feat(engine): add macro for reflection

2 files changed, 148 insertions, 0 deletions

diff --git a/engine/src/lib.rs b/engine/src/lib.rs
index 75bc921..b470cdc 100644
--- a/engine/src/lib.rs
+++ b/engine/src/lib.rs
@@ -33,6 +33,7 @@ pub mod math;
 pub mod mesh;
 pub mod model;
 pub mod projection;
+pub mod reflection;
 pub mod renderer;
 pub mod texture;
 pub mod transform;
diff --git a/engine/src/reflection.rs b/engine/src/reflection.rs
new file mode 100644
index 0000000..5bd2aef
--- /dev/null
+++ b/engine/src/reflection.rs
@@ -0,0 +1,147 @@
+use std::alloc::Layout;
+use std::any::TypeId;
+
+pub use engine_macros::Reflection;
+
+pub trait With: 'static
+{
+    const REFLECTION: &Reflection;
+
+    fn reflection() -> &'static Reflection
+    where
+        Self: Sized;
+
+    fn get_reflection(&self) -> &'static Reflection;
+}
+
+#[derive(Debug, Clone)]
+#[non_exhaustive]
+pub enum Reflection
+{
+    Struct(Struct),
+    Array(Array),
+    Slice(Slice),
+    Literal,
+}
+
+#[derive(Debug, Clone)]
+pub struct Struct
+{
+    pub fields: &'static [StructField],
+}
+
+#[derive(Debug, Clone)]
+pub struct StructField
+{
+    pub name: &'static str,
+    pub index: usize,
+    pub layout: Layout,
+    pub byte_offset: usize,
+    pub type_id: TypeId,
+    pub type_name: &'static str,
+    pub reflection: &'static Reflection,
+}
+
+#[derive(Debug, Clone)]
+pub struct Array
+{
+    pub item_reflection: &'static Reflection,
+    pub length: usize,
+}
+
+#[derive(Debug, Clone)]
+pub struct Slice
+{
+    pub item_reflection: &'static Reflection,
+}
+
+macro_rules! impl_with_for_literals {
+    ($($literal: ty),*) => {
+        $(
+            impl With for $literal
+            {
+                const REFLECTION: &Reflection = &Reflection::Literal;
+
+                fn reflection() -> &'static Reflection
+                where
+                    Self: Sized
+                {
+                    Self::REFLECTION
+                }
+
+                fn get_reflection(&self) -> &'static Reflection
+                {
+                    Self::reflection()
+                }
+            }
+        )*
+    };
+}
+
+impl_with_for_literals!(
+    u8,
+    i8,
+    u16,
+    i16,
+    u32,
+    i32,
+    u64,
+    i64,
+    u128,
+    i128,
+    f32,
+    f64,
+    usize,
+    isize,
+    &'static str
+);
+
+impl<T: With, const LEN: usize> With for [T; LEN]
+{
+    const REFLECTION: &Reflection = &Reflection::Array(Array {
+        item_reflection: T::REFLECTION,
+        length: LEN,
+    });
+
+    fn reflection() -> &'static Reflection
+    where
+        Self: Sized,
+    {
+        Self::REFLECTION
+    }
+
+    fn get_reflection(&self) -> &'static Reflection
+    {
+        Self::reflection()
+    }
+}
+
+impl<T: With> With for &'static [T]
+{
+    const REFLECTION: &Reflection =
+        &Reflection::Slice(Slice { item_reflection: T::REFLECTION });
+
+    fn reflection() -> &'static Reflection
+    where
+        Self: Sized,
+    {
+        Self::REFLECTION
+    }
+
+    fn get_reflection(&self) -> &'static Reflection
+    {
+        Self::reflection()
+    }
+}
+
+// Used by the Reflection derive macro
+#[doc(hidden)]
+pub mod __private
+{
+    pub const fn get_type_reflection<T>() -> &'static super::Reflection
+    where
+        T: super::With,
+    {
+        T::REFLECTION
+    }
+}