Module:Fallback

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.

Dependencies

Module:Fallbacklist catalogs old fallback chains for each language as it was set up on Commons a decade ago. Lua allows now to access the default MediaWiki fallback chains which are used by most templates.

--[[
  __  __           _       _        _____     _ _ _                _
 |  \/  | ___   __| |_   _| | ___ _|  ___|_ _| | | |__   __ _  ___| | __
 | |\/| |/ _ \ / _` | | | | |/ _ (_) |_ / _` | | | '_ \ / _` |/ __| |/ /
 | |  | | (_) | (_| | |_| | |  __/_|  _| (_| | | | |_) | (_| | (__|   < 
 |_|  |_|\___/ \__,_|\__,_|_|\___(_)_|  \__,_|_|_|_.__/ \__,_|\___|_|\_\
 
 Authors and maintainers:
* User:Zolo   - original version
* User:Jarekt 
]]

local p = {}

--[[
translatelua
 
Allows easy translation or internalization of pages in Lua. 
 
Example Usage from a template:
{{#invoke: fallback|translatelua| i18n/oil on canvas|lang={{{lang|}}}}}
 
Parameters:
  frame.args.1 - name of translation module
frame.args.2 - field name of the structure in Module:[frame.args.1] to use
  frame.args.lang - desired language (often user's native language)
 
 Error Handling:
 
]]
function p.translatelua(frame)
	local lang = mw.text.trim(frame.args.lang)
	local page = require('Module:' .. mw.text.trim(frame.args[1])) -- page should only contain a simple of translations
	if not lang or lang == '' then
		lang = frame:callParserFunction("int", "lang")
	end
	if frame.args[2] then
		page = page[mw.text.trim(frame.args[2])]
	end
	
	local langList = mw.language.getFallbacksFor(lang)
	table.insert(langList,1,lang)
	for _,language in ipairs(langList) do
		if page[language] then
			return page[language]
		end
	end
end

--[[
fblist
 
Similar to  mw.language.getFallbacksFor(lang) but uses Commons old fallback chain 
 
Parameters:
  lang - desired language (often user's native language)
 
 Error Handling:
 
]]
function p.fblist(lang) -- list the full fallback chain from a language to en
	local fbtable = p.fallbackloop{lang:lower()}
	table.insert(fbtable, 'default')
	table.insert(fbtable, 'en')
	return fbtable
end

local function _inArray(x, t)
	for i, v in ipairs(t) do
		if v == x then return i end
	end
	return -1
end

function p.fallbackloop(fbtable) --list of fallback languages in string format (more convenient than tables)
	local langlist = require('Module:Fallbacklist')
	local changes = false
	for i, j in ipairs(fbtable) do
		local seq = langlist[j]
		if seq then
			for k, l in ipairs(seq) do
				if _inArray(l, fbtable) == -1 then
					table.insert(fbtable, l)
					changes = true
				end
			end
		end
	end
	if changes then
		return p.fallbackloop(fbtable)
	end
	return fbtable
end

return p