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/ethash.rs

@@ -0,0 +1,75 @@
+// 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/>.
+
+//! Ethash params deserialization.
+
+use uint::Uint;
+use hash::Address;
+
+/// Ethash params deserialization.
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct EthashParams {
+	/// Tie breaking gas.
+	#[serde(rename="tieBreakingGas")]
+	pub tie_breaking_gas: bool,
+	/// Gas limit divisor.
+	#[serde(rename="gasLimitBoundDivisor")]
+	pub gas_limit_bound_divisor: Uint,
+	/// Minimum difficulty.
+	#[serde(rename="minimumDifficulty")]
+	pub minimum_difficulty: Uint,
+	/// Difficulty bound divisor.
+	#[serde(rename="difficultyBoundDivisor")]
+	pub difficulty_bound_divisor: Uint,
+	/// Block duration.
+	#[serde(rename="durationLimit")]
+	pub duration_limit: Uint,
+	/// Block reward.
+	#[serde(rename="blockReward")]
+	pub block_reward: Uint,
+	/// Namereg contract address.
+	pub registrar: Address,
+}
+
+/// Ethash engine deserialization.
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct Ethash {
+	/// Ethash params.
+	pub params: EthashParams,
+}
+
+#[cfg(test)]
+mod tests {
+	use serde_json;
+	use spec::ethash::Ethash;
+
+	#[test]
+	fn ethash_deserialization() {
+		let s = r#"{
+			"params": {
+				"tieBreakingGas": false,
+				"gasLimitBoundDivisor": "0x0400",
+				"minimumDifficulty": "0x020000",
+				"difficultyBoundDivisor": "0x0800",
+				"durationLimit": "0x0d",
+				"blockReward": "0x4563918244F40000",
+				"registrar" : "0xc6d9d2cd449a754c494264e1809c50e34d64562b"
+			}
+		}"#;
+
+		let _deserialized: Ethash = serde_json::from_str(s).unwrap();
+	}
+}