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::fmt;
use std::str::FromStr;

use ckey::Address as CoreAddress;
use primitives::{H256 as Hash256, H520 as Hash520, H64 as Hash64};
use rustc_hex::ToHex;
use serde::de::{Error, Visitor};
use serde::{Deserialize, Deserializer, Serialize, Serializer};

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_string();
                hex.push_str(&self.0.to_hex());
                serializer.serialize_str(&hex)
            }
        }
    };
}

impl_hash!(H64, Hash64);
impl_hash!(Address, CoreAddress);
impl_hash!(H256, Hash256);
impl_hash!(H520, Hash520);

#[cfg(test)]
mod test {
    use primitives;
    use serde_json;

    use super::H256;

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

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