add serde serialization support (#210)

Cargo.toml

@@ -36,17 +36,23 @@ harness = false
 # implement its `Allocator` trait.
 allocator-api2 = { version = "0.2.8", default-features = false, optional = true }
 
+# This dependency is here to allow integration with Serde, if the `serde` feature is enabled
+serde = { version = "1.0.171", optional = true }
+
 [dev-dependencies]
 quickcheck = "1.0.3"
 criterion = "0.3.6"
 rand = "0.8.5"
+serde = { version = "1.0.197", features = ["derive"] }
+serde_json = "1.0.115"
 
 [features]
 default = []
 collections = []
 boxed = []
 allocator_api = []
 std = []
+serde = ["dep:serde"]
 
 # [profile.bench]
 # debug = true

README.md

@@ -153,6 +153,37 @@ in its space itself.
 }
 ```
 
+#### Serde
+
+Adding the `serde` feature flag will enable transparent serialization of Vecs and 
+boxed values.
+
+```toml
+[dependencies]
+bumpalo = { version = "3.9", features = ["collections", "boxed", "serde"] }
+```
+
+```rust,ignore
+use bumpalo::{Bump, boxed::Box, collections::Vec};
+
+// Create a new bump arena.
+let bump = Bump::new();
+
+// Create a `Box`
+let box = Box::new_in("hello", &bump);
+
+// Serialize with serde_json
+assert_eq!(serde_json::to_string(&box).unwrap(), "\"hello\"");
+
+// Create a `Vec`
+let vec = Vec::new_in( &bump);
+vec.push(1);
+vec.push(2);
+
+// Serialize with serde_json
+assert_eq!(serde_json::to_string(&vec).unwrap(), "[1, 2]");
+```
+
 ### `#![no_std]` Support
 
 Bumpalo is a `no_std` crate by default. It depends only on the `alloc` and `core` crates.

src/boxed.rs

@@ -681,3 +681,19 @@ impl<'a, T, const N: usize> TryFrom<Box<'a, [T]>> for Box<'a, [T; N]> {
         }
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+
+    use serde::{Serialize, Serializer};
+
+    impl<'a, T> Serialize for Box<'a, T>
+    where
+        T: Serialize,
+    {
+        fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+            T::serialize(self, serializer)
+        }
+    }
+}

src/collections/vec.rs

@@ -2760,3 +2760,27 @@ impl<'bump> io::Write for Vec<'bump, u8> {
         Ok(())
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+
+    use serde::{ser::SerializeSeq, Serialize, Serializer};
+
+    impl<'a, T> Serialize for Vec<'a, T>
+    where
+        T: Serialize,
+    {
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            let mut seq = serializer.serialize_seq(Some(self.len))?;
+            for e in self.iter() {
+                seq.serialize_element(e)?;
+            }
+            seq.end()
+        }
+    }
+
+}

tests/all/main.rs

@@ -16,4 +16,7 @@ mod try_alloc_try_with;
 mod try_alloc_with;
 mod vec;
 
+#[cfg(feature = "serde")]
+mod serde;
+
 fn main() {}

tests/all/serde.rs

@@ -0,0 +1,119 @@
+#![cfg(feature = "collections")]
+#![cfg(feature = "serde")]
+
+use bumpalo::{boxed::Box, vec, Bump};
+use serde::{Deserialize, Serialize};
+
+macro_rules! compare_std_vec {
+    (in $bump:ident; $($x:expr),+) => {{
+        let mut vec = vec![in &$bump; $($x),+];
+        let std_vec = std::vec![$($x),+];
+        (vec, std_vec)
+    }}
+}
+
+macro_rules! compare_std_box {
+    (in $bump:ident; $x:expr) => {
+        (Box::new_in($x, &$bump), std::boxed::Box::new($x))
+    };
+}
+
+macro_rules! assert_eq_json {
+    ($a:ident, $b:ident) => {
+        assert_eq!(
+            serde_json::to_string(&$a).unwrap(),
+            serde_json::to_string(&$b).unwrap(),
+        )
+    };
+}
+
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
+#[serde(tag = "t", content = "c")]
+enum Test {
+    First,
+    Second,
+}
+
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
+#[serde()]
+struct Mixed {
+    i: i32,
+    s: String,
+    o: Option<String>,
+    e: Test,
+}
+
+#[test]
+fn test_vec_serializes_str() {
+    let bump = Bump::new();
+    let (vec, std_vec) = compare_std_vec![in bump; "hello", "world"];
+    assert_eq_json!(vec, std_vec);
+    let de: std::vec::Vec<String> =
+        serde_json::from_str(&serde_json::to_string(&vec).unwrap()).unwrap();
+    assert_eq!(de, std_vec);
+}
+
+#[test]
+fn test_vec_serializes_f32() {
+    let bump = Bump::new();
+    let (vec, std_vec) = compare_std_vec![in bump; 1.5707964, 3.1415927];
+    assert_eq_json!(vec, std_vec);
+    let de: std::vec::Vec<f32> =
+        serde_json::from_str(&serde_json::to_string(&vec).unwrap()).unwrap();
+    assert_eq!(de, std_vec);
+}
+
+#[cfg(feature = "serde")]
+#[test]
+fn test_vec_serializes_complex() {
+    let bump = Bump::new();
+    let (vec, std_vec) = compare_std_vec![
+        in bump;
+        Mixed {
+            i: 8,
+            s: "a".into(),
+            o: None,
+            e: Test::Second,
+        },
+        Mixed {
+            i: 8,
+            s: "b".into(),
+            o: Some("some".into()),
+            e: Test::First,
+        }
+    ];
+    assert_eq_json!(vec, std_vec);
+    let de: std::vec::Vec<Mixed> =
+        serde_json::from_str(&serde_json::to_string(&vec).unwrap()).unwrap();
+    assert_eq!(de, std_vec);
+}
+
+#[test]
+fn test_box_serializes() {
+    let bump = Bump::new();
+    let (box_int, std_box_int) = compare_std_box!(in bump; 1);
+    assert_eq_json!(box_int, std_box_int);
+    let (box_str, std_box_str) = compare_std_box!(in bump; 1);
+    assert_eq_json!(box_str, std_box_str);
+    let (box_vec, std_box_vec) = compare_std_box!(in bump; std::vec!["hello", "world"]);
+    assert_eq_json!(box_vec, std_box_vec);
+}
+
+#[cfg(feature = "serde")]
+#[test]
+fn test_box_serializes_complex() {
+    let bump = Bump::new();
+    let (vec, std_vec) = compare_std_box![
+        in bump;
+        Mixed {
+            i: 8,
+            s: "a".into(),
+            o: None,
+            e: Test::Second,
+        }
+    ];
+    assert_eq_json!(vec, std_vec);
+    let de: std::boxed::Box<Mixed> =
+        serde_json::from_str(&serde_json::to_string(&vec).unwrap()).unwrap();
+    assert_eq!(de, std_vec);
+}