1 files changed, 200 insertions, 0 deletions
diff --git a/advtrains_interlocking/distant.lua b/advtrains_interlocking/distant.lua
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+--- Distant signaling.
+-- This module implements a database backend for distant signal assignments.
+-- The actual modifications to signal aspects are still done by signal aspect accessors.
+-- @module advtrains.interlocking.distant
+
+local db_distant = {}
+local db_distant_of = {}
+
+local pts = advtrains.encode_pos
+local stp = advtrains.decode_pos
+
+--- Replace the distant signal assignment database.
+-- @function load
+-- @param db The new database to load.
+local function db_load(x)
+	if type(x) ~= "table" then
+		return
+	end
+	db_distant = x.distant
+	db_distant_of = x.distant_of
+end
+
+--- Retrieve the current distant signal assignment database.
+-- @function save
+-- @return The current database.
+local function db_save()
+	return {
+		distant = db_distant,
+		distant_of = db_distant_of,
+	}
+end
+
+local update_signal, update_main, update_dst
+
+--- Unassign a distant signal.
+-- @function unassign_dst
+-- @param dst The position of the distant signal.
+-- @param[opt=false] force Whether to skip callbacks.
+local function unassign_dst(dst, force)
+	local pts_dst = pts(dst)
+	local main = db_distant_of[pts_dst]
+	db_distant_of[pts_dst] = nil
+	if main then
+		local pts_main = main[1]
+		local t = db_distant[pts_main]
+		if t then
+			t[pts_dst] = nil
+		end
+	end
+	if not force then
+		update_dst(dst)
+	end
+end
+
+--- Unassign a main signal.
+-- @function unassign_main
+-- @param main The position of the main signal.
+-- @param[opt=false] force Whether to skip callbacks.
+local function unassign_main(main, force)
+	local pts_main = pts(main)
+	local t = db_distant[pts_main]
+	if not t then
+		return
+	end
+	for pts_dst in pairs(t) do
+		local realmain = db_distant_of[pts_dst]
+		if realmain and realmain[1] == pts_main then
+			db_distant_of[pts_dst] = nil
+			if not force then
+				local dst = stp(pts_dst)
+				update_dst(dst)
+			end
+		end
+	end
+	db_distant[pts_main] = nil
+end
+
+--- Remove all (main and distant) signal assignments from a signal.
+-- @function unassign_all
+-- @param pos The position of the signal.
+-- @param[opt=false] force Whether to skip callbacks.
+local function unassign_all(pos, force)
+	unassign_main(pos)
+	unassign_dst(pos, force)
+end
+
+--- Check whether a signal is "appropriate" for the distant signal system.
+-- Currently, a signal is considered appropriate if its signal aspect can be set.
+-- @function appropriate_signal
+-- @param pos The position of the signal
+local function appropriate_signal(pos)
+	local node = advtrains.ndb.get_node(pos)
+	local ndef = minetest.registered_nodes[node.name] or {}
+	if not ndef then
+		return false
+	end
+	local atdef = ndef.advtrains
+	if not atdef then
+		return false
+	end
+	return atdef.supported_aspects and atdef.set_aspect and true
+end
+
+--- Assign a distant signal to a main signal.
+-- @function assign
+-- @param main The position of the main signal.
+-- @param dst The position of the distant signal.
+-- @param[opt="manual"] by The method of assignment.
+-- @param[opt=false] skip_update Whether to skip callbacks.
+local function assign(main, dst, by, skip_update)
+	if not (appropriate_signal(main) and appropriate_signal(dst)) then
+		return
+	end
+	local pts_main = pts(main)
+	local pts_dst = pts(dst)
+	local t = db_distant[pts_main]
+	if not t then
+		t = {}
+		db_distant[pts_main] = t
+	end
+	if not by then
+		by = "manual"
+	end
+	unassign_dst(dst, true)
+	t[pts_dst] = by
+	db_distant_of[pts_dst] = {pts_main, by}
+	if not skip_update then
+		update_dst(dst)
+	end
+end
+
+--- Get the distant signals assigned to a main signal.
+-- @function get_distant
+-- @param main The position of the main signal.
+-- @treturn {[pos]=by,...} A table of distant signals, with the positions encoded using `advtrains.encode_pos`.
+local function get_distant(main)
+	local pts_main = pts(main)
+	return db_distant[pts_main] or {}
+end
+
+--- Get the main signal assigned the a distant signal.
+-- @function get_main
+-- @param dst The position of the distant signal.
+-- @return The position of the main signal.
+-- @return The method of assignment.
+local function get_main(dst)
+	local pts_dst = pts(dst)
+	local main = db_distant_of[pts_dst]
+	if not main then
+		return
+	end
+	if main[1] then
+		return stp(main[1]), unpack(main, 2)
+	else
+		return unpack(main)
+	end
+end
+
+--- Update all distant signals assigned to a main signal.
+-- @function update_main
+-- @param main The position of the main signal.
+update_main = function(main)
+	local pts_main = pts(main)
+	local t = get_distant(main)
+	for pts_dst in pairs(t) do
+		local dst = stp(pts_dst)
+		advtrains.interlocking.signal_readjust_aspect(dst)
+	end
+end
+
+--- Update the aspect of a distant signal.
+-- @function update_dst
+-- @param dst The position of the distant signal.
+update_dst = function(dst)
+	advtrains.interlocking.signal_readjust_aspect(dst)
+end
+
+--- Update the aspect of a combined (main and distant) signal and all distant signals assigned to it.
+-- @function update_signal
+-- @param pos The position of the signal.
+update_signal = function(pos)
+	update_main(pos)
+	update_dst(pos)
+end
+
+advtrains.distant = {
+	load = db_load,
+	save = db_save,
+	assign = assign,
+	unassign_dst = unassign_dst,
+	unassign_main = unassign_main,
+	unassign_all = unassign_all,
+	get_distant = get_distant,
+	get_dst = get_distant,
+	get_main = get_main,
+	update_main = update_main,
+	update_dst = update_dst,
+	update_signal = update_signal,
+	appropriate_signal = appropriate_signal,
+}