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Support trait-only and impl-only attributes #43

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69 changes: 56 additions & 13 deletions src/ast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -140,19 +140,17 @@ pub(crate) struct Attribute {

#[derive(Clone, Copy, PartialEq)]
pub(crate) enum AttributeKind {
// #[doc ...]
Doc,
// #[inline ...]
Inline,
Other,
TraitOnly,
ImplOnly,
TraitAndImpl,
}

impl Attribute {
pub(crate) fn new(tokens: Vec<TokenTree>) -> Self {
Self {
pound_token: Punct::new('#', Spacing::Alone),
tokens: Group::new(Delimiter::Bracket, tokens.into_iter().collect()),
kind: AttributeKind::Other,
kind: AttributeKind::TraitAndImpl,
}
}
}
Expand Down Expand Up @@ -311,15 +309,19 @@ pub(crate) struct TraitItemType {
pub(crate) mod parsing {
use std::iter::FromIterator;

use proc_macro::{Delimiter, Punct, Spacing, TokenStream, TokenTree};
use proc_macro::{Delimiter, Group, Punct, Spacing, TokenStream, TokenTree};

use super::{
Attribute, AttributeKind, BoundLifetimes, ConstParam, FnArg, GenericParam, Generics,
ImplItem, ImplItemConst, ImplItemMethod, ImplItemType, ItemImpl, Lifetime, LifetimeDef,
PredicateLifetime, PredicateType, Signature, TypeParam, TypeParamBound, Visibility,
WhereClause, WherePredicate,
};
use crate::{error::Result, iter::TokenIter, to_tokens::ToTokens};
use crate::{
error::{Error, Result},
iter::TokenIter,
to_tokens::ToTokens,
};

fn parse_until_punct(input: &mut TokenIter, ch: char) -> Result<(Vec<TokenTree>, Punct)> {
let mut buf = vec![];
Expand Down Expand Up @@ -388,27 +390,68 @@ pub(crate) mod parsing {

fn parse_attrs(input: &mut TokenIter) -> Result<Vec<Attribute>> {
let mut attrs = vec![];
let mut prev_kind_override: Option<(AttributeKind, Group)> = None;
while input.peek_t(&'#') {
let pound_token = input.parse_punct('#')?;
let tokens = input.parse_group(Delimiter::Bracket)?;
let mut kind = AttributeKind::Other;
let mut kind = AttributeKind::TraitAndImpl;
let mut cur_kind_override = None;
let mut iter = TokenIter::new(tokens.stream());
if let Some(TokenTree::Ident(i)) = iter.next() {
match iter.next() {
// ignore #[path ...]
Some(TokenTree::Punct(ref p)) if p.as_char() == ':' => {}
_ => match &*i.to_string() {
"doc" => kind = AttributeKind::Doc,
"inline" => kind = AttributeKind::Inline,
next => match &*i.to_string() {
"doc" => kind = AttributeKind::TraitOnly,
"inline" => kind = AttributeKind::ImplOnly,
"ext_attr" => {
if let Some(next) = next {
match &*next.to_string() {
"(impl_only)" => {
cur_kind_override = Some(AttributeKind::ImplOnly);
}
"(trait_only)" => {
cur_kind_override = Some(AttributeKind::TraitOnly);
}
_ => {
return Err(Error::new(
&tokens,
"invalid attribute tag".into(),
))
}
}
} else {
return Err(Error::new(&tokens, "missing attribute tag".into()));
}
}
_ => {}
},
}
}

match (prev_kind_override.take(), cur_kind_override) {
(Some((prev_kind_override, _)), None) => {
kind = prev_kind_override;
}
(None, Some(cur_kind_override)) => {
prev_kind_override = Some((cur_kind_override, tokens));
continue;
}
(Some(_), Some(_)) => {
return Err(Error::new(&tokens, "repeated attribute tag".into()))
}
(None, None) => {}
}

let attr = Attribute { pound_token, tokens, kind };
attrs.push(attr);
}
Ok(attrs)

if let Some((_, tokens)) = prev_kind_override {
Err(Error::new(&tokens, "unused attribute tag".into()))
} else {
Ok(attrs)
}
}

