Node graph dynamic execution (#824)

Restructure document node implementation

* Implement topological sort

* Enforce the usage of type annotations

* Add complete test case

node-graph/graph-craft/src/document/value.rs

@@ -0,0 +1,74 @@
+use dyn_any::StaticType;
+
+use dyn_clone::DynClone;
+
+use dyn_any::DynAny;
+
+pub type Value = Box<dyn ValueTrait>;
+
+pub trait ValueTrait: DynAny<'static> + std::fmt::Debug + DynClone {}
+
+pub trait IntoValue: Sized + ValueTrait + 'static {
+	fn into_any(self) -> Value {
+		Box::new(self)
+	}
+}
+
+impl<T: 'static + StaticType + std::fmt::Debug + PartialEq + Clone> ValueTrait for T {}
+
+impl<T: 'static + ValueTrait> IntoValue for T {}
+
+#[repr(C)]
+pub(crate) struct Vtable {
+	pub(crate) destructor: unsafe fn(*mut ()),
+	pub(crate) size: usize,
+	pub(crate) align: usize,
+}
+
+#[repr(C)]
+pub(crate) struct TraitObject {
+	pub(crate) self_ptr: *mut u8,
+	pub(crate) vtable: &'static Vtable,
+}
+
+impl PartialEq for Box<dyn ValueTrait> {
+	#[cfg_attr(miri, ignore)]
+	fn eq(&self, other: &Self) -> bool {
+		if self.type_id() != other.type_id() {
+			return false;
+		}
+		let self_trait_object = unsafe { std::mem::transmute::<&dyn ValueTrait, TraitObject>(self.as_ref()) };
+		let other_trait_object = unsafe { std::mem::transmute::<&dyn ValueTrait, TraitObject>(other.as_ref()) };
+		let size = self_trait_object.vtable.size;
+		let self_mem = unsafe { std::slice::from_raw_parts(self_trait_object.self_ptr, size) };
+		let other_mem = unsafe { std::slice::from_raw_parts(other_trait_object.self_ptr, size) };
+		self_mem == other_mem
+	}
+}
+
+impl Clone for Value {
+	fn clone(&self) -> Self {
+		let self_trait_object = unsafe { std::mem::transmute::<&dyn ValueTrait, TraitObject>(self.as_ref()) };
+		let size = self_trait_object.vtable.size;
+		let self_mem = unsafe { std::slice::from_raw_parts(self_trait_object.self_ptr, size) }.to_owned();
+		let ptr = Vec::leak(self_mem);
+		unsafe {
+			std::mem::transmute(TraitObject {
+				self_ptr: ptr as *mut [u8] as *mut u8,
+				vtable: self_trait_object.vtable,
+			})
+		}
+	}
+}
+
+#[cfg(test)]
+mod test {
+	use super::*;
+
+	#[test]
+	fn test_any_src() {
+		assert!(2_u32.into_any() == 2_u32.into_any());
+		assert!(2_u32.into_any() != 3_u32.into_any());
+		assert!(2_u32.into_any() != 3_i32.into_any());
+	}
+}