Add serde support for GString, StringName, NodePath and Array

Author: kuruk-mm

check.sh

@@ -171,6 +171,10 @@ for arg in "$@"; do
             echo "$HELP_TEXT"
             exit 0
             ;;
+        --use-serde)
+            extraCargoArgs+=("--features" "godot/serde")
+            extraCargoArgs+=("--features" "serde")
+            ;;
         --double)
             extraCargoArgs+=("--features" "godot/double-precision")
             ;;

godot-core/Cargo.toml

@@ -27,6 +27,7 @@ godot-ffi = { path = "../godot-ffi" }
 # See https://docs.rs/glam/latest/glam/index.html#feature-gates
 glam = { version = "0.23", features = ["debug-glam-assert"] }
 serde = { version = "1", features = ["derive"], optional = true }
+serde_json = { version = "1.0", optional = true }
 
 # Reverse dev dependencies so doctests can use `godot::` prefix
 [dev-dependencies]

godot-core/src/builtin/array.rs

@@ -215,15 +215,15 @@ impl<T: GodotType> Array<T> {
 
     #[doc(hidden)]
     pub fn as_inner(&self) -> inner::InnerArray {
-        // SAFETY: The memory layout of `TypedArray<T>` does not depend on `T`.
+        // SAFETY: The memory layout of `Array<T>` does not depend on `T`.
         inner::InnerArray::from_outer_typed(self)
     }
 
     /// Changes the generic type on this array, without changing its contents. Needed for API
     /// functions that return a variant array even though we know its type, and for API functions
     /// that take a variant array even though we want to pass a typed one.
     ///
-    /// This is marked `unsafe` since it can be used to break the invariant that a `TypedArray<T>`
+    /// This is marked `unsafe` since it can be used to break the invariant that a `Array<T>`
     /// always holds a Godot array whose runtime type is `T`.
     ///
     /// # Safety
@@ -236,7 +236,7 @@ impl<T: GodotType> Array<T> {
     /// In the current implementation, both cases will produce a panic rather than undefined
     /// behavior, but this should not be relied upon.
     unsafe fn assume_type<U: GodotType>(self) -> Array<U> {
-        // SAFETY: The memory layout of `TypedArray<T>` does not depend on `T`.
+        // SAFETY: The memory layout of `Array<T>` does not depend on `T`.
         unsafe { std::mem::transmute(self) }
     }
 }
@@ -276,7 +276,7 @@ impl<T: GodotType> Array<T> {
     ///
     /// If specified, `step` is the relative index between source elements. It can be negative,
     /// in which case `begin` must be higher than `end`. For example,
-    /// `TypedArray::from(&[0, 1, 2, 3, 4, 5]).slice(5, 1, -2)` returns `[5, 3]`.
+    /// `Array::from(&[0, 1, 2, 3, 4, 5]).slice(5, 1, -2)` returns `[5, 3]`.
     ///
     /// Array elements are copied to the slice, but any reference types (such as `Array`,
     /// `Dictionary` and `Object`) will still refer to the same value. To create a deep copy, use
@@ -292,7 +292,7 @@ impl<T: GodotType> Array<T> {
     ///
     /// If specified, `step` is the relative index between source elements. It can be negative,
     /// in which case `begin` must be higher than `end`. For example,
-    /// `TypedArray::from(&[0, 1, 2, 3, 4, 5]).slice(5, 1, -2)` returns `[5, 3]`.
+    /// `Array::from(&[0, 1, 2, 3, 4, 5]).slice(5, 1, -2)` returns `[5, 3]`.
     ///
     /// All nested arrays and dictionaries are duplicated and will not be shared with the original
     /// array. Note that any `Object`-derived elements will still be shallow copied. To create a
@@ -576,7 +576,7 @@ impl<T: GodotType + ToGodot> Array<T> {
         let len = self.len();
         assert!(
             index <= len,
-            "TypedArray insertion index {index} is out of bounds: length is {len}",
+            "Array insertion index {index} is out of bounds: length is {len}",
         );
         self.as_inner().insert(to_i64(index), value.to_variant());
     }
@@ -604,9 +604,9 @@ impl<T: GodotType + ToGodot> Array<T> {
 // but `[NAN] == [NAN]` is `true`. If they decide to make all NaNs equal, we can implement `Eq` and
 // `Ord`; if they decide to make all NaNs unequal, we can remove this comment.
 //
-// impl<T> Eq for TypedArray<T> {}
+// impl<T> Eq for Array<T> {}
 //
-// impl<T> Ord for TypedArray<T> {
+// impl<T> Ord for Array<T> {
 //     ...
 // }
 
