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