37 lines
971 B
Rust
37 lines
971 B
Rust
#![feature(box_patterns)]
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extern crate proc_macro;
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#[macro_use]
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extern crate quote;
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#[macro_use]
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extern crate syn;
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use self::proc_macro::TokenStream;
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use self::syn::fold::Fold;
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struct RecursiveDescentFn {
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}
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impl Fold for RecursiveDescentFn {
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fn fold_item_fn(&mut self, mut i: syn::ItemFn) -> syn::ItemFn {
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let box block = i.block;
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let mut stmts = block.stmts;
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let new_item: syn::Stmt = parse_quote! {
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println!("FROM PROC MACRO");
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};
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let mut new_stmts = vec![new_item];
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new_stmts.append(&mut stmts);
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let new_block = syn::Block { brace_token: block.brace_token, stmts: new_stmts };
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i.block = Box::new(new_block);
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i
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}
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}
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#[proc_macro_attribute]
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pub fn recursive_descent_method(attr: TokenStream, item: TokenStream) -> TokenStream {
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let input: syn::ItemFn = parse_macro_input!(item as syn::ItemFn);
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let mut folder = RecursiveDescentFn {};
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let output = folder.fold_item_fn(input);
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TokenStream::from(quote!(#output))
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}
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