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|
#![deny(clippy::all, clippy::pedantic)]
use proc_macro::TokenStream;
use quote::{ToTokens, format_ident, quote};
use syn::punctuated::Punctuated;
use syn::{
Item,
LitStr,
Path as SynPath,
PredicateType,
Token,
TraitBound,
TypeParamBound,
WhereClause,
WherePredicate,
parse,
};
macro_rules! syn_path {
($first_segment: ident $(::$segment: ident)*) => {
::syn::Path {
leading_colon: None,
segments: ::syn::punctuated::Punctuated::from_iter([
syn_path_segment!($first_segment),
$(syn_path_segment!($segment),)*
])
}
};
}
macro_rules! syn_path_segment {
($segment: ident) => {
::syn::PathSegment {
ident: ::proc_macro2::Ident::new(
stringify!($segment),
::proc_macro2::Span::call_site(),
),
arguments: ::syn::PathArguments::None,
}
};
}
#[proc_macro_derive(Reflection)]
pub fn reflection_derive(input: TokenStream) -> TokenStream
{
let input = parse::<Item>(input).unwrap();
let input = match input {
Item::Struct(input) => input,
Item::Enum(_) => unimplemented!(),
_ => panic!("Invalid input"),
};
let engine_crate_path = find_engine_crate_path().unwrap();
let input_ident = input.ident;
let (impl_generics, type_generics, where_clause) = input.generics.split_for_impl();
let mut where_clause = where_clause.cloned().unwrap_or_else(|| WhereClause {
where_token: <Token![where]>::default(),
predicates: Punctuated::new(),
});
where_clause
.predicates
.extend(input.fields.iter().map(|field| {
WherePredicate::Type(PredicateType {
lifetimes: None,
bounded_ty: field.ty.clone(),
colon_token: <Token![:]>::default(),
bounds: [TypeParamBound::Trait(TraitBound {
paren_token: None,
modifier: syn::TraitBoundModifier::None,
lifetimes: None,
path: engine_crate_path.join(syn_path!(reflection::With)),
})]
.into_iter()
.collect(),
})
}));
let fields = input.fields.into_iter().enumerate().map(|(index, field)| {
let field_ident = field.ident.unwrap_or_else(|| format_ident!("{index}"));
let field_type = &field.ty;
let field_name = LitStr::new(&field_ident.to_string(), field_ident.span());
// since std::any::type_name as const is not stable yet
let field_type_name = field_type.to_token_stream().to_string();
quote! {
#engine_crate_path::reflection::StructField {
name: #field_name,
index: #index,
layout: std::alloc::Layout::new::<#field_type>(),
byte_offset: std::mem::offset_of!(Self, #field_ident),
type_id: std::any::TypeId::of::<#field_type>(),
type_name: #field_type_name,
reflection:
#engine_crate_path::reflection::__private::get_type_reflection::<
#field_type
>()
}
}
});
quote! {
impl #impl_generics #engine_crate_path::reflection::With for
#input_ident #type_generics #where_clause
{
const REFLECTION: &#engine_crate_path::reflection::Reflection =
&const {
#engine_crate_path::reflection::Reflection::Struct(
#engine_crate_path::reflection::Struct {
fields: &[
#(#fields),*
]
}
)
};
fn reflection() -> &'static #engine_crate_path::reflection::Reflection
{
Self::REFLECTION
}
fn get_reflection(&self) -> &'static #engine_crate_path::reflection::Reflection
{
Self::reflection()
}
}
}
.into()
}
fn find_engine_crate_path() -> Option<SynPath>
{
let cargo_crate_name = std::env::var("CARGO_CRATE_NAME").ok()?;
let cargo_pkg_name = std::env::var("CARGO_PKG_NAME").ok()?;
if cargo_pkg_name == "engine" && cargo_crate_name != "engine" {
// Macro is used by a crate example/test/benchmark
return Some(syn_path!(engine));
}
if cargo_crate_name == "engine" {
return Some(syn_path!(crate));
}
Some(syn_path!(engine))
}
trait SynPathExt
{
fn join(&self, other: Self) -> Self;
}
impl SynPathExt for SynPath
{
fn join(&self, other: Self) -> Self
{
Self {
leading_colon: self.leading_colon.clone(),
segments: self
.segments
.iter()
.chain(&other.segments)
.cloned()
.collect(),
}
}
}
|
