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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
t = t[p.x]
if not t then
s[p.x] = {}
t = s[p.x]
end
return t[p.z]
end
local function occgetcreate(p)
local t = occ[p.y]
if not t then
occ[p.y] = {}
t = occ[p.y]
end
local s = t
t = t[p.x]
if not t then
s[p.x] = {}
t = s[p.x]
end
s = t
t = t[p.z]
if not t then
s[p.z] = {}
t = s[p.z]
end
return t
end
function o.set_item(train_id, pos, idx)
local t = occgetcreate(pos)
local i = 1
while t[i] do
if t[i]==train_id then
break
end
i = i + 2
end
t[i] = train_id
t[i+1] = idx
end
function o.clear_item(train_id, pos)
local t = occget(pos)
if not t then return end
local i = 1
local moving = false
while t[i] do
if t[i]==train_id then
if moving then
-- if, for some occasion, there should be a duplicate entry, erase this one too
atwarn("Duplicate occupation entry at",pos,"for train",train_id,":",t)
i = i - 2
end
moving = true
end
if moving then
t[i] = t[i+2]
t[i+1] = t[i+3]
end
i = i + 2
end
end
-- Checks whether some other train (apart from train_id) has it's 0 zone here
function o.check_collision(pos, train_id)
local npos = advtrains.round_vector_floor_y(pos)
local t = occget(npos)
if not t then return end
local i = 1
while t[i] do
local ti = t[i]
if ti~=train_id then
local idx = t[i+1]
local train = advtrains.trains[ti]
--atdebug("checking train",t[i],"index",idx,"<>",train.index,train.end_index)
if train and idx >= train.end_index and idx <= train.index then
--atdebug("collides.")
return train -- return train it collided with so we can couple when shunting is enabled
end
end
i = i + 2
end
return false
end
-- Gets a mapping of train id's to indexes of trains that share this path item with this train
-- The train itself will not be included.
-- If the requested index position is off-track, returns {}.
-- returns (table with train_id->index), position
function o.get_occupations(train, index)
local ppos, ontrack = advtrains.path_get(train, index)
if not ontrack then
atlog("Train",train.id,"get_occupations requested off-track",index)
return {}, ppos
end
local pos = advtrains.round_vector_floor_y(ppos)
local t = occget(pos)
if not t then return {} end
local r = {}
local i = 1
local train_id = train.id
while t[i] do
if t[i]~=train_id then
r[t[i]] = t[i+1]
end
i = i + 2
end
return r, pos
end
-- Gets a mapping of train id's to indexes of trains that stand or drive over
-- returns (table with train_id->index)
function o.get_trains_at(ppos)
local pos = advtrains.round_vector_floor_y(ppos)
local t = occget(pos)
if not t then return {} end
local r = {}
local i = 1
while t[i] do
local train = advtrains.trains[t[i]]
local idx = t[i+1]
if train.end_index - 0.5 <= idx and idx <= train.index + 0.5 then
r[t[i]] = idx
end
i = i + 2
end
return r
end
-- Gets a mapping of train id's to indexes of trains that have a path
-- generated over this node
-- returns (table with train_id->index)
function o.get_trains_over(ppos)
local pos = advtrains.round_vector_floor_y(ppos)
local t = occget(pos)
if not t then return {} end
local r = {}
local i = 1
while t[i] do
local idx = t[i+1]
r[t[i]] = idx
i = i + 2
end
return r
end
advtrains.occ = o
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