Merge #743

743: serde support for core types & VariantDispatch r=Bromeon a=Waridley

I got curious about how hard it would be to add serde support, and ended up basically fully implementing it so I figured I should start a PR 😂

There are no tests yet, and honestly I haven't really even tested it in my own project yet. I'll be doing so over the next few days probably, but for now I'll open this as a draft to allow for comments, feedback, and opinions.

The implementations for `Object` types is a bit hacky, but I really like the idea of being able to replace Godot's resource files with something more Rust-y. Since I had to wrap the references in newtypes, I suppose they could be part of a separate crate anyway, unless anyone has a better idea of how to get around the orphan rules. Even if we can implement serde's traits directly on `gdnative_core` types, there should probably be some discussion about whether it's actually desirable to skip properties that are set to their defaults (this would end up serializing a **LOT** of properties otherwise).

Would close #9 

Co-authored-by: Waridley <Waridley64@gmail.com>

gdnative-core/Cargo.toml

@@ -24,6 +24,7 @@ glam = "0.18.0"
 indexmap = "1.7.0"
 ahash = "0.7.4"
 once_cell = "1.8.0"
+serde = { version = "1", features = ["derive"], optional = true }
 
 gdnative-impl-proc-macros = { path = "../impl/proc_macros", version = "=0.9.3" }
 

gdnative-core/src/core_types/color.rs

@@ -6,6 +6,7 @@ use crate::core_types::GodotString;
 /// RGBA color with 32 bits floating point components.
 #[repr(C)]
 #[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Color {
     pub r: f32,
     pub g: f32,

gdnative-core/src/core_types/error.rs

@@ -2,6 +2,7 @@ use crate::sys;
 
 /// Error codes used in various Godot APIs.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(u32)]
 pub enum GodotError {
     Failed = sys::godot_error_GODOT_FAILED as u32,

gdnative-core/src/core_types/geom/aabb.rs

@@ -3,6 +3,7 @@ use crate::core_types::Vector3;
 /// Axis-aligned bounding box.
 #[repr(C)]
 #[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Aabb {
     pub position: Vector3,
     pub size: Vector3,

gdnative-core/src/core_types/geom/basis.rs

@@ -5,6 +5,7 @@ use glam::Mat3;
 /// A 3x3 matrix.
 #[repr(C)]
 #[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Basis {
     pub elements: [Vector3; 3],
 }

gdnative-core/src/core_types/geom/plane.rs

@@ -3,6 +3,7 @@ use crate::core_types::{IsEqualApprox, Vector3};
 /// Plane in hessian form.
 #[repr(C)]
 #[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Plane {
     pub normal: Vector3,
     pub d: f32,

gdnative-core/src/core_types/geom/transform.rs

@@ -3,6 +3,7 @@ use crate::core_types::{Basis, Vector3};
 /// 3D Transformation (3x4 matrix) Using basis + origin representation.
 #[repr(C)]
 #[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Transform {
     /// The basis is a matrix containing 3 Vector3 as its columns: X axis, Y axis, and Z axis.
     /// These vectors can be interpreted as the basis vectors of local coordinate system

gdnative-core/src/core_types/mod.rs

@@ -43,7 +43,7 @@ pub use rid::*;
 pub use string::*;
 pub use string_array::*;
 pub use transform2d::*;
-pub use typed_array::TypedArray;
+pub use typed_array::{Element, TypedArray};
 pub use variant::*;
 pub use variant_array::*;
 pub use vector2::*;

gdnative-core/src/core_types/node_path.rs

@@ -176,3 +176,60 @@ impl fmt::Debug for NodePath {
         write!(f, "NodePath({})", self.to_string())
     }
 }
+
+#[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_str(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)
+        }
+    }
+}

gdnative-core/src/core_types/quat.rs

@@ -3,6 +3,7 @@ use glam::EulerRot;
 use std::ops::{Mul, Neg};
 
 #[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Quat {
     pub x: f32,

gdnative-core/src/core_types/rect2.rs

@@ -1,5 +1,7 @@
 use super::Vector2;
 