@@ -1063,3 +1063,61 @@ impl fmt::Debug for TypeInfo {
         write!(f, "{:?}{}", self.variant_type, class_str)
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::{
+        de::{SeqAccess, Visitor},
+        ser::SerializeSeq,
+        Deserialize, Deserializer, Serialize, Serializer,
+    };
+    use std::marker::PhantomData;
+
+    impl<T: Serialize + GodotType> Serialize for Array<T> {
+        #[inline]
+        fn serialize<S>(&self, ser: S) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
+        where
+            S: Serializer,
+        {
+            let mut ser = ser.serialize_seq(Some(self.len()))?;
+            for e in self.iter_shared() {
+                ser.serialize_element(&e)?
+            }
+            ser.end()
+        }
+    }
+
+    impl<'de, T: Deserialize<'de> + GodotType> Deserialize<'de> for Array<T> {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, <D as Deserializer<'de>>::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct ArrayVisitor<T>(PhantomData<T>);
+            impl<'de, T: Deserialize<'de> + GodotType> Visitor<'de> for ArrayVisitor<T> {
+                type Value = Array<T>;
+
+                fn expecting(&self, formatter: &mut std::fmt::Formatter) -> fmt::Result {
+                    formatter.write_str(std::any::type_name::<Self::Value>())
+                }
+
+                fn visit_seq<A>(
+                    self,
+                    mut seq: A,
+                ) -> Result<Self::Value, <A as SeqAccess<'de>>::Error>
+                where
+                    A: SeqAccess<'de>,
+                {
+                    let mut vec = seq.size_hint().map_or_else(Vec::new, Vec::with_capacity);
+                    while let Some(val) = seq.next_element::<T>()? {
+                        vec.push(val);
+                    }
+                    Ok(Self::Value::from(vec.as_slice()))
+                }
+            }
+
+            deserializer.deserialize_seq(ArrayVisitor::<T>(PhantomData))
+        }
+    }
+}

godot-core/src/builtin/string/gstring.rs

@@ -313,3 +313,53 @@ impl From<NodePath> for GString {
         Self::from(&path)
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::{
+        de::{Error, Visitor},
+        Deserialize, Deserializer, Serialize, Serializer,
+    };
+    use std::fmt::Formatter;
+
+    impl Serialize for GString {
+        #[inline]
+        fn serialize<S>(
+            &self,
+            serializer: S,
+        ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
+        where
+            S: Serializer,
+        {
+            serializer.serialize_str(&self.to_string())
+        }
+    }
+
+    #[cfg(feature = "serde")]
+    impl<'de> serialize::Deserialize<'de> for GString {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, <D as Deserializer<'de>>::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct GStringVisitor;
+            impl<'de> Visitor<'de> for GStringVisitor {
+                type Value = GString;
+
+                fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                    formatter.write_str("a GString")
+                }
+
+                fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    Ok(GString::from(s))
+                }
+            }
+
+            deserializer.deserialize_str(GStringVisitor)
+        }
+    }
+}

godot-core/src/builtin/string/node_path.rs

@@ -150,3 +150,60 @@ impl From<StringName> for NodePath {
         Self::from(GString::from(string_name))
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::{
+        de::{Error, Visitor},
+        Deserialize, Deserializer, Serialize, Serializer,
+    };
+    use std::fmt::Formatter;
+
+    impl Serialize for NodePath {
+        #[inline]
+        fn serialize<S>(&self, ser: S) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
+        where
+            S: Serializer,
+        {
+            ser.serialize_newtype_struct("NodePath", &*self.to_string())
+        }
+    }
+
+    impl<'de> Deserialize<'de> for NodePath {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct NodePathVisitor;
+
+            impl<'de> Visitor<'de> for NodePathVisitor {
+                type Value = NodePath;
+
+                fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                    formatter.write_str("a NodePath")
+                }
+
+                fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    Ok(NodePath::from(s))
+                }
+
+                fn visit_newtype_struct<D>(
+                    self,
+                    deserializer: D,
+                ) -> Result<Self::Value, <D as Deserializer<'de>>::Error>
+                where
+                    D: Deserializer<'de>,
+                {
+                    deserializer.deserialize_str(self)
+                }
+            }
+
+            deserializer.deserialize_newtype_struct("NodePath", NodePathVisitor)
+        }
+    }
+}

