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use proc_macro::TokenStream;
use quote::{format_ident, quote};
use syn::punctuated::{Pair, Punctuated};
use syn::{
parse_macro_input, AttributeArgs, FnArg, Ident, ItemStruct, ItemTrait, Meta, NestedMeta, Pat, PatIdent, PatType,
Path, Token, TraitItem, Type, Visibility,
};
#[proc_macro_derive(HirMode)]
pub fn derive_hir_mode(input: TokenStream) -> TokenStream {
let s = parse_macro_input!(input as ItemStruct);
let name = s.ident;
let out = quote! {
impl HirMode for #name {}
};
TokenStream::from(out)
}
#[proc_macro_attribute]
pub fn mode_functionality(_attr: TokenStream, input: TokenStream) -> TokenStream {
let clone = input.clone();
let s = parse_macro_input!(input as ItemTrait);
let mut input = clone;
let trait_name = s.ident;
let inner_name = generate_inner_name(&trait_name);
let wrapper_name = generate_wrapper_name(&trait_name);
let inner_fn_name = generate_wrapper_fn_name(&trait_name);
let wrapper = generate_wrapper(&trait_name, &wrapper_name, &inner_name, &inner_fn_name, &s.vis);
let wrapper_impl = generate_wrapper_impl(&trait_name, &wrapper_name, &inner_name, &inner_fn_name);
let blanket = generate_blanket(&trait_name, &wrapper_name, &inner_fn_name, &s.items);
input.extend(wrapper);
input.extend(wrapper_impl);
input.extend(blanket);
input
}
fn generate_inner_name(trait_name: &Ident) -> Ident {
format_ident!("Inner{}", trait_name)
}
fn generate_wrapper_name(trait_name: &Ident) -> Ident {
format_ident!("{}Wrapper", trait_name)
}
fn generate_wrapper_fn_name(trait_name: &Ident) -> Ident {
format_ident!("inner_{}", trait_name)
}
fn generate_wrapper(
trait_name: &Ident,
wrapper_name: &Ident,
inner_name: &Ident,
inner_fn_name: &Ident,
vis: &Visibility,
) -> TokenStream {
let out = quote! {
#vis trait #wrapper_name {
type #inner_name: #trait_name;
#[allow(non_snake_case)]
fn #inner_fn_name(&self) -> &Self::#inner_name;
}
};
TokenStream::from(out)
}
fn generate_wrapper_impl(
trait_name: &Ident,
wrapper_name: &Ident,
inner_name: &Ident,
inner_fn_name: &Ident,
) -> TokenStream {
let out = quote! {
impl<M> #wrapper_name for Hir<M>
where
M: HirMode + #trait_name
{
type #inner_name = M;
fn #inner_fn_name(&self) -> &Self::#inner_name {
&self.mode
}
}
};
TokenStream::from(out)
}
fn generate_blanket(
trait_name: &Ident,
wrapper_name: &Ident,
inner_fn_name: &Ident,
content: &[TraitItem],
) -> TokenStream {
let content = content.iter().filter_map(|c| {
match c {
TraitItem::Method(m) => Some(m),
_ => None,
}
});
let sig = content.clone().map(|c| &c.sig);
let args = content.clone().cloned().map(|c| c.sig.inputs).map(|args| {
let mut ret = Punctuated::<Ident, Token![,]>::new();
for (arg, opt_p) in args.into_pairs().map(Pair::into_tuple) {
match arg {
FnArg::Receiver(_) => {}, FnArg::Typed(PatType { pat, .. }) => {
match *pat {
Pat::Ident(PatIdent { ident, .. }) => {
ret.push_value(ident);
if let Some(p) = opt_p {
ret.push_punct(p);
}
},
_ => panic!("Inner WTF"),
}
},
}
}
ret
});
let fn_name = content.map(|c| &c.sig.ident);
let out = quote! {
impl<T> #trait_name for T
where
T: #wrapper_name,
{
#( #sig { self.#inner_fn_name().#fn_name(#args) })*
}
};
TokenStream::from(out)
}
#[proc_macro_attribute]
pub fn covers_functionality(attr: TokenStream, input: TokenStream) -> TokenStream {
let clone = input.clone();
let s = parse_macro_input!(input as ItemStruct);
let mode_name = s.ident;
let attr = parse_macro_input!(attr as AttributeArgs);
assert_eq!(attr.len(), 2);
let sub_trait_name = extract_ident(&attr[0]);
let accessor = extract_ident(&attr[1]);
let sub_struct_name = s
.fields
.iter()
.find_map(|field| {
let name = field.ident.as_ref().expect("there can't be unnamed fields in structs");
if accessor == name {
if let Type::Path(tp) = &field.ty {
Some(tp.path.get_ident())
} else {
panic!("type of accessor is not a path to a type")
}
} else {
None
}
})
.expect("accessor not found in struct");
let sub_inner_name = generate_inner_name(sub_trait_name);
let sub_wrapper_name = generate_wrapper_name(sub_trait_name);
let sub_inner_fn_name = generate_wrapper_fn_name(sub_trait_name);
let mut input = clone;
let out = quote! {
impl #sub_wrapper_name for #mode_name {
type #sub_inner_name = #sub_struct_name;
fn #sub_inner_fn_name(&self) -> &Self::#sub_inner_name {
&self.#accessor
}
}
};
input.extend(TokenStream::from(out));
input
}
fn extract_ident(nm: &NestedMeta) -> &Ident {
extract_path(nm)
.get_ident()
.expect("extends_mode needs two arguments: the subsumed mode and a field refering to one.")
}
fn extract_path(nm: &NestedMeta) -> &Path {
match nm {
NestedMeta::Meta(Meta::Path(p)) => p,
NestedMeta::Meta(_) | NestedMeta::Lit(_) => {
panic!("extends_mode needs two arguments: the subsumed mode and a field refering to one.")
},
}
}