wesnoth/data/ai/lua/patrol.lua

function patrol_gen(n, wp) 	-- n is the name of the unit, like Kiressh
				-- wp - a table of waypoint tables of form {x,y}

	local unit = wesnoth.get_units({name=n})[1]
	
	local x, y = unit.x, unit.y
	local wpn = 1 --WayPoint Number - we have to remember which waypoint we are heading to

	if (x == wp[1].x and y == wp[1].y) then
		wpn = wpn + 1
		--w1, w2 = w2, w2 -- if we are standing on the first waypoint, swap them
	end

	--local waypoints = {w1, w2}	  -- this form might be just received from the args
	local wpcount = # wp 

	
	local patrol = {}
		
	patrol.exec = function()
		x, y = unit.x, unit.y
		if (x == wp[wpn].x and y == wp[wpn].y) then
			wpn = wpn % wpcount + 1 -- advance by one waypoint(this construct loops in range [1, wpcount])
		end
		ai.move_full(unit, wp[wpn].x, wp[wpn].y) -- @note: should we change this to ai.move()?
	end
	
	patrol.eval = function()
		return 300000
	end

	return patrol
end