Allow decode with custom DeserializeSeed

src/features/serde/de_borrowed.rs

@@ -25,6 +25,24 @@ where
     T::deserialize(serde_decoder)
 }
 
+/// Decode a borrowed type from the given slice using a seed. Some parts of the decoded type are expected to be referring to the given slice
+pub fn decode_seed_from_slice<'de, T, C>(seed: T, slice: &'de [u8], config: C) -> Result<T::Value, DecodeError>
+where
+    T: DeserializeSeed<'de>,
+    C: Config,
+{
+    if C::SKIP_FIXED_ARRAY_LENGTH {
+        return Err(SerdeDecodeError::SkipFixedArrayLengthNotSupported.into());
+    }
+    let reader = crate::de::read::SliceReader::new(slice);
+    let mut decoder = crate::de::DecoderImpl::new(reader, config);
+    let serde_decoder = SerdeDecoder {
+        de: &mut decoder,
+        pd: PhantomData,
+    };
+    seed.deserialize(serde_decoder)
+}
+
 pub(super) struct SerdeDecoder<'a, 'de, DE: BorrowDecoder<'de>> {
     pub(super) de: &'a mut DE,
     pub(super) pd: PhantomData<&'de ()>,
@@ -439,4 +457,4 @@ impl<'de, 'a, DE: BorrowDecoder<'de>> VariantAccess<'de> for SerdeDecoder<'a, 'd
     {
         Deserializer::deserialize_tuple(self, fields.len(), visitor)
     }
-}
+}