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| 1 | +// This file is Copyright its original authors, visible in version control |
| 2 | +// history. |
| 3 | +// |
| 4 | +// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE |
| 5 | +// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| 6 | +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option. |
| 7 | +// You may not use this file except in accordance with one or both of these |
| 8 | +// licenses. |
| 9 | + |
| 10 | +#![crate_name = "lightning_macros"] |
| 11 | + |
| 12 | +//! Proc macros used by LDK |
| 13 | +
|
| 14 | +#![cfg_attr(not(test), no_std)] |
| 15 | +#![deny(missing_docs)] |
| 16 | +#![forbid(unsafe_code)] |
| 17 | +#![deny(rustdoc::broken_intra_doc_links)] |
| 18 | +#![deny(rustdoc::private_intra_doc_links)] |
| 19 | +#![cfg_attr(docsrs, feature(doc_auto_cfg))] |
| 20 | + |
| 21 | +use proc_macro::TokenStream; |
| 22 | +use quote::quote; |
| 23 | +use syn::spanned::Spanned; |
| 24 | +use syn::{parse, ImplItemFn, Token}; |
| 25 | + |
| 26 | +fn add_async_method(mut parsed: ImplItemFn) -> TokenStream { |
| 27 | + let output = quote! { |
| 28 | + #[cfg(not(feature = "async-interface"))] |
| 29 | + #parsed |
| 30 | + }; |
| 31 | + |
| 32 | + parsed.sig.asyncness = Some(Token)); |
| 33 | + |
| 34 | + let output = quote! { |
| 35 | + #output |
| 36 | + |
| 37 | + #[cfg(feature = "async-interface")] |
| 38 | + #parsed |
| 39 | + }; |
| 40 | + |
| 41 | + output.into() |
| 42 | +} |
| 43 | + |
| 44 | +/// Makes a method `async`, if the `async-interface` feature is enabled. |
| 45 | +#[proc_macro_attribute] |
| 46 | +pub fn maybe_async(_attr: TokenStream, item: TokenStream) -> TokenStream { |
| 47 | + if let Ok(parsed) = parse(item) { |
| 48 | + add_async_method(parsed) |
| 49 | + } else { |
| 50 | + (quote! { |
| 51 | + compile_error!("#[maybe_async] can only be used on methods") |
| 52 | + }) |
| 53 | + .into() |
| 54 | + } |
| 55 | +} |
| 56 | + |
| 57 | +/// Awaits, if the `async-interface` feature is enabled. |
| 58 | +#[proc_macro] |
| 59 | +pub fn maybe_await(expr: TokenStream) -> TokenStream { |
| 60 | + let expr: proc_macro2::TokenStream = expr.into(); |
| 61 | + let quoted = quote! { |
| 62 | + { |
| 63 | + #[cfg(not(feature = "async-interface"))] |
| 64 | + { |
| 65 | + #expr |
| 66 | + } |
| 67 | + |
| 68 | + #[cfg(feature = "async-interface")] |
| 69 | + { |
| 70 | + #expr.await |
| 71 | + } |
| 72 | + } |
| 73 | + }; |
| 74 | + |
| 75 | + quoted.into() |
| 76 | +} |
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