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|
use quote::{format_ident, quote};
use crate::reflection::default_value::gen_get_default_value_fn;
use crate::reflection::field::{generate as generate_field, ReflectionFieldGenOptions};
use crate::reflection::options_attr::OptionsAttr;
use crate::util::find_engine_crate_path;
pub fn generate(input: syn::ItemStruct, options: OptionsAttr)
-> proc_macro2::TokenStream
{
let engine_crate_path = find_engine_crate_path().unwrap();
if input.generics.params.is_empty() {
return gen_impl(&input, None, &engine_crate_path);
}
let impls = options
.impl_with_generics
.into_iter()
.map(|generic_args| gen_impl(&input, Some(&generic_args), &engine_crate_path));
quote! {
#(#impls)*
}
}
fn gen_impl(
input: &syn::ItemStruct,
generic_args: Option<&syn::AngleBracketedGenericArguments>,
engine_crate_path: &syn::Path,
) -> proc_macro2::TokenStream
{
let fields = input.fields.iter().enumerate().map(|(field_index, field)| {
generate_field(
&field,
field_index,
&engine_crate_path,
ReflectionFieldGenOptions {
field_vis_override: None,
gen_get_byte_offset: &|field| {
if let Some(field_ident) = &field.ident {
quote! { std::mem::offset_of!(Self, #field_ident) }
} else {
quote! { std::mem::offset_of!(Self, #field_index) }
}
},
},
)
});
let get_default_value_fn = gen_get_default_value_fn(&input.ident, generic_args);
let input_ident = &input.ident;
let generics_type_aliases = input
.generics
.type_params()
.zip(
generic_args
.iter()
.map(|generic_args| &generic_args.args)
.flatten()
.flat_map(|generic_arg| match generic_arg {
syn::GenericArgument::Type(ty) => Some(ty),
_ => None,
}),
)
.map(|(type_param, generic_arg_type)| {
let type_param_ident = &type_param.ident;
quote! {
type #type_param_ident = #generic_arg_type;
}
});
let struct_pattern = match &input.fields {
syn::Fields::Unit => quote! { Self },
syn::Fields::Named(syn::FieldsNamed { named: named_fields, .. }) => {
let field_idents = named_fields.iter().map(|field| {
let Some(field_ident) = &field.ident else {
unreachable!();
};
field_ident
});
quote! { Self { #(#field_idents),* } }
}
syn::Fields::Unnamed(syn::FieldsUnnamed { unnamed: unnamed_fields, .. }) => {
let field_idents = unnamed_fields
.iter()
.enumerate()
.map(|(field_index, _)| format_ident!("field_{field_index}"));
quote! { Self(#(#field_idents),*) }
}
};
let field_index_match_arms = match &input.fields {
syn::Fields::Unit => quote! {},
syn::Fields::Named(syn::FieldsNamed { named: named_fields, .. }) => {
let match_arms =
named_fields.iter().enumerate().map(|(field_index, field)| {
let Some(field_ident) = &field.ident else {
unreachable!();
};
quote! { #field_index => { #field_ident } }
});
quote! { #(#match_arms)* }
}
syn::Fields::Unnamed(syn::FieldsUnnamed { unnamed: unnamed_fields, .. }) => {
let match_arms = unnamed_fields.iter().enumerate().map(|(field_index, _)| {
let field_ident = format_ident!("field_{field_index}");
quote! { #field_index => { #field_ident } }
});
quote! { #(#match_arms)* }
}
};
quote! {
unsafe impl #engine_crate_path::reflection::Reflection for
#input_ident #generic_args
{
const TYPE_REFLECTION: &#engine_crate_path::reflection::Type =
&const {
use std::any::Any;
use #engine_crate_path::reflection::GetError;
#(#generics_type_aliases)*
#engine_crate_path::reflection::Type::Struct(
#engine_crate_path::reflection::Struct {
fields: &[
#(#fields),*
],
get_default_value: || {
#get_default_value_fn
},
cast_dyn_any: |ptr| ptr.cast::<Self>(),
try_get_field: |target, field_index| { {
#![allow(unreachable_code)]
let target = target
.downcast_ref::<Self>()
.ok_or(GetError::WrongTargetType)?;
let #struct_pattern = target;
let field: &dyn Any = match field_index {
#field_index_match_arms
_ => {
return Err(GetError::IndexOutOfBounds);
}
};
Ok(field)
} },
try_get_field_mut: |target, field_index| { {
#![allow(unreachable_code)]
let target = target
.downcast_mut::<Self>()
.ok_or(GetError::WrongTargetType)?;
let #struct_pattern = target;
let field: &mut dyn Any = match field_index {
#field_index_match_arms
_ => {
return Err(GetError::IndexOutOfBounds);
}
};
Ok(field)
} },
}
)
};
}
}
}
|
