Refactored Slicable (#324)

* Refactored Slicable

* Docs

* Wasm build

* Wasm build

* Renamed traits

* Review nits

* Renamed Slicable as well

polkadot/api/src/full.rs

@@ -93,7 +93,7 @@ impl<B: LocalBackend<Block>> PolkadotApi for Client<B, LocalCallExecutor<B, Nati
 
 	fn evaluate_block(&self, at: &BlockId, block: Block) -> Result<bool> {
 		use substrate_executor::error::ErrorKind as ExecErrorKind;
-		use codec::Slicable;
+		use codec::{Decode, Encode};
 		use runtime::Block as RuntimeBlock;
 
 		let encoded = block.encode();
@@ -142,13 +142,13 @@ impl<B: LocalBackend<Block>> PolkadotApi for Client<B, LocalCallExecutor<B, Nati
 	}
 
 	fn inherent_extrinsics(&self, at: &BlockId, timestamp: Timestamp, new_heads: Vec<CandidateReceipt>) -> Result<Vec<UncheckedExtrinsic>> {
-		use codec::Slicable;
+		use codec::{Encode, Decode};
 
 		with_runtime!(self, at, || {
 			let extrinsics = ::runtime::inherent_extrinsics(timestamp, new_heads);
 			extrinsics.into_iter()
 				.map(|x| x.encode()) // get encoded representation
-				.map(|x| Slicable::decode(&mut &x[..])) // get byte-vec equivalent to extrinsic
+				.map(|x| Decode::decode(&mut &x[..])) // get byte-vec equivalent to extrinsic
 				.map(|x| x.expect("UncheckedExtrinsic has encoded representation equivalent to Vec<u8>; qed"))
 				.collect()
 		})

polkadot/api/src/light.rs

@@ -19,7 +19,7 @@
 use std::sync::Arc;
 use client::backend::{Backend, RemoteBackend};
 use client::{Client, CallExecutor};
-use codec::Slicable;
+use codec::Decode;
 use primitives::{AccountId, Block, BlockId, Hash, Index, SessionKey, Timestamp, UncheckedExtrinsic};
 use runtime::Address;
 use primitives::parachain::{CandidateReceipt, DutyRoster, Id as ParaId};

polkadot/cli/src/lib.rs

@@ -79,7 +79,7 @@ use std::net::SocketAddr;
 use std::path::{Path, PathBuf};
 use substrate_telemetry::{init_telemetry, TelemetryConfig};
 use polkadot_primitives::BlockId;
-use codec::Slicable;
+use codec::{Decode, Encode};
 use client::BlockOrigin;
 use runtime_primitives::generic::SignedBlock;
 
@@ -407,7 +407,7 @@ fn import_blocks<E>(matches: &clap::ArgMatches, exit: E) -> error::Result<()>
 	};
 
 	info!("Importing blocks");
-	let count: u32 = Slicable::decode(&mut file).ok_or("Error reading file")?;
+	let count: u32 = Decode::decode(&mut file).ok_or("Error reading file")?;
 	let mut block = 0;
 	for _ in 0 .. count {
 		if exit_recv.try_recv().is_ok() {

polkadot/consensus/src/evaluation.rs

@@ -18,7 +18,7 @@
 
 use super::MAX_TRANSACTIONS_SIZE;
 
-use codec::Slicable;
+use codec::{Decode, Encode};
 use polkadot_runtime::{Block as PolkadotGenericBlock, CheckedBlock};
 use polkadot_primitives::{Block, Hash, BlockNumber, Timestamp};
 use polkadot_primitives::parachain::Id as ParaId;
@@ -78,13 +78,13 @@ pub fn evaluate_initial(
 ) -> Result<CheckedBlock> {
 	const MAX_TIMESTAMP_DRIFT: Timestamp = 60;
 
