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use proc_macro2::{Ident, Span, TokenStream};
use quote::quote;
use syn::{Data, DataEnum, DeriveInput, Field, Index};
use crate::util::{
create_metadata_items, derive_all_ffi_traits, ident_to_string, mod_path, tagged_impl_header,
try_metadata_value_from_usize, try_read_field,
};
pub fn expand_enum(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStream> {
let enum_ = match input.data {
Data::Enum(e) => e,
_ => {
return Err(syn::Error::new(
Span::call_site(),
"This derive must only be used on enums",
))
}
};
let ident = &input.ident;
let ffi_converter_impl = enum_ffi_converter_impl(ident, &enum_, udl_mode);
let meta_static_var = (!udl_mode).then(|| {
enum_meta_static_var(ident, &enum_).unwrap_or_else(syn::Error::into_compile_error)
});
Ok(quote! {
#ffi_converter_impl
#meta_static_var
})
}
pub(crate) fn enum_ffi_converter_impl(
ident: &Ident,
enum_: &DataEnum,
udl_mode: bool,
) -> TokenStream {
enum_or_error_ffi_converter_impl(
ident,
enum_,
udl_mode,
quote! { ::uniffi::metadata::codes::TYPE_ENUM },
)
}
pub(crate) fn rich_error_ffi_converter_impl(
ident: &Ident,
enum_: &DataEnum,
udl_mode: bool,
) -> TokenStream {
enum_or_error_ffi_converter_impl(
ident,
enum_,
udl_mode,
quote! { ::uniffi::metadata::codes::TYPE_ENUM },
)
}
fn enum_or_error_ffi_converter_impl(
ident: &Ident,
enum_: &DataEnum,
udl_mode: bool,
metadata_type_code: TokenStream,
) -> TokenStream {
let name = ident_to_string(ident);
let impl_spec = tagged_impl_header("FfiConverter", ident, udl_mode);
let derive_ffi_traits = derive_all_ffi_traits(ident, udl_mode);
let mod_path = match mod_path() {
Ok(p) => p,
Err(e) => return e.into_compile_error(),
};
let write_match_arms = enum_.variants.iter().enumerate().map(|(i, v)| {
let v_ident = &v.ident;
let fields = v.fields.iter().map(|f| &f.ident);
let idx = Index::from(i + 1);
let write_fields = v.fields.iter().map(write_field);
quote! {
Self::#v_ident { #(#fields),* } => {
::uniffi::deps::bytes::BufMut::put_i32(buf, #idx);
#(#write_fields)*
}
}
});
let write_impl = quote! {
match obj { #(#write_match_arms)* }
};
let try_read_match_arms = enum_.variants.iter().enumerate().map(|(i, v)| {
let idx = Index::from(i + 1);
let v_ident = &v.ident;
let try_read_fields = v.fields.iter().map(try_read_field);
quote! {
#idx => Self::#v_ident { #(#try_read_fields)* },
}
});
let error_format_string = format!("Invalid {ident} enum value: {{}}");
let try_read_impl = quote! {
::uniffi::check_remaining(buf, 4)?;
Ok(match ::uniffi::deps::bytes::Buf::get_i32(buf) {
#(#try_read_match_arms)*
v => ::uniffi::deps::anyhow::bail!(#error_format_string, v),
})
};
quote! {
#[automatically_derived]
unsafe #impl_spec {
::uniffi::ffi_converter_rust_buffer_lift_and_lower!(crate::UniFfiTag);
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> {
#try_read_impl
}
const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(#metadata_type_code)
.concat_str(#mod_path)
.concat_str(#name);
}
#derive_ffi_traits
}
}
fn write_field(f: &Field) -> TokenStream {
let ident = &f.ident;
let ty = &f.ty;
quote! {
<#ty as ::uniffi::Lower<crate::UniFfiTag>>::write(#ident, buf);
}
}
pub(crate) fn enum_meta_static_var(ident: &Ident, enum_: &DataEnum) -> syn::Result<TokenStream> {
let name = ident_to_string(ident);
let module_path = mod_path()?;
let mut metadata_expr = quote! {
::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::ENUM)
.concat_str(#module_path)
.concat_str(#name)
};
metadata_expr.extend(variant_metadata(enum_)?);
Ok(create_metadata_items("enum", &name, metadata_expr, None))
}
pub fn variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStream>> {
let variants_len =
try_metadata_value_from_usize(enum_.variants.len(), "UniFFI limits enums to 256 variants")?;
std::iter::once(Ok(quote! { .concat_value(#variants_len) }))
.chain(
enum_.variants
.iter()
.map(|v| {
let fields_len = try_metadata_value_from_usize(
v.fields.len(),
"UniFFI limits enum variants to 256 fields",
)?;
let field_names = v.fields
.iter()
.map(|f| {
f.ident
.as_ref()
.ok_or_else(||
syn::Error::new_spanned(
v,
"UniFFI only supports enum variants with named fields (or no fields at all)",
)
)
.map(ident_to_string)
})
.collect::<syn::Result<Vec<_>>>()?;
let name = ident_to_string(&v.ident);
let field_types = v.fields.iter().map(|f| &f.ty);
Ok(quote! {
.concat_str(#name)
.concat_value(#fields_len)
#(
.concat_str(#field_names)
.concat(<#field_types as ::uniffi::Lower<crate::UniFfiTag>>::TYPE_ID_META)
// field defaults not yet supported for enums
.concat_bool(false)
)*
})
})
)
.collect()
}
|
