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    Farthest Frontier

    WLink – Module with functions for strings in context of wikilinks and external links (URL). This module was imported from de:Module:WLink.

    Usage

    All functions expect exactly one unnamed parameter (which should be provided to get a meaningful answer). Whitespace ahead and after content is ignored. HTML Entities would not disturb syntax and might be resolved. The parameter might contain single or double bracketed links which would be extracted if appropriate.

    The return value is an empty string (“nothing”), if the parameter value does not fulfil the expectations. If there is a result or the query condition is true, at least one visible character will be returned. The result does not begin or end with a space.

    ansiPercent
    Convert string by ANSI encoding rather than UTF-8 encoding
    Required for some 20th century servers
    Optional parameter space – encoding of spaces:
    • space=+ – common for query components
    • space=_ – as for Wikis
    • Default: %20
    formatURL
    Create bracketed link, if not yet, from URL or domain
    • [http://example.org/about Homepage] yields [http://example.org/about Homepage]
    • http://example.org/about yields [http://example.org/about example.org/about]
    • example.org yields [http://example.org/ example.org]
    getArticleBase
    Retrieve generic page title, no fragment nor brackets
    Use current page title, if omitted.
    getBaseTitle
    Retrieve last segment in subpage, no fragment
    getExtension
    Retrieve media extension
    Result is downcased (without leading dot).
    getFile
    Retrieve media page identifier
    getFragment
    Retrieve original (not decoded) fragment string after #
    getLanguage
    Retrieve language identifier
    getNamespace
    Retrieve namespace number
    getPlain
    Retrieve text with all links replaced by link titles
    getProject
    Retrieve project identifier within wikifarm (recommendable brief notation)
    getTarget
    Retrieve first target (wikilink or URL)
    getTargetPage
    Retrieve first target page (page name or URL of page)
    Same as getTarget if no fragment.
    getTitle
    Retrieve first link title (wikilink or URL), or wikilink target
    isBracketedLink
    Does attempt match a bracketed link?
    isBracketedURL
    Does attempt match a bracketed URL?
    isCategorization
    Does attempt match a categorization?
    isExternalLink
    Does attempt match an external link?
    isInterlanguage
    Does attempt match an interlanguage link?
    isInterwiki
    Does attempt match an interwiki link?
    isMedia
    Does attempt match a media translusion?
    isTitledLink
    Does attempt match a titled link?
    isValidLink
    Does attempt match a link?
    isWeblink
    Does attempt match an external link?
    isWikilink
    Does attempt match a wikilink?
    failsafe
    Version ID: 2016-10-05
    optional parameter 1 – required version
    result: empty, if requirement not met

    Examples (test page)

    A test page illustrates practical use.

    Functions for Lua modules (API)

    All functions described above can be used by other modules:

    local lucky, WLink = pcall( require, "Module:WLink" )
    if type( WLink ) == "table" then
        WLink = WLink.WLink()
    else
        -- failure; WLink is the error message
        return "<span class=\"error\">" .. WLink .. "</span>"
    end
    

    Subsequently there are available:

    • WLink.ansiPercent(story, space)
    • WLink.formatURL()
    • WLink.getArticleBase()
    • WLink.getBaseTitle()
    • WLink.getExtension()
    • WLink.getFile()
    • WLink.getFragment()
      false, if not found; but empty string if empty fragment.
      No leading # in result.
    • WLink.getLanguage()
    • WLink.getNamespace()
    • WLink.getPlain()
    • WLink.getProject()
    • WLink.getTarget()
    • WLink.getTargetPage()
    • WLink.getTitle()
    • WLink.isBracketedLink()
    • WLink.isBracketedURL()
    • WLink.isCategorization()
    • WLink.isExternalLink()
    • WLink.isInterlanguage()
    • WLink.isInterwiki()
    • WLink.isMedia()
    • WLink.isTitledLink()
    • WLink.isValidLink()
    • WLink.isWeblink()
    • WLink.isWikilink()
    • WLink.wikilink()
      Yields table with wikilink components, else false.
      Components might be, if provided:
      • lead – leading colon : present and required, if true
      • project – project interwiki within wikifarm (recommendable brief notation)
      • lang – known language version (downcased)
      • ns – number of namespace
      • space – local canonical name of namespace
      • title – page title as provided; at least empty string
    • WLink.failsafe(atleast)
      1. atleast
        optional
        nil or required version
      returns: string or false

    If succeeding, the WLink.get*() return a string, the WLink.is*() true (if no exception mentioned); on failure always false.


