ACTUALLY expose `RegistryKey` API

Also fixes a safety issue with RegistryKey, where you could use RegistryKeys
with mismatching Lua instances.

1 files changed, 25 insertions, 4 deletions

diff --git a/src/types.rs b/src/types.rs
index 21384a1..0d4c5ec 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,5 +1,6 @@
 use std::fmt;
 use std::os::raw::{c_int, c_void};
+use std::rc::Rc;
 
 use ffi;
 use error::Result;
@@ -15,12 +16,32 @@ pub type Number = ffi::lua_Number;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct LightUserData(pub *mut c_void);
 
+// Clone-able id where every clone of the same id compares equal, and are guaranteed unique.
+#[derive(Debug, Clone)]
+pub(crate) struct SharedId(Rc<()>);
+
+impl SharedId {
+    pub(crate) fn new() -> SharedId {
+        SharedId(Rc::new(()))
+    }
+}
+
+impl PartialEq for SharedId {
+    fn eq(&self, other: &SharedId) -> bool {
+        Rc::ptr_eq(&self.0, &other.0)
+    }
+}
+
+impl Eq for SharedId {}
+
 /// An auto generated key into the Lua registry.
-pub struct RegistryKey(pub(crate) c_int);
+pub struct RegistryKey {
+    pub(crate) lua_id: SharedId,
+    pub(crate) registry_id: c_int,
+}
 
-pub(crate) type Callback<'lua> = Box<
-    FnMut(&'lua Lua, MultiValue<'lua>) -> Result<MultiValue<'lua>> + 'lua,
->;
+pub(crate) type Callback<'lua> =
+    Box<FnMut(&'lua Lua, MultiValue<'lua>) -> Result<MultiValue<'lua>> + 'lua>;
 
 pub(crate) struct LuaRef<'lua> {
     pub lua: &'lua Lua,