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//! Deserialization support for [`Spanned`]
use serde_core::de::value::BorrowedStrDeserializer;
use serde_core::de::IntoDeserializer as _;
use crate::Spanned;
/// Check if deserializing a [`Spanned`]
pub fn is_spanned(name: &'static str) -> bool {
crate::spanned::is_spanned(name)
}
/// Deserializer / format support for emitting [`Spanned`]
pub struct SpannedDeserializer<'de, T, E>
where
T: serde_core::de::IntoDeserializer<'de, E>,
E: serde_core::de::Error,
{
start: Option<usize>,
end: Option<usize>,
value: Option<T>,
_lifetime: core::marker::PhantomData<&'de ()>,
_error: core::marker::PhantomData<E>,
}
impl<'de, T, E> SpannedDeserializer<'de, T, E>
where
T: serde_core::de::IntoDeserializer<'de, E>,
E: serde_core::de::Error,
{
/// Create a deserializer to emit [`Spanned`]
pub fn new(value: T, span: core::ops::Range<usize>) -> Self {
Self {
start: Some(span.start),
end: Some(span.end),
value: Some(value),
_lifetime: Default::default(),
_error: Default::default(),
}
}
}
impl<'de, T, E> serde_core::de::MapAccess<'de> for SpannedDeserializer<'de, T, E>
where
T: serde_core::de::IntoDeserializer<'de, E>,
E: serde_core::de::Error,
{
type Error = E;
fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Self::Error>
where
K: serde_core::de::DeserializeSeed<'de>,
{
if self.start.is_some() {
seed.deserialize(BorrowedStrDeserializer::new(Spanned::<T>::START_FIELD))
.map(Some)
} else if self.end.is_some() {
seed.deserialize(BorrowedStrDeserializer::new(Spanned::<T>::END_FIELD))
.map(Some)
} else if self.value.is_some() {
seed.deserialize(BorrowedStrDeserializer::new(Spanned::<T>::VALUE_FIELD))
.map(Some)
} else {
Ok(None)
}
}
fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Self::Error>
where
V: serde_core::de::DeserializeSeed<'de>,
{
if let Some(start) = self.start.take() {
seed.deserialize(start.into_deserializer())
} else if let Some(end) = self.end.take() {
seed.deserialize(end.into_deserializer())
} else if let Some(value) = self.value.take() {
seed.deserialize(value.into_deserializer())
} else {
panic!("next_value_seed called before next_key_seed")
}
}
}