76 lines
2.2 KiB
Rust
76 lines
2.2 KiB
Rust
use core::panic;
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use proc_macro::TokenStream;
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use quote::{format_ident, quote};
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use syn::{parse_macro_input, FnArg, ItemFn, Type, Visibility};
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#[proc_macro_attribute]
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pub fn bind(args: TokenStream, function: TokenStream) -> TokenStream {
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if !args.is_empty() {
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panic!("The bind attribute does not take any arguments");
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}
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let inner_fn = parse_macro_input!(function as ItemFn);
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if let Visibility::Public(_) = inner_fn.vis {
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} else {
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panic!("The bind attribute only works for public functions");
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}
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let inner_fn_name = format_ident!("{}", inner_fn.sig.ident);
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let outer_fn_name = format_ident!("__{}", inner_fn_name);
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let variadic = inner_fn.sig.inputs.len();
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let i = (0..variadic).map(syn::Index::from);
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let t: Vec<Type> = inner_fn
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.sig
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.inputs
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.iter()
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.map(|x| match x {
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FnArg::Receiver(_) => {
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panic!("all arguments must have specified types, no `self` allowed")
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}
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FnArg::Typed(item) => *item.ty.clone(),
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})
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.collect();
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// this is cursed...
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let (args, ty) = if variadic != 1 {
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(
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quote! {
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#( data.#i ),*
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},
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quote! {
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( #( #t ),* )
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},
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)
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} else {
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let ty = &t[0];
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(quote! { data }, quote! { #ty })
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};
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TokenStream::from(quote! {
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#[no_mangle]
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#inner_fn
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#[no_mangle]
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pub extern "C" fn #outer_fn_name(ptr: *const u8, len: usize) -> *const ::plugin::__Buffer {
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// setup
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let buffer = ::plugin::__Buffer { ptr, len };
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let data = unsafe { buffer.to_vec() };
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// operation
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let data: #ty = match ::plugin::bincode::deserialize(&data) {
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Ok(d) => d,
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Err(e) => panic!("Data passed to function not deserializable."),
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};
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let result = #inner_fn_name(#args);
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let new_data: Result<Vec<u8>, _> = ::plugin::bincode::serialize(&result);
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let new_data = new_data.unwrap();
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// teardown
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let new_buffer = unsafe { ::plugin::__Buffer::from_vec(new_data) };
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return new_buffer.leak_to_heap();
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}
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})
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}
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