Implement (De)Serialization for Pinned Smart Pointers

serde_with/CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+* Implement (De)Serialization for Pinned Smart Pointers by @Astralchroma (#733)
+
 ## [3.7.0] - 2024-03-11
 
 ### Added

serde_with/src/de/impls.rs

@@ -110,6 +110,25 @@ pub(crate) mod macros {
 ///////////////////////////////////////////////////////////////////////////////
 // region: Simple Wrapper types (e.g., Box, Option)
 
+#[allow(unused_macros)]
+macro_rules! pinned_wrapper {
+    ($wrapper:ident) => {
+        impl<'de, T, U> DeserializeAs<'de, Pin<$wrapper<T>>> for Pin<$wrapper<U>>
+        where
+            U: DeserializeAs<'de, T>,
+        {
+            fn deserialize_as<D>(deserializer: D) -> Result<Pin<$wrapper<T>>, D::Error>
+            where
+                D: Deserializer<'de>,
+            {
+                Ok($wrapper::pin(
+                    DeserializeAsWrap::<T, U>::deserialize(deserializer)?.into_inner(),
+                ))
+            }
+        }
+    };
+}
+
 #[cfg(feature = "alloc")]
 impl<'de, T, U> DeserializeAs<'de, Box<T>> for Box<U>
 where
@@ -125,6 +144,9 @@ where
     }
 }
 
+#[cfg(feature = "alloc")]
+pinned_wrapper!(Box);
+
 impl<'de, T, U> DeserializeAs<'de, Option<T>> for Option<U>
 where
     U: DeserializeAs<'de, T>,
@@ -207,6 +229,9 @@ where
     }
 }
 
+#[cfg(feature = "alloc")]
+pinned_wrapper!(Rc);
+
 #[cfg(feature = "alloc")]
 impl<'de, T, U> DeserializeAs<'de, RcWeak<T>> for RcWeak<U>
 where
@@ -236,6 +261,9 @@ where
     }
 }
 
+#[cfg(all(feature = "alloc", target_has_atomic = "ptr"))]
+pinned_wrapper!(Arc);
+
 #[cfg(all(feature = "alloc", target_has_atomic = "ptr"))]
 impl<'de, T, U> DeserializeAs<'de, ArcWeak<T>> for ArcWeak<U>
 where

serde_with/src/lib.rs

@@ -390,6 +390,7 @@ pub(crate) mod prelude {
         marker::PhantomData,
         ops::Bound,
         option::Option,
+        pin::Pin,
         result::Result,
         str::FromStr,
         time::Duration,

serde_with/src/ser/impls.rs

@@ -13,6 +13,8 @@ use indexmap_2::{IndexMap as IndexMap2, IndexSet as IndexSet2};
 #[cfg(feature = "alloc")]
 type BoxedSlice<T> = Box<[T]>;
 type Slice<T> = [T];
+type Ref<'a, T> = &'a T;
+type RefMut<'a, T> = &'a mut T;
 
 pub(crate) mod macros {
     // The unused_imports lint has false-positives around macros
@@ -84,6 +86,23 @@ pub(crate) mod macros {
 ///////////////////////////////////////////////////////////////////////////////
 // region: Simple Wrapper types (e.g., Box, Option)
 
+#[allow(unused_macros)]
+macro_rules! pinned_wrapper {
+    ($wrapper:ident $($lifetime:lifetime)?) => {
+        impl<$($lifetime,)? T, U> SerializeAs<Pin<$wrapper<$($lifetime,)? T>>> for Pin<$wrapper<$($lifetime,)? U>>
+        where
+            U: SerializeAs<T>,
+        {
+            fn serialize_as<S>(source: &Pin<$wrapper<$($lifetime,)? T>>, serializer: S) -> Result<S::Ok, S::Error>
+            where
+                S: Serializer,
+            {
+                SerializeAsWrap::<T, U>::new(source).serialize(serializer)
+            }
+        }
+    };
+}
+
 impl<'a, T, U> SerializeAs<&'a T> for &'a U
 where
     U: SerializeAs<T>,
@@ -112,6 +131,9 @@ where
     }
 }
 