-	let encoded = Slicable::encode(proposal);
+	let encoded = Encode::encode(proposal);
 	let proposal = PolkadotGenericBlock::decode(&mut &encoded[..])
 		.and_then(|b| CheckedBlock::new(b).ok())
 		.ok_or_else(|| ErrorKind::ProposalNotForPolkadot)?;
 
 	let transactions_size = proposal.extrinsics.iter().fold(0, |a, tx| {
-		a + Slicable::encode(tx).len()
+		a + Encode::encode(tx).len()
 	});
 
 	if transactions_size > MAX_TRANSACTIONS_SIZE {

polkadot/consensus/src/lib.rs

@@ -65,7 +65,7 @@ use std::collections::{HashMap, HashSet};
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 
-use codec::Slicable;
+use codec::{Decode, Encode};
 use polkadot_api::PolkadotApi;
 use polkadot_primitives::{Hash, Block, BlockId, BlockNumber, Header, Timestamp, SessionKey};
 use polkadot_primitives::parachain::{Id as ParaId, Chain, DutyRoster, BlockData, Extrinsic as ParachainExtrinsic, CandidateReceipt, CandidateSignature};
@@ -710,7 +710,7 @@ impl<C> CreateProposal<C> where C: PolkadotApi {
 				.join(", ")
 		);
 
-		let substrate_block = Slicable::decode(&mut polkadot_block.encode().as_slice())
+		let substrate_block = Decode::decode(&mut polkadot_block.encode().as_slice())
 			.expect("polkadot blocks defined to serialize to substrate blocks correctly; qed");
 
 		// TODO: full re-evaluation

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 {
+impl Encode for Status {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: codec::Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
 		match self.collating_for {
 			Some(ref details) => {
-				v.push(1);
+				dest.push_byte(1);
-				details.using_encoded(|s| v.extend(s));
+				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 })

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;

polkadot/parachain/src/lib.rs

@@ -61,7 +61,7 @@ extern crate error_chain;
 
 #[cfg(not(feature = "std"))]
 use alloc::vec::Vec;
-use codec::Slicable;
+use codec::{Encode, Decode, Input, Output};
 
 #[cfg(feature = "std")]
 pub mod wasm;
@@ -77,20 +77,18 @@ pub struct ValidationParams {
 	pub parent_head: Vec<u8>,
 }
 
-impl Slicable for ValidationParams {
+impl Encode for ValidationParams {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
+		dest.push(&self.block_data);
-
+		dest.push(&self.parent_head);
-		self.block_data.using_encoded(|s| v.extend(s));
-		self.parent_head.using_encoded(|s| v.extend(s));
-
-		v
 	}
+}
 
-	fn decode<I: codec::Input>(input: &mut I) -> Option<Self> {
+impl Decode for ValidationParams {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(ValidationParams {
-			block_data: Slicable::decode(input)?,
+			block_data: Decode::decode(input)?,
-			parent_head: Slicable::decode(input)?,
+			parent_head: Decode::decode(input)?,
 		})
 	}
 }
@@ -104,14 +102,16 @@ pub struct ValidationResult {
 	pub head_data: Vec<u8>
 }
 
-impl Slicable for ValidationResult {
+impl Encode for ValidationResult {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		self.head_data.encode()
+		dest.push(&self.head_data);
 	}
+}
 
-	fn decode<I: codec::Input>(input: &mut I) -> Option<Self> {
+impl Decode for ValidationResult {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(ValidationResult {
-			head_data: Slicable::decode(input)?,
+			head_data: Decode::decode(input)?,
 		})
 	}
 }

polkadot/parachain/src/wasm.rs

@@ -20,7 +20,7 @@
 //! Assuming the parameters are correct, this module provides a wrapper around
 //! a WASM VM for re-execution of a parachain candidate.
 
-use codec::Slicable;
+use codec::{Decode, Encode};
 
 use wasmi::{self, Module, ModuleInstance,  MemoryInstance, MemoryDescriptor, MemoryRef, ModuleImportResolver};
 use wasmi::{memory_units, RuntimeValue};

polkadot/parachain/test-chains/basic_add/src/lib.rs

@@ -33,7 +33,7 @@ extern crate wee_alloc;
 extern crate tiny_keccak;
 extern crate pwasm_libc;
 
-use parachain::codec::{Slicable, Input};
+use parachain::codec::{Decode, Encode, Input, Output};
 
 #[cfg(not(feature = "std"))]
 mod wasm;
@@ -41,9 +41,6 @@ mod wasm;
 #[cfg(not(feature = "std"))]
 pub use wasm::*;
 
-#[cfg(not(feature = "std"))]
-use alloc::vec::Vec;
-
 // Define global allocator.
 #[cfg(not(feature = "std"))]
 #[global_allocator]
@@ -60,22 +57,20 @@ struct HeadData {
 	post_state: [u8; 32],
 }
 
