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//! Untagged serialization/deserialization support for Option<Either<L, R>>.
//!
//! `Either` uses default, externally-tagged representation.
//! However, sometimes it is useful to support several alternative types.
//! For example, we may have a field which is generally Map<String, i32>
//! but in typical cases Vec<String> would suffice, too.
//!
//! ```rust
//! # fn main() -> Result<(), Box<dyn std::error::Error>> {
//! use either::Either;
//! use std::collections::HashMap;
//!
//! #[derive(serde::Serialize, serde::Deserialize, Debug)]
//! #[serde(transparent)]
//! struct IntOrString {
//! #[serde(with = "either::serde_untagged_optional")]
//! inner: Option<Either<Vec<String>, HashMap<String, i32>>>
//! };
//!
//! // serialization
//! let data = IntOrString {
//! inner: Some(Either::Left(vec!["Hello".to_string()]))
//! };
//! // notice: no tags are emitted.
//! assert_eq!(serde_json::to_string(&data)?, r#"["Hello"]"#);
//!
//! // deserialization
//! let data: IntOrString = serde_json::from_str(
//! r#"{"a": 0, "b": 14}"#
//! )?;
//! println!("found {:?}", data);
//! # Ok(())
//! # }
//! ```
use serde::{Deserialize, Deserializer, Serialize, Serializer};
#[derive(Serialize, Deserialize)]
#[serde(untagged)]
enum Either<L, R> {
Left(L),
Right(R),
}
pub fn serialize<L, R, S>(
this: &Option<super::Either<L, R>>,
serializer: S,
) -> Result<S::Ok, S::Error>
where
S: Serializer,
L: Serialize,
R: Serialize,
{
let untagged = match this {
Some(super::Either::Left(left)) => Some(Either::Left(left)),
Some(super::Either::Right(right)) => Some(Either::Right(right)),
None => None,
};
untagged.serialize(serializer)
}
pub fn deserialize<'de, L, R, D>(deserializer: D) -> Result<Option<super::Either<L, R>>, D::Error>
where
D: Deserializer<'de>,
L: Deserialize<'de>,
R: Deserialize<'de>,
{
match Option::deserialize(deserializer) {
Ok(Some(Either::Left(left))) => Ok(Some(super::Either::Left(left))),
Ok(Some(Either::Right(right))) => Ok(Some(super::Either::Right(right))),
Ok(None) => Ok(None),
Err(error) => Err(error),
}
}