// SPDX-License-Identifier: GPL-2.0use 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", ))?, }}
// 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",
))?,
}
}