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 instance 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 instance 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 instance 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 instance 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 instance_types = fields.iter().map(|field| {
let ty = &field.ty;
quote::quote! { <#ty as dunge::instance::MemberProjection>::TYPE }
});
let instance_set_members = iter::zip(0.., &fields).map(|(index, field)| {
let ident = member::make(index, field.ident.clone());
quote::quote! { dunge::instance::SetMember::set_member(&self.#ident, setter) }
});
let instance_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::instance::MemberProjection>::Field }
} else {
quote::quote! { #vis <#ty as dunge::instance::MemberProjection>::Field }
}
});
let instance_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::instance::MemberProjection>::member_projection(id + #index) }
});
let projection = if named {
quote::quote! {
pub struct #projection_name<#(#lts),*> {
#(#instance_fields),*,
}
}
} else {
quote::quote! {
pub struct #projection_name<#(#lts),*>(
#(#instance_fields),*,
);
}
};
quote::quote! {
impl<#(#lts),*> dunge::Instance for #name<#(#lts),*> {
type Projection = #projection_name<#(#static_lts),*>;
const DEF: dunge::sl::Define<dunge::types::ValueType> = dunge::sl::Define::new(&[
#(#instance_types),*,
]);
}
impl dunge::instance::Set for #name<#(#anon_lts),*> {
fn set(&self, setter: &mut dunge::instance::Setter<'_, '_>) {
#(#instance_set_members);*;
}
}
#projection
impl<#(#lts),*> dunge::instance::Projection for #projection_name<#(#lts),*> {
fn projection(id: ::core::primitive::u32) -> Self {
Self {
#(#instance_member_projections),*,
}
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn derive_instance() {
let input = quote::quote! {
struct Transform<'slice> {
pub pos: Row<[f32; 2]>,
pub col: RowSlice<'slice, [f32; 3]>,
}
};
let input = syn::parse2(input).expect("parse input");
let actual = derive(input);
let expected = quote::quote! {
impl<'slice> dunge::Instance for Transform<'slice> {
type Projection = TransformProj<'static>;
const DEF: dunge::sl::Define<dunge::types::ValueType> = dunge::sl::Define::new(&[
<Row<[f32; 2]> as dunge::instance::MemberProjection>::TYPE,
<RowSlice<'slice, [f32; 3]> as dunge::instance::MemberProjection>::TYPE,
]);
}
impl dunge::instance::Set for Transform<'_> {
fn set(&self, setter: &mut dunge::instance::Setter<'_, '_>) {
dunge::instance::SetMember::set_member(&self.pos, setter);
dunge::instance::SetMember::set_member(&self.col, setter);
}
}
pub struct TransformProj<'slice> {
pub pos: <Row<[f32; 2]> as dunge::instance::MemberProjection>::Field,
pub col: <RowSlice<'slice, [f32; 3]> as dunge::instance::MemberProjection>::Field,
}
impl<'slice> dunge::instance::Projection for TransformProj<'slice> {
fn projection(id: ::core::primitive::u32) -> Self {
Self {
pos: <Row<[f32; 2]> as dunge::instance::MemberProjection>::member_projection(id + 0u32),
col: <RowSlice<'slice, [f32; 3]> as dunge::instance::MemberProjection>::member_projection(id + 1u32),
}
}
}
};
helpers::eq_lines(&actual.to_string(), &expected.to_string());
}
#[test]
fn derive_tuple_instance() {
let input = quote::quote! {
struct Transform<'slice>(Row<[f32; 2]>, RowSlice<'slice, [f32; 3]>);
};
let input = syn::parse2(input).expect("parse input");
let actual = derive(input);
let expected = quote::quote! {
impl<'slice> dunge::Instance for Transform<'slice> {
type Projection = TransformProj<'static>;
const DEF: dunge::sl::Define<dunge::types::ValueType> = dunge::sl::Define::new(&[
<Row<[f32; 2]> as dunge::instance::MemberProjection>::TYPE,
<RowSlice<'slice, [f32; 3]> as dunge::instance::MemberProjection>::TYPE,
]);
}
impl dunge::instance::Set for Transform<'_> {
fn set(&self, setter: &mut dunge::instance::Setter<'_, '_>) {
dunge::instance::SetMember::set_member(&self.0, setter);
dunge::instance::SetMember::set_member(&self.1, setter);
}
}
pub struct TransformProj<'slice>(
<Row<[f32; 2]> as dunge::instance::MemberProjection>::Field,
<RowSlice<'slice, [f32; 3]> as dunge::instance::MemberProjection>::Field,
);
impl<'slice> dunge::instance::Projection for TransformProj<'slice> {
fn projection(id: ::core::primitive::u32) -> Self {
Self {
0: <Row<[f32; 2]> as dunge::instance::MemberProjection>::member_projection(id + 0u32),
1: <RowSlice<'slice, [f32; 3]> as dunge::instance::MemberProjection>::member_projection(id + 1u32),
}
}
}
};
helpers::eq_lines(&actual.to_string(), &expected.to_string());
}
}