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-- 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(, ...) 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*%[%[([^%[%]]-)%]%]" ) end

-- Gets the target of a redirect. If the page specified is not a redirect, -- returns nil. function p.getTarget(page) -- 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 return targetTitle.prefixedText 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"', 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) 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) local ret = target or rname ret = getTitle(ret) if ret then ret = ret.prefixedText 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) or end

-- Returns "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}) local titleObj = getTitle(args[1]) if not titleObj then return end if titleObj.isRedirect then return 'yes' else return end end

return p