use {
crate::member,
proc_macro2::{Span, TokenStream},
syn::{Data, DataStruct, DeriveInput, Fields, GenericParam, Ident, Lifetime, spanned::Spanned},
};
pub(crate) fn derive(input: DeriveInput) -> TokenStream {
use std::iter;
let Data::Struct(DataStruct { fields, .. }) = input.data else {
return quote::quote_spanned! { input.ident.span() =>
::std::compile_error!("the group type must be a struct");
};
};
let named = match &fields {
Fields::Named(_) => true,
Fields::Unnamed(_) => false,
Fields::Unit => {
return quote::quote_spanned! { input.ident.span() =>
::std::compile_error!("the group type cannot be a unit struct");
};
}
};
let mut lts = Vec::with_capacity(input.generics.params.len());
for param in input.generics.params {
let GenericParam::Lifetime(param) = param else {
return quote::quote_spanned! { param.span() =>
::std::compile_error!("the group struct cannot have non-lifetime generic parameters");
};
};
if !param.attrs.is_empty() {
return quote::quote_spanned! { param.span() =>
::std::compile_error!("the lifetime cannot have any attributes");
};
}
if !param.bounds.is_empty() {
return quote::quote_spanned! { param.span() =>
::std::compile_error!("the lifetime cannot have any bounds");
};
}
lts.push(param.lifetime);
}
if fields.is_empty() {
return quote::quote_spanned! { fields.span() =>
::std::compile_error!("the group struct must have some fields");
};
}
let static_lt = Lifetime {
apostrophe: Span::call_site(),
ident: Ident::new("static", Span::call_site()),
};
let static_lts = lts.iter().map(|_| &static_lt);
let anon_lt = Lifetime {
apostrophe: Span::call_site(),
ident: Ident::new("_", Span::call_site()),
};
let anon_lts = lts
.iter()
.map(|lt| if lt.ident == "static" { lt } else { &anon_lt });
let name = input.ident;
let projection_name = quote::format_ident!("{name}Proj");
let group_types = fields.iter().map(|field| {
let ty = &field.ty;
quote::quote! { <#ty as dunge::group::MemberProjection>::MEMBER }
});
let n_members = fields.len();
let group_visit_members = iter::zip(0.., &fields).map(|(index, field)| {
let ident = member::make(index, field.ident.clone());
quote::quote! { dunge::set::Visit::visit(&self.#ident, visitor) }
});
let group_fields = iter::zip(0.., &fields).map(|(index, field)| {
let vis = &field.vis;
let ident = member::make(index, field.ident.clone());
let ty = &field.ty;
if named {
quote::quote! { #vis #ident: <#ty as dunge::group::MemberProjection>::Field }
} else {
quote::quote! { #vis <#ty as dunge::group::MemberProjection>::Field }
}
});
let group_member_projections = iter::zip(0.., &fields).map(|(index, field)| {
let ident = member::make(index, field.ident.clone());
let ty = &field.ty;
quote::quote! { #ident: <#ty as dunge::group::MemberProjection>::member_projection(id, #index, out.clone()) }
});
let projection = if named {
quote::quote! {
pub struct #projection_name<#(#lts),*> {
#(#group_fields),*,
}
}
} else {
quote::quote! {
pub struct #projection_name<#(#lts),*>(
#(#group_fields),*,
);
}
};
quote::quote! {
impl<#(#lts),*> dunge::Group for #name<#(#lts),*> {
type Projection = #projection_name<#(#static_lts),*>;
const DEF: dunge::sl::Define<dunge::types::MemberData> = dunge::sl::Define::new(&[
#(#group_types),*,
]);
}
impl dunge::set::Visit for #name<#(#anon_lts),*> {
const N_MEMBERS: ::core::primitive::usize = #n_members;
fn visit<'visit>(&'visit self, visitor: &mut dunge::set::Visitor<'visit>) {
#(#group_visit_members);*;
}
}
#projection
impl<#(#lts),*> dunge::group::Projection for #projection_name<#(#lts),*> {
fn projection(id: ::core::primitive::u32, out: dunge::sl::GlobalOut) -> Self {
Self {
#(#group_member_projections),*,
}
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn derive_group() {
let input = quote::quote! {
struct Map<'tx> {
pub tex: BoundTexture,
pub sam: &'tx Sampler,
}
};
let input = syn::parse2(input).expect("parse input");
let actual = derive(input);
let expected = quote::quote! {
impl<'tx> dunge::Group for Map<'tx> {
type Projection = MapProj<'static>;
const DEF: dunge::sl::Define<dunge::types::MemberData> = dunge::sl::Define::new(&[
<BoundTexture as dunge::group::MemberProjection>::MEMBER,
<&'tx Sampler as dunge::group::MemberProjection>::MEMBER,
]);
}
impl dunge::set::Visit for Map<'_> {
const N_MEMBERS: ::core::primitive::usize = 2usize;
fn visit<'visit>(&'visit self, visitor: &mut dunge::set::Visitor<'visit>) {
dunge::set::Visit::visit(&self.tex, visitor);
dunge::set::Visit::visit(&self.sam, visitor);
}
}
pub struct MapProj<'tx> {
pub tex: <BoundTexture as dunge::group::MemberProjection>::Field,
pub sam: <&'tx Sampler as dunge::group::MemberProjection>::Field,
}
impl<'tx> dunge::group::Projection for MapProj<'tx> {
fn projection(id: ::core::primitive::u32, out: dunge::sl::GlobalOut) -> Self {
Self {
tex: <BoundTexture as dunge::group::MemberProjection>::member_projection(id, 0u32, out.clone()),
sam: <&'tx Sampler as dunge::group::MemberProjection>::member_projection(id, 1u32, out.clone()),
}
}
}
};
helpers::eq_lines(&actual.to_string(), &expected.to_string());
}
#[test]
fn derive_tuple_group() {
let input = quote::quote! {
struct Map<'tx>(BoundTexture, &'tx Sampler);
};
let input = syn::parse2(input).expect("parse input");
let actual = derive(input);
let expected = quote::quote! {
impl<'tx> dunge::Group for Map<'tx> {
type Projection = MapProj<'static>;
const DEF: dunge::sl::Define<dunge::types::MemberData> = dunge::sl::Define::new(&[
<BoundTexture as dunge::group::MemberProjection>::MEMBER,
<&'tx Sampler as dunge::group::MemberProjection>::MEMBER,
]);
}
impl dunge::set::Visit for Map<'_> {
const N_MEMBERS: ::core::primitive::usize = 2usize;
fn visit<'visit>(&'visit self, visitor: &mut dunge::set::Visitor<'visit>) {
dunge::set::Visit::visit(&self.0, visitor);
dunge::set::Visit::visit(&self.1, visitor);
}
}
pub struct MapProj<'tx>(
<BoundTexture as dunge::group::MemberProjection>::Field,
<&'tx Sampler as dunge::group::MemberProjection>::Field,
);
impl<'tx> dunge::group::Projection for MapProj<'tx> {
fn projection(id: ::core::primitive::u32, out: dunge::sl::GlobalOut) -> Self {
Self {
0: <BoundTexture as dunge::group::MemberProjection>::member_projection(id, 0u32, out.clone()),
1: <&'tx Sampler as dunge::group::MemberProjection>::member_projection(id, 1u32, out.clone()),
}
}
}
};
helpers::eq_lines(&actual.to_string(), &expected.to_string());
}
}