| 1 | // Copyright 2024 The Matrix.org Foundation C.I.C. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | use proc_macro::TokenStream; |
| 16 | use quote::quote; |
| 17 | use syn::{ImplItem, Item, TraitItem}; |
| 18 | |
| 19 | /// Attribute to specify the async runtime parameter for the `uniffi` |
| 20 | /// export macros if there any `async fn`s in the input. |
| 21 | #[proc_macro_attribute] |
| 22 | pub fn export(attr: TokenStream, item: TokenStream) -> TokenStream { |
| 23 | let has_async_fn = |item| { |
| 24 | if let Item::Fn(fun) = &item { |
| 25 | if fun.sig.asyncness.is_some() { |
| 26 | return true; |
| 27 | } |
| 28 | } else if let Item::Impl(blk) = &item { |
| 29 | for item in &blk.items { |
| 30 | if let ImplItem::Fn(fun) = item |
| 31 | && fun.sig.asyncness.is_some() |
| 32 | { |
| 33 | return true; |
| 34 | } |
| 35 | } |
| 36 | } else if let Item::Trait(blk) = &item { |
| 37 | for item in &blk.items { |
| 38 | if let TraitItem::Fn(fun) = item |
| 39 | && fun.sig.asyncness.is_some() |
| 40 | { |
| 41 | return true; |
| 42 | } |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | false |
| 47 | }; |
| 48 | |
| 49 | let attr2 = proc_macro2::TokenStream::from(attr); |
| 50 | let item2 = proc_macro2::TokenStream::from(item.clone()); |
| 51 | |
| 52 | let res = match syn::parse(item) { |
| 53 | Ok(item) => match has_async_fn(item) { |
| 54 | true => { |
| 55 | quote! { |
| 56 | #[cfg_attr(target_family = "wasm", uniffi::export(#attr2))] |
| 57 | #[cfg_attr(not(target_family = "wasm"), uniffi::export(async_runtime = "tokio", #attr2))] |
| 58 | } |
| 59 | } |
| 60 | false => quote! { #[uniffi::export(#attr2)] }, |
| 61 | }, |
| 62 | Err(e) => e.into_compile_error(), |
| 63 | }; |
| 64 | |
| 65 | quote! { |
| 66 | #res |
| 67 | #item2 |
| 68 | } |
| 69 | .into() |
| 70 | } |