    local WLink = { suite  = "WLink",
                    serial = "2016-10-05" };
    --[=[
    ansiPercent()
    formatURL()
    getArticleBase()
    getBaseTitle()
    getEscapedTitle()
    getExtension()
    getFile()
    getFragment()
    getLanguage()
    getNamespace()
    getPlain()
    getProject()
    getTarget()
    getTargetPage()
    getTitle()
    getWeblink()
    isBracketedLink()
    isBracketedURL()
    isCategorization()
    isExternalLink()
    isInterlanguage()
    isInterwiki()
    isMedia()
    isTitledLink()
    isValidLink()
    isWikilink()
    wikilink()
    failsafe()
    ]=]
    
    
    
    -- local globals
    local URLutil = false;
    
    
    
    local utilURL = function ()
        -- Attach URLutil library module
        -- Postcondition:
        --     Returns  table, with URLutil library
        --     Throws error, if not available
        if not URLutil then
            local lucky, util = pcall( require, "Module:URLutil" );
            if lucky then
                if type( util ) == "table" then
                    URLutil = util.URLutil();
                end
                util = "library URLutil invalid";
            end
            if type( URLutil ) ~= "table" then
                error( util, 0 );
            end
        end
        return URLutil;
    end -- utilURL()
    
    
    
    local contentExtlink = function ( attempt )
        -- Retrieve span of external link between brackets
        -- Precondition:
        --     attempt  -- string, with presumable link
        --                         the first char is expected to be "["
        -- Postcondition:
        --     Returns  string, number, number
        --                  string including whitespace
        --                  number with index of relevant "["
        --                  number with index after relevant "]"
        --              false if nothing found
        local r1 = false;
        local r2 = false;
        local r3 = attempt:find( "]", 2, true );
        if r3 then
            local s = attempt:sub( 2,  r3 - 1 );
            local i = s:find( "[", 1, true );
            if i then
                r1 = s:sub( i + 1 );
                r2 = i;
            else
                r1 = s;
                r2 = 1;
            end
        else
            r3 = false;
        end
        return r1, r2, r3;
    end -- contentExtlink()
    
    
    
    local contentWikilink = function ( attempt )
        -- Retrieve span of wikilink between brackets
        -- Precondition:
        --     attempt  -- string, with presumable link
        --                        the first two chars are expected to be "[["
        -- Postcondition:
        --     Returns  string, number, number
        --                  string including whitespace
        --                  number with index of relevant "[["
        --                  number with index after relevant "]]"
        --              false if nothing found
        local r1 = false;
        local r2 = false;
        local r3 = attempt:find( "]]", 3, true );
        if r3 then
            local s = attempt:sub( 3,  r3 - 1 );
            local i = s:find( "[[", 1, true );
            if i then
                r1 = s:sub( i + 2 );
                r2 = i;
            else
                r1 = s;
                r2 = 1;
            end
        end
        return r1, r2, r3;
    end -- contentWikilink()
    
    
    
    local extractExtlink = function ( attempt )
        -- Retrieve external link
        -- Precondition:
        --     attempt  -- string, with presumable link
        --                        the first char is expected to be "["
        -- Postcondition:
        --     Returns  string, string
        --                  first with target and title
        --                  second result false if not titled
        --              false if nothing found
        local r1 = false;
        local r2 = false;
        local s = contentExtlink( attempt );
        if s then
            local i = s:find( "%s", 1 );
            if i then
                r1 = s:sub( 1,  i - 1 );
                r2 = mw.text.trim( s:sub( i + 1 ) );
                if r2 == "" then
                    r2 = false;
                end
            else
                r1 = s;
            end
            if r1 then
                r1 = mw.text.trim( r1 );
                if r1 == ""  or
                   not utilURL().isResourceURL( r1 ) then
                    r1 = false;
                end
            end
            if not r1 then
                r2 = false;
            end
        end
        return r1, r2;
    end -- extractExtlink()
    
    
    
    local extractWikilink = function ( attempt )
        -- Retrieve wikilink
        -- Precondition:
        --     attempt  -- string, with presumable link
        --                        the first two chars are expected to be "[["
        -- Postcondition:
        --     Returns  string, string
        --                  first with target
        --                  second result title, or false if not piped
        --              false if nothing found
        local r1 = false;
        local r2 = false;
        local s = contentWikilink( attempt );
        if s then
            local i = s:find( "|", 1, true );
            if i then
                r1 = s:sub( 1,  i - 1 );
                r2 = s:sub( i + 1 );
            else
                r1 = s;
            end
            r1 = mw.text.trim( r1 );
            if r1 == "" then
                r1 = false;
            else
                r1 = r1:gsub( "_",        " " )
                       :gsub( "&nbsp;",   " " )
                       :gsub( "&thinsp;", " " )
                       :gsub( "&#160;",   " " )
                       :gsub( "&#8239;",  " " )
                       :gsub( "  +",      " " );
                r1 = mw.text.decode( r1 );
            end
        end
        return r1, r2;
    end -- extractWikilink()
    
