Modul:Str

 local Str = {} 

   function Str.len(frame)
     return mw.ustring.len(frame.args[1])
   end

   function Str.left(frame)
     local idx = tonumber(frame.args[2])
     if (not idx) or idx < 1 then
       return ""
     end
     return mw.ustring.sub(frame.args[1],1,idx)
   end

   function Str.right(frame)
     local laenge = tonumber(frame.args[2])
     if (not laenge) or laenge < 1 then
       return ""
     else
     laenge = - laenge
     end
     return mw.ustring.sub(frame.args[1],laenge,-1)
   end

   function Str.index(frame)
     local idx = tonumber(frame.args[2])
     if (not idx) or idx < 1 then
       return ""
     end
     return mw.ustring.sub(frame.args[1],idx,idx)
   end

   function Str.sub(frame)
     local von = tonumber(frame.args[2])
     local laenge = tonumber(frame.args[3])
     if (not von) or (not laenge) then
       return ""
     end
     if (von < 1) then
       von = 1
     end      
     local bis = von + laenge - 1
     if (bis < von) then
       return ""
     end
     return mw.ustring.sub(frame.args[1],von,bis)
   end

   function Str.crop(frame)
     local s = frame.args[1]
     local cut = tonumber(frame.args[2])
     local laenge =  mw.ustring.len(s)
     if (not cut) or (cut < 1) then
       return s
     end
     return mw.ustring.sub(s,1,laenge - cut)
   end

   function Str.cropleft(frame)
     local s = frame.args[1]
     local cut = tonumber(frame.args[2])
     local laenge =  mw.ustring.len(s)
     if (not cut) or (cut < 1) then
       return s
     end
     return mw.ustring.sub(s,cut+1,-1)
   end

   function Str.find(frame)
     if not frame.args[2] or frame.args[2] == "" then
       return 1
     end
     local  idx = mw.ustring.find(frame.args[1], frame.args[2],1, true)
     if idx then
         return idx
     else
         return -1
     end
   end

   function Str.hex2dez(frame)
     a = tonumber(frame.args[1],16)
     if a then
       return a
     else
       return 0
     end
   end

   function Str.match(frame)
       local text = frame.args[1] or ""
       local pattern = frame.args[2] or ""
       local index = tonumber(frame.args[3]) or 0
       if (text == "" or pattern == "") then return "" end

       -- return all captures (denoted by brackets in the pattern) if index is zero, otherwise return only the index-th capture
       if index <= 0 then
           return mw.ustring.match(text, pattern)
       else
           return ({mw.ustring.match(text, pattern)})[index]
       end
   end

return Str