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#![recursion_limit="128"] extern crate proc_macro; extern crate proc_macro2; extern crate syn; #[macro_use] extern crate quote; use std::iter; use proc_macro2::{TokenStream, Span}; #[proc_macro_derive(Visit, attributes(visit))] pub fn visit_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream { let ast = syn::parse_macro_input!(input as syn::DeriveInput); let gen = impl_visit(&ast); gen.into() } #[proc_macro_derive(HasExtent)] pub fn has_extent_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream { let ast = syn::parse_macro_input!(input as syn::DeriveInput); let gen = impl_has_extent(&ast); gen.into() } #[proc_macro_derive(ExtentIndex)] pub fn extent_index_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream { let ast = syn::parse_macro_input!(input as syn::DeriveInput); let gen = impl_extent_index(&ast); gen.into() } fn camelcase_to_snake_case(camelcase: &str) -> String { let mut s = String::new(); for c in camelcase.chars() { if c.is_lowercase() { s.push(c); } else { s.push('_'); s.extend(c.to_lowercase()); } } s } fn impl_visit(ast: &syn::DeriveInput) -> TokenStream { use syn::Ident; let name = &ast.ident; let method_name_base = camelcase_to_snake_case(&name.to_string()); let method_name = Ident::new(&format!("visit{}", method_name_base), Span::call_site()); let exit_method_name = Ident::new(&format!("exit{}", method_name_base), Span::call_site()); let visit_fields = impl_visit_fields(ast, IsMut(false)); let visit_fields_mut = impl_visit_fields(ast, IsMut(true)); quote! { impl crate::visit::Visit for #name { fn visit<'ast, V>(&'ast self, v: &mut V) where V: crate::visit::Visitor<'ast>, { if crate::visit::Control::Continue == v.#method_name(self) { #visit_fields; } v.#exit_method_name(self); } fn visit_mut<V>(&mut self, v: &mut V) where V: crate::visit::VisitorMut, { if crate::visit::Control::Continue == v.#method_name(self) { #visit_fields_mut; } v.#exit_method_name(self); } } } } struct IsMut(bool); fn impl_visit_fields(ast: &syn::DeriveInput, IsMut(is_mut): IsMut) -> TokenStream { use syn::{Ident, Data, Fields}; let method = if is_mut { "visit_mut" } else { "visit" }; let method = Ident::new(method, Span::call_site()); let method = iter::repeat(quote! { crate::visit::Visit::#method }); fn field_names<'a>(fields: impl IntoIterator<Item = &'a syn::Field>) -> Vec<Ident> { fields .into_iter() .enumerate() .filter(|&(_, ref f)| !is_ignore_field(f)) .map(|(i, f)| f.ident.clone().unwrap_or_else(|| Ident::new(&i.to_string(), Span::call_site()))) .collect() } match ast.data { Data::Enum(ref e) => { let enum_name = iter::repeat(&ast.ident); let variant_names = e.variants.iter().map(|variant| &variant.ident); if is_mut { quote! { match *self { #(#enum_name::#variant_names(ref mut x) => #method(x, v),)* } } } else { quote! { match *self { #(#enum_name::#variant_names(ref x) => #method(x, v),)* } } } } Data::Struct(ref s) => { let field_names: Vec<_> = match s.fields { Fields::Named(ref fields) => field_names(&fields.named), Fields::Unnamed(ref fields) => field_names(&fields.unnamed), Fields::Unit => vec![], }; if is_mut { quote! { #(#method(&mut self.#field_names, v);)* } } else { quote! { #(#method(&self.#field_names, v);)* } } } Data::Union(..) => panic!