make_singleton_derive/
lib.rs

1extern crate proc_macro;
2extern crate syn;
3#[macro_use]
4extern crate quote;
5
6use proc_macro::TokenStream;
7
8#[proc_macro_derive(MakeSingleton)]
9pub fn hello_world(input: TokenStream) -> TokenStream {
10    // Construct a string representation of the type definition
11    let s = input.to_string();
12
13    // Parse the string representation
14    let ast = syn::parse_derive_input(&s).unwrap();
15
16    // Build the impl
17    let gen = impl_make_singelton(&ast);
18
19    // Return the generated impl
20    gen.parse().unwrap()
21}
22
23fn impl_make_singelton(ast: &syn::DeriveInput) -> quote::Tokens {
24    let name = &ast.ident;
25    quote! {
26
27        pub trait MakeSingletonTrait<T> {
28            fn instance_thread_safe() -> Arc<Mutex<T>>;
29            fn instance_ptr() -> *const T;
30        }
31
32
33        impl MakeSingletonTrait<#name> for #name {
34            fn instance_thread_safe() -> Arc<Mutex<#name>> {
35                unsafe {
36                    static mut INSTANCE: *const Arc<Mutex<#name>> = 0 as *const Arc<Mutex<#name>>;
37                    static ONCE: Once = Once::new();
38
39                    ONCE.call_once(||{
40                        let tmp_instance = Arc::new(Mutex::new(#name{}));
41                        INSTANCE = mem::transmute(#name::instance_ptr());
42                    });
43
44                    (*INSTANCE).clone()
45                }
46            }
47
48            fn instance_ptr() -> *const #name {
49                unsafe {
50                    static mut INSTANCE: *const #name = 0 as *const #name;
51                    static ONCE: Once = Once::new();
52
53                    ONCE.call_once(||{
54                        let tmp_instance = #name{};
55                        INSTANCE = mem::transmute(Box::new(tmp_instance));
56                    });
57                    INSTANCE
58                }
59            }
60        }
61    }
62}
make_singleton_derive/lib.rs

make_singleton_derive/
lib.rs
