Module:WLink

 local WLink = { suite = "WLink",
 serial = "2016年10月05日" };
 --[=[
 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( " ", " " )
 :gsub( " ", " " )
 :gsub( " ", " " )
 :gsub( " ", " " )
 :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;