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|
use proc_macro2::{Ident, Span, TokenStream};
use quote::quote;
use syn::{
parse::{Parse, ParseStream},
punctuated::Punctuated,
Data, DeriveInput, Index, Token, Variant,
};
use uniffi_meta::{ErrorMetadata, VariantMetadata};
use crate::{
enum_::{enum_ffi_converter_impl, variant_metadata},
util::{
assert_type_eq, chain, create_metadata_static_var, either_attribute_arg, AttributeSliceExt,
UniffiAttribute,
},
};
pub fn expand_error(input: DeriveInput, module_path: Vec<String>) -> TokenStream {
let variants = match input.data {
Data::Enum(e) => Ok(e.variants),
_ => Err(syn::Error::new(
Span::call_site(),
"This derive currently only supports enums",
)),
};
let ident = &input.ident;
let attr = input.attrs.parse_uniffi_attributes::<ErrorAttr>();
let ffi_converter_impl = match &attr {
Ok(a) if a.flat.is_some() => flat_error_ffi_converter_impl(variants.as_ref().ok(), ident),
_ => enum_ffi_converter_impl(variants.as_ref().ok(), ident),
};
let meta_static_var = match (&variants, &attr) {
(Ok(vs), Ok(a)) => Some(match error_metadata(ident, vs, module_path, a) {
Ok(metadata) => create_metadata_static_var(ident, metadata.into()),
Err(e) => e.into_compile_error(),
}),
_ => None,
};
let type_assertion = assert_type_eq(ident, quote! { crate::uniffi_types::#ident });
let variant_errors: TokenStream = match variants {
Ok(vs) => vs
.iter()
.flat_map(|variant| {
chain(
variant.attrs.attributes_not_allowed_here(),
variant
.fields
.iter()
.flat_map(|field| field.attrs.attributes_not_allowed_here()),
)
})
.map(syn::Error::into_compile_error)
.collect(),
Err(e) => e.into_compile_error(),
};
let attr_error = attr.err().map(syn::Error::into_compile_error);
quote! {
#ffi_converter_impl
#[automatically_derived]
impl ::uniffi::FfiError for #ident {}
#meta_static_var
#type_assertion
#variant_errors
#attr_error
}
}
pub(crate) fn flat_error_ffi_converter_impl(
variants: Option<&Punctuated<Variant, Token![,]>>,
ident: &Ident,
) -> TokenStream {
let write_impl = match variants {
Some(variants) => {
let write_match_arms = variants.iter().enumerate().map(|(i, v)| {
let v_ident = &v.ident;
let idx = Index::from(i + 1);
quote! {
Self::#v_ident { .. } => {
::uniffi::deps::bytes::BufMut::put_i32(buf, #idx);
<::std::string::String as ::uniffi::FfiConverter>::write(error_msg, buf);
}
}
});
let write_impl = quote! {
let error_msg = ::std::string::ToString::to_string(&obj);
match obj { #(#write_match_arms)* }
};
write_impl
}
None => quote! { ::std::unimplemented!() },
};
quote! {
#[automatically_derived]
impl ::uniffi::RustBufferFfiConverter for #ident {
type RustType = Self;
fn write(obj: Self, buf: &mut ::std::vec::Vec<u8>) {
#write_impl
}
fn try_read(buf: &mut &[::std::primitive::u8]) -> ::uniffi::deps::anyhow::Result<Self> {
::std::panic!("try_read not supported for flat errors");
}
}
}
}
fn error_metadata(
ident: &Ident,
variants: &Punctuated<Variant, Token![,]>,
module_path: Vec<String>,
attr: &ErrorAttr,
) -> syn::Result<ErrorMetadata> {
let name = ident.to_string();
let flat = attr.flat.is_some();
let variants = if flat {
variants
.iter()
.map(|v| VariantMetadata {
name: v.ident.to_string(),
fields: vec![],
})
.collect()
} else {
variants
.iter()
.map(variant_metadata)
.collect::<syn::Result<_>>()?
};
Ok(ErrorMetadata {
module_path,
name,
variants,
flat,
})
}
mod kw {
syn::custom_keyword!(flat_error);
}
#[derive(Default)]
struct ErrorAttr {
flat: Option<kw::flat_error>,
}
impl Parse for ErrorAttr {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let flat = input.parse()?;
Ok(ErrorAttr { flat })
}
}
impl UniffiAttribute for ErrorAttr {
fn merge(self, other: Self) -> syn::Result<Self> {
Ok(Self {
flat: either_attribute_arg(self.flat, other.flat)?,
})
}
}
|