    
    
    local prefix = function ( ask, ahead )
        -- Interprete prefix of language or project type
        -- Precondition:
        --     ask    -- string, with presumable prefix
        --     ahead  -- true, if first segment
        -- Postcondition:
        --     Returns  string,string or nil
        --                     first  string one of "lead", "lang", "project"
        --                     second string is formatted value
        --                       type is one of "lead", "lang", "project"
        --              nil if nothing found
        local r1, r2;
        local prefixes = { b           = true,
                           c           = "commons",
                           d           = true,
                           commons     = true,
                           m           = "meta",
                           mediawiki   = "mw",
                           mw          = true,
                           meta        = true,
                           n           = true,
                           q           = true,
                           s           = true,
                           simple      = false,
                           v           = true,
                           voy         = true,
                           w           = true,
                           wikibooks   = "b",
                           wikidata    = "d",
                           wikinews    = "n",
                           wikipedia   = "w",
                           wikiquote   = "q",
                           wikisource  = "s",
                           wikiversity = "v",
                           wikivoyage  = "voy",
                           wikt        = true,
                           wiktionary  = "wikt"
                         };
        local s = mw.text.trim( ask );
        if s == "" then
            if ahead then
                r1 = "lead";
                r2 = true;
            end
        else
            local p;
            s = s:lower();
            p = prefixes[ s ];
            if p == true then
                r1 = "project";
                r2 = s;
            elseif p then
                r1 = "project";
                r2 = p;
            elseif p == false then
                r1 = "lang";
                r2 = s;
            elseif s:match( "^%l%l%l?$" )
                   and  mw.language.isSupportedLanguage( s ) then
                r1 = "lang";
                r2 = s;
            end
        end
        return r1, r2;
    end -- prefix()
    
    
    
    local target = function ( attempt, lonely )
        -- Retrieve first target (wikilink or URL), or entire string
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        --     lonely   -- remove fragment, if true
        -- Postcondition:
        --     Returns  string, number
        --                  string, with detected link target, or entire
        --                  number, with number of brackets, if found, or 2
        local r1, r2 = WLink.getTarget( attempt );
        if not r1 then
            r1 = mw.text.trim( attempt );
            r2 = 2;
        end
        if lonely then
            local i = r1:find( "#", 1, true );
            if i == 1 then
                r1 = "";
            elseif i then
                r1 = r1:sub( 1, i - 1 );
            end
        end
        return r1, r2;
    end -- target()
    
    
    
    function WLink.ansiPercent( attempt, alter )
        -- Convert string by ANSI encoding rather than UTF-8 encoding
        -- Precondition:
        --     attempt  -- string, with presumable ANSI characters
        --     alter    -- string or nil, to use for spaces instead of %20
        -- Postcondition:
        --     Returns  string, encoded
        local k, s;
        local r = attempt;
        if alter then
            r = r:gsub( " ", alter );
        end
        for i = mw.ustring.len( r ), 1, -1 do
            k = mw.ustring.codepoint( r, i, i );
            if k <= 32  or  k > 126 then
                if k > 255 then
                    s = mw.ustring.sub( r, i, i );
                    if k > 2047 then
                        s = string.format( "%%%2X%%%2X%%%2X",
                                           s:byte( 1, 1 ),
                                           s:byte( 2, 2 ),
                                           s:byte( 3, 3 ) );
                    else
                        s = string.format( "%%%2X%%%2X",
                                           s:byte( 1, 1 ),
                                           s:byte( 2, 2 ) );
                    end
                else
                    s = string.format( "%%%2X", k );
                end
                r = string.format( "%s%s%s",
                                   mw.ustring.sub( r,  1,  i - 1 ),
                                   s,
                                   mw.ustring.sub( r,  i + 1 ) );
            end
        end -- for --i
        r = mw.ustring.gsub(r, '^%*', '%%2A')
        return r;
    end -- WLink.ansiPercent()
    
