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| 1 | +extern crate proc_macro; |
| 2 | + |
| 3 | +use proc_macro::TokenStream; |
| 4 | +use quote::quote; |
| 5 | +use syn::parse::Parse; |
| 6 | +use syn::spanned::Spanned; |
| 7 | + |
| 8 | +#[proc_macro_attribute] |
| 9 | +pub fn duktape_fn(_attr: TokenStream, mut item: TokenStream) -> TokenStream { |
| 10 | + let ast: syn::ItemFn = syn::parse(item.clone()).expect("failed to parse token stream as fn"); |
| 11 | + let fn_name = ast.sig.ident; |
| 12 | + let duk_fn_name = syn::Ident::new( |
| 13 | + &format!("duk_derive_{}", fn_name), |
| 14 | + proc_macro2::Span::call_site(), |
| 15 | + ); |
| 16 | + let fn_arg_len_name = syn::Ident::new( |
| 17 | + &format!("{}_arg_len", duk_fn_name), |
| 18 | + proc_macro2::Span::call_site(), |
| 19 | + ); |
| 20 | + let mut arg_names = Vec::new(); |
| 21 | + let mut args = Vec::new(); |
| 22 | + for arg in ast.sig.inputs { |
| 23 | + let arg = match arg { |
| 24 | + syn::FnArg::Receiver(_) => { |
| 25 | + panic!("cannot derive `duktape_fn` on function that takes `self` as an argument") |
| 26 | + } |
| 27 | + syn::FnArg::Typed(a) => a, |
| 28 | + }; |
| 29 | + let name = format!("arg_{}", args.len()); |
| 30 | + let name_ident = syn::Ident::new(&name, arg.span()); |
| 31 | + let arg_idx = args.len() as i32; |
| 32 | + arg_names.push(name_ident.clone()); |
| 33 | + args.push(quote! { |
| 34 | + let #name_ident = match duk::deserialize_from_stack(ctx, #arg_idx) { |
| 35 | + Ok(a) => a, |
| 36 | + Err(e) => { |
| 37 | + duk::duk_sys::duk_push_error_object( |
| 38 | + ctx, |
| 39 | + duk::duk_sys::DUK_ERR_TYPE_ERROR as i32, |
| 40 | + format!("{}", e).as_ptr().cast() |
| 41 | + ); |
| 42 | + duk::duk_sys::duk_throw_raw(ctx); |
| 43 | + return 0; |
| 44 | + } |
| 45 | + }; |
| 46 | + }); |
| 47 | + } |
| 48 | + let fn_arg_len = args.len(); |
| 49 | + let ret = match ast.sig.output { |
| 50 | + syn::ReturnType::Type(_, _) => quote! { |
| 51 | + match duk::serialize_to_stack(ctx, &res) { |
| 52 | + Ok(_) => { |
| 53 | + 1 |
| 54 | + }, |
| 55 | + Err(e) => { |
| 56 | + duk::duk_sys::duk_push_error_object( |
| 57 | + ctx, |
| 58 | + duk::duk_sys::DUK_ERR_TYPE_ERROR as i32, |
| 59 | + format!("{}", e).as_ptr().cast() |
| 60 | + ); |
| 61 | + duk::duk_sys::duk_throw_raw(ctx); |
| 62 | + 0 |
| 63 | + } |
| 64 | + } |
| 65 | + }, |
| 66 | + _ => quote! { |
| 67 | + 0 |
| 68 | + }, |
| 69 | + }; |
| 70 | + let gen = quote! { |
| 71 | + unsafe extern "C" fn #duk_fn_name(ctx: *mut duk_sys::duk_context) -> i32 { |
| 72 | + #( |
| 73 | + #args |
| 74 | + )* |
| 75 | + |
| 76 | + let res = #fn_name(#( |
| 77 | + #arg_names, |
| 78 | + )*); |
| 79 | + |
| 80 | + #ret |
| 81 | + } |
| 82 | + const #fn_arg_len_name: usize = #fn_arg_len; |
| 83 | + }; |
| 84 | + item.extend(TokenStream::from(gen)); |
| 85 | + item |
| 86 | +} |
| 87 | + |
| 88 | +struct AddGlobalFn { |
| 89 | + ctx: syn::Expr, |
| 90 | + func: syn::Path, |
| 91 | +} |
| 92 | +impl Parse for AddGlobalFn { |
| 93 | + fn parse(input: syn::parse::ParseStream) -> syn::parse::Result<Self> { |
| 94 | + let ctx = input.parse()?; |
| 95 | + input.parse::<syn::Token![,]>()?; |
| 96 | + let func = input.parse()?; |
| 97 | + Ok(AddGlobalFn { ctx, func }) |
| 98 | + } |
| 99 | +} |
| 100 | + |
| 101 | +#[proc_macro] |
| 102 | +pub fn add_global_fn(input: TokenStream) -> TokenStream { |
| 103 | + let AddGlobalFn { ctx, func } = syn::parse_macro_input!(input as AddGlobalFn); |
| 104 | + |
| 105 | + let leaf = func.segments.iter().cloned().next_back().unwrap().ident; |
| 106 | + |
| 107 | + let derived = syn::Path { |
| 108 | + leading_colon: func.leading_colon, |
| 109 | + segments: func |
| 110 | + .segments |
| 111 | + .iter() |
| 112 | + .cloned() |
| 113 | + .take(func.segments.len() - 1) |
| 114 | + .chain(std::iter::once(syn::PathSegment { |
| 115 | + ident: syn::Ident::new(&format!("duk_derive_{}", leaf), leaf.span()), |
| 116 | + arguments: syn::PathArguments::None, |
| 117 | + })) |
| 118 | + .collect(), |
| 119 | + }; |
| 120 | + let derived_arg_len = syn::Path { |
| 121 | + leading_colon: func.leading_colon, |
| 122 | + segments: func |
| 123 | + .segments |
| 124 | + .iter() |
| 125 | + .cloned() |
| 126 | + .take(func.segments.len() - 1) |
| 127 | + .chain(std::iter::once(syn::PathSegment { |
| 128 | + ident: syn::Ident::new(&format!("duk_derive_{}_arg_len", leaf), leaf.span()), |
| 129 | + arguments: syn::PathArguments::None, |
| 130 | + })) |
| 131 | + .collect(), |
| 132 | + }; |
| 133 | + |
| 134 | + (quote! { |
| 135 | + unsafe { |
| 136 | + #ctx.add_global_fn(stringify!(#leaf), #derived, #derived_arg_len) |
| 137 | + } |
| 138 | + }) |
| 139 | + .into() |
| 140 | +} |
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