feat: integrate with derive-visitor

Cargo.toml

@@ -18,6 +18,7 @@ rust-version = "1.60"
 arbitrary  = { version = "1.0.0", optional = true }
 borsh      = { version = "1.2.0", optional = true, default-features = false }
 bytemuck   = { version = "1.12.2", optional = true, default-features = false }
+derive-visitor = { version = "0.4.0", optional = true }
 num-cmp    = { version = "0.1.0", optional = true }
 num-traits = { version = "0.2.1", default-features = false }
 proptest   = { version = "1.0.0", optional = true }

src/lib.rs

@@ -105,6 +105,71 @@ fn canonicalize_signed_zero<T: FloatCore>(x: T) -> T {
 #[repr(transparent)]
 pub struct OrderedFloat<T>(pub T);
 
+#[cfg(feature = "derive-visitor")]
+mod impl_derive_visitor {
+    use crate::OrderedFloat;
+    use derive_visitor::{Drive, DriveMut, Event, Visitor, VisitorMut};
+
+    impl<T: 'static> Drive for OrderedFloat<T> {
+        fn drive<V: Visitor>(&self, visitor: &mut V) {
+            visitor.visit(self, Event::Enter);
+            visitor.visit(self, Event::Exit);
+        }
+    }
+
+    impl<T: 'static> DriveMut for OrderedFloat<T> {
+        fn drive_mut<V: VisitorMut>(&mut self, visitor: &mut V) {
+            visitor.visit(self, Event::Enter);
+            visitor.visit(self, Event::Exit);
+        }
+    }
+
+    #[test]
+    pub fn test_derive_visitor() {
+        #[derive(Debug, Clone, PartialEq, Eq, Drive, DriveMut)]
+        pub enum Literal {
+            Null,
+            Float(OrderedFloat<f64>),
+        }
+
+        #[derive(Visitor, VisitorMut)]
+        #[visitor(Literal(enter))]
+        struct FloatExpr(bool);
+
+        impl FloatExpr {
+            fn enter_literal(&mut self, lit: &Literal) {
+                if let Literal::Float(_) = lit {
+                    self.0 = true;
+                }
+            }
+        }
+
+        assert!({
+            let mut visitor = FloatExpr(false);
+            Literal::Null.drive(&mut visitor);
+            !visitor.0
+        });
+
+        assert!({
+            let mut visitor = FloatExpr(false);
+            Literal::Null.drive_mut(&mut visitor);
+            !visitor.0
+        });
+
+        assert!({
+            let mut visitor = FloatExpr(false);
+            Literal::Float(OrderedFloat(0.0)).drive(&mut visitor);
+            visitor.0
+        });
+
+        assert!({
+            let mut visitor = FloatExpr(false);
+            Literal::Float(OrderedFloat(0.0)).drive_mut(&mut visitor);
+            visitor.0
+        });
+    }
+}
+
 #[cfg(feature = "num-cmp")]
 mod impl_num_cmp {
     use super::OrderedFloat;