Add Minetest Luon: ItemStack and AreaStore support

minetest.lua

@@ -9,4 +9,5 @@ load"raycast"
 load"wielditem_change"
 load"colorspec"
 load"schematic"
+load"luon"
 return _ENV

minetest/luon.lua

@@ -0,0 +1,29 @@
+-- Localize globals
+local getmetatable, AreaStore, ItemStack
+    = getmetatable, AreaStore, ItemStack
+
+-- Metatable lookup for classes specified in lua_api.txt, section "Class reference"
+local AreaStoreMT = getmetatable(AreaStore())
+local ItemStackMT = getmetatable(ItemStack"")
+local metatables = {
+    [AreaStoreMT] = {name = "AreaStore", method = AreaStoreMT.to_string},
+    [ItemStackMT] = {name = "ItemStack", method = ItemStackMT.to_table},
+    -- TODO expand
+}
+
+(...).luon = modlib.luon.new{
+    aux_write = function(_, value)
+        local type = metatables[getmetatable(value)]
+        if type then
+            return type.name, type.method(value)
+        end
+    end,
+    aux_read = {
+        AreaStore = function(...)
+            local store = AreaStore()
+            store:from_string(...)
+            return store
+        end,
+        ItemStack = ItemStack
+    }
+}

test.lua

@@ -238,6 +238,8 @@ end
 
 if not _G.minetest then return end
 
+assert(minetest.luon:read_string(minetest.luon:write_string(ItemStack"")))
+
 -- colorspec
 local colorspec = minetest.colorspec
 local function test_from_string(string, number)