add an 'equals' method to ItemStack and compatibility w/ lua '==' (#12771)

Co-authored-by: rubenwardy <rw@rubenwardy.com>
Co-authored-by: sfan5 <sfan5@live.de>

2 files changed, 37 insertions, 0 deletions

diff --git a/src/script/lua_api/l_item.cpp b/src/script/lua_api/l_item.cpp
index c555e90fd..f33dd1fef 100644
--- a/src/script/lua_api/l_item.cpp
+++ b/src/script/lua_api/l_item.cpp
@@ -433,6 +433,38 @@ int LuaItemStack::l_peek_item(lua_State *L)
 	return 1;
 }
 
+// equals(self, other) -> bool
+int LuaItemStack::l_equals(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+	LuaItemStack *o1 = checkObject<LuaItemStack>(L, 1);
+
+ 	// checks for non-userdata argument
+	if (!lua_isuserdata(L, 2)) {
+		lua_pushboolean(L, false);
+		return 1;
+	}
+
+ 	// check that the argument is an ItemStack
+	if (!lua_getmetatable(L, 2)) {
+		lua_pushboolean(L, false);
+		return 1;
+	}
+	lua_getfield(L, LUA_REGISTRYINDEX, className);
+	if (!lua_rawequal(L, -1, -2)) {
+		lua_pushboolean(L, false);
+		return 1;
+	}
+
+	LuaItemStack *o2 = checkObject<LuaItemStack>(L, 2);
+
+	ItemStack &item1 = o1->m_stack;
+	ItemStack &item2 = o2->m_stack;
+
+	lua_pushboolean(L, item1 == item2);
+	return 1;
+}
+
 LuaItemStack::LuaItemStack(const ItemStack &item):
 	m_stack(item)
 {
@@ -483,6 +515,7 @@ void LuaItemStack::Register(lua_State *L)
 	static const luaL_Reg metamethods[] = {
 		{"__tostring", mt_tostring},
 		{"__gc", gc_object},
+		{"__eq", l_equals},
 		{0, 0}
 	};
 	registerClass(L, className, methods, metamethods);
@@ -522,6 +555,7 @@ const luaL_Reg LuaItemStack::methods[] = {
 	luamethod(LuaItemStack, item_fits),
 	luamethod(LuaItemStack, take_item),
 	luamethod(LuaItemStack, peek_item),
+	luamethod(LuaItemStack, equals),
 	{0,0}
 };
 
diff --git a/src/script/lua_api/l_item.h b/src/script/lua_api/l_item.h
index 8f4b25cf4..a4cc706d8 100644
--- a/src/script/lua_api/l_item.h
+++ b/src/script/lua_api/l_item.h
@@ -140,6 +140,9 @@ private:
 	// peek_item(self, peekcount=1) -> itemstack
 	static int l_peek_item(lua_State *L);
 
+	// equals(self, other) -> bool
+	static int l_equals(lua_State *L);
+
 public:
 	DISABLE_CLASS_COPY(LuaItemStack)