+pinned_wrapper!(Ref 'a);
+pinned_wrapper!(RefMut 'a);
+
 #[cfg(feature = "alloc")]
 impl<T, U> SerializeAs<Box<T>> for Box<U>
 where
@@ -125,6 +147,9 @@ where
     }
 }
 
+#[cfg(feature = "alloc")]
+pinned_wrapper!(Box);
+
 impl<T, U> SerializeAs<Option<T>> for Option<U>
 where
     U: SerializeAs<T>,
@@ -171,6 +196,9 @@ where
     }
 }
 
+#[cfg(feature = "alloc")]
+pinned_wrapper!(Rc);
+
 #[cfg(feature = "alloc")]
 impl<T, U> SerializeAs<RcWeak<T>> for RcWeak<U>
 where
@@ -198,6 +226,9 @@ where
     }
 }
 
+#[cfg(all(feature = "alloc", target_has_atomic = "ptr"))]
+pinned_wrapper!(Arc);
+
 #[cfg(all(feature = "alloc", target_has_atomic = "ptr"))]
 impl<T, U> SerializeAs<ArcWeak<T>> for ArcWeak<U>
 where

serde_with/tests/serde_as/lib.rs

@@ -23,6 +23,7 @@ use alloc::{
 use core::{
     cell::{Cell, RefCell},
     ops::Bound,
+    pin::Pin,
 };
 use expect_test::expect;
 use serde::{Deserialize, Serialize};
@@ -44,12 +45,31 @@ fn test_basic_wrappers() {
 
     is_equal(SBox(Box::new(123)), expect![[r#""123""#]]);
 
+    // Deserialization in generally is not possible, only for unpin types
+    #[serde_as]
+    #[derive(Debug, Serialize, PartialEq)]
+    struct SPin<'a>(#[serde_as(as = "Pin<&DisplayFromStr>")] Pin<&'a u32>);
+    let tmp = 123;
+    check_serialization(SPin(Pin::new(&tmp)), expect![[r#""123""#]]);
+
+    #[serde_as]
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    struct SPinBox(#[serde_as(as = "Pin<Box<DisplayFromStr>>")] Pin<Box<u32>>);
+
+    is_equal(SPinBox(Box::pin(123)), expect![[r#""123""#]]);
+
     #[serde_as]
     #[derive(Debug, Serialize, Deserialize, PartialEq)]
     struct SRc(#[serde_as(as = "Rc<DisplayFromStr>")] Rc<u32>);
 
     is_equal(SRc(Rc::new(123)), expect![[r#""123""#]]);
 
+    #[serde_as]
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    struct SPinRc(#[serde_as(as = "Pin<Rc<DisplayFromStr>>")] Pin<Rc<u32>>);
+
+    is_equal(SPinRc(Rc::pin(123)), expect![[r#""123""#]]);
+
     #[serde_as]
     #[derive(Debug, Serialize, Deserialize)]
     struct SRcWeak(#[serde_as(as = "RcWeak<DisplayFromStr>")] RcWeak<u32>);
@@ -66,6 +86,12 @@ fn test_basic_wrappers() {
 
     is_equal(SArc(Arc::new(123)), expect![[r#""123""#]]);
 
+    #[serde_as]
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    struct SPinArc(#[serde_as(as = "Pin<Arc<DisplayFromStr>>")] Pin<Arc<u32>>);
+
+    is_equal(SPinArc(Arc::pin(123)), expect![[r#""123""#]]);
+
     #[serde_as]
     #[derive(Debug, Serialize, Deserialize)]
     struct SArcWeak(#[serde_as(as = "ArcWeak<DisplayFromStr>")] ArcWeak<u32>);