120 lines
3.1 KiB
Rust
120 lines
3.1 KiB
Rust
// Copyright 2015-2020 Parity Technologies (UK) Ltd.
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// This file is part of OpenEthereum.
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// OpenEthereum 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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// OpenEthereum 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 OpenEthereum. If not, see <http://www.gnu.org/licenses/>.
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//! Deserializer of empty string values into optionals.
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use serde::{
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de::{Error, IntoDeserializer, Visitor},
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Deserialize, Deserializer,
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};
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use std::{fmt, marker::PhantomData};
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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>
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where
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T: Deserialize<'a>,
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{
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fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
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where
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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>
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where
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T: Deserialize<'a>,
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{
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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>
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where
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E: Error,
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{
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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>
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where
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E: Error,
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{
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match value.is_empty() {
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true => Ok(MaybeEmpty::None),
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false => 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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mod tests {
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use crate::{hash::H256, maybe::MaybeEmpty};
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use ethereum_types;
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use serde_json;
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use std::str::FromStr;
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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!(
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deserialized,
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vec![
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MaybeEmpty::None,
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MaybeEmpty::Some(H256(
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ethereum_types::H256::from_str(
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"5a39ed1020c04d4d84539975b893a4e7c53eab6c2965db8bc3468093a31bc5ae"
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)
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.unwrap()
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))
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]
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);
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}
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}
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