示例
extern crate serde;
extern crate serde_json;
macro_rules! enum_str {
($name:ident { $($variant:ident($str:expr), )* }) => {
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum $name {
$($variant,)*
}
impl ::serde::Serialize for $name {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where S: ::serde::Serializer,
{
//将枚举序列化为字符串。
serializer.serialize_str(match *self {
$( $name::$variant => $str, )*
})
}
}
impl ::serde::Deserialize for $name {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where D: ::serde::Deserializer,
{
struct Visitor;
impl ::serde::de::Visitor for Visitor {
type Value = $name;
fn expecting(&self, formatter: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
write!(formatter, "a string for {}", stringify!($name))
}
fn visit_str<E>(self, value: &str) -> Result<$name, E>
where E: ::serde::de::Error,
{
match value {
$( $str => Ok($name::$variant), )*
_ => Err(E::invalid_value(::serde::de::Unexpected::Other(
&format!("unknown {} variant: {}", stringify!($name), value)
), &self)),
}
}
}
//从字符串反序列化枚举。
deserializer.deserialize_str(Visitor)
}
}
}
}
enum_str!(LanguageCode {
English("en"),
Spanish("es"),
Italian("it"),
Japanese("ja"),
Chinese("zh"),
});
fn main() {
use LanguageCode::*;
let languages = vec![English, Spanish, Italian, Japanese, Chinese];
// Prints ["en","es","it","ja","zh"]
println!("{}", serde_json::to_string(&languages).unwrap());
let input = r#" "ja" "#;
assert_eq!(Japanese, serde_json::from_str(input).unwrap());
}
