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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106// SPDX-License-Identifier: GPL-2.0
use std::{ collections::HashSet, iter::Extend, //};
use proc_macro2::{ Ident, TokenStream, //};use quote::ToTokens;use syn::{ parse_quote, Error, ImplItem, Item, ItemImpl, ItemTrait, Result, TraitItem, //};
fn handle_trait(mut item: ItemTrait) -> Result<ItemTrait> { let mut gen_items = Vec::new();
gen_items.push(parse_quote! { /// A marker to prevent implementors from forgetting to use [`#[vtable]`](vtable) /// attribute when implementing this trait. const USE_VTABLE_ATTR: (); });
for item in &item.items { if let TraitItem::Fn(fn_item) = item { let name = &fn_item.sig.ident; let gen_const_name = Ident::new( &format!("HAS_{}", name.to_string().to_uppercase()), name.span(), );
// We don't know on the implementation-site whether a method is required or provided // so we have to generate a const for all methods. let cfg_attrs = crate::helpers::gather_cfg_attrs(&fn_item.attrs); let comment = format!("Indicates if the `{name}` method is overridden by the implementor."); gen_items.push(parse_quote! { #(#cfg_attrs)* #[doc = #comment] const #gen_const_name: bool = false; }); } }
item.items.extend(gen_items); Ok(item)}
fn handle_impl(mut item: ItemImpl) -> Result<ItemImpl> { let mut gen_items = Vec::new(); let mut defined_consts = HashSet::new();
// Iterate over all user-defined constants to gather any possible explicit overrides. for item in &item.items { if let ImplItem::Const(const_item) = item { defined_consts.insert(const_item.ident.clone()); } }
gen_items.push(parse_quote! { const USE_VTABLE_ATTR: () = (); });
for item in &item.items { if let ImplItem::Fn(fn_item) = item { let name = &fn_item.sig.ident; let gen_const_name = Ident::new( &format!("HAS_{}", name.to_string().to_uppercase()), name.span(), ); // Skip if it's declared already -- this allows user override. if defined_consts.contains(&gen_const_name) { continue; } let cfg_attrs = crate::helpers::gather_cfg_attrs(&fn_item.attrs); gen_items.push(parse_quote! { #(#cfg_attrs)* const #gen_const_name: bool = true; }); } }
item.items.extend(gen_items); Ok(item)}
pub(crate) fn vtable(input: Item) -> Result<TokenStream> { match input { Item::Trait(item) => Ok(handle_trait(item)?.into_token_stream()), Item::Impl(item) => Ok(handle_impl(item)?.into_token_stream()), _ => Err(Error::new_spanned( input, "`#[vtable]` attribute should only be applied to trait or impl block", ))?, }}