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|
-- occupation.lua
--[[
Collects and manages positions where trains occupy and/or reserve/require space
It turned out that, especially for the TSS, some more, even overlapping zones are required.
Packing those into a data structure would just become a huge mess!
Instead, this occupation system will store the path indices of positions in the corresponding.
train's paths.
So, the occupation is a reverse lookup of paths.
Then, a callback system will handle changes in those indices, as follows:
Whenever the train generates new path items (path_get/path_create), their counterpart indices will be filled in here.
Whenever a path gets invalidated or path items are deleted, their index counterpart is erased from here.
When a train needs to know whether a position is blocked by another train, it will (and is permitted to)
query the train.index and train.end_index and compare them to the blocked position's index.
Callback system for 3rd-party path checkers:
advtrains.te_register_on_new_path(func(id, train))
-- Called when a train's path is re-initalized, either when it was invalidated
-- or the saves were just loaded
-- It can be assumed that everything is in the state of when the last run
-- of on_update was made, but all indices are shifted by an unknown amount.
advtrains.te_register_on_update(func(id, train))
-- Called each step and after a train moved, its length changed or some other event occured
-- The path is unmodified, and train.index and train.end_index can be reliably
-- queried for the new position and length of the train.
-- note that this function might be called multiple times per step, and this
-- function being called does not necessarily mean that something has changed.
-- It is ensured that on_new_path callbacks are executed prior to these callbacks whenever
-- an invalidation or a reload occured.
advtrains.te_register_on_create(func(id, train))
-- Called right after a train is created, right after the initial new_path callback
advtrains.te_register_on_remove(func(id, train))
-- Called right before a train is deleted
All callbacks are allowed to save certain values inside the train table, but they must ensure that
those are reinitialized in the on_new_path callback. The on_new_path callback must explicitly
set ALL OF those values to nil or to a new updated value, and must not rely on their existence.
]]--
local o = {}
local occ = {}
local occ_chg = {}
local function occget(p)
local t = occ[p.y]
if not t then
occ[p.y] = {}
t = occ[p.y]
end
local s = t
|
