1 files changed, 76 insertions, 2 deletions

diff --git a/engine-reflection/src/lib.rs b/engine-reflection/src/lib.rs
index c8b0004..4e5e8d8 100644
--- a/engine-reflection/src/lib.rs
+++ b/engine-reflection/src/lib.rs
@@ -1,5 +1,5 @@
 use std::alloc::Layout;
-use std::any::{type_name, TypeId};
+use std::any::{type_name, Any, TypeId};
 use std::borrow::Cow;
 use std::fmt::Debug;
 
@@ -64,12 +64,50 @@ impl Type
             _ => None,
         }
     }
+
+    #[inline]
+    pub fn default_value(&self) -> Option<Box<dyn Any>>
+    {
+        match self {
+            Self::Struct(struct_type) => struct_type.default_value(),
+            Self::Enum(enum_type) => enum_type.default_value(),
+            Self::Literal(literal_type) => literal_type.default_value(),
+            Self::Array(_) | Self::Slice(_) => None,
+        }
+    }
+
+    #[inline]
+    pub fn has_default_value(&self) -> bool
+    {
+        match self {
+            Self::Struct(struct_type) => struct_type.has_default_value(),
+            Self::Enum(enum_type) => enum_type.has_default_value(),
+            Self::Literal(literal_type) => literal_type.has_default_value(),
+            Self::Array(_) | Self::Slice(_) => false,
+        }
+    }
 }
 
 #[derive(Debug, Clone)]
 pub struct Struct
 {
     pub fields: &'static [Field],
+    pub get_default_value: fn() -> Option<DefaultValueFn>,
+}
+
+impl Struct
+{
+    #[inline]
+    pub fn default_value(&self) -> Option<Box<dyn Any>>
+    {
+        Some((self.get_default_value)()?())
+    }
+
+    #[inline]
+    pub fn has_default_value(&self) -> bool
+    {
+        (self.get_default_value)().is_some()
+    }
 }
 
 #[derive(Debug, Clone)]
@@ -83,6 +121,23 @@ pub struct Enum
 
     pub discriminant_layout: Layout,
     pub fields_layout: Option<Layout>,
+
+    pub get_default_value: fn() -> Option<DefaultValueFn>,
+}
+
+impl Enum
+{
+    #[inline]
+    pub fn default_value(&self) -> Option<Box<dyn Any>>
+    {
+        Some((self.get_default_value)()?())
+    }
+
+    #[inline]
+    pub fn has_default_value(&self) -> bool
+    {
+        (self.get_default_value)().is_some()
+    }
 }
 
 #[derive(Debug, Clone)]
@@ -169,6 +224,22 @@ pub struct Literal
     pub type_id: TypeId,
     pub ty: LiteralType,
     pub type_name: fn() -> &'static str,
+    pub get_default_value: fn() -> Option<DefaultValueFn>,
+}
+
+impl Literal
+{
+    #[inline]
+    pub fn default_value(&self) -> Option<Box<dyn Any>>
+    {
+        Some((self.get_default_value)()?())
+    }
+
+    #[inline]
+    pub fn has_default_value(&self) -> bool
+    {
+        (self.get_default_value)().is_some()
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -219,7 +290,8 @@ macro_rules! impl_reflection_for_literals {
                     layout: Layout::new::<$literal>(),
                     type_id: TypeId::of::<$literal>(),
                     ty: LiteralType::$literal_type,
-                    type_name: || type_name::<$literal>()
+                    type_name: || type_name::<$literal>(),
+                    get_default_value: || Some(|| Box::new(Self::default()))
                 });
             }
         )*
@@ -288,3 +360,5 @@ impl<Value: Debug> Debug for FnWithDebug<Value>
             .finish()
     }
 }
+
+type DefaultValueFn = fn() -> Box<dyn Any>;