static_map_macro/util.rs
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use pmutil::ToTokensExt;
use proc_macro2::Span;
use quote::quote;
use syn::{parse, Generics, ItemImpl, WhereClause};
/// Extension trait for `ItemImpl` (impl block).
pub trait ItemImplExt {
/// Instead of
///
/// ```rust,ignore
/// let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
///
/// let item: Item = Quote::new(def_site::<Span>())
/// .quote_with(smart_quote!(
/// Vars {
/// Type: type_name,
/// impl_generics,
/// ty_generics,
/// where_clause,
/// },
/// {
/// impl impl_generics ::swc_common::AstNode for Type ty_generics
/// where_clause {}
/// }
/// )).parse();
/// ```
///
/// You can use this like
///
/// ```rust,ignore
// let item = Quote::new(def_site::<Span>())
/// .quote_with(smart_quote!(Vars { Type: type_name }, {
/// impl ::swc_common::AstNode for Type {}
/// }))
/// .parse::<ItemImpl>()
/// .with_generics(input.generics);
/// ```
fn with_generics(self, generics: Generics) -> Self;
}
impl ItemImplExt for ItemImpl {
fn with_generics(mut self, mut generics: Generics) -> Self {
// TODO: Check conflicting name
let need_new_punct = !generics.params.empty_or_trailing();
if need_new_punct {
generics
.params
.push_punct(syn::token::Comma(Span::call_site()));
}
// Respan
if let Some(t) = generics.lt_token {
self.generics.lt_token = Some(t)
}
if let Some(t) = generics.gt_token {
self.generics.gt_token = Some(t)
}
let ty = self.self_ty;
// Handle generics defined on struct, enum, or union.
let mut item: ItemImpl = {
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let item = if let Some((ref polarity, ref path, ref for_token)) = self.trait_ {
quote! {
impl #impl_generics #polarity #path #for_token #ty #ty_generics #where_clause {}
}
} else {
quote! {
impl #impl_generics #ty #ty_generics #where_clause {}
}
};
parse(item.dump().into())
.unwrap_or_else(|err| panic!("with_generics failed: {}\n{}", err, item.dump()))
};
// Handle generics added by proc-macro.
item.generics
.params
.extend(self.generics.params.into_pairs());
match self.generics.where_clause {
Some(WhereClause {
ref mut predicates, ..
}) => {
println!("FOO");
predicates.extend(
generics
.where_clause
.into_iter()
.flat_map(|wc| wc.predicates.into_pairs()),
)
}
ref mut opt @ None => *opt = generics.where_clause,
}
ItemImpl {
attrs: self.attrs,
defaultness: self.defaultness,
unsafety: self.unsafety,
impl_token: self.impl_token,
brace_token: self.brace_token,
items: self.items,
..item
}
}
}