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use proc_macro2::{Literal, Punct, Spacing, Span, TokenStream};
use quote::{quote, ToTokens, TokenStreamExt};
use syn::{spanned::Spanned, Error, Lit, LitInt, Meta, NestedMeta};
#[derive(Clone, Copy)]
pub enum IntRepr {
I8,
I16,
I32,
I64,
I128,
U8,
U16,
U32,
U64,
U128,
}
impl ToTokens for IntRepr {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
Self::I8 => tokens.append_all(quote! { i8 }),
Self::I16 => tokens.append_all(quote! { i16 }),
Self::I32 => tokens.append_all(quote! { i32 }),
Self::I64 => tokens.append_all(quote! { i64 }),
Self::I128 => tokens.append_all(quote! { i128 }),
Self::U8 => tokens.append_all(quote! { u8 }),
Self::U16 => tokens.append_all(quote! { u16 }),
Self::U32 => tokens.append_all(quote! { u32 }),
Self::U64 => tokens.append_all(quote! { u64 }),
Self::U128 => tokens.append_all(quote! { u128 }),
}
}
}
impl IntRepr {
#[inline]
#[cfg(not(feature = "arbitrary_enum_discriminant"))]
pub fn enum_discriminant(&self, _: usize) -> Option<EnumDiscriminant> {
None
}
#[inline]
#[cfg(feature = "arbitrary_enum_discriminant")]
pub fn enum_discriminant(&self, index: usize) -> EnumDiscriminant {
#[cfg(not(any(
all(target_endian = "little", feature = "archive_be"),
all(target_endian = "big", feature = "archive_le"),
)))]
let value = index as u128;
#[cfg(any(
all(target_endian = "little", feature = "archive_be"),
all(target_endian = "big", feature = "archive_le"),
))]
let value = match self {
Self::I8 => (index as i8).swap_bytes() as u128,
Self::I16 => (index as i16).swap_bytes() as u128,
Self::I32 => (index as i32).swap_bytes() as u128,
Self::I64 => (index as i64).swap_bytes() as u128,
Self::I128 => (index as i128).swap_bytes() as u128,
Self::U8 => (index as u8).swap_bytes() as u128,
Self::U16 => (index as u16).swap_bytes() as u128,
Self::U32 => (index as u32).swap_bytes() as u128,
Self::U64 => (index as u64).swap_bytes() as u128,
Self::U128 => (index as u128).swap_bytes(),
};
EnumDiscriminant { repr: *self, value }
}
}
#[allow(dead_code)]
pub struct EnumDiscriminant {
repr: IntRepr,
value: u128,
}
impl ToTokens for EnumDiscriminant {
fn to_tokens(&self, tokens: &mut TokenStream) {
tokens.append(Punct::new('=', Spacing::Alone));
tokens.append(match self.repr {
IntRepr::I8 => Literal::i8_suffixed(self.value as i8),
IntRepr::I16 => Literal::i16_suffixed(self.value as i16),
IntRepr::I32 => Literal::i32_suffixed(self.value as i32),
IntRepr::I64 => Literal::i64_suffixed(self.value as i64),
IntRepr::I128 => Literal::i128_suffixed(self.value as i128),
IntRepr::U8 => Literal::u8_suffixed(self.value as u8),
IntRepr::U16 => Literal::u16_suffixed(self.value as u16),
IntRepr::U32 => Literal::u32_suffixed(self.value as u32),
IntRepr::U64 => Literal::u64_suffixed(self.value as u64),
IntRepr::U128 => Literal::u128_suffixed(self.value),
});
}
}
#[derive(Clone, Copy)]
pub enum BaseRepr {
C,
Transparent,
Int(IntRepr),
}
impl ToTokens for BaseRepr {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
BaseRepr::C => tokens.append_all(quote! { C }),
