1 files changed, 140 insertions, 0 deletions
diff --git a/src/de/key.rs b/src/de/key.rs
new file mode 100644
index 0000000..3da41df
--- /dev/null
+++ b/src/de/key.rs
@@ -0,0 +1,140 @@
+use serde::de::IntoDeserializer;
+
+use super::Error;
+
+pub(crate) struct KeyDeserializer {
+    span: Option<std::ops::Range<usize>>,
+    key: crate::InternalString,
+}
+
+impl KeyDeserializer {
+    pub(crate) fn new(key: crate::InternalString, span: Option<std::ops::Range<usize>>) -> Self {
+        KeyDeserializer { span, key }
+    }
+}
+
+impl<'de> serde::de::IntoDeserializer<'de, Error> for KeyDeserializer {
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self::Deserializer {
+        self
+    }
+}
+
+impl<'de> serde::de::Deserializer<'de> for KeyDeserializer {
+    type Error = Error;
+
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.key.into_deserializer().deserialize_any(visitor)
+    }
+
+    fn deserialize_enum<V>(
+        self,
+        name: &str,
+        variants: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        let _ = name;
+        let _ = variants;
+        visitor.visit_enum(self)
+    }
+
+    fn deserialize_struct<V>(
+        self,
+        name: &'static str,
+        fields: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value, Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        if serde_spanned::__unstable::is_spanned(name, fields) {
+            if let Some(span) = self.span.clone() {
+                return visitor.visit_map(super::SpannedDeserializer::new(self.key.as_str(), span));
+            }
+        }
+        self.deserialize_any(visitor)
+    }
+
+    serde::forward_to_deserialize_any! {
+        bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string seq
+        bytes byte_buf map option unit newtype_struct
+        ignored_any unit_struct tuple_struct tuple identifier
+    }
+}
+
+impl<'de> serde::de::EnumAccess<'de> for KeyDeserializer {
+    type Error = super::Error;
+    type Variant = UnitOnly<Self::Error>;
+
+    fn variant_seed<T>(self, seed: T) -> Result<(T::Value, Self::Variant), Self::Error>
+    where
+        T: serde::de::DeserializeSeed<'de>,
+    {
+        seed.deserialize(self).map(unit_only)
+    }
+}
+
+pub(crate) struct UnitOnly<E> {
+    marker: std::marker::PhantomData<E>,
+}
+
+fn unit_only<T, E>(t: T) -> (T, UnitOnly<E>) {
+    (
+        t,
+        UnitOnly {
+            marker: std::marker::PhantomData,
+        },
+    )
+}
+
+impl<'de, E> serde::de::VariantAccess<'de> for UnitOnly<E>
+where
+    E: serde::de::Error,
+{
+    type Error = E;
+
+    fn unit_variant(self) -> Result<(), Self::Error> {
+        Ok(())
+    }
+
+    fn newtype_variant_seed<T>(self, _seed: T) -> Result<T::Value, Self::Error>
+    where
+        T: serde::de::DeserializeSeed<'de>,
+    {
+        Err(serde::de::Error::invalid_type(
+            serde::de::Unexpected::UnitVariant,
+            &"newtype variant",
+        ))
+    }
+
+    fn tuple_variant<V>(self, _len: usize, _visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(serde::de::Error::invalid_type(
+            serde::de::Unexpected::UnitVariant,
+            &"tuple variant",
+        ))
+    }
+
+    fn struct_variant<V>(
+        self,
+        _fields: &'static [&'static str],
+        _visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(serde::de::Error::invalid_type(
+            serde::de::Unexpected::UnitVariant,
+            &"struct variant",
+        ))
+    }
+}