/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at
http://mozilla.org/MPL/2.0/. */
//! General handling for the derive and udl_derive macros
use crate::util::kw;
use proc_macro2::{Ident, Span, TokenStream};
use quote::{quote, ToTokens};
use syn::{
parse::{Parse, ParseStream},
DeriveInput,
};
pub fn expand_derive(
kind: DeriveKind,
input: DeriveInput,
options: DeriveOptions,
) -> syn::Result<TokenStream> {
match kind {
DeriveKind::Record(_) => crate::record::expand_record(input, options),
DeriveKind::Object(_) => crate::object::expand_object(input, options),
DeriveKind::Enum(_) => crate::enum_::expand_enum(input, options),
DeriveKind::Error(_) => crate::error::expand_error(input, options),
}
}
pub enum DeriveKind {
Record(kw::Record),
Enum(kw::Enum),
Error(kw::Error),
Object(kw::Object),
}
impl Parse for DeriveKind {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let lookahead = input.lookahead1();
if lookahead.peek(kw::Record) {
Ok(Self::Record(input.parse()?))
} else if lookahead.peek(kw::Enum) {
Ok(Self::Enum(input.parse()?))
} else if lookahead.peek(kw::Error) {
Ok(Self::Error(input.parse()?))
} else if lookahead.peek(kw::Object) {
Ok(Self::Object(input.parse()?))
} else {
Err(lookahead.error())
}
}
}
pub struct DeriveOptions {
/// Should we implement FFI traits for the local UniFfiTag only?
pub local_tag: bool,
/// Should we generate metadata symbols?
pub generate_metadata: bool,
}
/// default() is used to construct a DeriveOptions for a regular `derive` invocation
impl Default for DeriveOptions {
fn default() -> Self {
Self {
local_tag: false,
generate_metadata: true,
}
}
}
impl DeriveOptions {
/// Construct DeriveOptions for `udl_derive`
pub fn udl_derive() -> Self {
Self {
local_tag: true,
generate_metadata: false,
}
}
/// Generate the impl header for a FFI trait
///
/// This will output something like `impl<UT> FfiConverter<UT> for #type`. The caller is
/// responsible for providing the body if the impl block.
pub fn ffi_impl_header(&self, trait_name: &str, ident: &impl ToTokens) -> TokenStream {
let trait_name = Ident::new(trait_name, Span::call_site());
if self.local_tag {
quote! { impl ::uniffi::#trait_name<crate::UniFfiTag> for #ident }
} else {
quote! { impl<UT> ::uniffi::#trait_name<UT> for #ident }
}
}
/// Generate a call to `derive_ffi_traits!` that will derive all the FFI traits
pub fn derive_all_ffi_traits(&self, ty: &Ident) -> TokenStream {
if self.local_tag {
quote! { ::uniffi::derive_ffi_traits!(local #ty); }
} else {
quote! { ::uniffi::derive_ffi_traits!(blanket #ty); }
}
}
/// Generate a call to `derive_ffi_traits!` that will derive some of the FFI traits
pub fn derive_ffi_traits(&self, ty: impl ToTokens, trait_names: &[&str]) -> TokenStream {
let trait_idents = trait_names
.iter()
.map(|name| Ident::new(name, Span::call_site()));
if self.local_tag {
quote! {
#(
::uniffi::derive_ffi_traits!(impl #trait_idents<crate::UniFfiTag> for #ty);
)*
}
} else {
quote! {
#(
::uniffi::derive_ffi_traits!(impl<UT> #trait_idents<UT> for #ty);
)*
}
}
}
}
