tinymist_derive/
lib.rs

1extern crate proc_macro;
2
3use proc_macro::TokenStream;
4use quote::quote;
5use syn::{parse_macro_input, DeriveInput};
6
7#[proc_macro_derive(BindTyCtx, attributes(bind))]
8pub fn bind_ty_ctx(input: TokenStream) -> TokenStream {
9    // Parse the input tokens into a syntax tree
10    let input = parse_macro_input!(input as DeriveInput);
11
12    // Build the output, possibly using quasi-quotation
13    let expanded = match input.data {
14        syn::Data::Struct(..) => {
15            let name = &input.ident;
16            let bind_name = input
17                .attrs
18                .iter()
19                .find_map(|attr| {
20                    if attr.path().is_ident("bind") {
21                        Some(attr.parse_args::<syn::Expr>().unwrap())
22                    } else {
23                        None
24                    }
25                })
26                .unwrap_or_else(|| {
27                    let t = syn::Ident::new("tyctx", input.ident.span());
28                    syn::parse_quote!(#t)
29                });
30            let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
31
32            quote! {
33                impl #impl_generics TyCtx for #name #ty_generics #where_clause {
34                    fn global_bounds(&self, var: &Interned<TypeVar>, pol: bool) -> Option<DynTypeBounds> {
35                        self.#bind_name.global_bounds(var, pol)
36                    }
37                    fn local_bind_of(&self, var: &Interned<TypeVar>) -> Option<Ty> {
38                        self.#bind_name.local_bind_of(var)
39                    }
40                }
41            }
42        }
43        _ => panic!("only structs are supported"),
44    };
45
46    // Hand the output tokens back to the compiler
47    TokenStream::from(expanded)
48}
49
50#[proc_macro_derive(DeclEnum)]
51pub fn gen_decl_enum(input: TokenStream) -> TokenStream {
52    // In form of
53    // ```
54    // pub enum Decl {
55    //   Sub1(X),
56    //   Sub2(Y),
57    // }
58    // ```
59
60    // Parse the input tokens into a list of variants
61    let input = parse_macro_input!(input as DeriveInput);
62
63    let variants = match input.data {
64        syn::Data::Enum(data) => data.variants,
65        _ => panic!("only enums are supported"),
66    };
67
68    let names = variants.iter().map(|v| &v.ident).collect::<Vec<_>>();
69
70    let input_name = &input.ident;
71
72    let expanded = quote! {
73        impl #input_name {
74            pub fn name(&self) -> &Interned<str> {
75                match self {
76                    #(Self::#names(x) => x.name()),*
77                }
78            }
79
80            pub fn span(&self) -> Span {
81                match self {
82                    #(Self::#names(x) => x.span()),*
83                }
84            }
85        }
86
87        impl fmt::Debug for Decl {
88            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
89                match self {
90                    #(Self::#names(x) => write!(f, concat!(stringify!(#names), "({:?})"), x)),*
91                }
92            }
93        }
94
95    };
96
97    TokenStream::from(expanded)
98}
tinymist_derive/lib.rs

tinymist_derive/
lib.rs
