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// Copyright 2024, Linaro Limited
// Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
// SPDX-License-Identifier: GPL-2.0-or-later
use proc_macro::TokenStream;
use quote::quote;
use syn::{
parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spanned, token::Comma, Data,
DeriveInput, Field, Fields, Ident, Meta, Path, Token, Type, Variant, Visibility,
};
mod utils;
use utils::MacroError;
fn get_fields<'a>(
input: &'a DeriveInput,
msg: &str,
) -> Result<&'a Punctuated<Field, Comma>, MacroError> {
if let Data::Struct(s) = &input.data {
if let Fields::Named(fs) = &s.fields {
Ok(&fs.named)
} else {
Err(MacroError::Message(
format!("Named fields required for {}", msg),
input.ident.span(),
))
}
} else {
Err(MacroError::Message(
format!("Struct required for {}", msg),
input.ident.span(),
))
}
}
fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError> {
let expected = parse_quote! { #[repr(C)] };
if input.attrs.iter().any(|attr| attr == &expected) {
Ok(())
} else {
Err(MacroError::Message(
format!("#[repr(C)] required for {}", msg),
input.ident.span(),
))
}
}
fn derive_object_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> {
is_c_repr(&input, "#[derive(Object)]")?;
let name = &input.ident;
let parent = &get_fields(&input, "#[derive(Object)]")?[0].ident;
Ok(quote! {
::qemu_api::assert_field_type!(#name, #parent,
::qemu_api::qom::ParentField<<#name as ::qemu_api::qom::ObjectImpl>::ParentType>);
::qemu_api::module_init! {
MODULE_INIT_QOM => unsafe {
::qemu_api::bindings::type_register_static(&<#name as ::qemu_api::qom::ObjectImpl>::TYPE_INFO);
}
}
})
}
#[proc_macro_derive(Object)]
pub fn derive_object(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let expanded = derive_object_or_error(input).unwrap_or_else(Into::into);
TokenStream::from(expanded)
}
#[rustfmt::skip::macros(quote)]
fn derive_offsets_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> {
is_c_repr(&input, "#[derive(offsets)]")?;
let name = &input.ident;
let fields = get_fields(&input, "#[derive(offsets)]")?;
let field_names: Vec<&Ident> = fields.iter().map(|f| f.ident.as_ref().unwrap()).collect();
let field_types: Vec<&Type> = fields.iter().map(|f| &f.ty).collect();
let field_vis: Vec<&Visibility> = fields.iter().map(|f| &f.vis).collect();
Ok(quote! {
::qemu_api::with_offsets! {
struct #name {
#(#field_vis #field_names: #field_types,)*
}
}
})
}
#[proc_macro_derive(offsets)]
pub fn derive_offsets(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let expanded = derive_offsets_or_error(input).unwrap_or_else(Into::into);
TokenStream::from(expanded)
}
#[allow(non_snake_case)]
fn get_repr_uN(input: &DeriveInput, msg: &str) -> Result<Path, MacroError> {
let repr = input.attrs.iter().find(|attr| attr.path().is_ident("repr"));
if let Some(repr) = repr {
let nested = repr.parse_args_with(Punctuated::<Meta, Token![,]>::parse_terminated)?;
for meta in nested {
match meta {
Meta::Path(path) if path.is_ident("u8") => return Ok(path),
Meta::Path(path) if path.is_ident("u16") => return Ok(path),
Meta::Path(path) if path.is_ident("u32") => return Ok(path),
Meta::Path(path) if path.is_ident("u64") => return Ok(path),
_ => {}
}
}
}
Err(MacroError::Message(
format!("#[repr(u8/u16/u32/u64) required for {}", msg),
input.ident.span(),
))
}
fn get_variants(input: &DeriveInput) -> Result<&Punctuated<Variant, Comma>, MacroError> {
if let Data::Enum(e) = &input.data {
if let Some(v) = e.variants.iter().find(|v| v.fields != Fields::Unit) {
return Err(MacroError::Message(
"Cannot derive TryInto for enum with non-unit variants.".to_string(),
v.fields.span(),
));
}
Ok(&e.variants)
} else {
Err(MacroError::Message(
"Cannot derive TryInto for union or struct.".to_string(),
input.ident.span(),
))
}
}
#[rustfmt::skip::macros(quote)]
fn derive_tryinto_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> {
let repr = get_repr_uN(&input, "#[derive(TryInto)]")?;
let name = &input.ident;
let variants = get_variants(&input)?;
let discriminants: Vec<&Ident> = variants.iter().map(|f| &f.ident).collect();
Ok(quote! {
impl core::convert::TryFrom<#repr> for #name {
type Error = #repr;
fn try_from(value: #repr) -> Result<Self, Self::Error> {
#(const #discriminants: #repr = #name::#discriminants as #repr;)*;
match value {
#(#discriminants => Ok(Self::#discriminants),)*
_ => Err(value),
}
}
}
})
}
#[proc_macro_derive(TryInto)]
pub fn derive_tryinto(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let expanded = derive_tryinto_or_error(input).unwrap_or_else(Into::into);
TokenStream::from(expanded)
}
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