    
    
    function WLink.formatURL( adjust )
        -- Create bracketed link, if not yet
        -- Precondition:
        --     adjust  -- string, with URL or domain/path or bracketed link
        -- Postcondition:
        --     Returns  string, with bracketed link
        --              false on invalid format
        local r;
        if type( adjust ) == "string" then
            if WLink.isBracketedLink( adjust ) then
                r = adjust;
            else
                local url = mw.text.trim( adjust );
                local host;
                utilURL();
                host = URLutil.getHost( adjust );
                if not host then
                    url  = "http://" .. adjust;
                    host = URLutil.getHost( url );
                end
                if host then
                    local path = URLutil.getRelativePath( url );
                    local show;
                    if path == "/" then
                        if not url:match( "/$" ) then
                            url = url .. "/";
                        end
                        show = host;
                    else
                        local i = path:find( "#" );
                        if i then
                            path = path:sub( 1,  i - 1 );
                        end
                        show = host .. path;
                    end
                    r = string.format( "[%s %s]", url, show );
                else
                    r = adjust;
                end
            end
        else
            r = false;
        end
        return r;
    end -- WLink.formatURL()
    
    
    
    function WLink.getArticleBase( attempt )
        -- Retrieve generic article title, no fragment nor brackets
        -- Precondition:
        --     attempt  -- string, with wikilink or page title
        --                         current page title, if missing
        -- Postcondition:
        --     Returns  string, with identified lemma, or all
        --              false on invalid format
        local r;
        if attempt then
            local m;
            r, m = target( attempt, true );
            if m ~= 2 then
                r = false;
            end
        else
            r = mw.title.getCurrentTitle().text;
        end
        if r then
            local sub = r:match( "^(.*%S) *%(.+%)$" );
            if sub then
                r = sub;
            end
        end
        return r;
    end -- WLink.getArticleBase()
    
    
    
    function WLink.getBaseTitle( attempt )
        -- Retrieve last segment in subpage, no fragment
        -- Precondition:
        --     attempt  -- string, with wikilink or page title
        -- Postcondition:
        --     Returns  string, with identified segment, or all
        local r;
        local s, m = target( attempt, true );
        if m == 2 then
            local sub = s:match( "/([^/]+)$" );
            if sub then
                r = sub;
            else
                r = s;
            end
        else
            r = false;
        end
        return r;
    end -- WLink.getBaseTitle()
    
    function WLink.getEscapedTitle( attempt )
        -- Retrieve escaped link title
        -- Precondition:
        --     attempt  -- string, with presumable link title
        -- Postcondition:
        --     Returns  string, with suitable link title
        local s = mw.text.trim( attempt );
        return s:gsub( "\n", " " )
                :gsub( "%[", "&#91;" )
                :gsub( "%]", "&#93;" )
                :gsub( "|",  "&#124;" );
    end -- WLink.getEscapedTitle()
    
    function WLink.getExtension( attempt )
        -- Retrieve media extension
        -- Precondition:
        --     attempt  -- string, with wikilink (media link) or page title
        --                         if URL, PDF may be detected
        -- Postcondition:
        --     Returns  string, with detected downcased media type
        --              false if no extension found
        local r = false;
        local s, m = target( attempt );
        if m == 2 then
            s = s:match( "%.(%a+)$" );
            if s then
                r = s:lower();
            end
        elseif s:upper():match( "[%./](PDF)%W?" ) then
            r = "pdf";
        end
        return r;
    end -- WLink.getExtension()
    
    
    
    function WLink.getFile( attempt )
        -- Retrieve media page identifier
        -- Precondition:
        --     attempt  -- string, with wikilink (media link) or page title
        -- Postcondition:
        --     Returns  string, with detected file title
        --                      no namespace nor project
        --              false if no file found
        local r = false;
        local s, m = target( attempt );
        if m == 2 then
            local slow    = ":" .. s:lower();
            local find = function ( a )
                             local seek = string.format( ":%s:().+%%.%%a+$",
                                                         a:lower() );
                             local join = slow:find( seek );
                             local ret;
                             if join then
                                 ret = s:sub( join + #a + 1 );
                             end
                             return ret;
                         end;
            r = find( "file" );
            if not r then
                local trsl = mw.site.namespaces[6];
                r = find( trsl.name );
                if not r then
                    trsl = trsl.aliases;
                    for k, v in pairs( trsl ) do
                        r = find( v );
                        if r then
                            break; -- for k, v
                        end
                    end -- for k, v
                end
            end
        end
        return r;
    end -- WLink.getFile()
    
