From 4bba342e424ca245a61b33d68cc48fe33224d60a Mon Sep 17 00:00:00 2001
From: David Rajchenbach-Teller <david.teller@univ-orleans.fr>
Date: Tue, 23 Feb 2016 21:43:50 +0100
Subject: [PATCH] Resolves #183 - Serialize and Deserialize for PhantomData

---
 serde/src/de/impls.rs  | 28 ++++++++++++++++++++++++++++
 serde/src/ser/impls.rs | 12 ++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 2a8fc00f..0608a363 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -315,6 +315,34 @@ impl<T> Deserialize for Option<T> where T: Deserialize {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+/// A visitor that produces a `PhantomData`.
+pub struct PhantomDataVisitor<T> {
+    marker: PhantomData<T>,
+}
+
+impl<
+    T: Deserialize,
+> Visitor for PhantomDataVisitor<T> {
+    type Value = PhantomData<T>;
+
+    #[inline]
+    fn visit_unit<E>(&mut self) -> Result<PhantomData<T>, E>
+        where E: Error,
+    {
+        Ok(PhantomData)
+    }
+}
+
+impl<T> Deserialize for PhantomData<T> where T: Deserialize {
+    fn deserialize<D>(deserializer: &mut D) -> Result<PhantomData<T>, D::Error>
+        where D: Deserializer,
+    {
+        deserializer.visit_unit(PhantomDataVisitor {marker: PhantomData})
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 macro_rules! seq_impl {
     (
         $ty:ty,
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 6c33dddb..70db3b65 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -22,6 +22,7 @@ use std::ops;
 use std::path;
 use std::rc::Rc;
 use std::sync::Arc;
+use std::marker::PhantomData;
 
 #[cfg(feature = "nightly")]
 use core::nonzero::{NonZero, Zeroable};
@@ -119,6 +120,17 @@ impl<T> SeqVisitor for Option<T> where T: Serialize {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+impl<T> Serialize for PhantomData<T> {
+    #[inline]
+    fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
+        where S: Serializer,
+    {
+        serializer.visit_unit()
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 /// A `serde::Visitor` for sequence iterators.
 ///
 /// # Examples