openethereum/json/src/hash.rs

// Copyright 2015-2017 Parity Technologies (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/>.

//! Lenient hash json deserialization for test json files.

use std::str::FromStr;
use std::fmt;
use serde::{Deserialize, Deserializer, Serialize, Serializer};
use serde::de::{Error, Visitor};
use rustc_hex::ToHex;
use util::hash::{H64 as Hash64, H160 as Hash160, H256 as Hash256, H520 as Hash520, H2048 as Hash2048};


macro_rules! impl_hash {
	($name: ident, $inner: ident) => {
		/// Lenient hash json deserialization for test json files.
		#[derive(Default, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Clone)]
		pub struct $name(pub $inner);

		impl From<$name> for $inner {
			fn from(other: $name) -> $inner {
				other.0
			}
		}

		impl From<$inner> for $name {
			fn from(i: $inner) -> Self {
				$name(i)
			}
		}

		impl<'a> Deserialize<'a> for $name {
			fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
				where D: Deserializer<'a> {

				struct HashVisitor;

				impl<'b> Visitor<'b> for HashVisitor {
					type Value = $name;

					fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
						write!(formatter, "a 0x-prefixed hex-encoded hash")
					}

					fn visit_str<E>(self, value: &str) -> Result<Self::Value, E> where E: Error {
						let value = match value.len() {
							0 => $inner::from(0),
							2 if value == "0x" => $inner::from(0),
							_ if value.starts_with("0x") => $inner::from_str(&value[2..]).map_err(|e| {
								Error::custom(format!("Invalid hex value {}: {}", value, e).as_str())
							})?,
							_ => $inner::from_str(value).map_err(|e| {
								Error::custom(format!("Invalid hex value {}: {}", value, e).as_str())
							})?,
						};

						Ok($name(value))
					}

					fn visit_string<E>(self, value: String) -> Result<Self::Value, E> where E: Error {
						self.visit_str(value.as_ref())
					}
				}

				deserializer.deserialize_any(HashVisitor)
			}
		}

		impl Serialize for $name {
			fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
				let mut hex = "0x".to_owned();
				hex.push_str(&self.0.to_hex());
				serializer.serialize_str(&hex)
			}
		}
	}
}

impl_hash!(H64, Hash64);
impl_hash!(Address, Hash160);
impl_hash!(H256, Hash256);
impl_hash!(H520, Hash520);
impl_hash!(Bloom, Hash2048);

#[cfg(test)]
mod test {
	use std::str::FromStr;
	use serde_json;
	use util::hash;
	use hash::H256;

	#[test]
	fn hash_deserialization() {
		let s = r#"["", "5a39ed1020c04d4d84539975b893a4e7c53eab6c2965db8bc3468093a31bc5ae"]"#;
		let deserialized: Vec<H256> = serde_json::from_str(s).unwrap();
		assert_eq!(deserialized, vec![
				   H256(hash::H256::from(0)),
				   H256(hash::H256::from_str("5a39ed1020c04d4d84539975b893a4e7c53eab6c2965db8bc3468093a31bc5ae").unwrap())
		]);
	}

	#[test]
	fn hash_into() {
		assert_eq!(hash::H256::from(0), H256(hash::H256::from(0)).into());
	}
}