--nef_20230307
do             -- DEMO
-- SOH   
   local function min_path(...)
     min_path = assert(game.min_path,'minpath not loaded.'); return min_path(...) end
   
   local featured = setmetatable({},{  -- FEATURED_TEXT
     __index = function(t,k) local ft = assert(log.featured, 'Featured text not loaded')
       return assert(ft[k], 'Featured '..k..' not loaded.'  ) end;}) 
   local function ftext (...) ftext = featured.ftext; return ftext (...) end

   local SP       = setmetatable({},{  -- SUPPORT_basic
     __index = function(t,k) local SP = assert(game.SP, 'Support package not loaded')
       return assert(SP[k], 'Support '..k..' not loaded.') end;}) 
   local function user  (...) user   = SP.user;       return user  (...) end
   local function colored_link(...) 
                colored_link = SP.colored_link; return colored_link(...) end
-- SUPPORT_extended
   local function get_link_bb(...)
                get_link_bb  = SP.get_link_bb;  return get_link_bb (...) end
-- STX
   local report = function(tile,...)
     if chat then chat.msg(...)     log.normal(...)
     else notify.event(user(),tile,E.BROADCAST_REPORT,...) end
   end
   
   local wrap, type = coroutine.wrap, tolua.type

   local path_demo = { -- destination and city added by demo() 
-- boolean    (Tile):has_extra          (string (rule_name)) 
       edger      = function (_ENV, distance, tile, neighbour)
         if false then
         elseif neighbour:has_extra('railroad') then return 10
         elseif neighbour:has_extra('road')     then return 12
         end        end;
-- City	   (Tile):city	             ()
       terminator = function (_ENV, distance, tile) city = tile:city ();
         return (tile == destination or not destination and city) and distance
                    end;
                     }
-- Tile          (City).tile
   function demo(city1,city2,mc)
     city1 = get_link_bb(city1); city2 = get_link_bb(city2)
     assert(type(city1) == 'City','Arg. 1 must be a city' )
     mc = type(mc) == 'number' and mc > 0 and mc or 1
     local _ENV, path, iterate = path_demo
     destination = type(city2) == 'City' and city2.tile 
     for i = 1, mc do local co = wrap(min_path)
         repeat city = nil; path, iterate = co (_ENV, city1.tile)
                if mc == i and (destination or city) then
                   report(nil, (path and 'Path length = '..path or 'No path')..
                            ' from city ' ..ftext(city1)..
                            ' to '        ..colored_link(city2 or city) ..
                            '' )
                end
         until destination or not path 
     end
     
     if destination and path then
        do  report(destination, colored_link(destination)..' ('..path..')'); end
        for destination, path in iterate(destination)
        do  report(destination, colored_link(destination)..' ('..path..')'); end
     end
   end
-- EOT
end
------------  end DEMO