Improve Encodable/Decodable impls

native/src/core/derive/decodable.rs

@@ -20,16 +20,12 @@ pub(crate) fn derive_decodable(input: proc_macro::TokenStream) -> proc_macro::To
 
     let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
 
-    let sum = gen_size_sum(&input.data);
     let encode = gen_encode(&input.data);
     let decode = gen_decode(&input.data);
 
     let expanded = quote! {
         // The generated impl.
         impl #impl_generics crate::socket::Encodable for #name #ty_generics #where_clause {
-            fn encoded_len(&self) -> usize {
-                #sum
-            }
             fn encode(&self, w: &mut impl std::io::Write) -> std::io::Result<()> {
                 #encode
                 Ok(())
@@ -45,32 +41,6 @@ pub(crate) fn derive_decodable(input: proc_macro::TokenStream) -> proc_macro::To
     proc_macro::TokenStream::from(expanded)
 }
 
-// Generate an expression to sum up the size of each field.
-fn gen_size_sum(data: &Data) -> TokenStream {
-    match *data {
-        Data::Struct(ref data) => {
-            match data.fields {
-                Fields::Named(ref fields) => {
-                    // Expands to an expression like
-                    //
-                    //     0 + self.x.encoded_len() + self.y.encoded_len() + self.z.encoded_len()
-                    let recurse = fields.named.iter().map(|f| {
-                        let name = &f.ident;
-                        quote_spanned! { f.span() =>
-                            crate::socket::Encodable::encoded_len(&self.#name)
-                        }
-                    });
-                    quote! {
-                        0 #(+ #recurse)*
-                    }
-                }
-                _ => unimplemented!(),
-            }
-        }
-        Data::Enum(_) | Data::Union(_) => unimplemented!(),
-    }
-}
-
 // Generate an expression to encode each field.
 fn gen_encode(data: &Data) -> TokenStream {
     match *data {

native/src/core/socket.rs

@@ -7,8 +7,6 @@ use std::os::fd::{FromRawFd, IntoRawFd, OwnedFd, RawFd};
 use std::os::unix::net::{AncillaryData, SocketAncillary, UnixStream};
 
 pub trait Encodable {
-    #[allow(dead_code)]
-    fn encoded_len(&self) -> usize;
     fn encode(&self, w: &mut impl Write) -> io::Result<()>;
 }
 
@@ -19,11 +17,6 @@ pub trait Decodable: Sized + Encodable {
 macro_rules! impl_pod_encodable {
     ($($t:ty)*) => ($(
         impl Encodable for $t {
-            #[inline(always)]
-            fn encoded_len(&self) -> usize {
-                size_of::<Self>()
-            }
-
             #[inline(always)]
             fn encode(&self, w: &mut impl Write) -> io::Result<()> {
                 w.write_pod(self)
@@ -43,11 +36,6 @@ macro_rules! impl_pod_encodable {
 impl_pod_encodable! { u8 u32 i32 usize }
 
 impl Encodable for bool {
-    #[inline(always)]
-    fn encoded_len(&self) -> usize {
-        size_of::<u8>()
-    }
-
     #[inline(always)]
     fn encode(&self, w: &mut impl Write) -> io::Result<()> {
         match *self {
@@ -64,11 +52,24 @@ impl Decodable for bool {
     }
 }
 
-impl<T: Decodable> Encodable for Vec<T> {
+// impl<E: Encodable, T: AsRef<E>> Encodable for T
-    fn encoded_len(&self) -> usize {
+macro_rules! impl_encodable_as_ref {
-        size_of::<i32>() + size_of::<T>() * self.len()
+    ($( ($t:ty, $e:ty, $($g:tt)*) )*) => ($(
+        impl<$($g)*> Encodable for $t {
+            #[inline(always)]
+            fn encode(&self, w: &mut impl Write) -> io::Result<()> {
+                AsRef::<$e>::as_ref(self).encode(w)
             }
+        }
+    )*)
+}
 
+impl_encodable_as_ref! {
+    (String, str,)
+    (Vec<T>, [T], T: Encodable)
+}
+
+impl<T: Encodable> Encodable for [T] {
     fn encode(&self, w: &mut impl Write) -> io::Result<()> {
         (self.len() as i32).encode(w)?;
         self.iter().try_for_each(|e| e.encode(w))
@@ -87,26 +88,12 @@ impl<T: Decodable> Decodable for Vec<T> {
 }
 
 impl Encodable for str {
-    fn encoded_len(&self) -> usize {
-        size_of::<i32>() + self.len()
-    }
-
     fn encode(&self, w: &mut impl Write) -> io::Result<()> {
         (self.len() as i32).encode(w)?;
         w.write_all(self.as_bytes())
     }
 }
 
-impl Encodable for String {
-    fn encoded_len(&self) -> usize {
-        self.as_str().encoded_len()
-    }
-
-    fn encode(&self, w: &mut impl Write) -> io::Result<()> {
-        self.as_str().encode(w)
-    }
-}
-
 impl Decodable for String {
     fn decode(r: &mut impl Read) -> io::Result<String> {
         let len = i32::decode(r)?;