134 lines
3.3 KiB
Rust
134 lines
3.3 KiB
Rust
// Copyright 2015-2020 Parity Technologies (UK) Ltd.
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// This file is part of Parity Ethereum.
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// Parity Ethereum is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity Ethereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity Ethereum. If not, see <http://www.gnu.org/licenses/>.
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//! Deserializer of empty string values into optionals.
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use std::fmt;
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use std::marker::PhantomData;
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use ethereum_types::U256;
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use serde::{Deserialize, Deserializer};
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use serde::de::{Error, Visitor, IntoDeserializer};
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use crate::uint::Uint;
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/// Deserializer of empty string values into optionals.
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#[derive(Debug, PartialEq, Clone)]
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pub enum MaybeEmpty<T> {
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/// Some.
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Some(T),
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/// None.
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None,
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}
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impl<'a, T> Deserialize<'a> for MaybeEmpty<T> where T: Deserialize<'a> {
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fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
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where D: Deserializer<'a>
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{
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deserializer.deserialize_any(MaybeEmptyVisitor::new())
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}
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}
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struct MaybeEmptyVisitor<T> {
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_phantom: PhantomData<T>
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}
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impl<T> MaybeEmptyVisitor<T> {
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fn new() -> Self {
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MaybeEmptyVisitor {
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_phantom: PhantomData
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}
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}
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}
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impl<'a, T> Visitor<'a> for MaybeEmptyVisitor<T> where T: Deserialize<'a> {
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type Value = MaybeEmpty<T>;
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fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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write!(formatter, "an empty string or string-encoded type")
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}
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fn visit_str<E>(self, value: &str) -> Result<Self::Value, E> where E: Error {
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self.visit_string(value.to_owned())
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}
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fn visit_string<E>(self, value: String) -> Result<Self::Value, E> where E: Error {
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if value.is_empty() {
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Ok(MaybeEmpty::None)
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} else {
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T::deserialize(value.into_deserializer()).map(MaybeEmpty::Some)
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}
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}
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}
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impl<T> Into<Option<T>> for MaybeEmpty<T> {
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fn into(self) -> Option<T> {
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match self {
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MaybeEmpty::Some(s) => Some(s),
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MaybeEmpty::None => None
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}
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}
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}
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#[cfg(test)]
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impl From<Uint> for MaybeEmpty<Uint> {
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fn from(uint: Uint) -> Self {
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MaybeEmpty::Some(uint)
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}
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}
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impl From<MaybeEmpty<Uint>> for U256 {
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fn from(maybe: MaybeEmpty<Uint>) -> U256 {
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match maybe {
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MaybeEmpty::Some(v) => v.0,
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MaybeEmpty::None => U256::zero(),
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}
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}
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}
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impl From<MaybeEmpty<Uint>> for u64 {
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fn from(maybe: MaybeEmpty<Uint>) -> u64 {
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match maybe {
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MaybeEmpty::Some(v) => v.0.low_u64(),
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MaybeEmpty::None => 0u64,
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}
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}
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}
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impl Default for MaybeEmpty<Uint> {
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fn default() -> Self {
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MaybeEmpty::Some(Uint::default())
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}
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}
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#[cfg(test)]
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mod tests {
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use std::str::FromStr;
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use super::MaybeEmpty;
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use crate::hash::H256;
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#[test]
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fn maybe_deserialization() {
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let s = r#"["", "5a39ed1020c04d4d84539975b893a4e7c53eab6c2965db8bc3468093a31bc5ae"]"#;
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let deserialized: Vec<MaybeEmpty<H256>> = serde_json::from_str(s).unwrap();
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assert_eq!(deserialized, vec![
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MaybeEmpty::None,
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MaybeEmpty::Some(H256(ethereum_types::H256::from_str("5a39ed1020c04d4d84539975b893a4e7c53eab6c2965db8bc3468093a31bc5ae").unwrap()))
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]);
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}
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}
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