Remove custom implementations of SeqDeserializer and MapDeserializer for enums

Those deserializers are used to deserialize tuple or struct variants from Content
which is used by internally tagged enums and by flatten

FlatMapDeserializer is reached in the following tests:
    flatten::enum_::externally_tagged::newtype
    flatten::enum_::externally_tagged::struct_from_map
    flatten::enum_::externally_tagged::struct_from_seq
    flatten::enum_::externally_tagged::tuple

ContentDeserializer is reached in the following tests:
    test_enum_in_internally_tagged_enum
    test_internally_tagged_struct_variant_containing_unit_variant

Author: Mingun

serde/src/private/de.rs

@@ -207,6 +207,7 @@ mod content {
 
     use __private::size_hint;
     use actually_private;
+    use de::value::{MapDeserializer, SeqDeserializer};
     use de::{
         self, Deserialize, DeserializeSeed, Deserializer, EnumAccess, Expected, IgnoredAny,
         MapAccess, SeqAccess, Unexpected, Visitor,
@@ -299,6 +300,17 @@ mod content {
         }
     }
 
+    impl<'de, E> de::IntoDeserializer<'de, E> for Content<'de>
+    where
+        E: de::Error,
+    {
+        type Deserializer = ContentDeserializer<'de, E>;
+
+        fn into_deserializer(self) -> Self::Deserializer {
+            ContentDeserializer::new(self)
+        }
+    }
+
     struct ContentVisitor<'de> {
         value: PhantomData<Content<'de>>,
     }
@@ -1074,7 +1086,7 @@ mod content {
         E: de::Error,
     {
         let seq = content.into_iter().map(ContentDeserializer::new);
-        let mut seq_visitor = de::value::SeqDeserializer::new(seq);
+        let mut seq_visitor = SeqDeserializer::new(seq);
         let value = try!(visitor.visit_seq(&mut seq_visitor));
         try!(seq_visitor.end());
         Ok(value)
@@ -1091,7 +1103,7 @@ mod content {
         let map = content
             .into_iter()
             .map(|(k, v)| (ContentDeserializer::new(k), ContentDeserializer::new(v)));
-        let mut map_visitor = de::value::MapDeserializer::new(map);
+        let mut map_visitor = MapDeserializer::new(map);
         let value = try!(visitor.visit_map(&mut map_visitor));
         try!(map_visitor.end());
         Ok(value)
@@ -1569,7 +1581,7 @@ mod content {
         {
             match self.value {
                 Some(Content::Seq(v)) => {
-                    de::Deserializer::deserialize_any(SeqDeserializer::new(v), visitor)
+                    de::Deserializer::deserialize_any(SeqDeserializer::new(v.into_iter()), visitor)
                 }
                 Some(other) => Err(de::Error::invalid_type(
                     other.unexpected(),
@@ -1592,10 +1604,10 @@ mod content {
         {
             match self.value {
                 Some(Content::Map(v)) => {
-                    de::Deserializer::deserialize_any(MapDeserializer::new(v), visitor)
+                    de::Deserializer::deserialize_any(MapDeserializer::new(v.into_iter()), visitor)
                 }
                 Some(Content::Seq(v)) => {
-                    de::Deserializer::deserialize_any(SeqDeserializer::new(v), visitor)
+                    de::Deserializer::deserialize_any(SeqDeserializer::new(v.into_iter()), visitor)
                 }
                 Some(other) => Err(de::Error::invalid_type(
                     other.unexpected(),
@@ -1609,156 +1621,6 @@ mod content {
         }
     }
 
-    struct SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        iter: <Vec<Content<'de>> as IntoIterator>::IntoIter,
-        err: PhantomData<E>,
-    }
-
-    impl<'de, E> SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        fn new(vec: Vec<Content<'de>>) -> Self {
-            SeqDeserializer {
-                iter: vec.into_iter(),
-                err: PhantomData,
-            }
-        }
-    }
-
-    impl<'de, E> de::Deserializer<'de> for SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        #[inline]
-        fn deserialize_any<V>(mut self, visitor: V) -> Result<V::Value, Self::Error>
-        where
-            V: de::Visitor<'de>,
-        {
-            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_any! {
-            bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
-            bytes byte_buf option unit unit_struct newtype_struct seq tuple
-            tuple_struct map struct enum identifier ignored_any
-        }
-    }
-
-    impl<'de, E> de::SeqAccess<'de> for SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
-        where
-            T: de::DeserializeSeed<'de>,
-        {
-            match self.iter.next() {
-                Some(value) => seed.deserialize(ContentDeserializer::new(value)).map(Some),
-                None => Ok(None),
-            }
-        }
-
-        fn size_hint(&self) -> Option<usize> {
-            size_hint::from_bounds(&self.iter)
-        }
-    }
-
-    struct MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        iter: <Vec<(Content<'de>, Content<'de>)> as IntoIterator>::IntoIter,
-        value: Option<Content<'de>>,
-        err: PhantomData<E>,
-    }
-
-    impl<'de, E> MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        fn new(map: Vec<(Content<'de>, Content<'de>)>) -> Self {
-            MapDeserializer {
-                iter: map.into_iter(),
-                value: None,
-                err: PhantomData,
-            }
-        }
-    }
-
-    impl<'de, E> de::MapAccess<'de> for MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        fn next_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
-        where
-            T: de::DeserializeSeed<'de>,
-        {
-            match self.iter.next() {
-                Some((key, value)) => {
-                    self.value = Some(value);
-                    seed.deserialize(ContentDeserializer::new(key)).map(Some)
-                }
-                None => Ok(None),
-            }
-        }
-
-        fn next_value_seed<T>(&mut self, seed: T) -> Result<T::Value, Self::Error>
-        where
-            T: de::DeserializeSeed<'de>,
-        {
-            match self.value.take() {
-                Some(value) => seed.deserialize(ContentDeserializer::new(value)),
-                None => Err(de::Error::custom("value is missing")),
-            }
-        }
-
-        fn size_hint(&self) -> Option<usize> {
-            size_hint::from_bounds(&self.iter)
-        }
-    }
-
-    impl<'de, E> de::Deserializer<'de> for MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        #[inline]
-        fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
-        where
-            V: de::Visitor<'de>,
-        {
-            visitor.visit_map(self)
-        }
-
-        forward_to_deserialize_any! {
-            bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
-            bytes byte_buf option unit unit_struct newtype_struct seq tuple
-            tuple_struct map struct enum identifier ignored_any
-        }
-    }
-
     /// Not public API.
     pub struct ContentRefDeserializer<'a, 'de: 'a, E> {
         content: &'a Content<'de>,
@@ -1820,7 +1682,7 @@ mod content {
         E: de::Error,
     {
         let seq = content.iter().map(ContentRefDeserializer::new);
-        let mut seq_visitor = de::value::SeqDeserializer::new(seq);
+        let mut seq_visitor = SeqDeserializer::new(seq);
         let value = try!(visitor.visit_seq(&mut seq_visitor));
         try!(seq_visitor.end());
         Ok(value)
@@ -1840,7 +1702,7 @@ mod content {
                 ContentRefDeserializer::new(v),
             )
         });
-        let mut map_visitor = de::value::MapDeserializer::new(map);
+        let mut map_visitor = MapDeserializer::new(map);
         let value = try!(visitor.visit_map(&mut map_visitor));
         try!(map_visitor.end());
         Ok(value)