1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
use proc_macro2::TokenStream;
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;
use syn::{parse_macro_input, Data, DeriveInput, Fields};
#[proc_macro_derive(Decode)]
pub fn decode_macro(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let name = input.ident;
let expr = gen_expr(&input.data);
let expanded = quote! {
impl ::ts3::Decode for #name {
type Error = ::ts3::Error;
fn decode(buf: &[u8]) -> ::std::result::Result<Self, Self::Error> {
let mut st = #name::default();
for s in buf.split(|c| *c == b' ') {
let parts: ::std::vec::Vec<&[u8]> = s.splitn(2, |c| *c == b'=').collect();
match *parts.get(0).unwrap() {
#expr
_ => (),
}
}
Ok(st)
}
}
};
proc_macro::TokenStream::from(expanded)
}
fn gen_expr(data: &Data) -> TokenStream {
match *data {
Data::Struct(ref data) => match data.fields {
Fields::Named(ref fields) => {
let recurse = fields.named.iter().map(|f| {
let name = &f.ident;
let ty = &f.ty;
let bytes = name.clone().unwrap().to_string().as_bytes().to_owned();
let bytes_fmt = bin_to_tokens(&bytes);
quote_spanned! {f.span()=>
#bytes_fmt => {
st.#name = match <#ty>::decode(match parts.get(1) {
Some(val) => val,
None => continue,
}) {
Ok(val) => val,
Err(err) => return Err(err.into()),
}
},
}
});
quote! {
#(#recurse)*
}
}
_ => unimplemented!(),
},
_ => unimplemented!(),
}
}
fn bin_to_tokens(slice: &[u8]) -> TokenStream {
let recurse = slice.iter().map(|b| quote!(#b));
quote! {
[#(#recurse),*]
}
}