fn generate_deserializer()

in src/descriptors/struct_desc.rs [40:81]

• 28 lines of code
• 3 McCabe index (conditional complexity)

    fn generate_deserializer(&self) -> proc_macro2::TokenStream {
        let mut versioned_deserializers = proc_macro2::TokenStream::new();
        let struct_ident = format_ident!("{}", self.ty);

        for i in 1..=self.version {
            let mut versioned_deserializer = proc_macro2::TokenStream::new();
            let mut semantic_deserializer = proc_macro2::TokenStream::new();

            // Generate field and semantic deserializers for all fields.
            // Not all fields have semantic deserializers defined and some fields
            // might be missing in version `i`. In these cases the generate_deserializer() and
            // generate_semantic_deserializer() will return an empty token stream.
            for field in &self.fields {
                versioned_deserializer.extend(field.generate_deserializer(i));
                semantic_deserializer.extend(field.generate_semantic_deserializer(i));
            }

            // Generate the match arm for version `i`.
            //
            // The semantic deserialization functions will be called after the object is constructed
            // using the previously generated field deserializers.
            versioned_deserializers.extend(quote! {
                #i => {
                    let mut object = #struct_ident {
                        #versioned_deserializer
                    };
                    #semantic_deserializer
                    Ok(object)
                }
            });
        }

        // Generate code to map the app version to struct version and wrap the
        // deserializers with the `version` match.
        quote! {
            let version = version_map.get_type_version(app_version, <Self as Versionize>::type_id());
            match version {
                #versioned_deserializers
                _ => panic!("Unknown {:?} version {}.", <Self as Versionize>::type_id(), version)
            }
        }
    }