spec loading cleanup (#858)

* spec loading cleanup in progress

* changed engine field in json spec

* refactored engine params

* polishing spec loading refactor

* fixed compiling json tests

* fixed compiling parity

* removed warnings

* removed commented out code

* fixed failing test

* bringing back removed TODO in spec.

json/src/spec/seal.rs

@@ -0,0 +1,73 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity 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.
+
+// Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Spec seal deserialization.
+
+use hash::{H64, H256};
+use bytes::Bytes;
+
+/// Ethereum seal.
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct Ethereum {
+	/// Seal nonce.
+	pub nonce: H64,
+	/// Seal mix hash.
+	#[serde(rename="mixHash")]
+	pub mix_hash: H256,
+}
+
+/// Generic seal.
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct Generic {
+	/// Number of fields.
+	pub fields: usize,
+	/// Their rlp.
+	pub rlp: Bytes,
+}
+
+/// Seal variants.
+#[derive(Debug, PartialEq, Deserialize)]
+pub enum Seal {
+	/// Ethereum seal.
+	#[serde(rename="ethereum")]
+	Ethereum(Ethereum),
+	/// Generic seal.
+	#[serde(rename="generic")]
+	Generic(Generic),
+}
+
+#[cfg(test)]
+mod tests {
+	use serde_json;
+	use spec::Seal;
+
+	#[test]
+	fn builtin_deserialization() {
+		let s = r#"[{
+			"ethereum": {
+				"nonce": "0x0000000000000042",
+				"mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000"
+			}
+		},{
+			"generic": {
+				"fields": 1,
+				"rlp": "0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fa"
+			}
+		}]"#;
+		let _deserialized: Vec<Seal> = serde_json::from_str(s).unwrap();
+		// TODO: validate all fields
+	}
+}