Add method to transpose valid options

src/lib.rs

@@ -115,12 +115,21 @@ impl<T: Vet> Vet for Option<T> {
 
     fn is_valid(&self) -> Result<(), Self::VetError> {
         match self {
-            Some(t) => t.is_valid(),
+            Some(o) => o.is_valid(),
             None => Ok(()),
         }
     }
 }
 
+impl<T: Vet> Valid<Option<T>> {
+    pub fn transpose(self) -> Option<Valid<T>> {
+        match self {
+            Valid(Some(o)) => Some(Valid(o)),
+            Valid(None) => None,
+        }
+    }
+}
+
 #[cfg(feature = "alloc")]
 impl<T: Vet> Vet for alloc::vec::Vec<T> {
     type VetError = T::VetError;

src/tests.rs

@@ -50,6 +50,15 @@ fn vet_option() {
     assert!(foo.is_valid().is_err());
 }
 
+#[test]
+fn transpose_valid_option() {
+    let foo = None::<EvenUsize>.vet().unwrap();
+    assert_eq!(foo.transpose(), None);
+
+    let foo = Some(EvenUsize(84)).vet().unwrap();
+    assert_eq!(foo.transpose(), Some(Valid(EvenUsize(84))));
+}
+
 #[test]
 #[cfg(feature = "alloc")]
 fn vet_vec() {