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use quote::quote;
use crate::reflection::visibility::generate as generate_visibility;
pub struct ReflectionFieldGenOptions<'a>
{
pub field_vis_override: Option<syn::Visibility>,
pub gen_get_byte_offset: &'a dyn Fn(&syn::Field) -> proc_macro2::TokenStream,
}
pub fn generate(
field: &syn::Field,
field_index: usize,
engine_crate_path: &syn::Path,
options: ReflectionFieldGenOptions<'_>,
) -> proc_macro2::TokenStream
{
let field_ident = &field.ident;
let field_type = &field.ty;
let field_name = if let Some(field_ident) = field_ident {
let field_name = syn::LitStr::new(&field_ident.to_string(), field_ident.span());
quote! { Some(#field_name) }
} else {
quote! { None }
};
let field_byte_offset = (options.gen_get_byte_offset)(field);
let field_vis = options.field_vis_override.as_ref().unwrap_or(&field.vis);
let field_reflection_vis = generate_visibility(field_vis, &engine_crate_path);
quote! {
#engine_crate_path::reflection::Field {
name: #field_name,
index: #field_index,
layout: std::alloc::Layout::new::<#field_type>(),
byte_offset: #field_byte_offset,
type_id: std::any::TypeId::of::<#field_type>(),
get_type_name: #engine_crate_path::reflection::FnWithDebug::new(|| {
std::any::type_name::<#field_type>()
}),
get_type: #engine_crate_path::reflection::FnWithDebug::new(|| {
struct SpecializationTarget<Field>(std::marker::PhantomData<Field>);
trait FieldHasReflection
{
fn field_type_reflection(&self)
-> Option<&'static #engine_crate_path::reflection::Type>;
}
trait FieldDoesNotHaveReflection
{
fn field_type_reflection(&self)
-> Option<&'static #engine_crate_path::reflection::Type>;
}
impl<Field> FieldDoesNotHaveReflection for &SpecializationTarget<Field>
{
fn field_type_reflection(&self)
-> Option<&'static #engine_crate_path::reflection::Type>
{
None
}
}
impl<Field> FieldHasReflection for SpecializationTarget<Field>
where
Field: #engine_crate_path::reflection::Reflection
{
fn field_type_reflection(&self)
-> Option<&'static #engine_crate_path::reflection::Type>
{
Some(Field::type_reflection())
}
}
(&SpecializationTarget::<#field_type>(std::marker::PhantomData))
.field_type_reflection()
}),
visibility: #field_reflection_vis
}
}
}
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