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// SPDX-License-Identifier: Apache-2.0 OR MIT
use proc_macro2::{Ident, TokenStream};
use quote::{format_ident, ToTokens};
use syn::{Attribute, GenericParam, Generics, Index, Member, Token};
use crate::DiagCtxt;
pub(crate) trait AttrListExt {
fn extract_cfg_attrs(&mut self) -> Vec<TokenStream>;
/// Extract attribute with identifier `path`.
///
/// Report error if the attribute appears multiple times.
fn extract_single_attr(&mut self, dcx: &DiagCtxt, path: &str) -> Option<Attribute>;
}
impl AttrListExt for Vec<Attribute> {
fn extract_cfg_attrs(&mut self) -> Vec<TokenStream> {
let cfg: Vec<_> = self
.iter()
.filter(|a| a.path().is_ident("cfg"))
.map(|a| {
a.parse_args::<TokenStream>()
.expect("parse as token stream cannot fail")
})
.collect();
if !cfg.is_empty() {
self.retain(|a| !a.path().is_ident("cfg"));
}
cfg
}
fn extract_single_attr(&mut self, dcx: &DiagCtxt, path: &str) -> Option<Attribute> {
// FIXME: Replace with `extract_if` when MSRV >= 1.85.
let attr_pos = self.iter().position(|attr| attr.path().is_ident(path))?;
let attr = self.remove(attr_pos);
self.retain(|attr| {
if !attr.path().is_ident(path) {
return true;
}
dcx.error(
attr,
format!("`#[{path}]` attribute specified more than once"),
);
false
});
Some(attr)
}
}
pub(crate) trait MemberExt {
/// Returns an identifier for the member.
///
/// Tuple fields have no name of their own, so they are named `_0`, `_1`, ... instead.
fn as_ident(&self) -> Ident;
/// Obtain a display name for the member in diagnostics.
fn display_name(&self) -> String;
}
impl MemberExt for Member {
fn as_ident(&self) -> Ident {
match self {
Member::Named(ident) => ident.clone(),
Member::Unnamed(Index { index, span }) => format_ident!("_{index}", span = *span),
}
}
fn display_name(&self) -> String {
match self {
Member::Named(ident) => format!("`{ident}`"),
Member::Unnamed(Index { index, .. }) => format!("index `{index}`"),
}
}
}
pub(crate) struct CombinedGenerics<'a>(pub(crate) Vec<&'a Generics>);
pub(crate) struct CombinedImplGenerics<'a>(&'a CombinedGenerics<'a>);
pub(crate) struct CombinedTypeGenerics<'a>(&'a CombinedGenerics<'a>);
impl CombinedGenerics<'_> {
pub(crate) fn split_for_impl(
&self,
) -> (
CombinedImplGenerics<'_>,
CombinedTypeGenerics<'_>,
// A stub type so `split_for_impl` signature matches that of `syn`'s.
impl Sized,
) {
(CombinedImplGenerics(self), CombinedTypeGenerics(self), ())
}
}
impl ToTokens for CombinedGenerics<'_> {
fn to_tokens(&self, tokens: &mut TokenStream) {
// Most of the time we are only adding lifetimes, so we prefer to place
// the user provided generics last.
self.0
.last()
.and_then(|x| x.lt_token)
.unwrap_or_default()
.to_tokens(tokens);
let comma: Token![,] = Default::default();
// Output lifetimes first.
for generics in self.0.iter() {
for param in generics.params.pairs() {
if let GenericParam::Lifetime(lt) = param.value() {
lt.to_tokens(tokens);
param.punct().unwrap_or(&&comma).to_tokens(tokens);
}
}
}
for generics in self.0.iter() {
for param in generics.params.pairs() {
if let GenericParam::Lifetime(_) = param.value() {
continue;
};
param.value().to_tokens(tokens);
param.punct().unwrap_or(&&comma).to_tokens(tokens);
}
}
self.0
.last()
.and_then(|x| x.gt_token)
.unwrap_or_default()
.to_tokens(tokens);
}
}
impl ToTokens for CombinedImplGenerics<'_> {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.0
.0
.last()
.and_then(|x| x.lt_token)
.unwrap_or_default()
.to_tokens(tokens);
let comma: Token![,] = Default::default();
// Output lifetimes first.
for generics in self.0 .0.iter() {
for param in generics.params.pairs() {
if let GenericParam::Lifetime(lt) = param.value() {
lt.to_tokens(tokens);
param.punct().unwrap_or(&&comma).to_tokens(tokens);
}
}
}
for generics in self.0 .0.iter() {
for param in generics.params.pairs() {
// Leave out defaults.
match param.value() {
GenericParam::Lifetime(_) => continue,
GenericParam::Type(param) => {
param.ident.to_tokens(tokens);
if !param.bounds.is_empty() {
param
.colon_token
.unwrap_or_else(Default::default)
.to_tokens(tokens);
param.bounds.to_tokens(tokens);
}
}
GenericParam::Const(param) => {
param.const_token.to_tokens(tokens);
param.ident.to_tokens(tokens);
param.colon_token.to_tokens(tokens);
param.ty.to_tokens(tokens);
}
}
param.punct().unwrap_or(&&comma).to_tokens(tokens);
}
}
self.0
.0
.last()
.and_then(|x| x.gt_token)
.unwrap_or_default()
.to_tokens(tokens);
}
}
impl ToTokens for CombinedTypeGenerics<'_> {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.0
.0
.last()
.and_then(|x| x.lt_token)
.unwrap_or_default()
.to_tokens(tokens);
let comma: Token![,] = Default::default();
// Output lifetimes first.
for generics in self.0 .0.iter() {
for param in generics.params.pairs() {
if let GenericParam::Lifetime(lt) = param.value() {
// Leave out bounds
lt.lifetime.to_tokens(tokens);
param.punct().unwrap_or(&&comma).to_tokens(tokens);
}
}
}
for generics in self.0 .0.iter() {
for param in generics.params.pairs() {
// Leave out bounds and defaults.
match param.value() {
GenericParam::Lifetime(_) => continue,
GenericParam::Type(param) => {
param.ident.to_tokens(tokens);
}
GenericParam::Const(param) => {
param.ident.to_tokens(tokens);
}
}
param.punct().unwrap_or(&&comma).to_tokens(tokens);
}
}
self.0
.0
.last()
.and_then(|x| x.gt_token)
.unwrap_or_default()
.to_tokens(tokens);
}
}
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