-impl Slicable for HeadData {
+impl Encode for HeadData {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
+		dest.push(&self.number);
-
+		dest.push(&self.parent_hash);
-		self.number.using_encoded(|s| v.extend(s));
+		dest.push(&self.post_state);
-		self.parent_hash.using_encoded(|s| v.extend(s));
-		self.post_state.using_encoded(|s| v.extend(s));
-
-		v
 	}
+}
 
+impl Decode for HeadData {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(HeadData {
-			number: Slicable::decode(input)?,
+			number: Decode::decode(input)?,
-			parent_hash: Slicable::decode(input)?,
+			parent_hash: Decode::decode(input)?,
-			post_state: Slicable::decode(input)?,
+			post_state: Decode::decode(input)?,
 		})
 	}
 }
@@ -89,20 +84,18 @@ struct BlockData {
 	add: u64,
 }
 
-impl Slicable for BlockData {
+impl Encode for BlockData {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
+		dest.push(&self.state);
-
+		dest.push(&self.add);
-		self.state.using_encoded(|s| v.extend(s));
-		self.add.using_encoded(|s| v.extend(s));
-
-		v
 	}
+}
 
+impl Decode for BlockData {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(BlockData {
-			state: Slicable::decode(input)?,
+			state: Decode::decode(input)?,
-			add: Slicable::decode(input)?,
+			add: Decode::decode(input)?,
 		})
 	}
 }

polkadot/parachain/test-chains/basic_add/src/wasm.rs

@@ -18,7 +18,7 @@
 
 use core::{intrinsics, panic, alloc};
 use parachain::{self, ValidationResult};
-use parachain::codec::Slicable;
+use parachain::codec::{Encode, Decode};
 use super::{HeadData, BlockData};
 
 #[panic_implementation]

polkadot/parachain/tests/basic_add.rs

@@ -20,7 +20,7 @@ extern crate polkadot_parachain as parachain;
 extern crate tiny_keccak;
 
 use parachain::ValidationParams;
-use parachain::codec::{Slicable, Input};
+use parachain::codec::{Decode, Encode, Input, Output};
 
 // Head data for this parachain.
 #[derive(Default, Clone)]
@@ -33,22 +33,20 @@ struct HeadData {
 	post_state: [u8; 32],
 }
 
-impl Slicable for HeadData {
+impl Encode for HeadData {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
+		dest.push(&self.number);
-
+		dest.push(&self.parent_hash);
-		self.number.using_encoded(|s| v.extend(s));
+		dest.push(&self.post_state);
-		self.parent_hash.using_encoded(|s| v.extend(s));
-		self.post_state.using_encoded(|s| v.extend(s));
-
-		v
 	}
+}
 
+impl Decode for HeadData {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(HeadData {
-			number: Slicable::decode(input)?,
+			number: Decode::decode(input)?,
-			parent_hash: Slicable::decode(input)?,
+			parent_hash: Decode::decode(input)?,
-			post_state: Slicable::decode(input)?,
+			post_state: Decode::decode(input)?,
 		})
 	}
 }
@@ -62,20 +60,18 @@ struct BlockData {
 	add: u64,
 }
 
-impl Slicable for BlockData {
+impl Encode for BlockData {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
+		dest.push(&self.state);
-
+		dest.push(&self.add);
-		self.state.using_encoded(|s| v.extend(s));
-		self.add.using_encoded(|s| v.extend(s));
-
-		v
 	}
+}
 
+impl Decode for BlockData {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(BlockData {
-			state: Slicable::decode(input)?,
+			state: Decode::decode(input)?,
-			add: Slicable::decode(input)?,
+			add: Decode::decode(input)?,
 		})
 	}
 }

polkadot/primitives/src/lib.rs

@@ -42,7 +42,7 @@ use primitives::bytes;
 use rstd::prelude::*;
 use runtime_primitives::traits::BlakeTwo256;
 use runtime_primitives::generic;
-use codec::{Input, Slicable};
+use codec::{Encode, Decode, Input, Output};
 
 pub mod parachain;
 
@@ -109,12 +109,14 @@ pub type BlockId = generic::BlockId<Block>;
 #[cfg_attr(feature = "std", derive(Serialize, Deserialize, Debug))]
 pub struct Log(#[cfg_attr(feature = "std", serde(with="bytes"))] pub Vec<u8>);
 
-impl Slicable for Log {
+impl Decode for Log {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Vec::<u8>::decode(input).map(Log)
 	}
+}
 
-	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+impl Encode for Log {
-		self.0.using_encoded(f)
+	fn encode_to<T: Output>(&self, dest: &mut T) {
+		self.0.encode_to(dest)
 	}
 }

polkadot/primitives/src/parachain.rs

@@ -16,7 +16,7 @@
 
 //! Polkadot parachain types.
 
