Module:Delink

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This module removes links from wikitext. It de-links wikilinks, URL links, removes HTML comments, and normalises whitespace. It handles most wikitext correctly, including category links, the colon trick, the pipe trick (normal and reverse), nested wikilinks, and invalid link characters.


-- This module de-links most wikitext.

p = {}

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

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

local function delinkWikilink(s)
    local result = s
    -- Deal with the reverse pipe trick.
    if mw.ustring.match(result, "%[%[|") then
        return delinkReversePipeTrick(result)
    end
    
    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 mw.ustring.match(result, "|") then -- Find if we're dealing with a piped link.
        titlearea = mw.ustring.match(result, "^%[%[(.-)|.*%]%]")
    else
        titlearea = mw.ustring.match(result, "^%[%[(.-)%]%]")
    end
    -- Check for bad characters.
    if mw.ustring.match(titlearea, "[%[%]<>{}%%%c\n]") then
        return s
    end
    
    -- Check for categories, interwikis, and files.
    local colonprefix = mw.ustring.match(result, "%[%[(.-):.*%]%]") or "" -- Get the text before the first colon.
    local ns = mw.site.namespaces[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 ""
    end
    
    -- Remove the colon if the link is using the [[Help:Colon trick]].
    if mw.ustring.match(result, "%[%[:") then
        result = "[[" .. mw.ustring.match(result, "%[%[:(.*%]%])")
    end
    
    -- Deal with links using the [[Help:Pipe trick]].
    if mw.ustring.match(result, "^%[%[[^|]*|%]%]") then
        return delinkPipeTrick(result)
    end
    
    -- Find the display area of the wikilink
    if mw.ustring.match(result, "|") then -- Find if we're dealing with a piped link.
        result = mw.ustring.match(result, "^%[%[.-|(.+)%]%]")
        -- Remove new lines from the display of multiline piped links,
        -- where the pipe is before the first new line.
        result = mw.ustring.gsub(result, "\n", "")
    else
        result = mw.ustring.match(result, "^%[%[(.-)%]%]")
    end

    return result
end

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 mw.ustring.match(s, "\n") then
        return s
    end
    
    -- 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
            break
        end
    end
    
    -- Get display text
    if not url_prefix then
        return s
    end
    s = mw.ustring.match(s, "^%[" .. url_prefix .. "(.*)%]") -- Grab all of the text after the URL prefix and before the final square bracket.
    s = mw.ustring.match(s, '^.-(["<> ].*)') 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.
    
    s_decoded = mw.text.decode(s, true)
    if mw.ustring.match(s_decoded, "%c") then
        return s
    else    
        return s_decoded
    end
end

local function delinkLinkClass(s, pattern, delinkFunction)
    if not type(s) == "string" then
        error("Attempt to de-link non-string input.", 2)
    end
    if not ( type(pattern) == "string" and mw.ustring.sub(pattern, 1, 1) == "^" ) then
        error('Invalid pattern detected. Patterns must begin with "^".', 2)
    end
    -- 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 mw.ustring.len(s) > 0 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)
    end
    return result
end

function p._delink(args)
    local text = args[1] or ""
    if args.refs == "yes" then
        -- Remove any [[Help:Strip markers]] representing ref tags. In most situations 
        -- this is not a good idea - only use it if you know what you are doing!
        text = mw.ustring.gsub(text, "UNIQ%w*%-ref%-%d*%-QINU", "")
    end
    if not (args.comments == "no") then
        text = mw.ustring.gsub(text, "<!%-%-.-%-%->", "") -- Remove html comments.
    end
    if not (args.wikilinks == "no") then
        text = delinkLinkClass(text, "^%[%[.-%]%]", delinkWikilink) -- De-link wikilinks.
    end
    if not (args.urls == "no") then
        text = delinkLinkClass(text, "^%[.-%]", delinkURL) -- De-link URLs.
    end
    if not (args.whitespace == "no") then
        -- 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")
        text = mw.ustring.gsub(text, "[ \t]+", " ") -- Remove extra tabs and spaces.
    end
    return text
end

function p.delink(frame)
    local args
    if frame == mw.getCurrentFrame() then
        -- We're being called via #invoke. If the invoking template passed any args, use
        -- them. Otherwise, use the args that were passed into the template.
        args = frame:getParent().args
        for k, v in pairs(frame.args) do
            args = frame.args
            break
        end
    else
        -- We're being called from another module or from the debug console, so assume
        -- the args are passed in directly.
        args = frame
    end
    return p._delink(args)
end

return p