Alter yaserde_derive crate to support skip_serialize_if for attributes

yaserde_derive/src/common/field.rs

@@ -145,13 +145,18 @@ impl YaSerdeField {
       .map(|builder| quote!(let yaserde_inner = #builder;))
       .unwrap_or_default();
 
+    let skip_if = self
+      .get_skip_serializing_if_function()
+      .map(|skip_if_function| quote!(!self.#skip_if_function(&self.#label)))
+      .unwrap_or(quote!(true));
+
     self
       .get_default_function()
       .map(|default_function| {
         quote! {
           #yaserde_inner_definition
           let struct_start_event =
-            if self.#label != #default_function() {
+            if #skip_if && self.#label != #default_function() {
               #setter
             } else {
               struct_start_event
@@ -160,7 +165,7 @@ impl YaSerdeField {
       })
       .unwrap_or(quote! {
         #yaserde_inner_definition
-        let struct_start_event = #setter;
+        let struct_start_event = if #skip_if { #setter } else { struct_start_event };
       })
   }
 }

yaserde_derive/src/lib.rs

@@ -14,7 +14,7 @@ pub fn derive_deserialize(input: TokenStream) -> TokenStream {
   let ast = syn::parse(input).unwrap();
   match de::expand_derive_deserialize(&ast) {
     Ok(expanded) => expanded.into(),
-    Err(msg) => panic!(msg),
+    Err(msg) => panic!("{}", msg),
   }
 }
 
@@ -23,6 +23,6 @@ pub fn derive_serialize(input: TokenStream) -> TokenStream {
   let ast = syn::parse(input).unwrap();
   match ser::expand_derive_serialize(&ast) {
     Ok(expanded) => expanded.into(),
-    Err(msg) => panic!(msg),
+    Err(msg) => panic!("{}", msg),
   }
 }