    
    
    function WLink.getFragment( attempt )
        -- Retrieve fragment
        -- Precondition:
        --     attempt  -- string, with presumable fragment
        -- Postcondition:
        --     Returns  string, with detected fragment
        --              false if no address found
        local r = false;
        local s, m = target( attempt );
        if s then
            local i = s:find( "#", 1, true );
            if i then
                if i > 1 then
                    s = s:sub( i - 1 );
                    i = 2;
                end
                if s:find( "&#", 1, true ) then
                    s = mw.text.decode( s );
                    i = s:find( "#", 1, true );
                    if not i then
                       s = "";
                       i = 0;
                    end
                end
                s = s:sub( i + 1 );
                r = mw.text.trim( s );
                if r == "" then
                    r = false;
                elseif m == 2 then
                    r = r:gsub( "%.(%x%x)", "%%%1" )
                         :gsub( "_", " " );
                    r = mw.uri.decode( r, "PATH" );
                end
            end
        end
        return r;
    end -- WLink.getFragment()
    
    
    
    function WLink.getLanguage( attempt )
        -- Retrieve language project identifier
        -- Precondition:
        --     attempt  -- string, with wikilink or page title
        -- Postcondition:
        --     Returns  string, with detected downcased language identifier
        --              false if no project language found
        local r = false;
        local s, m = WLink.getTarget( attempt );
        if m == 2 then
            local w = WLink.wikilink( s );
            if w  and  w.lang then
                r = w.lang;
            end
        end
        return r;
    end -- WLink.getLanguage()
    
    
    
    function WLink.getNamespace( attempt )
        -- Retrieve namespace number
        -- Precondition:
        --     attempt  -- string, with wikilink or page title
        -- Postcondition:
        --     Returns  number, of detected namespace
        --              false if no namespace found
        local r = false;
        local s, m = WLink.getTarget( attempt );
        if m == 2 then
            local w = WLink.wikilink( s );
            if w  and  not w.lang  and  not w.project  and  w.ns then
                r = w.ns;
            end
        end
        return r;
    end -- WLink.getNamespace()
    
    
    
    function WLink.getPlain( attempt )
        -- Retrieve text with all links replaced by link titles
        -- Precondition:
        --     attempt  -- string, with wikitext
        -- Postcondition:
        --     Returns  string, with modified wikitext without links
        local r = attempt;
        local i = 1;
        local j, k, n, lean, s, shift, space, suffix;
        while ( true ) do
            j = r:find( "[", i, true );
            if j then
                suffix = r:sub( j );
                i      = j + 1;
                lean   = ( r:byte( i, i ) == 91 );
                if lean then
                    s, k, n = contentWikilink( suffix );
                else
                    s, k, n = contentExtlink( suffix );
                end
                if s then
                    if k > 1 then
                        n      = n - k;
                        i      = j + k;
                        j      = i - 1;
                        suffix = r:sub( j );
                    end
                    if lean then
                        s, shift = extractWikilink( suffix );
                        if s then
                            space = s:match( "^([^:]+):" );
                            if space then
                                space = mw.site.namespaces[ space ];
                                if space then
                                    space = space.id;
                                end
                            end
                            if space == 6  or  space == 14 then
                                shift = "";
                            elseif not shift then
                                shift = s;
                            end
                        else
                            s     = "";
                            shift = "";
                        end
                    else
                        s, shift = extractExtlink( suffix );
                        if not s then
                            s = "";
                        end
                        if not shift then
                            shift = "";
                        end
                        i = i - 1;
                    end
                    if j > 1 then
                        s = r:sub( 1, j - 1 );
                    else
                        s = "";
                    end
                    r = string.format( "%s%s%s",
                                       s,  shift,  r:sub( n + i ) );
                    i = i + #shift;
                else
                    break; -- while true
                end
            else
                break; -- while true
            end
        end -- while true
        return r;
    end -- WLink.getPlain()
    
    
    
    function WLink.getProject( attempt )
        -- Retrieve wikifarm project identifier
        -- Precondition:
        --     attempt  -- string, with wikilink or page title
        -- Postcondition:
        --     Returns  string, with detected downcased project identifier
        --              false if no project identifier found
        local r = false;
        local s, m = WLink.getTarget( attempt );
        if m == 2 then
            local w = WLink.wikilink( s );
            if w  and  w.project then
                r = w.project;
            end
        end
        return r;
    end -- WLink.getProject()
    
