Implement Clone for the value deserializers

serde/src/de/value.rs

@@ -61,7 +61,7 @@ impl<'de, E> IntoDeserializer<'de, E> for ()
 }
 
 /// A helper deserializer that deserializes a `()`.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct UnitDeserializer<E> {
     marker: PhantomData<E>,
 }
@@ -95,7 +95,7 @@ impl<'de, E> de::Deserializer<'de> for UnitDeserializer<E>
 macro_rules! primitive_deserializer {
     ($ty:ty, $name:ident, $method:ident $($cast:tt)*) => {
         /// A helper deserializer that deserializes a number.
-        #[derive(Debug)]
+        #[derive(Clone, Debug)]
         pub struct $name<E> {
             value: $ty,
             marker: PhantomData<E>
@@ -149,7 +149,7 @@ primitive_deserializer!(f64, F64Deserializer, visit_f64);
 primitive_deserializer!(char, CharDeserializer, visit_char);
 
 /// A helper deserializer that deserializes a number.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct U32Deserializer<E> {
     value: u32,
     marker: PhantomData<E>,
@@ -212,7 +212,7 @@ impl<'de, E> de::EnumVisitor<'de> for U32Deserializer<E>
 ///////////////////////////////////////////////////////////////////////////////
 
 /// A helper deserializer that deserializes a `&str`.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct StrDeserializer<'a, E> {
     value: &'a str,
     marker: PhantomData<E>,
@@ -276,7 +276,7 @@ impl<'de, 'a, E> de::EnumVisitor<'de> for StrDeserializer<'a, E>
 
 /// A helper deserializer that deserializes a `String`.
 #[cfg(any(feature = "std", feature = "collections"))]
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct StringDeserializer<E> {
     value: String,
     marker: PhantomData<E>,
@@ -343,7 +343,7 @@ impl<'de, 'a, E> de::EnumVisitor<'de> for StringDeserializer<E>
 
 /// A helper deserializer that deserializes a `String`.
 #[cfg(any(feature = "std", feature = "collections"))]
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct CowStrDeserializer<'a, E> {
     value: Cow<'a, str>,
     marker: PhantomData<E>,
@@ -412,7 +412,7 @@ impl<'de, 'a, E> de::EnumVisitor<'de> for CowStrDeserializer<'a, E>
 ///////////////////////////////////////////////////////////////////////////////
 
 /// A helper deserializer that deserializes a sequence.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct SeqDeserializer<I, E> {
     iter: iter::Fuse<I>,
     count: usize,
@@ -548,7 +548,7 @@ impl<'de, T, E> IntoDeserializer<'de, E> for HashSet<T>
 ///////////////////////////////////////////////////////////////////////////////
 
 /// A helper deserializer that deserializes a sequence using a `SeqVisitor`.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct SeqVisitorDeserializer<V_> {
     visitor: V_,
 }
@@ -764,6 +764,27 @@ impl<'de, I, E> de::SeqVisitor<'de> for MapDeserializer<'de, I, E>
     }
 }
 
+// Cannot #[derive(Clone)] because of the bound:
+//
+//    <I::Item as private::Pair>::Second: Clone
+impl<'de, I, E> Clone for MapDeserializer<'de, I, E>
+    where I: Iterator + Clone,
+          I::Item: private::Pair,
+          <I::Item as private::Pair>::First: IntoDeserializer<'de, E>,
+          <I::Item as private::Pair>::Second: IntoDeserializer<'de, E> + Clone,
+          E: de::Error
+{
+    fn clone(&self) -> Self {
+        MapDeserializer {
+            iter: self.iter.clone(),
+            value: self.value.clone(),
+            count: self.count,
+            lifetime: self.lifetime,
+            error: self.error,
+        }
+    }
+}
+
 // Cannot #[derive(Debug)] because of the bound:
 //
 //    <I::Item as private::Pair>::Second: Debug
@@ -912,7 +933,7 @@ impl<'de, K, V, E> IntoDeserializer<'de, E> for HashMap<K, V>
 ///////////////////////////////////////////////////////////////////////////////
 
 /// A helper deserializer that deserializes a map using a `MapVisitor`.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct MapVisitorDeserializer<V_> {
     visitor: V_,
 }
@@ -951,7 +972,7 @@ mod private {
 
     use de::{self, Unexpected};
 
-    #[derive(Debug)]
+    #[derive(Clone, Debug)]
     pub struct UnitOnly<E> {
         marker: PhantomData<E>,
     }