struct_split_macro/lib.rs
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use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, DeriveInput, Ident, Data, Fields, Path};
use itertools::Itertools;
use proc_macro2::{Span};
use proc_macro2 as pm;
// =============
// === Utils ===
// =============
/// Get the current crate name;
fn crate_name() -> Ident {
let macro_lib = env!("CARGO_PKG_NAME");
let suffix = "-macro";
if !macro_lib.ends_with(suffix) { panic!("Internal error.") }
let crate_name = ¯o_lib[..macro_lib.len() - suffix.len()].replace('-',"_");
Ident::new(crate_name, Span::call_site())
}
/// Extract the module macro attribute.
fn extract_module_attr(input: &DeriveInput) -> Path {
let mut module: Option<Path> = None;
for attr in &input.attrs {
if attr.path().is_ident("module") {
let tokens = attr.meta.require_list().unwrap().tokens.clone();
if let Ok(path) = syn::parse2::<Path>(tokens) {
module = Some(path);
}
}
}
module.expect("The 'module' attribute is required.")
}
// =============
// === Macro ===
// =============
/// Derive impl. Comments in the code show expansion of the following example struct:
/// ```ignore
/// pub struct Ctx {
/// geometry: GeometryCtx,
/// material: MaterialCtx,
/// mesh: MeshCtx,
/// scene: SceneCtx,
/// }
/// ```
#[proc_macro_derive(Split, attributes(module))]
pub fn split_derive(input: TokenStream) -> TokenStream {
let lib = crate_name();
let input = parse_macro_input!(input as DeriveInput);
let module = extract_module_attr(&input);
let struct_ident = input.ident;
let ref_struct_ident = Ident::new(&format!("{struct_ident}Ref"), struct_ident.span());
let fields = if let Data::Struct(data) = &input.data {
if let Fields::Named(fields) = &data.fields {
fields.named.iter().collect::<Vec<_>>()
} else {
Vec::new()
}
} else {
Vec::new()
};
let field_idents = fields.iter().map(|f| f.ident.as_ref().unwrap()).collect_vec();
let field_types = fields.iter().map(|f| &f.ty).collect_vec();
let params = field_idents.iter().map(|i| Ident::new(&i.to_string(), i.span())).collect_vec();
let bounds_params_access = quote! { #(#params: #lib::Access,)* };
let field_values = field_types.iter().zip(params.iter()).map(|(field_ty, param)| {
quote! { #lib::Value<'_t, #param, #field_ty> }
}).collect_vec();
// Generates:
// #[repr(C)]
// pub struct CtxRef<'t, geometry, material, mesh, scene> {
// geometry: Value<'t, geometry, GeometryCtx>,
// material: Value<'t, material, MaterialCtx>,
// mesh: Value<'t, mesh, MeshCtx>,
// scene: Value<'t, scene, SceneCtx>,
// }
let ref_struct = quote! {
#[derive(Debug)]
#[repr(C)]
#[allow(non_camel_case_types)]
pub struct #ref_struct_ident<'_t, #(#params),*>
where #bounds_params_access {
#(pub #field_idents : #field_values),*
}
};
// Generates:
// impl<'t, geometry, material, mesh, scene>
// AsRefs<'t, CtxRef<'t, geometry, material, mesh, scene>> for Ctx
// where
// geometry: Access,
// material: Access,
// mesh: Access,
// scene: Access,
// GeometryCtx: RefCast<'t, Value<'t, geometry, GeometryCtx>>,
// MaterialCtx: RefCast<'t, Value<'t, material, MaterialCtx>>,
// MeshCtx: RefCast<'t, Value<'t, mesh, MeshCtx>>,
// SceneCtx: RefCast<'t, Value<'t, scene, SceneCtx>>,
// {
// fn as_refs_impl(&'t mut self) -> CtxRef<'t, geometry, material, mesh, scene> {
// CtxRef {
// geometry: RefCast::ref_cast(&mut self.geometry),
// material: RefCast::ref_cast(&mut self.material),
// mesh: RefCast::ref_cast(&mut self.mesh),
// scene: RefCast::ref_cast(&mut self.scene),
// }
// }
// }
