Generate deserialize impls for identifiers

serde/src/private/de.rs

@@ -8,7 +8,7 @@
 
 use lib::*;
 
-use de::{Deserialize, Deserializer, Error, Visitor};
+use de::{Deserialize, Deserializer, IntoDeserializer, Error, Visitor};
 
 #[cfg(any(feature = "std", feature = "collections"))]
 use de::Unexpected;
@@ -1740,3 +1740,110 @@ mod content {
         }
     }
 }
+
+////////////////////////////////////////////////////////////////////////////////
+
+// Like `IntoDeserializer` but also implemented for `&[u8]`. This is used for
+// the newtype fallthrough case of `field_identifier`.
+//
+//    #[derive(Deserialize)]
+//    #[serde(field_identifier)]
+//    enum F {
+//        A,
+//        B,
+//        Other(String), // deserialized using IdentifierDeserializer
+//    }
+pub trait IdentifierDeserializer<'de, E: Error> {
+    type Deserializer: Deserializer<'de, Error = E>;
+
+    fn from(self) -> Self::Deserializer;
+}
+
+impl<'de, E> IdentifierDeserializer<'de, E> for u32
+where
+    E: Error,
+{
+    type Deserializer = <u32 as IntoDeserializer<'de, E>>::Deserializer;
+
+    fn from(self) -> Self::Deserializer {
+        self.into_deserializer()
+    }
+}
+
+pub struct StrDeserializer<'a, E> {
+    value: &'a str,
+    marker: PhantomData<E>,
+}
+
+impl<'a, E> IdentifierDeserializer<'a, E> for &'a str
+where
+    E: Error,
+{
+    type Deserializer = StrDeserializer<'a, E>;
+
+    fn from(self) -> Self::Deserializer {
+        StrDeserializer {
+            value: self,
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'de, 'a, E> Deserializer<'de> for StrDeserializer<'a, E>
+where
+    E: Error,
+{
+    type Error = E;
+
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        visitor.visit_str(self.value)
+    }
+
+    forward_to_deserialize_any! {
+        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
+        byte_buf option unit unit_struct newtype_struct seq seq_fixed_size
+        tuple tuple_struct map struct identifier enum ignored_any
+    }
+}
+
+pub struct BytesDeserializer<'a, E> {
+    value: &'a [u8],
+    marker: PhantomData<E>,
+}
+
+impl<'a, E> IdentifierDeserializer<'a, E> for &'a [u8]
+where
+    E: Error,
+{
+    type Deserializer = BytesDeserializer<'a, E>;
+
+    fn from(self) -> Self::Deserializer {
+        BytesDeserializer {
+            value: self,
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'de, 'a, E> Deserializer<'de> for BytesDeserializer<'a, E>
+where
+    E: Error,
+{
+    type Error = E;
+
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        visitor.visit_bytes(self.value)
+    }
+
+    forward_to_deserialize_any! {
+        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
+        byte_buf option unit unit_struct newtype_struct seq seq_fixed_size
+        tuple tuple_struct map struct identifier enum ignored_any
+    }
+}