add inventory.decrement, inventory.set_count

res/scripts/stdlib.lua

@@ -102,7 +102,6 @@ function inventory.get_uses(invid, slot)
     return uses
 end
 
-
 function inventory.use(invid, slot)
     local itemid, count = inventory.get(invid, slot)
     if itemid == nil then
@@ -119,6 +118,16 @@ function inventory.use(invid, slot)
     end
 end
 
+function inventory.decrement(invid, slot, count)
+    count = count or 1
+    local itemid, itemcount = inventory.get(invid, slot)
+    if itemcount <= count then
+        inventory.set(invid, slot, 0)
+    else
+        inventory.set_count(invid, slot, itemcount - count)
+    end
+end
+
 ------------------------------------------------
 ------------------- Events ---------------------
 ------------------------------------------------

src/logic/scripting/lua/libs/libinventory.cpp

@@ -71,6 +71,15 @@ static int l_set(lua::State* L, ItemStack& item) {
     return 0;
 }
 
+static int l_set_count(lua::State* L, ItemStack& item) {
+    auto count = lua::tointeger(L, 3);
+    if (item.getItemId() == ITEM_EMPTY) {
+        return 0;
+    }
+    item.setCount(count);
+    return 0;
+}
+
 static int l_size(lua::State* L) {
     auto invid = lua::tointeger(L, 1);
     const auto& inv = get_inventory(invid);
@@ -226,6 +235,7 @@ static int l_set_data(lua::State* L, ItemStack& stack) {
 const luaL_Reg inventorylib[] = {
     {"get", wrap_slot<l_get>},
     {"set", wrap_slot<l_set>},
+    {"set_count", wrap_slot<l_set_count>},
     {"size", lua::wrap<l_size>},
     {"add", lua::wrap<l_add>},
     {"move", lua::wrap<l_move>},