Module:Redirect: Difference between revisions

    From Nonbinary Wiki
    (add getTarget and isRedirect functions, format comments)
    m (Changed protection level of Module:Redirect: High-risk Lua module: allow template editors ([Edit=Allow only template editors and admins] (indefinite) [Move=Allow only template editors and admins] (indefinite)))
    (No difference)

    Revision as of 05:38, 11 June 2014

    Documentation for this module may be created at Module:Redirect/doc

    -- 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 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 = string.match(
    		titleObj:getContent() or "",
    		"^%s*#[Rr][Ee][Dd][Ii][Rr][Ee][Cc][Tt]%s*:?%s*%[%[([^%[%]]-)%]%]"
    	)
    	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