# Module:Redirect

-- 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*%[%[([^%[%]|]-)|[^%[%]]-%]%]"
) or string.match(
text,
"வழிமாற்று")
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
local args = require('Module:Arguments').getArgs(, {frameOnly = true})
return p.luaMain(args[1], args.bracket) 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
local args = require('Module:Arguments').getArgs(, {frameOnly = true})
if p.luaIsRedirect(args[1]) then
return 'yes'
else
return ''
end
end  
return p