55 lines
1.8 KiB
Rust
55 lines
1.8 KiB
Rust
use proc_macro::TokenStream;
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use syn::{ItemFn, parse::Parse, Token, LitInt};
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use quote::quote;
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struct NativeFuncParams {
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arity: LitInt,
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variadic: Option<Token![..]>,
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}
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impl Parse for NativeFuncParams {
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fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
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let arity = input.parse()?;
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let variadic = input.parse()?;
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Ok(Self { arity , variadic })
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}
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}
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#[proc_macro_attribute]
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pub fn native_func(input: TokenStream, annotated_item: TokenStream) -> TokenStream {
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let itemfn: ItemFn = syn::parse(annotated_item).unwrap();
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let input: NativeFuncParams = syn::parse(input).unwrap();
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let arity = input.arity;
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let variadic = input.variadic.is_some();
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let visibility = itemfn.vis;
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let block = itemfn.block;
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let name = itemfn.sig.ident;
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let name_str = name.to_string();
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let inputs = itemfn.sig.inputs;
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let output = itemfn.sig.output;
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assert!(itemfn.sig.constness.is_none(), "item must not be const");
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assert!(itemfn.sig.asyncness.is_none(), "item must not be async");
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assert!(itemfn.sig.unsafety.is_none(), "item must not be unsafe");
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assert!(itemfn.sig.abi.is_none(), "item must not contain an ABI specifier");
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assert!(itemfn.sig.variadic.is_none(), "item must not be variadic");
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let expanded = quote! {
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#visibility fn #name() -> ::std::rc::Rc< ::matrix_lang::prelude::Function> {
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::std::rc::Rc::new( ::matrix_lang::prelude::Function {
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name: ::std::rc::Rc::from( #name_str ),
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arity: #arity,
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variadic: #variadic,
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fun: ::matrix_lang::prelude::InnerFunction::Native(
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::std::rc::Rc::new(
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|#inputs| #output #block
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)
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)
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})
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}
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};
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TokenStream::from(expanded)
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}
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