| 49 | } |
| 50 | |
| 51 | pub fn derive(input: DeriveInput) -> Result<TokenStream> { |
| 52 | let ident = input.ident; |
| 53 | let generics = &input.generics; |
| 54 | let (impl_generics, type_generics, _) = generics.split_for_impl(); |
| 55 | let feature: CSSFeatureName = CSSFeatureName::try_from(input.attrs.as_slice())?; |
| 56 | let steps = match &input.data { |
| 57 | Data::Union(_) => return Err(Error::new(ident.span(), "Cannot derive on a Union")), |
| 58 | |
| 59 | Data::Struct(DataStruct { fields, .. }) => { |
| 60 | if fields.is_empty() { |
| 61 | return Err(Error::new(ident.span(), "Cannot derive on empty Struct")); |
| 62 | } else { |
| 63 | quote! {} |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | Data::Enum(DataEnum { variants, .. }) => { |
| 68 | if variants.is_empty() { |
| 69 | return Err(Error::new(ident.span(), "Cannot derive on empty Enum")); |
| 70 | } else { |
| 71 | let variants = variants |
| 72 | .iter() |
| 73 | .map(|variant| { |
| 74 | let variant_ident = &variant.ident; |
| 75 | let pattern = match &variant.fields { |
| 76 | Fields::Named(fields) => { |
| 77 | let ignores = fields.named.iter().map(|f| { |
| 78 | let fname = f.ident.as_ref().unwrap(); |
| 79 | quote! { #fname: _ } |
| 80 | }); |
| 81 | quote! { Self::#variant_ident { #(#ignores),* } } |
| 82 | } |
| 83 | _ => { |
| 84 | let members = variant.fields.members().map(|_| quote! { _ }); |
| 85 | quote! { Self::#variant_ident(#(#members),*) } |
| 86 | } |
| 87 | }; |
| 88 | if let Ok(feature) = CSSFeatureName::try_from(variant.attrs.as_slice()) { |
| 89 | let step = by_feature_name(feature.to_string()); |
| 90 | quote! { #pattern => { #step }, } |
| 91 | } else { |
| 92 | let str = feature.to_string(); |
| 93 | let guessed_step = |
| 94 | by_feature_name(format!("{}.{}", str, variant_ident.to_string().to_kebab_case())); |
| 95 | let or_step = by_feature_name(feature.to_string()); |
| 96 | quote! { #pattern => { #guessed_step.or_else(|| #or_step) }, } |
| 97 | } |
| 98 | }) |
| 99 | .collect::<Vec<_>>(); |
| 100 | let by_feature_name = by_feature_name(feature.to_string()); |
| 101 | quote! { |
| 102 | match self { |
| 103 | #(#variants)* |
| 104 | _ => { #by_feature_name }, |
| 105 | } |
| 106 | } |
| 107 | } |
| 108 | } |