fn parse_generics(input: &mut TokenIter) -> Result<Generics> {
Expand Down
17 changes: 10 additions & 7 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -457,7 +457,8 @@ fn trait_from_impl(item: &mut ItemImpl, trait_name: Ident) -> Result<ItemTrait>
})?;

let mut attrs = item.attrs.clone();
find_remove(&mut item.attrs, AttributeKind::Doc); // https://github.com/taiki-e/easy-ext/issues/20
find_remove(&mut item.attrs, AttributeKind::TraitOnly);
find_remove(&mut attrs, AttributeKind::ImplOnly);
attrs.push(Attribute::new(vec![
TokenTree::Ident(Ident::new("allow", Span::call_site())),
TokenTree::Group(Group::new(
Expand Down Expand Up @@ -522,8 +523,9 @@ fn trait_item_from_impl_item(
let vis = mem::replace(&mut impl_const.vis, Visibility::Inherited);
check_visibility(vis, prev_vis, impl_vis, &impl_const.ident)?;

let attrs = impl_const.attrs.clone();
find_remove(&mut impl_const.attrs, AttributeKind::Doc); // https://github.com/taiki-e/easy-ext/issues/20
let mut attrs = impl_const.attrs.clone();
find_remove(&mut impl_const.attrs, AttributeKind::TraitOnly);
find_remove(&mut attrs, AttributeKind::ImplOnly);
Ok(TraitItem::Const(TraitItemConst {
attrs,
const_token: impl_const.const_token.clone(),
Expand All @@ -537,8 +539,9 @@ fn trait_item_from_impl_item(
let vis = mem::replace(&mut impl_type.vis, Visibility::Inherited);
check_visibility(vis, prev_vis, impl_vis, &impl_type.ident)?;

let attrs = impl_type.attrs.clone();
find_remove(&mut impl_type.attrs, AttributeKind::Doc); // https://github.com/taiki-e/easy-ext/issues/20
let mut attrs = impl_type.attrs.clone();
find_remove(&mut impl_type.attrs, AttributeKind::TraitOnly);
find_remove(&mut attrs, AttributeKind::ImplOnly);
Ok(TraitItem::Type(TraitItemType {
attrs,
type_token: impl_type.type_token.clone(),
Expand All @@ -552,8 +555,8 @@ fn trait_item_from_impl_item(
check_visibility(vis, prev_vis, impl_vis, &impl_method.sig.ident)?;

let mut attrs = impl_method.attrs.clone();
find_remove(&mut impl_method.attrs, AttributeKind::Doc); // https://github.com/taiki-e/easy-ext/issues/20
find_remove(&mut attrs, AttributeKind::Inline); // `#[inline]` is ignored on function prototypes
find_remove(&mut impl_method.attrs, AttributeKind::TraitOnly);
find_remove(&mut attrs, AttributeKind::ImplOnly);
Ok(TraitItem::Method(TraitItemMethod {
attrs,
sig: {
Expand Down
62 changes: 62 additions & 0 deletions tests/test.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -666,3 +666,65 @@ fn arbitrary_self_types() {
Rc::new(String::default()).recv_rc_mut();
Box::pin(String::default()).recv_pin_box();
}

#[test]
fn impl_only_attrs() {
#![deny(unused_variables)]
#![allow(non_camel_case_types)]

#[ext(E1)]
#[ext_attr(impl_only)]
#[allow(unused_variables)]
impl str {
fn foo(&self) {
let x = 0;
}
}

#[ext(E2)]
impl str {
#[ext_attr(impl_only)]
#[allow(unused_variables)]
fn foo(&self) {
let x = 0;
}
}

#[ext(not_camel_case)]
#[ext_attr(impl_only)]
#[deny(non_camel_case_types)]
impl str {
fn foo(&self) {}
}
}

#[test]
fn trait_only_attrs() {
#![allow(unused_variables)]
#![deny(non_camel_case_types)]

#[ext(E1)]
#[ext_attr(trait_only)]
#[deny(unused_variables)]
impl str {
fn foo(&self) {
let x = 0;
}
}

#[ext(E2)]
impl str {
#[ext_attr(trait_only)]
#[deny(unused_variables)]
fn foo(&self) {
let x = 0;
}
}

#[ext(not_camel_case)]
#[ext_attr(trait_only)]
#[allow(non_camel_case_types)]
impl str {
fn foo(&self) {}
}
}