adaptors

.rustfmt.toml

@@ -0,0 +1,3 @@
+imports_granularity = "Crate"
+newline_style = "Unix"
+group_imports = "StdExternalCrate"

src/strategy.rs

@@ -0,0 +1,46 @@
+use core::marker::PhantomData;
+
+use stuff::Backend;
+
+pub trait SafeStuffingStrategy<B> {
+    type Extra;
+
+    fn stuff_extra(extra: &Self::Extra) -> B;
+
+    fn extract_extra(addr: B) -> Option<Self::Extra>;
+}
+
+/// An internal type to convert from the safe to the unsafe trait
+pub(crate) struct SafeStrategyAdaptor<S>(PhantomData<S>);
+
+// SAFETY: `extract_extra` panics if an invalid extra is returned
+//         `stuff_extra` never drops the extra
+//         pointer stuffing is just identity
+unsafe impl<S, B> stuff::StuffingStrategy<B> for SafeStrategyAdaptor<S>
+where
+    S: SafeStuffingStrategy<B>,
+{
+    type Extra = S::Extra;
+
+    fn is_extra(data: B) -> bool {
+        S::extract_extra(data).is_some()
+    }
+
+    fn stuff_extra(inner: Self::Extra) -> B {
+        let b = S::stuff_extra(&inner);
+        core::mem::forget(inner);
+        b
+    }
+
+    unsafe fn extract_extra(data: B) -> Self::Extra {
+        S::extract_extra(data).unwrap()
+    }
+
+    fn stuff_ptr(addr: usize) -> B {
+        addr
+    }
+
+    fn extract_ptr(inner: B) -> usize {
+        inner
+    }
+}