Merge pull request #787 from 46bit/issue-775

Fix internally tagged enums by implementing ContentDeserializer::deserialize_enum
2026-04-25 01:07:56 +00:00 · 2017-02-22 18:23:18 -08:00
parent 017e6d304f 5e7883945b
commit 8e5f472e27
1 changed files with 258 additions and 4 deletions
@@ -58,6 +58,32 @@ pub enum Content {
    Map(Vec<(Content, Content)>),
 }

+impl Content {
+    fn unexpected(&self) -> Unexpected {
+        match *self {
+            Content::Bool(b) => Unexpected::Bool(b),
+            Content::U8(n) => Unexpected::Unsigned(n as u64),
+            Content::U16(n) => Unexpected::Unsigned(n as u64),
+            Content::U32(n) => Unexpected::Unsigned(n as u64),
+            Content::U64(n) => Unexpected::Unsigned(n),
+            Content::I8(n) => Unexpected::Signed(n as i64),
+            Content::I16(n) => Unexpected::Signed(n as i64),
+            Content::I32(n) => Unexpected::Signed(n as i64),
+            Content::I64(n) => Unexpected::Signed(n),
+            Content::F32(f) => Unexpected::Float(f as f64),
+            Content::F64(f) => Unexpected::Float(f),
+            Content::Char(c) => Unexpected::Char(c),
+            Content::String(ref s) => Unexpected::Str(s),
+            Content::Bytes(ref b) => Unexpected::Bytes(b),
+            Content::None | Content::Some(_) => Unexpected::Option,
+            Content::Unit => Unexpected::Unit,
+            Content::Newtype(_) => Unexpected::NewtypeStruct,
+            Content::Seq(_) => Unexpected::Seq,
+            Content::Map(_) => Unexpected::Map,
+        }
+    }
+}
+
 impl Deserialize for Content {
    fn deserialize<D: Deserializer>(deserializer: D) -> Result<Self, D::Error> {
        // Untagged and internally tagged enums are only supported in
@@ -607,10 +633,41 @@ impl<E> Deserializer for ContentDeserializer<E>
        visitor.visit_newtype_struct(self)
    }

+    fn deserialize_enum<V>(self, _name: &str, _variants: &'static [&'static str], visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor,
+    {
+        let (variant, value) = match self.content {
+            Content::Map(value) => {
+                let mut iter = value.into_iter();
+                let (variant, value) = match iter.next() {
+                    Some(v) => v,
+                    None => {
+                        return Err(de::Error::invalid_value(de::Unexpected::Map, &"map with a single key"));
+                    }
+                };
+                // enums are encoded in json as maps with a single key:value pair
+                if iter.next().is_some() {
+                    return Err(de::Error::invalid_value(de::Unexpected::Map, &"map with a single key"));
+                }
+                (variant, Some(value))
+            }
+            Content::String(variant) => (Content::String(variant), None),
+            other => {
+                return Err(de::Error::invalid_type(other.unexpected(), &"string or map"));
+            }
+        };
+
+        visitor.visit_enum(EnumDeserializer {
+            variant: variant,
+            value: value,
+            err: PhantomData,
+        })
+    }
+
    forward_to_deserialize! {
        bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string unit seq
        seq_fixed_size bytes byte_buf map unit_struct tuple_struct struct
-        struct_field tuple enum ignored_any
+        struct_field tuple ignored_any
    }
 }