let impl_as_refs = quote! {
#[allow(non_camel_case_types)]
impl<'_t, #(#params,)*>
#lib::AsRefs<'_t, #ref_struct_ident<'_t, #(#params,)*>> for #struct_ident
where #bounds_params_access #(#field_types: #lib::RefCast<'_t, #field_values>,)* {
fn as_refs_impl(& '_t mut self) -> #ref_struct_ident<'_t, #(#params,)*> {
#ref_struct_ident {
#(#field_idents: #lib::RefCast::ref_cast(&mut self.#field_idents),)*
}
}
}
};
// Generates:
// impl Ctx {
// pub fn as_ref_mut<'t>(&'t mut self) -> CtxRef<'t, RefMut, RefMut, RefMut, RefMut> {
// CtxRef {
// geometry: &mut self.geometry,
// material: &mut self.material,
// mesh: &mut self.mesh,
// scene: &mut self.scene,
// }
// }
// }
let impl_as_ref_mut = {
let ref_muts = params.iter().map(|_| quote!{#lib::RefMut}).collect_vec();
quote! {
#[allow(non_camel_case_types)]
impl #struct_ident {
pub fn as_ref_mut<'_t>(&'_t mut self) -> #ref_struct_ident<'_t, #(#ref_muts,)*> {
#ref_struct_ident {
#(#field_idents: &mut self.#field_idents,)*
}
}
}
}
};
// Generates:
// impl<'t, geometry_target, material_target, mesh_target, scene_target,
// geometry, material, mesh, scene>
// Split<CtxRef<'t, geometry_target, material_target, mesh_target, scene_target>>
// for CtxRef<'t, geometry, material, mesh, scene>
// where
// geometry: Access,
// material: Access,
// mesh: Access,
// scene: Access,
// geometry_target: Access,
// material_target: Access,
// mesh_target: Access,
// scene_target: Access,
// geometry: Acquire<geometry_target>,
// material: Acquire<material_target>,
// mesh: Acquire<mesh_target>,
// scene: Acquire<scene_target>,
// {
// type Rest = CtxRef<'t,
// Acquired<geometry, target_geometry>,
// Acquired<material, target_material>,
// Acquired<mesh, target_mesh>,
// Acquired<scene, target_scene>,
// >;
// }
let impl_split = {
let target_params = params.iter().map(|i| Ident::new(&format!("{i}_target"), i.span())).collect_vec();
let bounds_target_params_access = quote! { #(#target_params: #lib::Access,)* };
quote! {
#[allow(non_camel_case_types)]
impl<'_t, #(#params,)* #(#target_params,)*>
#lib::Split<#ref_struct_ident<'_t, #(#target_params,)*>> for #ref_struct_ident<'_t, #(#params,)*>
where
#bounds_params_access
#bounds_target_params_access
#(#params: #lib::Acquire<#target_params>,)*
{
type Rest = #ref_struct_ident<'_t, #(#lib::Acquired<#params, #target_params>,)*>;
}
}
};
// Generates:
// #[macro_export]
// macro_rules! _Ctx {
// ($lt:lifetime $ ($ts:tt) *) => {
// CtxImpl! { $lt [[None] [None] [None] [None]] [$($ts)*] }
// };
// ($($ts:tt)*) => {
// CtxImpl! { '_ [[None] [None] [None] [None]] [, $ ($ts) *] }
// };
// }
//
// #[macro_export]
// macro_rules! CtxImpl {
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [,* $($xs:tt)*]) => {
// CtxImpl! { $lt [[Ref] [Ref] [Ref] [Ref]] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, mut * $ ($xs:tt) *]) => {
// CtxImpl! { $lt [[RefMut] [RefMut] [RefMut] [RefMut]] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, geometry $ ($xs:tt) *]) => {
// CtxImpl! { $lt [[Ref] $t1 $t2 $t3] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, material $ ($xs:tt) *]) => {
// CtxImpl! { $lt [$t0 [Ref] $t2 $t3] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, mesh $ ($xs:tt) *]) => {
// CtxImpl! { $lt [$t0 $t1 [Ref] $t3] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, scene $ ($xs:tt) *]) => {
// CtxImpl! { $lt [$t0 $t1 $t2 [Ref]] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, mut geometry $ ($xs:tt) *]) => {