BaseRepr::Transparent => tokens.append_all(quote! { transparent }),
BaseRepr::Int(int_repr) => tokens.append_all(quote! { #int_repr }),
}
}
}
#[derive(Clone)]
pub enum Modifier {
Packed,
Align(LitInt),
}
impl ToTokens for Modifier {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
Modifier::Packed => tokens.append_all(quote! { packed }),
Modifier::Align(n) => tokens.append_all(quote! { align(#n) }),
}
}
}
#[derive(Clone, Default)]
pub struct Repr {
pub base_repr: Option<(BaseRepr, Span)>,
pub modifier: Option<(Modifier, Span)>,
}
impl Repr {
fn try_set_modifier<S: ToTokens>(
&mut self,
modifier: Modifier,
spanned: S,
) -> Result<(), Error> {
if self.modifier.is_some() {
Err(Error::new_spanned(
spanned,
"only one repr modifier may be specified",
))
} else {
self.modifier = Some((modifier, spanned.span()));
Ok(())
}
}
fn try_set_base_repr<S: ToTokens>(&mut self, repr: BaseRepr, spanned: S) -> Result<(), Error> {
if self.base_repr.is_some() {
Err(Error::new_spanned(
spanned,
"only one repr may be specified",
))
} else {
self.base_repr = Some((repr, spanned.span()));
Ok(())
}
}
pub fn parse_args<'a>(
&mut self,
args: impl Iterator<Item = &'a NestedMeta>,
) -> Result<(), Error> {
for arg in args {
if let NestedMeta::Meta(meta) = arg {
match meta {
Meta::Path(path) => {
if path.is_ident("packed") {
self.try_set_modifier(Modifier::Packed, path)?;
} else {
let parsed_repr = if path.is_ident("transparent") {
BaseRepr::Transparent
} else if path.is_ident("C") {
BaseRepr::C
} else if path.is_ident("i8") {
BaseRepr::Int(IntRepr::I8)
} else if path.is_ident("i16") {
BaseRepr::Int(IntRepr::I16)
} else if path.is_ident("i32") {
BaseRepr::Int(IntRepr::I32)
} else if path.is_ident("i64") {
BaseRepr::Int(IntRepr::I64)
} else if path.is_ident("i128") {
BaseRepr::Int(IntRepr::I128)
} else if path.is_ident("u8") {
BaseRepr::Int(IntRepr::U8)
} else if path.is_ident("u16") {
BaseRepr::Int(IntRepr::U16)
} else if path.is_ident("u32") {
BaseRepr::Int(IntRepr::U32)
} else if path.is_ident("u64") {
BaseRepr::Int(IntRepr::U64)
} else if path.is_ident("u128") {
BaseRepr::Int(IntRepr::U128)
} else {
return Err(Error::new_spanned(
path,
"invalid repr, available reprs are transparent, C, i* and u*",
));
};
self.try_set_base_repr(parsed_repr, path)?;
}
}
Meta::List(list) => {
if list.path.is_ident("align") {
if list.nested.len() != 1 {
return Err(Error::new_spanned(list, "missing arguments to align"));
} else if let Some(NestedMeta::Lit(Lit::Int(alignment))) =
list.nested.first()
{
self.try_set_modifier(
Modifier::Align(alignment.clone()),
alignment,
)?;
}
}
}
_ => return Err(Error::new_spanned(meta, "invalid repr argument")),
}
} else {
return Err(Error::new_spanned(arg, "invalid repr argument"));
}
}
Ok(())
}
}
impl ToTokens for Repr {
fn to_tokens(&self, tokens: &mut TokenStream) {
let base_repr = self.base_repr.as_ref().map(|(b, _)| b);
let base_repr_iter = base_repr.iter();
let modifier = self.modifier.as_ref().map(|(m, _)| m);
let modifier_iter = modifier.iter();
tokens.append_all(quote! { #[repr(#(#base_repr_iter,)* #(#modifier_iter,)*)] });
}
}
