Adds serde support.

.travis.yml

@@ -8,8 +8,10 @@ script:
   - cd gc
   - cargo build
   - cargo test
+  - cargo test --features serde
   - ([ $TRAVIS_RUST_VERSION != nightly ] || cargo build --features nightly)
   - ([ $TRAVIS_RUST_VERSION != nightly ] || cargo test --features nightly)
+  - ([ $TRAVIS_RUST_VERSION != nightly ] || cargo test --features nightly,serde)
 after_success: bash ../upload-docs.sh
 env:
   global:

gc/Cargo.toml

@@ -15,6 +15,8 @@ derive = ["gc_derive"]
 
 [dependencies]
 gc_derive = { path = "../gc_derive", version = "0.4.1", optional = true }
+serde = { version = "1.0.0", optional = true }
 
 [dev-dependencies]
 gc_derive = { path = "../gc_derive", version = "0.4.1" }
+serde_json = { version = "1.0.66" }

gc/src/lib.rs

@@ -24,6 +24,8 @@ use std::marker::Unsize;
 use std::ops::CoerceUnsized;
 
 mod gc;
+#[cfg(feature = "serde")]
+mod serde;
 mod trace;
 
 #[cfg(feature = "derive")]

gc/src/serde.rs

@@ -0,0 +1,20 @@
+use crate::{Gc, Trace};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+impl<'de, T: Deserialize<'de> + Trace> Deserialize<'de> for Gc<T> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        T::deserialize(deserializer).map(Gc::new)
+    }
+}
+
+impl<T: Serialize + Trace> Serialize for Gc<T> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        T::serialize(&self, serializer)
+    }
+}

gc/tests/serde.rs

@@ -0,0 +1,23 @@
+#![cfg(feature = "serde")]
+
+use gc::Gc;
+use serde_json::json;
+use std::collections::HashMap;
+
+type Example = Gc<HashMap<String, Gc<Vec<i32>>>>;
+
+#[test]
+fn serde_tests() {
+    let value = json!({
+        "hello": [104, 101, 108, 108, 111],
+        "world": [119, 111, 114, 108, 100],
+    });
+
+    let mut expected = HashMap::new();
+    expected.insert("hello".to_string(), Gc::new(vec![104, 101, 108, 108, 111]));
+    expected.insert("world".to_string(), Gc::new(vec![119, 111, 114, 108, 100]));
+    let expected = Gc::new(expected);
+
+    assert_eq!(serde_json::to_value(&expected).unwrap(), value);
+    assert_eq!(serde_json::from_value::<Example>(value).unwrap(), expected);
+}