allow constructing and cloning ParseWrapper and TokenStreamWrapper

src/ibidem.rs

@@ -21,7 +21,7 @@ use crate::serde_tokenstream::spanned_error;
 /// it is not used in the context of [`from_tokenstream`].
 ///
 /// [`from_tokenstream`]: crate::from_tokenstream
-#[derive(Debug)]
+#[derive(Clone, Debug, Default)]
 pub struct TokenStreamWrapper(TokenStream);
 
 impl TokenStreamWrapper {
@@ -30,6 +30,12 @@ impl TokenStreamWrapper {
     }
 }
 
+impl From<TokenStream> for TokenStreamWrapper {
+    fn from(inner: TokenStream) -> Self {
+        Self(inner)
+    }
+}
+
 impl<'de> Deserialize<'de> for TokenStreamWrapper {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -60,7 +66,7 @@ impl std::ops::Deref for TokenStreamWrapper {
 ///
 /// [`Parse`]: syn::parse::Parse
 /// [`from_tokenstream`]: crate::from_tokenstream
-#[derive(Debug, Hash, Eq, PartialEq)]
+#[derive(Clone, Debug, Default, Hash, Eq, PartialEq)]
 pub struct ParseWrapper<P: syn::parse::Parse>(P);
 
 impl<P: syn::parse::Parse> ParseWrapper<P> {
@@ -69,6 +75,12 @@ impl<P: syn::parse::Parse> ParseWrapper<P> {
     }
 }
 
+impl<P: syn::parse::Parse> From<P> for ParseWrapper<P> {
+    fn from(inner: P) -> Self {
+        Self(inner)
+    }
+}
+
 impl<'de, P: syn::parse::Parse> Deserialize<'de> for ParseWrapper<P> {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where

src/serde_tokenstream.rs

@@ -2124,6 +2124,62 @@ mod tests {
         .unwrap();
     }
 
+    #[test]
+    fn test_parse_wrapper_default_and_clone() {
+        fn default_ident() -> ParseWrapper<syn::Ident> {
+            ParseWrapper::from(syn::Ident::new(
+                "fallback",
+                proc_macro2::Span::call_site(),
+            ))
+        }
+
+        #[derive(Deserialize, Clone)]
+        struct Input {
+            #[serde(default = "default_ident")]
+            ident: ParseWrapper<syn::Ident>,
+        }
+
+        let input = from_tokenstream::<Input>(&quote! {}).unwrap();
+        assert_eq!(*input.clone().ident, "fallback");
+
+        let input =
+            from_tokenstream::<Input>(&quote! { ident = given }).unwrap();
+        assert_eq!(*input.ident, "given");
+
+        #[derive(Deserialize)]
+        struct Generic {
+            #[serde(default)]
+            generics: ParseWrapper<syn::Generics>,
+        }
+
+        let input = from_tokenstream::<Generic>(&quote! {}).unwrap();
+        assert!(input.generics.params.is_empty());
+
+        let input =
+            from_tokenstream::<Generic>(&quote! { generics = <T: Copy> })
+                .unwrap();
+        assert_eq!(input.generics.params.len(), 1);
+    }
+
+    #[test]
+    fn test_token_stream_wrapper_default_and_clone() {
+        #[derive(Deserialize, Clone)]
+        struct Input {
+            #[serde(default)]
+            tokens: TokenStreamWrapper,
+        }
+
+        let input = from_tokenstream::<Input>(&quote! {}).unwrap();
+        assert!(input.clone().tokens.is_empty());
+
+        let input =
+            from_tokenstream::<Input>(&quote! { tokens = a + b }).unwrap();
+        assert_eq!(input.tokens.to_string(), "a + b");
+
+        let wrapper = TokenStreamWrapper::from(quote! { x });
+        assert_eq!(wrapper.into_inner().to_string(), "x");
+    }
+
     #[test]
     fn parse_u128() {
         #[derive(Deserialize)]