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

-- Taken from Wikipedia:
-- This module de-links most wikitext.

local p = {}

local function delinkReversePipeTrick(s)
    if s:match("^%[%[|.*[|\n]") then -- Check for newlines or multiple pipes.
        return s
        return s:match("%[%[|(.*)%]%]")

local function delinkPipeTrick(s)
    local linkarea, display = "", ""
    -- We need to deal with colons, brackets, and commas, per [[wikipedia:Help:Pipe trick]].
    -- First, remove the text before the first colon, if any.
    if s:match(":") then
        s = s:match("%[%[.-:(.*)|%]%]")
    -- If there are no colons, grab all of the text apart from the square brackets and the pipe.
        s = s:match("%[%[(.*)|%]%]")
    -- Next up, brackets and commas.
    if s:match("%(.-%)$") then -- Brackets trump commas.
        s = s:match("(.-) ?%(.-%)$")
    elseif s:match(",") then -- If there are no brackets, display only the text before the first comma.
        s = s:match("(.-),.*$")
    return s

local function delinkWikilink(s)
    local result = s
    -- Deal with the reverse pipe trick.
    if result:match("%[%[|") then
        return delinkReversePipeTrick(result)
    result = mw.uri.decode(result, "PATH") -- decode percent-encoded entities. Leave underscores and plus signs.
    result = mw.text.decode(result, true) -- decode HTML entities.
    -- Check for bad titles. To do this we need to find the
    -- title area of the link, i.e. the part before any pipes.
    local titlearea
    if result:match("|") then -- Find if we're dealing with a piped link.
        titlearea = result:match("^%[%[(.-)|.*%]%]")
        titlearea = result:match("^%[%[(.-)%]%]")
    -- Check for bad characters.
    if mw.ustring.match(titlearea, "[%[%]<>{}%%%c\n]") then
        return s
    -- Check for categories, interwikis, and files.
    local colonprefix = result:match("%[%[(.-):.*%]%]") or "" -- Get the text before the first colon.
    local ns =[colonprefix] -- see if this is a known namespace
    if --[[mw.language.isKnownLanguageTag(colonprefix)
    or ]]( ns and ( ns.canonicalName == "File" or ns.canonicalName == "Category" ) ) then
        return ""
    -- Remove the colon if the link is using the [[wikipedia:Help:Colon trick]].
    if result:match("%[%[:") then
        result = "[[" .. result:match("%[%[:(.*%]%])")
    -- Deal with links using the [[wikipedia:Help:Pipe trick]].
    if mw.ustring.match(result, "^%[%[[^|]*|%]%]") then
        return delinkPipeTrick(result)
    -- Find the display area of the wikilink
    if result:match("|") then -- Find if we're dealing with a piped link.
        result = result:match("^%[%[.-|(.+)%]%]")
        -- Remove new lines from the display of multiline piped links,
        -- where the pipe is before the first new line.
        result = result:gsub("\n", "")
        result = result:match("^%[%[(.-)%]%]")

    return result

local function delinkURL(s)
    -- Assume we have already delinked internal wikilinks, and that
    -- we have been passed some text between two square brackets [foo].
    -- If the text contains a line break it is not formatted as a URL, regardless of other content.
    if s:match("\n") then
        return s
    -- Check if the text has a valid URL prefix and at least one valid URL character.
    local valid_url_prefixes = {"//", "http://", "https://", "ftp://", "gopher://", "mailto:", "news:", "irc://"} 
    local url_prefix
    for i,v in ipairs(valid_url_prefixes) do
        if mw.ustring.match(s, '^%[' .. v ..'[^"%s].*%]' ) then
            url_prefix = v
    -- Get display text
    if not url_prefix then
        return s
    s = s:match("^%[" .. url_prefix .. "(.*)%]") -- Grab all of the text after the URL prefix and before the final square bracket.
    s = s:match('^.-(["<> ].*)') or "" -- Grab all of the text after the first URL separator character ("<> ).
    s = mw.ustring.match(s, "^%s*(%S.*)$") or "" -- If the separating character was a space, trim it off.
    local s_decoded = mw.text.decode(s, true)
    if mw.ustring.match(s_decoded, "%c") then
        return s
        return s_decoded

local function delinkLinkClass(s, pattern, delinkFunction)
    -- Iterate over the text string, and replace any matched text. using the 
    -- delink function. We need to iterate character by character rather 
    -- than just use gsub, otherwise nested links aren't detected properly.
    local result = ""
    while s ~= '' do
        -- Replace text using one iteration of gsub.
        s = mw.ustring.gsub(s, pattern, delinkFunction, 1)
        -- Append the left-most character to the result string.
        result = result .. mw.ustring.sub(s, 1, 1)
        s = mw.ustring.sub(s, 2, -1)
    return result

function p.delink(frame)
    local text = frame.args[1] or ""

    -- Remove any [[wikipedia:Help:Strip markers]] representing ref tags.
    text = mw.ustring.gsub(text, "UNIQ%w*%-ref%-%d*%-QINU", "")

    -- Remove html comments.
    text = text:gsub("<!%-%-.-%-%->", "")

    -- De-link wikilinks.
    text = delinkLinkClass(text, "^%[%[.-%]%]", delinkWikilink)
    -- De-link URLs.
    text = delinkLinkClass(text, "^%[.-%]", delinkURL)
    -- Replace single new lines with a single space, but leave double new lines
    -- and new lines only containing spaces or tabs before a second new line.
    text = mw.ustring.gsub(text, "([^\n \t][ \t]*)\n([ \t]*[^\n \t])", "%1 %2")

    -- Remove extra tabs and spaces.
    text = text:gsub("[ \t]+", " ")

    -- Remove bold/italics.
    text = text:gsub("''+","")

    return text

return p
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