Add Luacontroller library support

Fixes upstream #557

2 files changed, 38 insertions, 0 deletions

diff --git a/mesecons/util.lua b/mesecons/util.lua
index 7fb95cc..a89d234 100644
--- a/mesecons/util.lua
+++ b/mesecons/util.lua
@@ -474,3 +474,21 @@ function mesecon.execute_autoconnect_hooks_queue(pos, node)
 		mesecon.queue:add_action(pos, "autoconnect_hook_"..name, {node})
 	end
 end
+
+-- Performs a deep copy of a table, changing the environment of any functions.
+-- Adapted from the builtin table.copy() function.
+function mesecon.tablecopy_change_env(t, env, seen)
+	local n = {}
+	seen = seen or {}
+	seen[t] = n
+	for k, v in pairs(t) do
+		if type(v) == "function" then
+			setfenv(v, env)
+			n[(type(k) == "table" and (seen[k] or mesecon.tablecopy_change_env(k, env, seen))) or k] = v
+		else
+		n[(type(k) == "table" and (seen[k] or mesecon.tablecopy_change_env(k, env, seen))) or k] =
+			(type(v) == "table" and (seen[v] or mesecon.tablecopy_change_env(v, env, seen))) or v
+		end
+	end
+	return n
+end
diff --git a/mesecons_luacontroller/init.lua b/mesecons_luacontroller/init.lua
index 1c411dd..3abe6ed 100644
--- a/mesecons_luacontroller/init.lua
+++ b/mesecons_luacontroller/init.lua
@@ -37,6 +37,24 @@ local rules = {
 	d = {x =  0, y = 0, z = -1, name="D"},
 }
 
+-- Mods can place their own "libraries" in here to be loaded via require() from in a Luacontroller.
+-- These can take two different forms:
+-- Function (recommended for libraries adding new functionality): A function that, when called, returns something that will be passed to the LuaC code.
+-- Function signature is getlibrary(env, pos) where 'env' is the environment that the Luacontroller code is running in, and 'pos' is the position of the controller.
+-- Table (recommended for libraries containing mostly lookup tables): A table that will be copied, and the copy returned to the LuaC code.
+-- When using the table format, any functions in the table will have their environment changed to that of the Luacontroller.
+mesecon.luacontroller_libraries = {}
+
+--This prepares the actual require() function that will be available in the LuaC environment.
+local function get_require(pos, env)
+	return function(name)
+		if type(mesecon.luacontroller_libraries[name]) == "function" then
+			return mesecon.luacontroller_libraries[name](env, pos)
+		elseif type(mesecon.luacontroller_libraries[name]) == "table" then
+			return mesecon.tablecopy_change_env(mesecon.luacontroller_libraries[name], env)
+		end
+	end
+end
 
 ------------------
 -- Action stuff --
@@ -546,6 +564,8 @@ local function create_environment(pos, mem, event, itbl, send_warning)
 	for _, name in pairs(safe_globals) do
 		env[name] = _G[name]
 	end
+	
+	env.require = get_require(pos, env)
 
 	return env
 end