-use codec::{Slicable, Input};
+use codec::{Encode, Decode, Input, Output};
 use rstd::prelude::*;
 use rstd::cmp::Ordering;
 use super::Hash;
@@ -47,11 +47,13 @@ impl Id {
 	}
 }
 
-impl Slicable for Id {
+impl Decode for Id {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		u32::decode(input).map(Id)
 	}
+}
 
+impl Encode for Id {
 	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
 		self.0.using_encoded(f)
 	}
@@ -67,30 +69,26 @@ pub enum Chain {
 	Parachain(Id),
 }
 
-impl Slicable for Chain {
+impl Decode for Chain {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		let disc = input.read_byte()?;
 		match disc {
 			0 => Some(Chain::Relay),
-			1 => Some(Chain::Parachain(Slicable::decode(input)?)),
+			1 => Some(Chain::Parachain(Decode::decode(input)?)),
 			_ => None,
 		}
 	}
+}
 
-	fn encode(&self) -> Vec<u8> {
+impl Encode for Chain {
-		let mut v = Vec::new();
+	fn encode_to<T: Output>(&self, dest: &mut T) {
 		match *self {
-			Chain::Relay => { v.push(0); }
+			Chain::Relay => { dest.push_byte(0); }
 			Chain::Parachain(id) => {
-				v.push(1u8);
+				dest.push_byte(1u8);
-				id.using_encoded(|s| v.extend(s));
+				dest.push(&id);
 			}
 		}
-		v
-	}
-
-	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
-		f(&self.encode().as_slice())
 	}
 }
 
@@ -105,25 +103,19 @@ pub struct DutyRoster {
 	pub guarantor_duty: Vec<Chain>,
 }
 
-impl Slicable for DutyRoster {
+impl Decode for DutyRoster {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(DutyRoster {
-			validator_duty: Slicable::decode(input)?,
+			validator_duty: Decode::decode(input)?,
-			guarantor_duty: Slicable::decode(input)?,
+			guarantor_duty: Decode::decode(input)?,
 		})
 	}
+}
 
-	fn encode(&self) -> Vec<u8> {
+impl Encode for DutyRoster {
-		let mut v = Vec::new();
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-
+		dest.push(&self.validator_duty);
-		v.extend(self.validator_duty.encode());
+		dest.push(&self.guarantor_duty);
-		v.extend(self.guarantor_duty.encode());
-
-		v
-	}
-
-	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
-		f(&self.encode().as_slice())
 	}
 }
 
@@ -158,32 +150,30 @@ pub struct CandidateReceipt {
 	pub block_data_hash: Hash,
 }
 
-impl Slicable for CandidateReceipt {
+impl Encode for CandidateReceipt {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
+		dest.push(&self.parachain_index);
-
+		dest.push(&self.collator);
-		self.parachain_index.using_encoded(|s| v.extend(s));
+		dest.push(&self.signature);
-		self.collator.using_encoded(|s| v.extend(s));
+		dest.push(&self.head_data.0);
-		self.signature.using_encoded(|s| v.extend(s));
+		dest.push(&self.balance_uploads);
-		self.head_data.0.using_encoded(|s| v.extend(s));
+		dest.push(&self.egress_queue_roots);
-		self.balance_uploads.using_encoded(|s| v.extend(s));
+		dest.push(&self.fees);
-		self.egress_queue_roots.using_encoded(|s| v.extend(s));
+		dest.push(&self.block_data_hash);
-		self.fees.using_encoded(|s| v.extend(s));
-		self.block_data_hash.using_encoded(|s| v.extend(s));
-
-		v
 	}
+}
 