("Unions are not supported"), } } fn is_ignore_field(field: &syn::Field) -> bool { use syn::Meta; field.attrs.iter().any(|attr| { let meta = attr.parse_meta().expect("Unknown attribute structure"); match meta { Meta::List(ref list) => { list.path.is_ident("visit") && list.nested.iter().any(ignore_field_inner) }, _ => false, } }) } fn ignore_field_inner(item: &syn::NestedMeta) -> bool { use syn::{NestedMeta, Meta}; match *item { NestedMeta::Meta(Meta::Path(ref p)) => p.is_ident("ignore"), _ => false } } #[proc_macro_derive(Decompose)] pub fn decompose_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream { let ast = syn::parse_macro_input!(input as syn::DeriveInput); let gen = impl_decompose(&ast); gen.into() } fn impl_decompose(ast: &syn::DeriveInput) -> TokenStream { use syn::{Ident, Data, Fields, Type}; let name = &ast.ident; let e = match ast.data { Data::Enum(ref e) => e, _ => panic!("Can only decompose enums"), }; let enum_name = &ast.ident; struct Info<'a> { variant_name: &'a Ident, variant_snake_name: String, variant_type: &'a Type, } let enum_info: Vec<_> = e.variants.iter().map(|variant| { let fields = match variant.fields { Fields::Unnamed(ref fields) => fields, _ => panic!("Can only decompose tuple variants"), }; let field = match fields.unnamed.len() { 1 => &fields.unnamed[0], _ => panic!("can only decompose exactly one field"), }; Info { variant_name: &variant.ident, variant_snake_name: camelcase_to_snake_case(&variant.ident.to_string()), variant_type: &field.ty, } }).collect(); let into_fns = enum_info.iter().map(|info| { let Info { variant_name, ref variant_snake_name, variant_type } = *info; let method_name = Ident::new(&format!("into{}", variant_snake_name), Span::call_site()); quote! { pub fn #method_name(self) -> Option<#variant_type> { match self { #enum_name::#variant_name(x) => Some(x), _ => None, } } } }); let as_fns = enum_info.iter().map(|info| { let Info { variant_name, ref variant_snake_name, variant_type } = *info; let method_name = Ident::new(&format!("as{}", variant_snake_name), Span::call_site()); quote! { pub fn #method_name(&self) -> Option<&#variant_type> { match *self { #enum_name::#variant_name(ref x) => Some(x), _ => None, } } } }); let is_fns = enum_info.iter().map(|info| { let Info { variant_name, ref variant_snake_name, .. } = *info; let method_name = Ident::new(&format!("is{}", variant_snake_name), Span::call_site()); quote! { pub fn #method_name(&self) -> bool { match *self { #enum_name::#variant_name(..) => true, _ => false, } } } }); quote! { impl #name { #(#into_fns)* #(#as_fns)* #(#is_fns)* } } } fn impl_has_extent(ast: &syn::DeriveInput) -> TokenStream { let name = &ast.ident; use syn::{Data, Fields}; let body = match ast.data { Data::Enum(ref e) => { let enum_name = iter::repeat(&ast.ident); let variant_names = e.variants.iter().map(|variant| &variant.ident); quote! { match *self { #(#enum_name::#variant_names(ref x) => crate::HasExtent::extent(x),)* } } } Data::Struct(ref s) => { match s.fields { Fields::Named(..) => { quote! { self.extent } } Fields::Unnamed(..) | Fields::Unit => { panic!("Don't know how to implement HasExtent for tuple or unit structs"); } } } Data::Union(..) => panic!("Don't know how to implement HasExtent for unions"), }; quote! { impl crate::HasExtent for #name { fn extent(&self) -> Extent { #body } } } } fn impl_extent_index(ast: &syn::DeriveInput) -> TokenStream { let name = &ast.ident; quote! { impl std::ops::Index<#name> for str { type Output = str; fn index(&self, i: #name) -> &Self::Output { let Extent(s, e) = i.extent(); &self[s..e] } } impl<'a> std::ops::Index<&'a #name> for str { type Output = str; fn index(&self, i: &'a #name) -> &Self::Output { let Extent(s, e) = i.extent(); &self[s..e] } } } }