70 lines
2.0 KiB
Rust
70 lines
2.0 KiB
Rust
//! Untagged serialization/deserialization support for Either<L, R>.
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//!
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//! `Either` uses default, externally-tagged representation.
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//! However, sometimes it is useful to support several alternative types.
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//! For example, we may have a field which is generally Map<String, i32>
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//! but in typical cases Vec<String> would suffice, too.
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//!
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//! ```rust
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//! # fn main() -> Result<(), Box<dyn std::error::Error>> {
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//! use either::Either;
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//! use std::collections::HashMap;
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//!
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//! #[derive(serde::Serialize, serde::Deserialize, Debug)]
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//! #[serde(transparent)]
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//! struct IntOrString {
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//! #[serde(with = "either::serde_untagged")]
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//! inner: Either<Vec<String>, HashMap<String, i32>>
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//! };
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//!
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//! // serialization
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//! let data = IntOrString {
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//! inner: Either::Left(vec!["Hello".to_string()])
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//! };
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//! // notice: no tags are emitted.
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//! assert_eq!(serde_json::to_string(&data)?, r#"["Hello"]"#);
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//!
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//! // deserialization
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//! let data: IntOrString = serde_json::from_str(
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//! r#"{"a": 0, "b": 14}"#
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//! )?;
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//! println!("found {:?}", data);
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//! # Ok(())
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//! # }
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//! ```
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use serde::{Deserialize, Deserializer, Serialize, Serializer};
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#[derive(serde::Serialize, serde::Deserialize)]
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#[serde(untagged)]
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enum Either<L, R> {
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Left(L),
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Right(R),
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}
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pub fn serialize<L, R, S>(this: &super::Either<L, R>, serializer: S) -> Result<S::Ok, S::Error>
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where
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S: Serializer,
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L: Serialize,
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R: Serialize,
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{
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let untagged = match this {
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super::Either::Left(left) => Either::Left(left),
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super::Either::Right(right) => Either::Right(right),
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};
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untagged.serialize(serializer)
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}
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pub fn deserialize<'de, L, R, D>(deserializer: D) -> Result<super::Either<L, R>, D::Error>
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where
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D: Deserializer<'de>,
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L: Deserialize<'de>,
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R: Deserialize<'de>,
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{
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match Either::deserialize(deserializer) {
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Ok(Either::Left(left)) => Ok(super::Either::Left(left)),
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Ok(Either::Right(right)) => Ok(super::Either::Right(right)),
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Err(error) => Err(error),
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}
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}
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