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use proc_macro2::TokenStream;
use quote::quote;
use syn::{DataEnum, DataStruct, DataUnion, DeriveInput};
#[proc_macro_derive(InspectorOptions, attributes(inspector))]
pub fn inspectable(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input = syn::parse_macro_input!(input as syn::DeriveInput);
let result = match &input.data {
syn::Data::Struct(data) => expand_struct(&input, data),
syn::Data::Enum(data) => expand_enum(&input, data),
syn::Data::Union(data) => expand_union(&input, data),
};
result.unwrap_or_else(|err| err.into_compile_error()).into()
}
fn expand_struct(input: &DeriveInput, data: &DataStruct) -> syn::Result<TokenStream> {
let bevy_reflect = quote! { bevy_inspector_egui::__macro_exports::bevy_reflect };
let fields = data
.fields
.iter()
.enumerate()
.filter_map(|(i, field)| {
let ty = &field.ty;
let attrs = match collect_attrs(field) {
Ok(attrs) => attrs,
Err(e) => return Some(Err(e)),
};
if attrs.is_empty() {
return None;
}
let attrs = attrs.into_iter().map(|(name, value)| quote! {
field_options.#name = std::convert::Into::into(#value);
});
Some(Ok(quote! {
let mut field_options = <#ty as bevy_inspector_egui::inspector_options::InspectorOptionsType>::TypedOptions::default();
#(#attrs)*
options.insert(bevy_inspector_egui::inspector_options::Target::Field(#i), <#ty as bevy_inspector_egui::inspector_options::InspectorOptionsType>::Options::from(field_options));
}))
})
.collect::<syn::Result<Vec<_>>>()?;
let type_name = &input.ident;
Ok(quote! {
impl #bevy_reflect::FromType<#type_name> for bevy_inspector_egui::InspectorOptions {
fn from_type() -> Self {
let mut options = bevy_inspector_egui::InspectorOptions::default();
#(#fields)*
options
}
}
})
}
fn expand_enum(input: &DeriveInput, data: &DataEnum) -> syn::Result<TokenStream> {
let bevy_reflect = quote! { bevy_inspector_egui::__macro_exports::bevy_reflect };
let fields = data
.variants
.iter()
.map(|variant| {
let variant_name = variant.ident.to_string();
let attrs = variant
.fields
.iter()
.enumerate()
.filter_map(|(i, field)| {
let ty = &field.ty;
let attrs = match collect_attrs(field) {
Ok(attrs) => attrs,
Err(e) => return Some(Err(e)),
};
if attrs.is_empty() {
return None;
}
let attrs = attrs.into_iter().map(|(name, value)| quote! {
field_options.#name = std::convert::Into::into(#value);
});
Some(Ok(quote! {
let mut field_options = <#ty as bevy_inspector_egui::inspector_options::InspectorOptionsType>::TypedOptions::default();
#(#attrs)*
options.insert(bevy_inspector_egui::inspector_options::Target::VariantField(std::borrow::Cow::Borrowed(#variant_name), #i), <#ty as bevy_inspector_egui::inspector_options::InspectorOptionsType>::Options::from(field_options));
}))
})
.collect::<syn::Result<Vec<_>>>()?;
Ok(attrs)
})
.collect::<syn::Result<Vec<_>>>()?;
let type_name = &input.ident;
Ok(quote! {
impl #bevy_reflect::FromType<#type_name> for bevy_inspector_egui::InspectorOptions {
fn from_type() -> Self {
let mut options = bevy_inspector_egui::InspectorOptions::default();
#(#(#fields)*)*
options
}
}
})
}
fn expand_union(_: &DeriveInput, data: &DataUnion) -> syn::Result<TokenStream> {
Err(syn::Error::new_spanned(
data.union_token,
"`InspectorOptions` for unions is not implemented",
))
}
fn collect_attrs(field: &syn::Field) -> Result<Vec<(syn::Ident, syn::Lit)>, syn::Error> {
let fields = field
.attrs
.iter()
.filter(|attr| attr.path.is_ident("inspector"))
.map(|attr| {
let meta = attr.parse_meta()?;
let list = meta_list(meta)?;
let key_value = list
.nested
.into_iter()
.map(|meta| {
let name_value = nested_meta_meta(meta).and_then(meta_name_value)?;
let path = name_value
.path
.get_ident()
.ok_or_else(|| {
syn::Error::new_spanned(
&name_value.path,
"expected a simple identifier",
)
})?
.clone();
Ok((path, name_value.lit))
})
.collect::<syn::Result<Vec<_>>>()?;
Ok(key_value)
})
.collect::<syn::Result<Vec<_>>>()?
.into_iter()
.flatten();
Ok(fields.collect())
}
fn meta_list(meta: syn::Meta) -> Result<syn::MetaList, syn::Error> {
match meta {
syn::Meta::Path(path) => Err(syn::Error::new_spanned(path, "unexpected path")),
syn::Meta::NameValue(name_value) => Err(syn::Error::new_spanned(
name_value,
"unexpected name value pair",
)),
syn::Meta::List(list) => Ok(list),
}
}
fn meta_name_value(meta: syn::Meta) -> Result<syn::MetaNameValue, syn::Error> {
match meta {
syn::Meta::Path(path) => Err(syn::Error::new_spanned(path, "unexpected path")),
syn::Meta::List(list) => Err(syn::Error::new_spanned(list, "unexpected list")),
syn::Meta::NameValue(name_value) => Ok(name_value),
}
}
fn nested_meta_meta(meta: syn::NestedMeta) -> Result<syn::Meta, syn::Error> {
match meta {
syn::NestedMeta::Lit(lit) => Err(syn::Error::new_spanned(lit, "unexpected literal")),
syn::NestedMeta::Meta(meta) => Ok(meta),
}
}