Initial implementation of owned Lua types

src/string.rs

@@ -12,7 +12,7 @@ use {
 
 use crate::error::{Error, Result};
 use crate::ffi;
-use crate::types::LuaRef;
+use crate::types::{LuaOwnedRef, LuaRef};
 
 /// Handle to an internal Lua string.
 ///
@@ -20,6 +20,17 @@ use crate::types::LuaRef;
 #[derive(Clone, Debug)]
 pub struct String<'lua>(pub(crate) LuaRef<'lua>);
 
+/// Owned handle to an internal Lua string.
+#[derive(Clone, Debug)]
+pub struct OwnedString(pub(crate) LuaOwnedRef);
+
+impl OwnedString {
+    /// Get borrowed handle to the underlying Lua string.
+    pub const fn to_ref(&self) -> String {
+        String(self.0.to_ref())
+    }
+}
+
 impl<'lua> String<'lua> {
     /// Get a `&str` slice if the Lua string is valid UTF-8.
     ///
@@ -122,6 +133,12 @@ impl<'lua> String<'lua> {
         let ref_thread = self.0.lua.ref_thread();
         unsafe { ffi::lua_topointer(ref_thread, self.0.index) }
     }
+
+    /// Convert this handle to owned version.
+    #[inline]
+    pub fn into_owned(self) -> OwnedString {
+        OwnedString(self.0.into_owned())
+    }
 }
 
 impl<'lua> AsRef<[u8]> for String<'lua> {