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extern crate proc_macro;
extern crate proc_macro2;
#[macro_use]
extern crate quote;
extern crate syn;
#[proc_macro_derive(Enumoid)]
pub fn derive_enumoid(
input: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
let input: syn::DeriveInput = syn::parse(input).unwrap();
let output = if let syn::Data::Enum(data_enum) = input.data {
let name = input.ident;
let elem_count = data_enum.variants.len();
let flag_bytes = (elem_count + 7) / 8;
let sz_type = match elem_count {
0..=0xff => quote! { u8 },
0x100..=0xffff => quote! { u16 },
0x10000..=0xffffffff => quote! { u32 },
_ => quote! { usize },
};
let variant_names: Vec<&proc_macro2::Ident> =
data_enum.variants.iter().map(|x| &x.ident).collect();
let indices: Vec<_> = (0..elem_count).collect();
quote! {
impl enumoid::Enumoid for #name {
type CompactSize = #sz_type;
const SIZE: usize = #elem_count;
#[inline]
fn into_usize(value: Self) -> usize {
match value {
#(
#name::#variant_names => #indices,
)*
}
}
#[inline]
fn from_usize(value: usize) -> Self {
match value {
#(
#indices => #name::#variant_names,
)*
_ => unreachable!()
}
}
#[inline(always)]
fn uncompact_size(sz: Self::CompactSize) -> usize
{
sz as usize
}
#[inline(always)]
fn compact_size(sz: usize) -> Self::CompactSize
{
sz as Self::CompactSize
}
}
impl enumoid::base::EnumFlagsHelper for #name {
type FlagsArray = [u8; #flag_bytes];
#[inline(always)]
fn slice_flags(arr: &Self::FlagsArray) -> &[u8] { arr }
#[inline(always)]
fn slice_flags_mut(arr: &mut Self::FlagsArray) -> &mut [u8] { arr }
}
impl<V> enumoid::base::EnumArrayHelper<V> for #name {
type PartialArray = [std::mem::MaybeUninit<V>; #elem_count];
type TotalArray = [V; #elem_count];
#[inline(always)]
fn partial_slice(p: &Self::PartialArray)
-> &[std::mem::MaybeUninit<V>] { p }
#[inline(always)]
fn partial_slice_mut(p: &mut Self::PartialArray)
-> &mut [std::mem::MaybeUninit<V>] { p }
#[inline]
unsafe fn partial_to_total(p: Self::PartialArray)
-> Self::TotalArray {
enumoid::base::unconstrained_transmute::<_, Self::TotalArray>(p) }
#[inline(always)]
fn total_slice(t: &Self::TotalArray) -> &[V] { t }
#[inline(always)]
fn total_slice_mut(t: &mut Self::TotalArray) -> &mut [V] { t }
#[inline]
fn total_to_partial(t: Self::TotalArray)
-> Self::PartialArray {
unsafe {
enumoid::base::unconstrained_transmute::<_, Self::PartialArray>(
t)
}
}
}
}
} else {
quote!(compile_error! {"#[derive(Enumoid)] can only be applied to enums"})
};
output.into()
}