51 lines
1.3 KiB
Rust
51 lines
1.3 KiB
Rust
#![feature(box_patterns)]
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#![recursion_limit="128"]
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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 ref ident = i.ident;
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let new_block: syn::Block = parse_quote! {
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{
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let next_token_before_parse = self.token_handler.peek();
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let record = ParseRecord {
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production_name: stringify!(#ident).to_string(),
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next_token: format!("{}", next_token_before_parse.to_string_with_metadata()),
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level: self.parse_level,
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};
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self.parse_level += 1;
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self.parse_record.push(record);
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let result = { #block };
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if self.parse_level != 0 {
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self.parse_level -= 1;
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}
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result
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}
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};
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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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