83 lines
2.6 KiB
Rust
83 lines
2.6 KiB
Rust
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use quote::quote;
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use synstructure::BindingInfo;
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pub(super) fn visitable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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if let syn::Data::Union(_) = s.ast().data {
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panic!("cannot derive on union")
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}
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let has_attr = |bind: &BindingInfo<'_>, name| {
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let mut found = false;
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bind.ast().attrs.iter().for_each(|attr| {
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if !attr.path().is_ident("visitable") {
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return;
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}
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let _ = attr.parse_nested_meta(|nested| {
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if nested.path.is_ident(name) {
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found = true;
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}
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Ok(())
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});
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});
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found
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};
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let get_attr = |bind: &BindingInfo<'_>, name: &str| {
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let mut content = None;
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bind.ast().attrs.iter().for_each(|attr| {
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if !attr.path().is_ident("visitable") {
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return;
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}
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let _ = attr.parse_nested_meta(|nested| {
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if nested.path.is_ident(name) {
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let value = nested.value()?;
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let value = value.parse()?;
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content = Some(value);
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}
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Ok(())
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});
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});
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content
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};
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s.add_bounds(synstructure::AddBounds::Generics);
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s.bind_with(|_| synstructure::BindStyle::Ref);
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let ref_visit = s.each(|bind| {
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let extra = get_attr(bind, "extra").unwrap_or(quote! {});
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if has_attr(bind, "ignore") {
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quote! {}
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} else {
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quote! { rustc_ast_ir::try_visit!(crate::visit::Visitable::visit(#bind, __visitor, (#extra))) }
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}
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});
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s.bind_with(|_| synstructure::BindStyle::RefMut);
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let mut_visit = s.each(|bind| {
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let extra = get_attr(bind, "extra").unwrap_or(quote! {});
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if has_attr(bind, "ignore") {
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quote! {}
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} else {
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quote! { crate::mut_visit::MutVisitable::visit_mut(#bind, __visitor, (#extra)) }
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}
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});
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s.gen_impl(quote! {
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gen impl<'__ast, __V> crate::visit::Walkable<'__ast, __V> for @Self
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where __V: crate::visit::Visitor<'__ast>,
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{
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fn walk_ref(&'__ast self, __visitor: &mut __V) -> __V::Result {
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match *self { #ref_visit }
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<__V::Result as rustc_ast_ir::visit::VisitorResult>::output()
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}
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}
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gen impl<__V> crate::mut_visit::MutWalkable<__V> for @Self
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where __V: crate::mut_visit::MutVisitor,
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{
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fn walk_mut(&mut self, __visitor: &mut __V) {
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match *self { #mut_visit }
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}
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}
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})
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}
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