+impl Decode for CandidateReceipt {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(CandidateReceipt {
-			parachain_index: Slicable::decode(input)?,
+			parachain_index: Decode::decode(input)?,
-			collator: Slicable::decode(input)?,
+			collator: Decode::decode(input)?,
-			signature: Slicable::decode(input)?,
+			signature: Decode::decode(input)?,
-			head_data: Slicable::decode(input).map(HeadData)?,
+			head_data: Decode::decode(input).map(HeadData)?,
-			balance_uploads: Slicable::decode(input)?,
+			balance_uploads: Decode::decode(input)?,
-			egress_queue_roots: Slicable::decode(input)?,
+			egress_queue_roots: Decode::decode(input)?,
-			fees: Slicable::decode(input)?,
+			fees: Decode::decode(input)?,
-			block_data_hash: Slicable::decode(input)?,
+			block_data_hash: Decode::decode(input)?,
 		})
 	}
 }
@@ -283,13 +273,15 @@ pub struct ValidationCode(#[cfg_attr(feature = "std", serde(with="bytes"))] pub
 #[cfg_attr(feature = "std", derive(Serialize, Deserialize, Debug))]
 pub struct Activity(#[cfg_attr(feature = "std", serde(with="bytes"))] pub Vec<u8>);
 
-impl Slicable for Activity {
+impl Decode for Activity {
 	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Vec::<u8>::decode(input).map(Activity)
 	}
+}
 
-	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+impl Encode for Activity {
-		self.0.using_encoded(f)
+	fn encode_to<T: Output>(&self, dest: &mut T) {
+		self.0.encode_to(dest)
 	}
 }
 

polkadot/runtime/src/lib.rs

@@ -257,7 +257,7 @@ pub mod api {
 mod tests {
 	use super::*;
 	use substrate_primitives as primitives;
-	use ::codec::Slicable;
+	use codec::{Encode, Decode};
 	use substrate_primitives::hexdisplay::HexDisplay;
 	use substrate_serializer as ser;
 	use runtime_primitives::traits::{Digest as DigestT, Header as HeaderT};
@@ -376,7 +376,7 @@ mod tests {
 		// df0f0200
 		// 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 
-		let v = Slicable::encode(&tx);
+		let v = Encode::encode(&tx);
 		assert_eq!(&v[..], &hex!["6f000000ff0101010101010101010101010101010101010101010101010101010101010101e70300000300df0f02000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"][..]);
 		println!("{}", HexDisplay::from(&v));
 		assert_eq!(UncheckedExtrinsic::decode(&mut &v[..]).unwrap(), tx);
@@ -393,7 +393,7 @@ mod tests {
 				))
 			))),
 		};
-		let v = Slicable::encode(&xt);
+		let v = Encode::encode(&xt);
 		assert_eq!(Extrinsic::decode(&mut &v[..]).unwrap(), xt);
 	}
 

polkadot/runtime/src/parachains.rs

@@ -17,7 +17,7 @@
 //! Main parachains logic. For now this is just the determination of which validators do what.
 
 use rstd::prelude::*;
-use codec::Slicable;
+use codec::Decode;
 
 use runtime_primitives::traits::{Hash, BlakeTwo256, Executable, RefInto, MaybeEmpty};
 use primitives::parachain::{Id, Chain, DutyRoster, CandidateReceipt};
@@ -217,7 +217,7 @@ impl<T: Trait> runtime_primitives::BuildStorage for GenesisConfig<T>
 	fn build_storage(mut self) -> ::std::result::Result<runtime_io::TestExternalities, String> {
 		use std::collections::HashMap;
 		use runtime_io::twox_128;
-		use codec::Slicable;
+		use codec::Encode;
 
 		self.parachains.sort_unstable_by_key(|&(ref id, _)| id.clone());
 		self.parachains.dedup_by_key(|&mut (ref id, _)| id.clone());

polkadot/service/src/lib.rs

@@ -43,7 +43,7 @@ pub mod chain_spec;
 use std::sync::Arc;
 use std::collections::HashMap;
 
-use codec::Slicable;
+use codec::Encode;
 use transaction_pool::TransactionPool;
 use polkadot_api::{PolkadotApi, light::RemotePolkadotApiWrapper};
 use polkadot_primitives::{Block, BlockId, Hash};
@@ -265,7 +265,7 @@ impl<B, E, A> network::TransactionPool<Block> for TransactionPoolAdapter<B, E, A
 		}
 
 		let encoded = transaction.encode();
-		if let Some(uxt) = codec::Slicable::decode(&mut &encoded[..]) {
+		if let Some(uxt) = codec::Decode::decode(&mut &encoded[..]) {
 			let best_block_id = self.best_block_id()?;
 			match self.pool.import_unchecked_extrinsic(best_block_id, uxt) {
 				Ok(xt) => Some(*xt.hash()),

polkadot/statement-table/src/generic.rs

@@ -31,7 +31,7 @@ use std::collections::hash_map::{HashMap, Entry};
 use std::hash::Hash;
 use std::fmt::Debug;
 
