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| 1 | +extern crate proc_macro; |
| 2 | + |
| 3 | +use proc_macro::TokenStream; |
| 4 | +use quote::quote; |
| 5 | +use syn::spanned::Spanned; |
| 6 | + |
| 7 | +#[proc_macro_attribute] |
| 8 | +pub fn duktape_fn(_attr: TokenStream, mut item: TokenStream) -> TokenStream { |
| 9 | + let duk_path = if std::env::var("CARGO_PKG_NAME").unwrap() == "duk" { |
| 10 | + quote! { crate } |
| 11 | + } else { |
| 12 | + quote! { ::duk } |
| 13 | + }; |
| 14 | + let ast: syn::ItemFn = syn::parse(item.clone()).expect("failed to parse token stream as fn"); |
| 15 | + let fn_name = ast.sig.ident; |
| 16 | + let fn_vis = ast.vis; |
| 17 | + let fn_name_str = syn::LitStr::new(&format!("{}", fn_name), fn_name.span()); |
| 18 | + let mut arg_names = Vec::new(); |
| 19 | + let mut args = Vec::new(); |
| 20 | + for arg in ast.sig.inputs { |
| 21 | + let arg = match arg { |
| 22 | + syn::FnArg::Receiver(s) => { |
| 23 | + return syn::Error::new( |
| 24 | + s.span(), |
| 25 | + "cannot derive `duktape_fn` on function that takes `self` as an argument", |
| 26 | + ) |
| 27 | + .to_compile_error() |
| 28 | + .into(); |
| 29 | + } |
| 30 | + syn::FnArg::Typed(a) => a, |
| 31 | + }; |
| 32 | + let name = format!("arg_{}", args.len()); |
| 33 | + let name_ident = syn::Ident::new(&name, arg.span()); |
| 34 | + let arg_idx = args.len() as i32; |
| 35 | + arg_names.push(name_ident.clone()); |
| 36 | + args.push(quote! { |
| 37 | + let #name_ident = match #duk_path::deserialize_from_stack(ctx, #arg_idx) { |
| 38 | + Ok(a) => a, |
| 39 | + Err(e) => { |
| 40 | + #duk_path::duk_sys::duk_push_error_object( |
| 41 | + ctx, |
| 42 | + #duk_path::duk_sys::DUK_ERR_TYPE_ERROR as i32, |
| 43 | + std::ffi::CString::new(format!("{}", e)).unwrap_or_default().into_raw(), |
| 44 | + ); |
| 45 | + #duk_path::duk_sys::duk_throw_raw(ctx); |
| 46 | + return 0; |
| 47 | + } |
| 48 | + }; |
| 49 | + }); |
| 50 | + } |
| 51 | + let fn_arg_len = args.len(); |
| 52 | + let ret = match ast.sig.output { |
| 53 | + syn::ReturnType::Type(_, _) => quote! { |
| 54 | + match #duk_path::serialize_to_stack(ctx, &res) { |
| 55 | + Ok(_) => { |
| 56 | + 1 |
| 57 | + }, |
| 58 | + Err(e) => { |
| 59 | + #duk_path::duk_sys::duk_push_error_object( |
| 60 | + ctx, |
| 61 | + #duk_path::duk_sys::DUK_ERR_TYPE_ERROR as i32, |
| 62 | + std::ffi::CString::new(format!("{}", e)).unwrap_or_default().into_raw(), |
| 63 | + ); |
| 64 | + #duk_path::duk_sys::duk_throw_raw(ctx); |
| 65 | + 0 |
| 66 | + } |
| 67 | + } |
| 68 | + }, |
| 69 | + _ => quote! { |
| 70 | + 0 |
| 71 | + }, |
| 72 | + }; |
| 73 | + let gen = quote! { |
| 74 | + #fn_vis mod #fn_name { |
| 75 | + use super::#fn_name as fn_impl; |
| 76 | + |
| 77 | + pub struct DukFnImpl; |
| 78 | + |
| 79 | + unsafe impl #duk_path::DukFunction for DukFnImpl { |
| 80 | + const NARGS: usize = #fn_arg_len; |
| 81 | + const NAME: &'static str = #fn_name_str; |
| 82 | + unsafe extern "C" fn duk_call(ctx: *mut #duk_path::duk_sys::duk_context) -> i32 { |
| 83 | + #( |
| 84 | + #args |
| 85 | + )* |
| 86 | + let res = match std::panic::catch_unwind(|| fn_impl(#( |
| 87 | + #arg_names, |
| 88 | + )*)) { |
| 89 | + Ok(res) => res, |
| 90 | + Err(e) => { |
| 91 | + let error = if let Some(msg) = e.downcast_ref::<&str>() { |
| 92 | + format!("panic: {}", *msg) |
| 93 | + } else if let Some(msg) = e.downcast_ref::<String>() { |
| 94 | + format!("panic: {}", msg) |
| 95 | + } else { |
| 96 | + "panic: unknown error".into() |
| 97 | + }; |
| 98 | + #duk_path::duk_sys::duk_push_error_object( |
| 99 | + ctx, |
| 100 | + #duk_path::duk_sys::DUK_ERR_ERROR as i32, |
| 101 | + std::ffi::CString::new(error).unwrap_or_default().into_raw(), |
| 102 | + ); |
| 103 | + #duk_path::duk_sys::duk_throw_raw(ctx); |
| 104 | + return 0; |
| 105 | + } |
| 106 | + }; |
| 107 | + #ret |
| 108 | + } |
| 109 | + } |
| 110 | + } |
| 111 | + }; |
| 112 | + item.extend(TokenStream::from(gen)); |
| 113 | + item |
| 114 | +} |
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