fn variable_size_object_helper()

in lain_derive/src/lib.rs [186:247]

• 53 lines of code
• 8 McCabe index (conditional complexity)

fn variable_size_object_helper(input: &DeriveInput) -> TokenStream {
    // TODO: refactor this to use the same pattern as Mutatable/NewFuzzed introduced
    // in v0.2.0
    let imp: TokenStream;

    match input.data {
        Data::Enum(ref data) => {
            let mut simple_variants = true;
            for variant in &data.variants {
                match variant.fields {
                    Fields::Unit => {
                        continue;
                    }
                    _ => {
                        simple_variants = false;
                    }
                }
            }

            imp = if simple_variants {
                quote! {false}
            } else {
                quote! {true}
            };
        }
        Data::Struct(ref data) => {
            if let Fields::Named(ref fields) = data.fields {
                if fields.named.len() == 0 {
                    imp = quote! {false};
                } else {
                    let mut tokens = quote! {false};

                    for field in fields.named.iter() {
                        let ty = &field.ty;
                        tokens.extend(quote_spanned! { field.span() =>
                            || <#ty>::is_variable_size()
                        });
                    }

                    imp = tokens;
                }
            } else {
                panic!("Need to add support for unnamed struct fields");
            }
        }
        _ => panic!("Non-enum/struct data types are not supported"),
    }

    let name = &input.ident;

    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();

    quote! {
        #[allow(clippy)]
        #[allow(unknown_lints)]
        impl #impl_generics ::lain::traits::VariableSizeObject for #name #ty_generics #where_clause {
            fn is_variable_size() -> bool {
                #imp
            }
        }
    }
}