Macro enum_number_declare

macro_rules! enum_number_declare {
    ($visibility:vis $name:ident { $($variant:ident = $value:expr, )* }) => { ... };
}

This contains both serialization and ser/deserialization of a enum into and from numbers. The reference implementation does not work if your enum has negative values. This enum_number handles this also.

Example

serde_aux::enum_number_declare!(pub TestEnum {
    Up = 1,
    None = 0,
    Down = -1,
});

let s = r#"1"#;
let a: TestEnum = serde_json::from_str(s).unwrap();
assert_eq!(a, TestEnum::Up);

let s = r#"0"#;
let a: TestEnum = serde_json::from_str(s).unwrap();
assert_eq!(a, TestEnum::None);

let s = r#"-1"#;
let a: TestEnum = serde_json::from_str(s).unwrap();
assert_eq!(a, TestEnum::Down);

let s = r#"5"#;
assert!(serde_json::from_str::<TestEnum>(s).is_err());