    
    
    function WLink.getTarget( attempt )
        -- Retrieve first target (wikilink or URL)
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  string, number
        --                  string, with first detected link target
        --                  number, with number of brackets, if found
        --              false if nothing found
        local r1 = false;
        local r2 = false;
        local i  = attempt:find( "[", 1, true );
        if i then
            local m;
            r1 = attempt:sub( i );
            if r1:byte( 2, 2 ) == 91 then
                m  = 2;
                r1 = extractWikilink( r1 );
            else
                m  = 1;
                r1 = extractExtlink( r1 );
            end
            if r1 then
                r2 = m;
            end
        else
            r1 = attempt:match( "%A?([hf]t?tps?://%S+)%s?" );
            if r1 then
                if utilURL().isResourceURL( r1 ) then
                    r2 = 0;
                else
                    r1 = false;
                end
            else
                r1 = false;
            end
        end
        return r1, r2;
    end -- WLink.getTarget()
    
    
    
    function WLink.getTargetPage( attempt )
        -- Retrieve first target page (page name or URL of page)
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  string, with first detected linked page
        --              false if nothing found
        local r1, r2 = WLink.getTarget( attempt );
        if r1 then
            local i = r1:find( "#", 1, true );
            if i then
                if i == 1 then
                    r1 = false;
                else
                    r1 = mw.text.trim( r1:sub( 1,  i - 1 ) );
                end
            end
        end
        return r1, r2;
    end -- WLink.getTargetPage()
    
    
    
    function WLink.getTitle( attempt )
        -- Retrieve first link title (wikilink or URL), or wikilink target
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  string, with first detected link target
        --              false if nothing found
        local r = false;
        local i = attempt:find( "[", 1, true );
        if i then
            local s1, s2;
            r = attempt:sub( i );
            if r:byte( 2, 2 ) == 91 then
                s1, s2 = extractWikilink( r );
                if s2 then
                    r = s2;
                else
                    r = s1;
                end
            else
                s1, r = extractExtlink( r );
            end
        end
        return r;
    end -- WLink.getTitle()
    
    
    
    function WLink.getWeblink( attempt, anURLutil )
        -- Retrieve bracketed link from resource URL
        -- Precondition:
        --     attempt    -- string, with URL, or something different
        --     anURLutil  -- library module object, or nil
        -- Postcondition:
        --     Returns  string, with first detected link target
        --              false if nothing found
        local second = ".ac.co.go.gv.or.";
        local r;
        if type( anURLutil ) == "table" then
            URLutil = anURLutil;
        else
            utilURL();
        end
        if URLutil.isResourceURL( attempt ) then
            local site = URLutil.getAuthority( attempt );
            local show;
            if #attempt == #site then
               site = site .. "/";
            end
            show = URLutil.getTop3domain( "//" .. site );
            if show then
                local scan   = "[%./](%a+)(%.%l%l%.)(%a+)$";
                local search = "." .. show;
                local s1, s2, s3 = search:match( scan );
                if s2 then
                    if not second:find( s2, 1, true ) then
                        show = string.format( "%s.%s", s2, s3 );
                    end
                else
                    show = false;
                end
            end
            if not show then
                show = URLutil.getTop2domain( "//" .. site );
                if not show then
                    show = URLutil.getHost( "//" .. site );
                end
            end
            r = string.format( "[%s %s]", attempt, show );
        else
            r = attempt;
        end
        return r;
    end -- WLink.getWeblink()
    
    
    
    function WLink.isBracketedLink( attempt )
        -- Does attempt match a bracketed link?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local r = false;
        local i = attempt:find( "[", 1, true );
        if i then
            local s = attempt:sub( i );
            if s:byte( 2, 2 ) == 91 then
                s = extractWikilink( s );
            else
                s = extractExtlink( s );
            end
            if s then
                r = true;
            end
        end
        return r;
    end -- WLink.isBracketedLink()
    
    
    
    function WLink.isBracketedURL( attempt )
        -- Does attempt match a bracketed URL?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local s, r = WLink.getTarget( attempt );
        return ( r == 1 );
    end -- WLink.isBracketedURL()
    
    
    
    function WLink.isCategorization( attempt )
        -- Does attempt match a categorization?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local r = false;
        local s, m = WLink.getTarget( attempt );
        if m == 2 then
            local w = WLink.wikilink( s );
            if w  and  w.ns == 14
                  and  not ( w.lead or w.lang or w.project )
                  and  w.title ~= "" then
                r = true;
            end
        end
        return r;
    end -- WLink.isCategorization()
    
    
    
    function WLink.isExternalLink( attempt )
        -- Does attempt match an external link?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local s, r = WLink.getTarget( attempt );
        if r then
            r = ( r < 2 );
        end
        return r;
    end -- WLink.isExternalLink()
    
