LuaItemStack: Add __tostring metamethod (#8785)

* LuaItemStack: Add __tostring metamethod

* Clean up LuaItemStack::checkobject

5 files changed, 41 insertions, 22 deletions

diff --git a/builtin/common/misc_helpers.lua b/builtin/common/misc_helpers.lua
index a88adf96d..e29a9f422 100644
--- a/builtin/common/misc_helpers.lua
+++ b/builtin/common/misc_helpers.lua
@@ -20,6 +20,8 @@ local function basic_dump(o)
 	-- dump's output is intended for humans.
 	--elseif tp == "function" then
 	--	return string.format("loadstring(%q)", string.dump(o))
+	elseif tp == "userdata" then
+		return tostring(o)
 	else
 		return string.format("<%s>", tp)
 	end
diff --git a/src/inventory.cpp b/src/inventory.cpp
index 77ecf5876..349ee503d 100644
--- a/src/inventory.cpp
+++ b/src/inventory.cpp
@@ -56,28 +56,31 @@ ItemStack::ItemStack(const std::string &name_, u16 count_,
 		count = 1;
 }
 
-void ItemStack::serialize(std::ostream &os) const
+void ItemStack::serialize(std::ostream &os, bool serialize_meta) const
 {
 	if (empty())
 		return;
 
 	// Check how many parts of the itemstring are needed
 	int parts = 1;
-	if(count != 1)
-		parts = 2;
-	if(wear != 0)
-		parts = 3;
 	if (!metadata.empty())
 		parts = 4;
+	else if (wear != 0)
+		parts = 3;
+	else if (count != 1)
+		parts = 2;
 
-	os<<serializeJsonStringIfNeeded(name);
-	if(parts >= 2)
-		os<<" "<<count;
-	if(parts >= 3)
-		os<<" "<<wear;
+	os << serializeJsonStringIfNeeded(name);
+	if (parts >= 2)
+		os << " " << count;
+	if (parts >= 3)
+		os << " " << wear;
 	if (parts >= 4) {
 		os << " ";
-		metadata.serialize(os);
+		if (serialize_meta)
+			metadata.serialize(os);
+		else
+			os << "<metadata size=" << metadata.size() << ">";
 	}
 }
 
@@ -240,10 +243,10 @@ void ItemStack::deSerialize(const std::string &str, IItemDefManager *itemdef)
 	deSerialize(is, itemdef);
 }
 
-std::string ItemStack::getItemString() const
+std::string ItemStack::getItemString(bool include_meta) const
 {
 	std::ostringstream os(std::ios::binary);
-	serialize(os);
+	serialize(os, include_meta);
 	return os.str();
 }
 
diff --git a/src/inventory.h b/src/inventory.h
index 2828d3e5a..67a7859ed 100644
--- a/src/inventory.h
+++ b/src/inventory.h
@@ -40,13 +40,13 @@ struct ItemStack
 	~ItemStack() = default;
 
 	// Serialization
-	void serialize(std::ostream &os) const;
+	void serialize(std::ostream &os, bool serialize_meta = true) const;
 	// Deserialization. Pass itemdef unless you don't want aliases resolved.
 	void deSerialize(std::istream &is, IItemDefManager *itemdef = NULL);
 	void deSerialize(const std::string &s, IItemDefManager *itemdef = NULL);
 
 	// Returns the string used for inventory
-	std::string getItemString() const;
+	std::string getItemString(bool include_meta = true) const;
 	// Returns the tooltip
 	std::string getDescription(IItemDefManager *itemdef) const;
 
diff --git a/src/script/lua_api/l_item.cpp b/src/script/lua_api/l_item.cpp
index 0a403acbd..d67cab76f 100644
--- a/src/script/lua_api/l_item.cpp
+++ b/src/script/lua_api/l_item.cpp
@@ -37,6 +37,15 @@ int LuaItemStack::gc_object(lua_State *L)
 	return 0;
 }
 
+// __tostring metamethod
+int LuaItemStack::mt_tostring(lua_State *L)
+{
+	LuaItemStack *o = checkobject(L, 1);
+	std::string itemstring = o->m_stack.getItemString(false);
+	lua_pushfstring(L, "ItemStack(\"%s\")", itemstring.c_str());
+	return 1;
+}
+
 // is_empty(self) -> true/false
 int LuaItemStack::l_is_empty(lua_State *L)
 {
@@ -433,12 +442,9 @@ int LuaItemStack::create(lua_State *L, const ItemStack &item)
 	return 1;
 }
 
-LuaItemStack* LuaItemStack::checkobject(lua_State *L, int narg)
+LuaItemStack *LuaItemStack::checkobject(lua_State *L, int narg)
 {
-	luaL_checktype(L, narg, LUA_TUSERDATA);
-	void *ud = luaL_checkudata(L, narg, className);
-	if(!ud) luaL_typerror(L, narg, className);
-	return *(LuaItemStack**)ud;  // unbox pointer
+	return *(LuaItemStack **)luaL_checkudata(L, narg, className);
 }
 
 void LuaItemStack::Register(lua_State *L)
@@ -448,9 +454,10 @@ void LuaItemStack::Register(lua_State *L)
 	luaL_newmetatable(L, className);
 	int metatable = lua_gettop(L);
 
+	// hide metatable from Lua getmetatable()
 	lua_pushliteral(L, "__metatable");
 	lua_pushvalue(L, methodtable);
-	lua_settable(L, metatable);  // hide metatable from Lua getmetatable()
+	lua_settable(L, metatable);
 
 	lua_pushliteral(L, "__index");
 	lua_pushvalue(L, methodtable);
@@ -460,12 +467,16 @@ void LuaItemStack::Register(lua_State *L)
 	lua_pushcfunction(L, gc_object);
 	lua_settable(L, metatable);
 
+	lua_pushliteral(L, "__tostring");
+	lua_pushcfunction(L, mt_tostring);
+	lua_settable(L, metatable);
+
 	lua_pop(L, 1);  // drop metatable
 
 	luaL_openlib(L, 0, methods, 0);  // fill methodtable
 	lua_pop(L, 1);  // drop methodtable
 
-	// Can be created from Lua (LuaItemStack(itemstack or itemstring or table or nil))
+	// Can be created from Lua (ItemStack(itemstack or itemstring or table or nil))
 	lua_register(L, className, create_object);
 }
 
diff --git a/src/script/lua_api/l_item.h b/src/script/lua_api/l_item.h
index 6fab58045..98744c071 100644
--- a/src/script/lua_api/l_item.h
+++ b/src/script/lua_api/l_item.h
@@ -34,6 +34,9 @@ private:
 	// garbage collector
 	static int gc_object(lua_State *L);
 
+	// __tostring metamethod
+	static int mt_tostring(lua_State *L);
+
 	// is_empty(self) -> true/false
 	static int l_is_empty(lua_State *L);