nil and args.default==nil and args.nocat==nil then
		args = mw.getCurrentFrame():getParent().args 
	end
	local lang = args.lang
	if not lang or not mw.language.isKnownLanguageTag(lang) then
		lang = frame:callParserFunction( "int", "lang" ) -- get user's chosen language 
	end
	
	-- add text of invisible tag brodcasted by the template which allows creation of QuickStatements command used to add this info to Wikidata
	local labels = ''
	if args.add_labels then
		labels = add_labels(args)
	end
	
	-- Try quick switch which checks the most likely option when fallback is not needed
	args.quick = true;
	local val = p._langSwitch(args, lang)
	if val then
		return val .. labels
	end
	
	-- Allow input in format: {{LangSwitch|de=Grün|es/it/pt=Verde|fr=Vert|en=Green |lang=en}}
	-- with multiple languages mapping to a single value
	local args1 = {}
	for name, value in pairs( args ) do 
		if value ~= '' and type(name)=='string' then 
    		for str in string.gmatch( name, "([^/]+)" ) do
				args1[str] = value
			end
		end
	end
	return p._langSwitch(args1, lang) .. labels
end

return p