nom_tracable_macros/
lib.rs

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1#![recursion_limit = "128"]
2
3extern crate proc_macro;
4
5use crate::proc_macro::TokenStream;
6use quote::ToTokens;
7use syn::{self, parse_macro_input, parse_quote, AttributeArgs, FnArg, ItemFn, Stmt};
8
9#[proc_macro_attribute]
10pub fn tracable_parser(attr: TokenStream, item: TokenStream) -> TokenStream {
11    let attr = parse_macro_input!(attr as AttributeArgs);
12    let item = parse_macro_input!(item as ItemFn);
13    impl_tracable_parser(&attr, &item)
14}
15
16fn impl_tracable_parser(_attr: &AttributeArgs, item: &ItemFn) -> TokenStream {
17    let default = impl_tracable_parser_default(&item);
18    let trace = impl_tracable_parser_trace(&item);
19
20    let mut item = item.clone();
21
22    item.block.stmts.clear();
23    item.block.stmts.push(default);
24    item.block.stmts.push(trace);
25
26    item.into_token_stream().into()
27}
28
29fn impl_tracable_parser_default(item: &ItemFn) -> Stmt {
30    let body = item.block.as_ref();
31    parse_quote! {
32        #[cfg(not(feature = "trace"))]
33        {
34            #body
35        }
36    }
37}
38
39fn impl_tracable_parser_trace(item: &ItemFn) -> Stmt {
40    let ident = &item.sig.ident;
41
42    let input = if let Some(x) = &item.sig.inputs.first() {
43        match x {
44            FnArg::Typed(arg) => &arg.pat,
45            _ => panic!("function with #[tracable_parser] must have an argument"),
46        }
47    } else {
48        panic!("function with #[tracable_parser] must have an argument");
49    };
50
51    let body = item.block.as_ref();
52
53    parse_quote! {
54        #[cfg(feature = "trace")]
55        {
56            let (depth, #input) = nom_tracable::forward_trace(#input, stringify!(#ident));
57
58            let body_ret = {
59                let body = || { #body };
60                body()
61            };
62
63            nom_tracable::backward_trace(body_ret, stringify!(#ident), depth)
64        }
65    }
66}
nom_tracable_macros/lib.rs

nom_tracable_macros/
lib.rs