godot-core/src/builtin/string/string_name.rs

@@ -245,3 +245,52 @@ impl From<NodePath> for StringName {
         Self::from(GString::from(path))
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::{
+        de::{Error, Visitor},
+        Deserialize, Deserializer, Serialize, Serializer,
+    };
+    use std::fmt::Formatter;
+
+    impl Serialize for StringName {
+        #[inline]
+        fn serialize<S>(
+            &self,
+            serializer: S,
+        ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
+        where
+            S: Serializer,
+        {
+            serializer.serialize_str(&self.to_string())
+        }
+    }
+
+    impl<'de> serialize::Deserialize<'de> for StringName {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, <D as Deserializer<'de>>::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct StringNameVisitor;
+            impl<'de> Visitor<'de> for StringNameVisitor {
+                type Value = StringName;
+
+                fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                    formatter.write_str("a StringName")
+                }
+
+                fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    Ok(StringName::from(s))
+                }
+            }
+
+            deserializer.deserialize_str(StringNameVisitor)
+        }
+    }
+}

godot/Cargo.toml

@@ -12,7 +12,7 @@ default = ["codegen-full"]
 custom-godot = ["godot-core/custom-godot"]
 double-precision = ["godot-core/double-precision"]
 formatted = ["godot-core/codegen-fmt"]
-serde = ["godot-core/serde"]
+serde = ["godot-core/serde", "godot-core/serde_json"]
 lazy-function-tables = ["godot-core/codegen-lazy-fptrs"]
 experimental-threads = ["godot-core/experimental-threads"]
 experimental-godot-api = ["godot-core/experimental-godot-api"]

itest/rust/Cargo.toml

@@ -10,11 +10,14 @@ crate-type = ["cdylib"]
 
 [features]
 default = []
+serde = ["dep:serde", "dep:serde_json"]
 # Do not add features here that are 1:1 forwarded to the `godot` crate.
 # Instead, compile itest with `--features godot/my-feature`.
 
 [dependencies]
 godot = { path = "../../godot", default-features = false }
+serde = { version = "1", features = ["derive"], optional = true }
+serde_json = { version = "1.0", optional = true }
 
 [build-dependencies]
 godot-bindings = { path = "../../godot-bindings" } # emit_godot_version_cfg

itest/rust/src/builtin_tests/containers/array_test.rs

@@ -460,3 +460,38 @@ impl ArrayTest {
         (1..(n + 1)).collect()
     }
 }
+
+#[itest]
+#[cfg(feature = "serde")]
+fn serde_roundtrip() {
+    #[derive(serde::Deserialize, serde::Serialize, PartialEq, Debug)]
+    struct P {
+        sequence: Array<i32>,
+        names: Array<GString>,
+        vectors: Array<Vector2i>,
+    }
+    let value = P {
+        sequence: Array::from(&[1, 2, 3, 4, 5, 6]),
+        names: Array::from(&[
+            "Godot".into_godot(),
+            "Rust".into_godot(),
+            "Rocks".into_godot(),
+        ]),
+        vectors: Array::from(&[
+            Vector2i::new(1, 1),
+            Vector2i::new(2, 2),
+            Vector2i::new(3, 3),
+        ]),
+    };
+
+    let expected_json = r#"{"sequence":[1,2,3,4,5,6],"names":["Godot","Rust","Rocks"],"vectors":[{"x":1,"y":1},{"x":2,"y":2},{"x":3,"y":3}]}"#;
+
+    let json: String = serde_json::to_string(&value).unwrap();
+    let back: P = serde_json::from_str(json.as_str()).unwrap();
+
+    assert_eq!(back, value, "serde round-trip changes value");
+    assert_eq!(
+        json, expected_json,
+        "value does not conform to expected JSON"
+    );
+}