Refactored Slicable (#324)

* Refactored Slicable

* Docs

* Wasm build

* Wasm build

* Renamed traits

* Review nits

* Renamed Slicable as well

substrate/polkadot/network/src/lib.rs

@@ -47,7 +47,7 @@ mod collator_pool;
 mod router;
 pub mod consensus;
 
-use codec::Slicable;
+use codec::{Decode, Encode};
 use futures::sync::oneshot;
 use parking_lot::Mutex;
 use polkadot_consensus::{Statement, SignedStatement, GenericStatement};
@@ -81,25 +81,25 @@ pub struct Status {
 	collating_for: Option<(AccountId, ParaId)>,
 }
 
-impl Slicable for Status {
-	fn encode(&self) -> Vec<u8> {
-		let mut v = Vec::new();
+impl Encode for Status {
+	fn encode_to<T: codec::Output>(&self, dest: &mut T) {
 		match self.collating_for {
 			Some(ref details) => {
-				v.push(1);
-				details.using_encoded(|s| v.extend(s));
+				dest.push_byte(1);
+				dest.push(details);
 			}
 			None => {
-				v.push(0);
+				dest.push_byte(0);
 			}
 		}
-		v
 	}
+}
 
-	fn decode<I: ::codec::Input>(input: &mut I) -> Option<Self> {
+impl Decode for Status {
+	fn decode<I: codec::Input>(input: &mut I) -> Option<Self> {
 		let collating_for = match input.read_byte()? {
 			0 => None,
-			1 => Some(Slicable::decode(input)?),
+			1 => Some(Decode::decode(input)?),
 			_ => return None,
 		};
 		Some(Status { collating_for })

substrate/polkadot/network/src/tests.rs

@@ -23,7 +23,7 @@ use polkadot_consensus::GenericStatement;
 use polkadot_primitives::{Block, Hash, SessionKey};
 use polkadot_primitives::parachain::{CandidateReceipt, HeadData, BlockData};
 use substrate_primitives::H512;
-use codec::Slicable;
+use codec::Encode;
 use substrate_network::{PeerId, PeerInfo, ClientHandle, Context, message::Message as SubstrateMessage, message::Role, specialization::Specialization, generic_message::Message as GenericMessage};
 
 use std::sync::Arc;