-use codec::{Slicable, Input};
+use codec::{Decode, Encode, Input, Output};
 
 /// Context for the statement table.
 pub trait Context {
@@ -97,44 +97,43 @@ enum StatementKind {
 	Available = 4,
 }
 
-impl<C: Slicable, D: Slicable> Slicable for Statement<C, D> {
+impl<C: Encode, D: Encode> Encode for Statement<C, D> {
-	fn encode(&self) -> Vec<u8> {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
-		let mut v = Vec::new();
 		match *self {
 			Statement::Candidate(ref candidate) => {
-				v.push(StatementKind::Candidate as u8);
+				dest.push_byte(StatementKind::Candidate as u8);
-				candidate.using_encoded(|s| v.extend(s));
+				dest.push(candidate);
 			}
 			Statement::Valid(ref digest) => {
-				v.push(StatementKind::Valid as u8);
+				dest.push_byte(StatementKind::Valid as u8);
-				digest.using_encoded(|s| v.extend(s));
+				dest.push(digest);
 			}
 			Statement::Invalid(ref digest) => {
-				v.push(StatementKind::Invalid as u8);
+				dest.push_byte(StatementKind::Invalid as u8);
-				digest.using_encoded(|s| v.extend(s));
+				dest.push(digest);
 			}
 			Statement::Available(ref digest) => {
-				v.push(StatementKind::Available as u8);
+				dest.push_byte(StatementKind::Available as u8);
-				digest.using_encoded(|s| v.extend(s));
+				dest.push(digest);
 			}
 		}
+	}
+}
 
-		v
+impl<C: Decode, D: Decode> Decode for Statement<C, D> {
-	}
-
 	fn decode<I: Input>(value: &mut I) -> Option<Self> {
 		match value.read_byte() {
 			Some(x) if x == StatementKind::Candidate as u8 => {
-				Slicable::decode(value).map(Statement::Candidate)
+				Decode::decode(value).map(Statement::Candidate)
 			}
 			Some(x) if x == StatementKind::Valid as u8 => {
-				Slicable::decode(value).map(Statement::Valid)
+				Decode::decode(value).map(Statement::Valid)
 			}
 			Some(x) if x == StatementKind::Invalid as u8 => {
-				Slicable::decode(value).map(Statement::Invalid)
+				Decode::decode(value).map(Statement::Invalid)
 			}
 			Some(x) if x == StatementKind::Available as u8 => {
-				Slicable::decode(value).map(Statement::Available)
+				Decode::decode(value).map(Statement::Available)
 			}
 			_ => None,
 		}

polkadot/transaction-pool/src/lib.rs

@@ -43,7 +43,7 @@ use std::{
 	sync::Arc,
 };
 
-use codec::Slicable;
+use codec::{Decode, Encode};
 use extrinsic_pool::{Pool, Listener, txpool::{self, Readiness, scoring::{Change, Choice}}};
 use extrinsic_pool::api::{ExtrinsicPool, EventStream};
 use polkadot_api::PolkadotApi;
@@ -75,7 +75,7 @@ impl VerifiedTransaction {
 
 	/// Convert to primitive unchecked extrinsic.
 	pub fn primitive_extrinsic(&self) -> ::primitives::UncheckedExtrinsic {
-		Slicable::decode(&mut self.as_transaction().encode().as_slice())
+		Decode::decode(&mut self.as_transaction().encode().as_slice())
 			.expect("UncheckedExtrinsic shares repr with Vec<u8>; qed")
 	}
 
@@ -418,7 +418,7 @@ mod tests {
 	use std::sync::{atomic::{self, AtomicBool}, Arc};
 	use super::TransactionPool;
 	use substrate_keyring::Keyring::{self, *};
-	use codec::Slicable;
+	use codec::{Decode, Encode};
 	use polkadot_api::{PolkadotApi, BlockBuilder, Result};
 	use primitives::{AccountId, AccountIndex, Block, BlockId, Hash, Index, SessionKey, Timestamp,
 		UncheckedExtrinsic as FutureProofUncheckedExtrinsic};