    
    
    function WLink.isInterlanguage( attempt )
        -- Does attempt match an interlanguage link?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local r = false;
        local s, m = WLink.getTarget( attempt );
        if m == 2 then
            local w = WLink.wikilink( s );
            if w and w.lang and not w.project and not w.lead
                 and  w.title ~= "" then
                r = true;
            end
        end
        return r;
    end -- WLink.isInterlanguage()
    
    
    
    function WLink.isInterwiki( attempt )
        -- Does attempt match an interwiki link within wikifarm?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local r = false;
        local s, m = WLink.getTarget( attempt );
        if m == 2 then
            local w = WLink.wikilink( s );
            if w  and  ( w.lang or w.project )  and  w.title ~= "" then
                r = true;
            end
        end
        return r;
    end -- WLink.isInterwiki()
    
    
    
    function WLink.isMedia( attempt )
        -- Does attempt match a media translusion?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local r = false;
        local s, m = WLink.getTarget( attempt );
        if m == 2 then
            local w = WLink.wikilink( s );
            if w  and  w.ns == 6
               and  not ( w.lead or w.lang or w.project )
               and  w.title ~= ""
               and  WLink.getExtension( w.title ) then
                r = true;
            end
        end
        return r;
    end -- WLink.isMedia()
    
    
    
    function WLink.isTitledLink( attempt )
        -- Does attempt match a titled link?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local r = false;
        local i = attempt:find( "[", 1, true );
        if i then
            local c, n;
            local s = attempt:sub( i );
            if s:byte( 2, 2 ) == 91 then
                n = s:find( "%]%]", 5 );
                c = "|";
            else
                n = s:find( "%]", 8 );
                c = "%s%S";
            end
            if n then
                local m = s:find( c, 2 );
                if m  and  m + 1 < n  and  WLink.getTarget( attempt ) then
                    r = true;
                end
            end
        end
        return r;
    end -- WLink.isTitledLink()
    
    
    
    function WLink.isValidLink( attempt )
        -- Does attempt match a link?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local s, r = WLink.getTarget( attempt );
        if r then
            r = true;
        end
        return r;
    end -- WLink.isValidLink()
    
    
    
    function WLink.isWikilink( attempt )
        -- Does attempt match a wikilink?
        -- Precondition:
        --     attempt  -- string, with presumable link somewhere
        -- Postcondition:
        --     Returns  boolean
        local s, m = WLink.getTarget( attempt );
        return ( m == 2 );
    end -- WLink.isWikilink()
    
    
    
    function WLink.wikilink( attempt )
        -- Retrieve wikilink components
        -- Precondition:
        --     attempt  -- string, with presumable link
        --                         expected to be enclosed in "[[" "]]"
        --                         else wikilink
        -- Postcondition:
        --     Returns  table or false
        --              table of assignments with { type, value}
        --                       type is one of "lead",
        --                          "project", "lang",
        --                          "ns", "space", "title"
        --              false if nothing found
        local s = contentWikilink( attempt );
        local got, n, r;
        if not s then
            s = attempt;
        end
        i = s:find( "|", 1, true );
        if i then
            s = s:sub( 1, i - 1 );
        end
        got = mw.text.split( s, ":" );
        n   = table.maxn( got );
        if n == 1 then
            r = { title = mw.text.trim( s ) };
        else
            local j, k, o, v;
            r = { title = "" };
            if n > 4 then
                k = 4;
            else
                k = n - 1;
            end
            j = k;
            for i = 1, j do
                s = mw.text.trim( got[ i ] );
                if s ~= "" then
                    o = mw.site.namespaces[ mw.text.trim( got[ i ] ) ];
                    if o then
                        r.ns    = o.id;
                        r.space = o.name;
                        k = i + 1;
                        j = i - 1;
                        break; -- for i
                    end
                end
            end -- for i
            for i = 1, j do
                o, v = prefix( got[ i ],  ( i == 1 ) );
                if o then
                    if r[ o ] then
                        k = i;
                        break; -- for i
                    else
                        r[ o ] = v;
                    end
                else
                    k = i;
                    break; -- for i
                end
            end -- for i
            for i = k, n do
                r.title = r.title .. got[ i ];
                if i < n then
                    r.title = r.title .. ":";
                end
            end -- for i
        end
        if r.lead and
           ( r.project  or  not r.title  or
             ( not r.lang  and  r.ns ~= 6  and  r.ns ~= 14 ) ) then
            r.lead = false;
        end
        return r;
    end -- WLink.wikilink()
    