// CtxImpl! { $lt [[RefMut] $t1 $t2 $t3] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, mut material $ ($xs:tt) *]) => {
// CtxImpl! { $lt [$t0 [RefMut] $t2 $t3] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, mut mesh $ ($xs:tt) *]) => {
// CtxImpl! { $lt [$t0 $t1 [RefMut] $t3] [$ ($xs) *] }
// };
// ($lt:lifetime [$t0:tt $t1:tt $t2:tt $t3:tt] [, mut scene $ ($xs:tt) *]) => {
// CtxImpl! { $lt [$t0 $t1 $t2 [RefMut]] [$ ($xs) *] }
// };
// ($lt:lifetime [$ ([$ ($ts:tt) *]) *] [$ (,) *]) => {
// CtxRef < $lt, $ ($ ($ts) *), * >
// };
// }
// pub use _Ctx as Ctx;
let ref_macro = {
let q_none = quote! {[#lib::None]};
let q_ref = quote! {[#lib::Ref]};
let q_ref_mut = quote! {[#lib::RefMut]};
let all_none = field_idents.iter().map(|_| &q_none).collect_vec();
let all_ref = field_idents.iter().map(|_| &q_ref).collect_vec();
let all_ref_mut = field_idents.iter().map(|_| &q_ref_mut).collect_vec();
let ts_idents = field_idents.iter().enumerate().map(|(i, _)| Ident::new(&format!("t{i}"), Span::call_site())).collect_vec();
let ts = ts_idents.iter().map(|t| quote!($#t)).collect_vec();
let struct_ident2 = Ident::new(&format!("_{}", struct_ident), struct_ident.span());
let gen_patterns = |pattern: pm::TokenStream, access: &pm::TokenStream| {
field_idents.iter().enumerate().map(|(i, name)| {
let mut result = ts.iter().collect_vec();
result[i] = access;
quote! { (@ $lt:lifetime [#(#ts:tt)*] [, #pattern #name $($xs:tt)*]) => {
$crate::#struct_ident! {@ $lt [#(#result)*] [$($xs)*]} };
}
}).collect_vec()
};
let patterns_ref = gen_patterns(quote!{}, &q_ref);
let patterns_ref_mut = gen_patterns(quote!{mut}, &q_ref_mut);
quote! {
#[macro_export]
macro_rules! #struct_ident2 {
(@ $lt:lifetime [#(#ts:tt)*] [,* $($xs:tt)*]) => {
$crate::#struct_ident! {@ $lt [#(#all_ref)*] [$($xs)*]}
};
(@ $lt:lifetime [#(#ts:tt)*] [,mut * $($xs:tt)*]) => {
$crate::#struct_ident! {@ $lt [#(#all_ref_mut)*] [$($xs)*]}
};
#(#patterns_ref)*
#(#patterns_ref_mut)*
(@ $lt:lifetime [$([$($ts:tt)*])*] [$(,)*]) => { #module::#ref_struct_ident<$lt, $($($ts)*),*> };
(@ $($ts:tt)*) => { error };
($lt:lifetime $($ts:tt)*) => {
$crate::#struct_ident! {@ $lt [#(#all_none)*] [$($ts)*]}
};
($($ts:tt)*) => {
$crate::#struct_ident! {@ '_ [#(#all_none)*] [,$($ts)*]}
};
}
pub use #struct_ident2 as #struct_ident;
}
};
// Generates:
// impl<'t, geometry, material, mesh, scene>
// CtxRef<'t, geometry, material, mesh, scene>
// where geometry: Access, material: Access, mesh: Access, scene: Access {
// pub fn extract_geometry(&mut self)
// -> (&mut GeometryCtx, &mut <Self as Split<Ctx!['t, mut geometry]>>::Rest)
// where geometry: Acquire<RefMut> {
// let (a, b) = <Self as Split<Ctx! ['t, mut geometry]>>::split_impl(self);
// (a.geometry, b)
// }
// ...
// }
let impl_extract_fields = {
let fns = field_idents.iter().zip(field_types.iter()).map(|(field, ty)| {
let name = Ident::new(&format!("extract_{field}"), field.span());
quote! {
pub fn #name(&mut self) -> (&mut #ty, &mut <Self as #lib::Split<#struct_ident!['_t, mut #field]>>::Rest)
where #field: #lib::Acquire<#lib::RefMut> {
let (a, b) = <Self as #lib::Split<#struct_ident!['_t, mut #field]>>::split_impl(self);
(a.#field, b)
}
}
}).collect_vec();
quote! {
#[allow(non_camel_case_types)]
impl<'_t, #(#params,)*> #ref_struct_ident<'_t, #(#params,)*>
where #bounds_params_access {
#(#fns)*
}
}
};
let out = quote! {
#ref_struct
#impl_as_refs
#impl_as_ref_mut
#impl_split
#ref_macro
#impl_extract_fields
};
// println!(">>> {}", out);
TokenStream::from(out)
}