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Rect2 {
     pub position: Vector2,

gdnative-core/src/core_types/string.rs

@@ -612,6 +612,56 @@ where
     }
 }
 
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::{
+        de::{Error, Visitor},
+        Deserialize, Deserializer, Serialize, Serializer,
+    };
+    use std::fmt::Formatter;
+
+    impl Serialize for GodotString {
+        #[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 GodotString {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, <D as Deserializer<'de>>::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct GodotStringVisitor;
+            impl<'de> Visitor<'de> for GodotStringVisitor {
+                type Value = GodotString;
+
+                fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                    formatter.write_str("a GodotString")
+                }
+
+                fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    Ok(GodotString::from(s))
+                }
+            }
+
+            deserializer.deserialize_str(GodotStringVisitor)
+        }
+    }
+}
+
 godot_test!(test_string {
     use crate::core_types::{GodotString, Variant, VariantType, ToVariant};
 

gdnative-core/src/core_types/transform2d.rs

@@ -1,5 +1,7 @@
 use super::Vector2;
 
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Transform2D {
     pub x: Vector2,

gdnative-core/src/core_types/typed_array.rs

@@ -483,3 +483,63 @@ macros::impl_typed_array_element! {
 mod private {
     pub trait Sealed {}
 }
+
+#[cfg(feature = "serde")]
+mod serialize {
+    use super::*;
+    use serde::{
+        de::{SeqAccess, Visitor},
+        ser::SerializeSeq,
+        Deserialize, Deserializer, Serialize, Serializer,
+    };
+    use std::fmt::Formatter;
+    use std::marker::PhantomData;
+
+    impl<T: Serialize + Element> Serialize for TypedArray<T> {
+        #[inline]
+        fn serialize<S>(&self, ser: S) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
+        where
+            S: Serializer,
+        {
+            let read = self.read();
+            let mut ser = ser.serialize_seq(Some(read.len()))?;
+            for e in read.iter() {
+                ser.serialize_element(e)?
+            }
+            ser.end()
+        }
+    }
+
+    impl<'de, T: Deserialize<'de> + Element> Deserialize<'de> for TypedArray<T> {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, <D as Deserializer<'de>>::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct TypedArrayVisitor<T>(PhantomData<T>);
+            impl<'de, T: Deserialize<'de> + Element> Visitor<'de> for TypedArrayVisitor<T> {
+                type Value = TypedArray<T>;
+
+                fn expecting(&self, formatter: &mut 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(vec))
+                }
+            }
+
+            deserializer.deserialize_seq(TypedArrayVisitor::<T>(PhantomData))
+        }
+    }
+}

gdnative-core/src/core_types/variant.rs

@@ -9,6 +9,9 @@ use crate::object::*;
 use crate::private::{get_api, ManuallyManagedClassPlaceholder};
 use crate::thread_access::*;
 
+#[cfg(feature = "serde")]
+mod serialize;
+
 // TODO: implement Debug, PartialEq, etc.
 
 /// A `Variant` can represent many of godot's core types.
@@ -109,6 +112,13 @@ macro_rules! decl_variant_type {
             )*
         }
 
+        impl VariantType {
+            /// The potential names of VariantTypes. Mostly used for serialization.
+            pub const NAMES: &'static [&'static str] = &[
+                $(stringify!($variant),)*
+            ];
+        }
+
         /// Rust enum associating each primitive variant type to its value.
         ///
         /// For `Variant`s containing objects, the original `Variant` is returned unchanged, due to
@@ -132,6 +142,19 @@ macro_rules! decl_variant_type {
                 }
             }
         }
+
+        impl<'a> From<&'a VariantDispatch> for Variant {
+            #[inline]
+            fn from(v: &'a VariantDispatch) -> Self {
+                match v {
+                    $($(VariantDispatch::$variant(v) => {
+                        let v: &$inner = v;
+                        v.to_variant()
+                    })?)*
+                    _ => Variant::new()
+                }
+            }
+        }
     }
 }
 
@@ -173,6 +196,15 @@ impl VariantType {
     pub fn from_sys(v: sys::godot_variant_type) -> VariantType {
         unsafe { transmute(v as u32) }
     }
+
+    /// The `stringify!` representation of this variant. Mostly used for serialization.
+    #[inline]
+    pub const fn name(self) -> &'static str {
+        // NOTE: this assumes that the discriminants remain sequential, since any additions to the
+        // VariantType enum would require a breaking change anyway since it is not marked as non-exhaustive.
+        // See also the Deserialize implementation in the serde submodule.
+        Self::NAMES[self as usize]
+    }
 }
 
 #[repr(u32)]