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use std::ops::Deref; use syn::{self, DeriveInput}; use quote::ToTokens; use proc_macro2::TokenStream; use field::{Field, Fields, FieldsKind}; #[derive(Debug, Clone)] pub enum ItemInput { Struct(syn::ItemStruct), Enum(syn::ItemEnum), Union(syn::ItemUnion), } impl From<DeriveInput> for ItemInput { fn from(input: DeriveInput) -> Self { match input.data { syn::Data::Struct(v) => { ItemInput::Struct(syn::ItemStruct { attrs: input.attrs, vis: input.vis, struct_token: v.struct_token, ident: input.ident, generics: input.generics, fields: v.fields, semi_token: v.semi_token, }) } syn::Data::Enum(v) => { ItemInput::Enum(syn::ItemEnum { attrs: input.attrs, vis: input.vis, enum_token: v.enum_token, ident: input.ident, generics: input.generics, brace_token: v.brace_token, variants: v.variants, }) } syn::Data::Union(v) => { ItemInput::Union(syn::ItemUnion { attrs: input.attrs, vis: input.vis, ident: input.ident, generics: input.generics, union_token: v.union_token, fields: v.fields, }) } } } } macro_rules! getter { ($name:ident -> [$($kind:tt)*] $field:ident $T:ty) => ( pub fn $name($($kind)* self) -> $T { match self { ItemInput::Struct(v) => $($kind)* v.$field, ItemInput::Enum(v) => $($kind)* v.$field, ItemInput::Union(v) => $($kind)* v.$field, } } ) } impl ItemInput { getter!(attrs -> [&] attrs &[syn::Attribute]); getter!(attrs_mut -> [&mut] attrs &mut Vec<syn::Attribute>); getter!(vis -> [&] vis &syn::Visibility); getter!(vis_mut -> [&mut] vis &mut syn::Visibility); getter!(ident -> [&] ident &syn::Ident); getter!(ident_mut -> [&mut] ident &mut syn::Ident); getter!(generics -> [&] generics &syn::Generics); getter!(generics_mut -> [&mut] generics &mut syn::Generics); } impl ToTokens for ItemInput { fn to_tokens(&self, tokens: &mut TokenStream) { match self { ItemInput::Struct(v) => v.to_tokens(tokens), ItemInput::Enum(v) => v.to_tokens(tokens), ItemInput::Union(v) => v.to_tokens(tokens), } } } #[derive(Debug, Copy, Clone)] pub enum Input<'v> { Struct(Struct<'v>), Enum(Enum<'v>), Union(Union<'v>) } impl<'v> From<&'v ItemInput> for Input<'v> { fn from(input: &'v ItemInput) -> Self { match input { ItemInput::Struct(v) => Input::Struct(Derived::from(&v, input)), ItemInput::Enum(v) => Input::Enum(Derived::from(&v, input)), ItemInput::Union(v) => Input::Union(Derived::from(&v, input)), } } } impl ToTokens for Input<'_> { fn to_tokens(&self, tokens: &mut TokenStream) { match self { Input::Struct(v) => v.parent.to_tokens(tokens), Input::Enum(v) => v.parent.to_tokens(tokens), Input::Union(v) => v.parent.to_tokens(tokens), } } } impl Deref for Input<'_> { type Target = ItemInput; fn deref(&self) -> &Self::Target { match self { Input::Struct(v) => v.parent, Input::Enum(v) => v.parent, Input::Union(v) => v.parent, } } } #[derive(Debug)] pub struct Derived<'p, T, P = &'p ItemInput> { pub parent: P, pub inner: &'p T, } pub type Variant<'v> = Derived<'v, syn::Variant, Enum<'v>>; pub type Struct<'v> = Derived<'v, syn::ItemStruct>; pub type Enum<'v> = Derived<'v, syn::ItemEnum>; pub type Union<'v> = Derived<'v, syn::ItemUnion>; impl<'p, T, P> Derived<'p, T, P> { pub fn from(value: &'p T, parent: P) -> Self { Derived { parent, inner: value } } } impl<'p, T, P> Deref for Derived<'p, T, P> { type Target = T; fn deref(&self) -> &T { self.inner } } impl<'p, T: ToTokens, P> ToTokens for Derived<'p, T, P> { fn to_tokens(&self, tokens: &mut TokenStream) { self.inner.to_tokens(tokens) } } impl<'p, T, P: Copy> Copy for Derived<'p, T, P> { } impl<'p, T, P: Clone> Clone for Derived<'p, T, P> { fn clone(&self) -> Self { Self { parent: self.parent.clone(), inner: self.inner, } } } impl<'f> Variant<'f> { pub fn builder<F: Fn(Field) -> TokenStream>(&self, f: F) -> TokenStream { let variant = &self.ident; let expression = self.fields().iter().map(f); let enum_name = &self.parent.ident; match self.fields().kind { FieldsKind::Named(..) => { let field_name = self.fields.iter() .map(|f| f.ident.as_ref().unwrap()); quote! { #enum_name::#variant { #(#field_name: #expression),* } } }, FieldsKind::Unnamed(..) => { quote!( #enum_name::#variant(#(#expression),*) ) } FieldsKind::Unit => quote!(#enum_name::#variant), } } pub fn fields(self) -> Fields<'f> { self.into() } } impl<'p> Enum<'p> { pub fn variants(self) -> impl Iterator<Item = Variant<'p>> + Clone { self.inner.variants.iter() .map(move |v| Derived::from(v, self)) } } impl<'p> Struct<'p> { pub fn fields(self) -> Fields<'p> { self.into() } pub fn builder<F: Fn(Field) -> TokenStream>(&self, f: F) -> TokenStream { let expression = self.fields().iter().map(f); let struct_name = &self.parent.ident(); match self.fields().kind { FieldsKind::Named(..) => { let field_name = self.fields.iter() .map(|f| f.ident.as_ref().unwrap()); quote!(#struct_name { #(#field_name: #expression),* }) }, FieldsKind::Unnamed(..) => { quote!(#struct_name ( #(#expression),* )) } FieldsKind::Unit => quote!(#struct_name), } } }