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use proc_macro::TokenStream;
use quote::{quote, ToTokens};
use syn::spanned::Spanned;
use syn::{parse, Ident, Item, ItemEnum, ItemStruct, ItemUnion};
#[proc_macro_derive(Component)]
pub fn component_derive(input: TokenStream) -> TokenStream
{
let item: TypeItem = parse::<Item>(input).unwrap().try_into().unwrap();
let item_ident = item.ident();
quote! {
impl ecs::component::Component for #item_ident
{
fn as_any_mut(&mut self) -> &mut dyn std::any::Any
{
self
}
fn as_any(&self) -> &dyn std::any::Any
{
self
}
}
impl ecs::system::Input for #item_ident {}
}
.into()
}
enum TypeItem
{
Struct(ItemStruct),
Enum(ItemEnum),
Union(ItemUnion),
}
impl TypeItem
{
fn ident(&self) -> &Ident
{
match self {
Self::Struct(struct_item) => &struct_item.ident,
Self::Enum(enum_item) => &enum_item.ident,
Self::Union(union_item) => &union_item.ident,
}
}
}
impl TryFrom<Item> for TypeItem
{
type Error = syn::Error;
fn try_from(item: Item) -> Result<Self, Self::Error>
{
match item {
Item::Struct(struct_item) => Ok(Self::Struct(struct_item)),
Item::Enum(enum_item) => Ok(Self::Enum(enum_item)),
Item::Union(union_item) => Ok(Self::Union(union_item)),
_ => Err(syn::Error::new(
item.span(),
"Expected a struct, a enum or a union",
)),
}
}
}
impl ToTokens for TypeItem
{
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream)
{
match self {
Self::Struct(struct_item) => struct_item.to_tokens(tokens),
Self::Enum(enum_item) => enum_item.to_tokens(tokens),
Self::Union(union_item) => union_item.to_tokens(tokens),
}
}
}
|
