Phase 1 of repo reorg (#719)

* Remove unneeded script

* Rename Substrate Demo -> Substrate

* Rename demo -> node

* Build wasm from last rename.

* Merge ed25519 into substrate-primitives

* Minor tweak

* Rename substrate -> core

* Move substrate-runtime-support to core/runtime/support

* Rename/move substrate-runtime-version

* Move codec up a level

* Rename substrate-codec -> parity-codec

* Move environmental up a level

* Move pwasm-* up to top, ready for removal

* Remove requirement of s-r-support from s-r-primitives

* Move core/runtime/primitives into core/runtime-primitives

* Remove s-r-support dep from s-r-version

* Remove dep of s-r-support from bft

* Remove dep of s-r-support from node/consensus

* Sever all other core deps from s-r-support

* Forgot the no_std directive

* Rename non-SRML modules to sr-* to avoid match clashes

* Move runtime/* to srml/*

* Rename substrate-runtime-* -> srml-*

* Move srml to top-level

substrate/core/client/src/backend.rs

@@ -0,0 +1,107 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Polkadot Client data backend
+
+use error;
+use primitives::AuthorityId;
+use runtime_primitives::bft::Justification;
+use runtime_primitives::generic::BlockId;
+use runtime_primitives::traits::{Block as BlockT, NumberFor};
+use state_machine::backend::Backend as StateBackend;
+use patricia_trie::NodeCodec;
+use hashdb::Hasher;
+
+/// Block insertion operation. Keeps hold if the inserted block state and data.
+pub trait BlockImportOperation<Block, H, C>
+where
+	Block: BlockT,
+	H: Hasher,
+	C: NodeCodec<H>,
+{
+	/// Associated state backend type.
+	type State: StateBackend<H, C>;
+
+	/// Returns pending state. Returns None for backends with locally-unavailable state data.
+	fn state(&self) -> error::Result<Option<&Self::State>>;
+	/// Append block data to the transaction.
+	fn set_block_data(
+		&mut self,
+		header: Block::Header,
+		body: Option<Vec<Block::Extrinsic>>,
+		justification: Option<Justification<Block::Hash>>,
+		is_new_best: bool
+	) -> error::Result<()>;
+
+	/// Append authorities set to the transaction. This is a set of parent block (set which
+	/// has been used to check justification of this block).
+	fn update_authorities(&mut self, authorities: Vec<AuthorityId>);
+	/// Inject storage data into the database.
+	fn update_storage(&mut self, update: <Self::State as StateBackend<H, C>>::Transaction) -> error::Result<()>;
+	/// Inject storage data into the database replacing any existing data.
+	fn reset_storage<I: Iterator<Item=(Vec<u8>, Vec<u8>)>>(&mut self, iter: I) -> error::Result<()>;
+}
+
+/// Client backend. Manages the data layer.
+///
+/// Note on state pruning: while an object from `state_at` is alive, the state
+/// should not be pruned. The backend should internally reference-count
+/// its state objects.
+///
+/// The same applies for live `BlockImportOperation`s: while an import operation building on a parent `P`
+/// is alive, the state for `P` should not be pruned.
+pub trait Backend<Block, H, C>: Send + Sync
+where
+	Block: BlockT,
+	H: Hasher,
+	C: NodeCodec<H>,
+{
+	/// Associated block insertion operation type.
+	type BlockImportOperation: BlockImportOperation<Block, H, C>;
+	/// Associated blockchain backend type.
+	type Blockchain: ::blockchain::Backend<Block>;
+	/// Associated state backend type.
+	type State: StateBackend<H, C>;
+
+	/// Begin a new block insertion transaction with given parent block id.
+	/// When constructing the genesis, this is called with all-zero hash.
+	fn begin_operation(&self, block: BlockId<Block>) -> error::Result<Self::BlockImportOperation>;
+	/// Commit block insertion.
+	fn commit_operation(&self, transaction: Self::BlockImportOperation) -> error::Result<()>;
+	/// Returns reference to blockchain backend.
+	fn blockchain(&self) -> &Self::Blockchain;
+	/// Returns state backend with post-state of given block.
+	fn state_at(&self, block: BlockId<Block>) -> error::Result<Self::State>;
+	/// Attempts to revert the chain by `n` blocks. Returns the number of blocks that were
+	/// successfully reverted.
+	fn revert(&self, n: NumberFor<Block>) -> error::Result<NumberFor<Block>>;
+}
+
+/// Mark for all Backend implementations, that are making use of state data, stored locally.
+pub trait LocalBackend<Block, H, C>: Backend<Block, H, C>
+where
+	Block: BlockT,
+	H: Hasher,
+	C: NodeCodec<H>,
+{}
+
+/// Mark for all Backend implementations, that are fetching required state data from remote nodes.
+pub trait RemoteBackend<Block, H, C>: Backend<Block, H, C>
+where
+	Block: BlockT,
+	H: Hasher,
+	C: NodeCodec<H>,
+{}