55 lines
1.4 KiB
Rust
55 lines
1.4 KiB
Rust
#![feature(box_patterns)]
|
|
#![recursion_limit="128"]
|
|
extern crate proc_macro;
|
|
#[macro_use]
|
|
extern crate quote;
|
|
#[macro_use]
|
|
extern crate syn;
|
|
|
|
use self::proc_macro::TokenStream;
|
|
use self::syn::fold::Fold;
|
|
|
|
struct RecursiveDescentFn {
|
|
}
|
|
|
|
impl Fold for RecursiveDescentFn {
|
|
fn fold_item_fn(&mut self, mut i: syn::ItemFn) -> syn::ItemFn {
|
|
let box block = i.block;
|
|
let ref ident = i.ident;
|
|
|
|
let new_block: syn::Block = parse_quote! {
|
|
{
|
|
let next_token = self.peek_with_token_offset();
|
|
let record = ParseRecord {
|
|
production_name: stringify!(#ident).to_string(),
|
|
next_token: format!("{}", next_token.to_string_with_metadata()),
|
|
level: self.parse_level,
|
|
};
|
|
self.parse_level += 1;
|
|
self.parse_record.push(record);
|
|
let result = { #block };
|
|
|
|
if self.parse_level != 0 {
|
|
self.parse_level -= 1;
|
|
}
|
|
match result {
|
|
Err(ParseError { token: None, msg }) =>
|
|
Err(ParseError { token: Some(next_token), msg }),
|
|
_ => result
|
|
}
|
|
}
|
|
};
|
|
i.block = Box::new(new_block);
|
|
i
|
|
}
|
|
}
|
|
|
|
#[proc_macro_attribute]
|
|
pub fn recursive_descent_method(_attr: TokenStream, item: TokenStream) -> TokenStream {
|
|
|
|
let input: syn::ItemFn = parse_macro_input!(item as syn::ItemFn);
|
|
let mut folder = RecursiveDescentFn {};
|
|
let output = folder.fold_item_fn(input);
|
|
TokenStream::from(quote!(#output))
|
|
}
|