Initial validator trait. (#14)

* Initial validator trait.

* Add missing docs warning.

* Fix formatting.

* Fix validator output and serialization.

* Get rid of redundant ValidationCode type.

substrate/primitives/src/validator.rs

@@ -0,0 +1,104 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Validator primitives.
+
+use bytes;
+
+/// Parachain incoming messages.
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct IngressPosts(#[serde(with="bytes")] pub Vec<u8>);
+
+/// Parachain incoming messages delta.
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct IngressPostsDelta(#[serde(with="bytes")] pub Vec<u8>);
+
+/// Parachain outgoing messages.
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct EgressPosts(#[serde(with="bytes")] pub Vec<u8>);
+
+/// Validity result of particular proof and ingress queue.
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(tag="type", content="data")]
+pub enum ProofValidity {
+	/// The proof is invalid.
+	#[serde(rename="invalid")]
+	Invalid,
+	#[serde(rename="valid")]
+	/// The proof is processed and new egress queue is created.
+	/// Also includes current ingress queue delta.
+	Valid(IngressPostsDelta, EgressPosts),
+}
+
+impl ProofValidity {
+	/// The proof is valid.
+	pub fn is_valid(&self) -> bool {
+		match *self {
+			ProofValidity::Invalid => false,
+			ProofValidity::Valid(..) => true,
+		}
+	}
+}
+
+impl From<Option<(IngressPostsDelta, EgressPosts)>> for ProofValidity {
+	fn from(posts: Option<(IngressPostsDelta, EgressPosts)>) -> Self {
+		match posts {
+			Some((delta, posts)) => ProofValidity::Valid(delta, posts),
+			None => ProofValidity::Invalid,
+		}
+	}
+}
+
+// TODO [ToDr] This shouldn't be here!
+/// Validator logic.
+pub trait Validator {
+	/// Validation error.
+	type Error: ::std::error::Error;
+
+	/// Validates if the provided proof holds given a current ingress queue.
+	///
+	/// In case of success produces egress posts.
+	fn validate(
+		&self,
+		messages: &IngressPosts,
+		proof: &::parachain::Proof,
+		code: &[u8],
+	) -> Result<ProofValidity, Self::Error>;
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use polkadot_serializer as ser;
+
+	#[test]
+	fn test_proof_validity_serialization() {
+		assert_eq!(
+			ser::to_string_pretty(&ProofValidity::Invalid),
+			r#"{
+  "type": "invalid"
+}"#);
+		assert_eq!(
+			ser::to_string_pretty(&ProofValidity::Valid(IngressPostsDelta(vec![1]), EgressPosts(vec![1, 2, 3]))),
+			r#"{
+  "type": "valid",
+  "data": [
+    "0x01",
+    "0x010203"
+  ]
+}"#);
+	}
+}