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#[macro_export]
macro_rules! cenum {
($name:ident { $($variants:ident),+ $(,)? }) => {
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
#[repr(u8)]
pub enum $name {
$(
$variants,
)+
}
impl $name {
pub const VARIANTS: &'static [Self] = &[
$(
Self::$variants,
)+
];
paste::paste! {
#[allow(unused)]
pub const NAMES: &'static [&'static str] = &[
$(
stringify!([<$variants:snake:lower>])
),+
];
}
fn into_discriminant(self) -> u8 {
self as u8
}
fn from_discriminant(discriminant: u8) -> Option<Self> {
Self::VARIANTS.get(usize::from(discriminant)).copied()
}
fn from_str(v: &str) -> Option<Self> {
paste::paste! {
match v {
$(
stringify!([<$variants:snake:lower>]) => Some(<$name>::$variants),
)+
_ => None,
}
}
}
#[allow(unused)]
pub const fn name(self) -> &'static str {
paste::paste! {
match self {
$(
Self::$variants => stringify!([<$variants:snake:lower>]),
)+
}
}
}
}
const _: () = {
pub struct TheDeserializer<'de, E> {
value: $name,
_lifetime: ::std::marker::PhantomData<&'de ()>,
_error: ::std::marker::PhantomData<E>,
}
impl<'de, E: ::serde::de::Error> TheDeserializer<'de, E> {
fn new(value: $name) -> Self {
Self {
value,
_lifetime: ::std::marker::PhantomData,
_error: ::std::marker::PhantomData,
}
}
}
impl<'de, E: ::serde::de::Error> ::serde::de::IntoDeserializer<'de, E> for $name {
type Deserializer = TheDeserializer<'de, E>;
fn into_deserializer(self) -> Self::Deserializer {
Self::Deserializer::new(self)
}
}
impl<'de, E: ::serde::de::Error> ::serde::de::Deserializer<'de> for TheDeserializer<'de, E> {
type Error = E;
fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
where
V: ::serde::de::Visitor<'de>,
{
visitor.visit_u8(self.value.into_discriminant())
}
fn deserialize_identifier<V>(self, visitor: V) -> Result<V::Value, Self::Error>
where
V: ::serde::de::Visitor<'de>,
{
visitor.visit_str(self.value.name())
}
::serde::forward_to_deserialize_any! {
char str string bytes byte_buf option unit unit_struct seq map
tuple tuple_struct struct enum newtype_struct ignored_any
bool i8 i16 i32 i64 i128 u8 u16 u32 u64 f32 f64
}
}
impl<'de> ::serde::Deserialize<'de> for $name {
fn deserialize<D>(deserializer: D) -> Result<$name, D::Error>
where
D: ::serde::de::Deserializer<'de>,
{
struct TheVisitor;
impl<'de> ::serde::de::Visitor<'de> for TheVisitor {
type Value = $name;
fn expecting(&self, formatter: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
formatter.write_str(concat!("a valid ", stringify!($name), " identifier"))
}
fn visit_i64<E>(self, v: i64) -> Result<Self::Value, E>
where
E: ::serde::de::Error,
{
match u8::try_from(v).ok().and_then(<$name>::from_discriminant) {
Some(kind) => Ok(kind),
None => Err(E::invalid_value(::serde::de::Unexpected::Signed(v), &self)),
}
}
fn visit_u64<E>(self, v: u64) -> Result<Self::Value, E>
where
E: ::serde::de::Error,
{
match u8::try_from(v).ok().and_then(<$name>::from_discriminant) {
Some(kind) => Ok(kind),
None => Err(E::invalid_value(::serde::de::Unexpected::Unsigned(v), &self)),
}
}
fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
where
E: ::serde::de::Error,
{
paste::paste! {
match <$name>::from_str(v) {
Some(kind) => Ok(kind),
_ => Err(E::unknown_variant(v, &[
$(
stringify!([<$variants:snake:lower>])
),+
])),
}
}
}
}
deserializer.deserialize_any(TheVisitor)
}
}
impl ::serde::Serialize for $name {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: serde::ser::Serializer,
{
serializer.serialize_u8(self.into_discriminant())
}
}
};
paste::paste! {
#[cfg(test)]
mod [< $name:snake:lower _tests>] {
use super::*;
#[allow(unused_assignments)]
#[test]
fn serialize() {
let mut expected = 0;
$(
let result = serde_json::to_value(<$name>::$variants).unwrap();
assert_eq!(result, serde_json::json!(expected));
expected += 1;
)+
}
#[allow(unused_assignments)]
#[test]
fn deserialize() {
let mut value = 0;
$(
let result = serde_json::from_value::<$name>(serde_json::json!(value)).unwrap();
assert_eq!(result, <$name>::$variants);
value += 1;
)+
}
#[allow(unused_assignments)]
#[test]
fn deserialize_str() {
$(
let result = serde_json::from_value::<$name>(serde_json::json!(<$name>::$variants.name())).unwrap();
assert_eq!(result, <$name>::$variants);
)+
}
}
}
}
}