@@ -624,6 +681,203 @@ impl<E> ContentDeserializer<E> {
    }
 }

+struct EnumDeserializer<E> where E: de::Error {
+    variant: Content,
+    value: Option<Content>,
+    err: PhantomData<E>,
+}
+
+impl<E> de::EnumVisitor for EnumDeserializer<E> where E: de::Error {
+    type Error = E;
+    type Variant = VariantDeserializer<Self::Error>;
+
+    fn visit_variant_seed<V>(self, seed: V) -> Result<(V::Value, VariantDeserializer<E>), Self::Error>
+        where V: de::DeserializeSeed,
+    {
+        let visitor = VariantDeserializer { value: self.value, err: PhantomData, };
+        seed.deserialize(ContentDeserializer::new(self.variant)).map(|v| (v, visitor))
+    }
+}
+
+struct VariantDeserializer<E> where E: de::Error {
+    value: Option<Content>,
+    err: PhantomData<E>,
+}
+
+impl<E> de::VariantVisitor for VariantDeserializer<E> where E: de::Error {
+    type Error = E;
+
+    fn visit_unit(self) -> Result<(), E> {
+        match self.value {
+            Some(value) => de::Deserialize::deserialize(ContentDeserializer::new(value)),
+            None => Ok(()),
+        }
+    }
+
+    fn visit_newtype_seed<T>(self, seed: T) -> Result<T::Value, E>
+        where T: de::DeserializeSeed
+    {
+        match self.value {
+            Some(value) => seed.deserialize(ContentDeserializer::new(value)),
+            None => Err(de::Error::invalid_type(de::Unexpected::UnitVariant, &"newtype variant")),
+        }
+    }
+
+    fn visit_tuple<V>(
+        self,
+        _len: usize,
+        visitor: V
+    ) -> Result<V::Value, Self::Error>
+        where V: de::Visitor
+    {
+        match self.value {
+            Some(Content::Seq(v)) => {
+                de::Deserializer::deserialize(SeqDeserializer::new(v), visitor)
+            }
+            Some(other) => Err(de::Error::invalid_type(other.unexpected(), &"tuple variant")),
+            None => Err(de::Error::invalid_type(de::Unexpected::UnitVariant, &"tuple variant"))
+        }
+    }
+
+    fn visit_struct<V>(
+        self,
+        _fields: &'static [&'static str],
+        visitor: V
+    ) -> Result<V::Value, Self::Error>
+        where V: de::Visitor
+    {
+        match self.value {
+            Some(Content::Map(v)) => {
+                de::Deserializer::deserialize(MapDeserializer::new(v), visitor)
+            }
+            Some(other) => Err(de::Error::invalid_type(other.unexpected(), &"struct variant")),
+            _ => Err(de::Error::invalid_type(de::Unexpected::UnitVariant, &"struct variant"))
+        }
+    }
+}
+
+struct SeqDeserializer<E> where E: de::Error {
+    iter: <Vec<Content> as IntoIterator>::IntoIter,
+    err: PhantomData<E>,
+}
+
+impl<E> SeqDeserializer<E> where E: de::Error {
+    fn new(vec: Vec<Content>) -> Self {
+        SeqDeserializer {
+            iter: vec.into_iter(),
+            err: PhantomData,
+        }
+    }
+}
+
+impl<E> de::Deserializer for SeqDeserializer<E> where E: de::Error {
+    type Error = E;
+
+    #[inline]
+    fn deserialize<V>(mut self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: de::Visitor,
+    {
+        let len = self.iter.len();
+        if len == 0 {
+            visitor.visit_unit()
+        } else {
+            let ret = try!(visitor.visit_seq(&mut self));
+            let remaining = self.iter.len();
+            if remaining == 0 {
+                Ok(ret)
+            } else {
+                Err(de::Error::invalid_length(len, &"fewer elements in array"))
+            }
+        }
+    }
+
+    forward_to_deserialize! {
+        bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string unit option
+        seq seq_fixed_size bytes byte_buf map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
+    }
+}
+
+impl<E> de::SeqVisitor for SeqDeserializer<E> where E: de::Error {
+    type Error = E;
+
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+        where T: de::DeserializeSeed,
+    {
+        match self.iter.next() {
+            Some(value) => seed.deserialize(ContentDeserializer::new(value)).map(Some),
+            None => Ok(None),
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+struct MapDeserializer<E> where E: de::Error {
+    iter: <Vec<(Content, Content)> as IntoIterator>::IntoIter,
+    value: Option<Content>,
+    err: PhantomData<E>,
+}
+
+impl<E> MapDeserializer<E> where E: de::Error {
+    fn new(map: Vec<(Content, Content)>) -> Self {
+        MapDeserializer {
+            iter: map.into_iter(),
+            value: None,
+            err: PhantomData,
+        }
+    }
+}
+
+impl<E> de::MapVisitor for MapDeserializer<E> where E: de::Error {
+    type Error = E;
+
+    fn visit_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+        where T: de::DeserializeSeed,
+    {
+        match self.iter.next() {
+            Some((key, value)) => {
+                self.value = Some(value);
+                seed.deserialize(ContentDeserializer::new(key)).map(Some)
+            }
+            None => Ok(None),
+        }
+    }
+
+    fn visit_value_seed<T>(&mut self, seed: T) -> Result<T::Value, Self::Error>
+        where T: de::DeserializeSeed,
+    {
+        match self.value.take() {
+            Some(value) => seed.deserialize(ContentDeserializer::new(value)),
+            None => Err(de::Error::custom("value is missing")),
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl<E> de::Deserializer for MapDeserializer<E> where E: de::Error {
+    type Error = E;
+
+    #[inline]
+    fn deserialize<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: de::Visitor,
+    {
+        visitor.visit_map(self)
+    }
+
+    forward_to_deserialize! {
+        bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string unit option
+        seq seq_fixed_size bytes byte_buf map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
+    }
+}
+
+
 /// Not public API.
 pub struct ContentRefDeserializer<'a, E> {
    content: &'a Content,
@@ -637,7 +891,7 @@ impl<'a, E> Deserializer for ContentRefDeserializer<'a, E>
 {
    type Error = E;

-    fn deserialize<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    fn deserialize<V>(self, visitor: V) -> Result<V::Value, E>
        where V: Visitor
    {
        match *self.content {
@@ -678,7 +932,7 @@ impl<'a, E> Deserializer for ContentRefDeserializer<'a, E>
        }
    }

-    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, E>
        where V: Visitor
    {
        match *self.content {
@@ -689,7 +943,7 @@ impl<'a, E> Deserializer for ContentRefDeserializer<'a, E>
        }
    }

-    fn deserialize_newtype_struct<V>(self, _name: &str, visitor: V) -> Result<V::Value, Self::Error>
+    fn deserialize_newtype_struct<V>(self, _name: &str, visitor: V) -> Result<V::Value, E>
        where V: Visitor
    {
        visitor.visit_newtype_struct(self)