introspection_derive/
lib.rs

1extern crate proc_macro;
2extern crate syn;
3#[macro_use]
4extern crate quote;
5extern crate introspection;
6
7use proc_macro::TokenStream;
8
9#[proc_macro_derive(Introspection)]
10pub fn introspection(input: TokenStream) -> TokenStream {
11    // Construct a string representation of the type definition
12    let s = input.to_string();
13
14    // Parse the string representation
15    let ast = syn::parse_derive_input(&s).unwrap();
16
17    // Build the impl
18    let gen = impl_introspection(&ast);
19
20    // Return the generated impl
21    gen.parse().unwrap()
22}
23
24fn get_entity_type(ast: &syn::DeriveInput) -> introspection::Type {
25    if let syn::Body::Enum(_) = ast.body {
26        return introspection::Type::Enum;
27    }
28    introspection::Type::Struct
29}
30
31fn get_fields(ast: &syn::DeriveInput) -> Vec<String> {
32    match ast.body {
33        syn::Body::Enum(ref variants) => {
34            variants.iter().map(|v| v.ident.clone().to_string()).collect::<Vec<String>>()
35        },
36        syn::Body::Struct(ref variant_data) => {
37            variant_data.fields().iter().map(|f| {
38                if let Some(ref id) = f.ident {
39                    id.clone().to_string()
40                } else {
41                    String::default()
42                }
43            }).collect::<Vec<String>>()
44        },
45    }
46}
47
48fn quote_fields(fields: Vec<String>) -> quote::Tokens {
49    quote! {
50        vec![
51            #(#fields.to_owned(),)*
52        ]
53    }
54}
55
56fn impl_introspection(ast: &syn::DeriveInput) -> quote::Tokens {
57    let name = &ast.ident;
58    let vis = introspection::Visibility::from(ast.vis.clone());
59    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
60    let entity_type = get_entity_type(&ast);
61    let fields = quote_fields(get_fields(&ast));
62    quote! {
63        impl #impl_generics introspection::Introspection for #name #ty_generics #where_clause {
64            fn introspection() -> introspection::IntrospectionInfo {
65                introspection::IntrospectionInfo {
66                    ident: stringify!(#name).to_owned(),
67                    visibility: #vis,
68                    entity_type: #entity_type,
69                    fields: #fields,
70                }
71            }
72        }
73    }
74}
introspection_derive/lib.rs

introspection_derive/
lib.rs
