Add serde support for GString, StringName, NodePath and Array

Author: kuruk-mm

check.sh

@@ -171,6 +171,9 @@ for arg in "$@"; do
             echo "$HELP_TEXT"
             exit 0
             ;;
+        --use-serde)
+            extraCargoArgs+=("--features" "serde")
+            ;;
         --double)
             extraCargoArgs+=("--features" "godot/double-precision")
             ;;

godot-core/Cargo.toml

@@ -31,6 +31,7 @@ serde = { version = "1", features = ["derive"], optional = true }
 # Reverse dev dependencies so doctests can use `godot::` prefix
 [dev-dependencies]
 godot = { path = "../godot" }
+serde_json = { version = "1.0" }
 
 [build-dependencies]
 godot-bindings = { path = "../godot-bindings" }

godot-core/src/builtin/array.rs

@@ -1063,3 +1063,62 @@ impl fmt::Debug for TypeInfo {
         write!(f, "{:?}{}", self.variant_type, class_str)
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::de::{SeqAccess, Visitor};
+    use serde::ser::SerializeSeq;
+    use serde::{Deserialize, Deserializer, Serialize, Serializer};
+    use std::marker::PhantomData;
+
+    impl<T: Serialize + GodotType> Serialize for Array<T> {
+        #[inline]
+        fn serialize<S>(
+            &self,
+            serializer: S,
+        ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
+        where
+            S: Serializer,
+        {
+            let mut sequence = serializer.serialize_seq(Some(self.len()))?;
+            for e in self.iter_shared() {
+                sequence.serialize_element(&e)?
+            }
+            sequence.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 +313,51 @@ impl From<NodePath> for GString {
         Self::from(&path)
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::de::{Error, Visitor};
+    use serde::{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 +150,61 @@ impl From<StringName> for NodePath {
         Self::from(GString::from(string_name))
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::de::{Error, Visitor};
+    use serde::{Deserialize, Deserializer, Serialize, Serializer};
+    use std::fmt::Formatter;
+
+    impl Serialize for NodePath {
+        #[inline]
+        fn serialize<S>(
+            &self,
+            serializer: S,
+        ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
+        where
+            S: Serializer,
+        {
+            serializer.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 +245,50 @@ impl From<NodePath> for StringName {
         Self::from(GString::from(path))
     }
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::de::{Error, Visitor};
+    use serde::{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)
+        }
+    }
+}

itest/rust/Cargo.toml

@@ -10,11 +10,14 @@ crate-type = ["cdylib"]
 
 [features]
 default = []
+serde = ["dep:serde", "dep:serde_json", "godot/serde"]
 # 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/mod.rs

@@ -35,3 +35,6 @@ mod string {
 mod color_test;
 
 mod convert_test;
+
+#[cfg(feature = "serde")]
+mod serde_test;

itest/rust/src/builtin_tests/serde_test.rs

@@ -0,0 +1,73 @@
+use crate::framework::itest;
+use godot::builtin::{array, Array, GString, NodePath, StringName, Vector2i};
+use serde::{Deserialize, Serialize};
+
+fn serde_roundtrip<T>(value: &T, expected_json: &str)
+where
+    T: for<'a> Deserialize<'a> + Serialize + PartialEq + std::fmt::Debug,
+{
+    let json: String = serde_json::to_string(value).unwrap();
+    let back: T = 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"
+    );
+}
+
+#[itest]
+fn serde_gstring() {
+    let value = GString::from("hello world");
+
+    let expected_json = "\"hello world\"";
+
+    serde_roundtrip(&value, expected_json);
+}
+
+#[itest]
+fn serde_node_path() {
+    let value = NodePath::from("res://icon.png");
+    let expected_json = "\"res://icon.png\"";
+
+    serde_roundtrip(&value, expected_json);
+}
+
+#[itest]
+fn serde_string_name() {
+    let value = StringName::from("hello world");
+    let expected_json = "\"hello world\"";
+
+    serde_roundtrip(&value, expected_json);
+}
+
+#[itest]
+fn serde_array_rust_native_type() {
+    let value: Array<i32> = array![1, 2, 3, 4, 5, 6];
+
+    let expected_json = r#"[1,2,3,4,5,6]"#;
+
+    serde_roundtrip(&value, expected_json)
+}
+
+#[itest]
+fn serde_array_godot_builtin_type() {
+    let value: Array<GString> = array!["Godot".into(), "Rust".into(), "Rocks".into()];
+
+    let expected_json = r#"["Godot","Rust","Rocks"]"#;
+
+    serde_roundtrip(&value, expected_json)
+}
+
+#[itest]
+fn serde_array_godot_type() {
+    let value: Array<Vector2i> = array![
+        Vector2i::new(1, 1),
+        Vector2i::new(2, 2),
+        Vector2i::new(3, 3)
+    ];
+
+    let expected_json = r#"[{"x":1,"y":1},{"x":2,"y":2},{"x":3,"y":3}]"#;
+
+    serde_roundtrip(&value, expected_json)
+}