    
    
    function WLink.failsafe( assert )
        -- Retrieve versioning and check for compliance
        -- Precondition:
        --     assert  -- string, with required version, or false
        -- Postcondition:
        --     Returns  string with appropriate version, or false
        local r;
        if assert  and  assert > WLink.serial then
            r = false;
        else
            r = WLink.serial;
        end
        return r
    end -- WLink.failsafe()
    
    
    
    local function Template( frame, action, leave, lone )
        -- Run actual code from template transclusion
        -- Precondition:
        --     frame   -- object
        --     action  -- string, with function name
        --     leave   -- true: keep whitespace around
        --     lone    -- true: permit call without parameters
        -- Postcondition:
        --     Return string; might be error message
        local lucky = true;
        local s = false;
        local r = false;
        local space;
        for k, v in pairs( frame.args ) do
            if k == 1 then
                if leave then
                    s = v;
                else
                    s = mw.text.trim( v );
                end
            elseif action == "ansiPercent"  and  k == "space" then
                if v ~= "" then
                    space = v;
                end
            elseif k ~= "template" then
                lucky = false;
                if r then
                    r = r .. "|";
                else
                    r = "Unknown parameter: ";
                end
                r = string.format( "%s%s=", r, k );
            end
        end -- for k, v
        if lucky then
            if s or lone then
                lucky, r = pcall( WLink[ action ],  s,  space );
            else
                r = "Parameter missing";
                lucky = false;
            end
        end
        if lucky then
            if type( r ) == "boolean" then
                if r then
                    r = "1";
                else
                    r = "";
                end
            end
        else
            r = string.format( "<span class=\"error\">%s</span>", r );
        end
        return r;
    end -- Template()
    
    
    
    -- Export
    local p = { };
    
    p.ansiPercent = function ( frame )
        return Template( frame, "ansiPercent" );
    end
    p.formatURL = function ( frame )
        return Template( frame, "formatURL" );
    end
    p.getArticleBase = function ( frame )
        return Template( frame, "getArticleBase", false, true );
    end
    p.getBaseTitle = function ( frame )
        return Template( frame, "getBaseTitle" );
    end
    p.getEscapedTitle = function ( frame )
        return Template( frame, "getEscapedTitle" );
    end
    p.getExtension = function ( frame )
        return Template( frame, "getExtension" );
    end
    p.getFile = function ( frame )
        return Template( frame, "getFile" );
    end
    p.getFragment = function ( frame )
        return Template( frame, "getFragment" );
    end
    p.getInterwiki = function ( frame )
        return Template( frame, "getInterwiki" );
    end
    p.getLanguage = function ( frame )
        return Template( frame, "getLanguage" );
    end
    p.getNamespace = function ( frame )
        return tostring( Template( frame, "getNamespace" ) );
    end
    p.getPlain = function ( frame )
        return Template( frame, "getPlain" );
    end
    p.getProject = function ( frame )
        return Template( frame, "getProject" );
    end
    p.getTarget = function ( frame )
        return Template( frame, "getTarget" );
    end
    p.getTargetPage = function ( frame )
        return Template( frame, "getTargetPage" );
    end
    p.getTitle = function ( frame )
        return Template( frame, "getTitle" );
    end
    p.getWeblink = function ( frame )
        return Template( frame, "getWeblink" );
    end
    p.isBracketedLink = function ( frame )
        return Template( frame, "isBracketedLink" );
    end
    p.isBracketedURL = function ( frame )
        return Template( frame, "isBracketedURL" );
    end
    p.isCategorization = function ( frame )
        return Template( frame, "isCategorization" );
    end
    p.isExternalLink = function ( frame )
        return Template( frame, "isExternalLink" );
    end
    p.isInterlanguage = function ( frame )
        return Template( frame, "isInterlanguage" );
    end
    p.isInterwiki = function ( frame )
        return Template( frame, "isInterwiki" );
    end
    p.isMedia = function ( frame )
        return Template( frame, "isMedia" );
    end
    p.isTitledLink = function ( frame )
        return Template( frame, "isTitledLink" );
    end
    p.isValidLink = function ( frame )
        return Template( frame, "isValidLink" );
    end
    p.isWeblink = function ( frame )
        return Template( frame, "isWeblink" );
    end
    p.isWikilink = function ( frame )
        return Template( frame, "isWikilink" );
    end
    p.failsafe = function ( frame )
        local since = frame.args[ 1 ];
        if since then
            since = mw.text.trim( since );
            if since == "" then
                since = false;
            end
        end
        return WLink.failsafe( since ) or "";
    end
    p.WLink = function ()
        return WLink;
    end
    
    return p;
    
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