Module:Redirect

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This module contains functions to find the target of a redirect page.

Main[edit source]

The main function accepts the name of a single page. It determines if the page is a redirect; if so it looks up the page, extracts the target, and returns the target name as text. Its usage is {{#invoke:redirect|main|redirect-page-name}}.

The template normally neither takes nor gives square brackets, so to show the result as a link use [[{{#invoke:redirect|main|redirect-page-name}}]]. An error is produced if the redirect does not exist, but for versatility no error is given if the file is not a redirect (returns the original text) or if the file name is blank (returns blank).

However, if the parameter bracket is given a nonblank value, brackets will be passed on if present.

Examples[edit source]

  • {{#invoke:redirect|main|Snow}} → Snow Block
  • {{#invoke:redirect|main|[[Copper Helmet]]|bracket=yes}}Copper armor
  • {{#invoke:redirect|main|Terraria Wiki}} → Terraria Wiki

Note: Snow and Copper Helmet are both redirects, but Terraria Wiki is not.

LuaMain[edit source]

If you want to use the main function from another Lua module, you may want to use the luaMain function. This provides the same functionality as the main function, but doesn't require that a frame object be available.

To use this, first load the module.

local mRedirect = require('Module:Redirect')

Then use the function with the following syntax:

mRedirect.luaMain(rname, bracket)

rname is the name of the redirect page, and if bracket is anything but false or nil, the module will produce a link rather than just a page name.

IsRedirect[edit source]

The isRedirect function is used from wiki pages to find out if a given page is a redirect or not. If the page is a redirect, the function returns "yes", and if not the output is blank. Its usage is {{#invoke:redirect|isRedirect|redirect-page-name}}.

Examples[edit source]

  • {{#invoke:redirect|isRedirect|Copper Helmet}} → yes
  • {{#invoke:redirect|isRedirect|Terraria Wiki}}

LuaIsRedirect[edit source]

The isRedirect can be accessed from other Lua modules in the same way as the main function:

local mRedirect = require('Module:Redirect')
mRedirect.luaIsRedirect(rname)

GetTarget[edit source]

The getTarget function fetches the target page name of a redirect page, and is only usable from Lua. If the page specified is a redirect, then the target is returned; otherwise the function returns nil.

To use it, first load the module.

local mRedirect = require('Module:Redirect')

Then use the function with the following syntax:

mRedirect.getTarget(page)

page can be either the name of the redirect page as a string, or a mw.title object.


-- This module provides functions for getting the target of a redirect page.

local p = {}

-- Gets a mw.title object, using pcall to avoid generating script errors if we
-- are over the expensive function count limit (among other possible causes).
local function getTitle(...)
	local success, titleObj = pcall(mw.title.new, ...)
	if success then
		return titleObj
	else
		return nil
	end
end

-- Gets the name of a page that a redirect leads to, or nil if it isn't a
-- redirect.
function p.getTargetFromText(text)
	return string.match(
		text,
		"^%s*#[Rr][Ee][Dd][Ii][Rr][Ee][Cc][Tt]%s*:?%s*%[%[([^%[%]|]-)%]%]"
	) or string.match(
		text,
		"^%s*#[Rr][Ee][Dd][Ii][Rr][Ee][Cc][Tt]%s*:?%s*%[%[([^%[%]|]-)|[^%[%]]-%]%]"
	)
end

-- Gets the target of a redirect. If the page specified is not a redirect,
-- returns nil.
function p.getTarget(page, fulltext)
	-- Get the title object. Both page names and title objects are allowed
	-- as input.
	local titleObj
	if type(page) == 'string' or type(page) == 'number' then
		titleObj = getTitle(page)
	elseif type(page) == 'table' and type(page.getContent) == 'function' then
		titleObj = page
	else
		error(string.format(
			"bad argument #1 to 'getTarget'"
				.. " (string, number, or title object expected, got %s)",
			type(page)
		), 2)
	end
	if not titleObj or not titleObj.isRedirect then
		return nil
	end
	
	-- Find the target by using string matching on the page content.
	local target = p.getTargetFromText(titleObj:getContent() or "")
	if target then
		local targetTitle = getTitle(target)
		if targetTitle then
			if fulltext then
				return targetTitle.fullText
			else
				return targetTitle.prefixedText
			end
		else
			return nil
		end
	else
		-- The page is a redirect, but matching failed. This indicates a bug in
		-- the redirect matching pattern, so throw an error.
		error(string.format(
			'could not parse redirect on page "%s"',
			fulltext and titleObj.fullText or titleObj.prefixedText
		))
	end
end

--[[
-- Given a single page name determines what page it redirects to and returns the
-- target page name, or the passed page name when not a redirect. The passed
-- page name can be given as plain text or as a page link.
-- 
-- Returns page name as plain text, or when the bracket parameter is given, as a
-- page link. Returns an error message when page does not exist or the redirect
-- target cannot be determined for some reason.
--]]
function p.luaMain(rname, bracket, fulltext)
	if type(rname) ~= "string" or not rname:find("%S") then
		return nil
	end
	bracket = bracket and "[[%s]]" or "%s"
	rname = rname:match("%[%[(.+)%]%]") or rname
	local target = p.getTarget(rname, fulltext)
	local ret = target or rname
	ret = getTitle(ret)
	if ret then
		if fulltext then
			ret = ret.fullText
		else
			ret = ret.prefixedText
		end
		return bracket:format(ret)
	else
		return nil
	end
end

-- Provides access to the luaMain function from wikitext.
function p.main(frame)
	local args = require('Module:Arguments').getArgs(frame, {frameOnly = true})
	return p.luaMain(args[1], args.bracket, args.fulltext) or ''
end

-- Returns true if the specified page is a redirect, and false otherwise.
function p.luaIsRedirect(page)
	local titleObj = getTitle(page)
	if not titleObj then
		return false
	end
	if titleObj.isRedirect then
		return true
	else
		return false
	end
end

-- Provides access to the luaIsRedirect function from wikitext, returning 'yes'
-- if the specified page is a redirect, and the blank string otherwise.
function p.isRedirect(frame)
	local args = require('Module:Arguments').getArgs(frame, {frameOnly = true})
	if p.luaIsRedirect(args[1]) then
		return 'yes'
	else
		return ''
	end
end

return p