matrix_sdk_ffi_macros/
lib.rs

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
15use proc_macro::TokenStream;
16use quote::quote;
17use 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]
22pub 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                    if fun.sig.asyncness.is_some() {
32                        return true;
33                    }
34                }
35            }
36        } else if let Item::Trait(blk) = &item {
37            for item in &blk.items {
38                if let TraitItem::Fn(fun) = item {
39                    if fun.sig.asyncness.is_some() {
40                        return true;
41                    }
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}
matrix_sdk_ffi_macros/lib.rs

matrix_sdk_ffi_macros/
lib.rs
