src/doc/book/listings/ch19-advanced-features/no-listing-21-pancakes/hello_macro/hello_macro_derive/src/lib.rs

   1 use proc_macro::TokenStream;
   2 use quote::quote;
   3 use syn;
   4
   5 #[proc_macro_derive(HelloMacro)]
   6 pub fn hello_macro_derive(input: TokenStream) -> TokenStream {
   7     // Construct a representation of Rust code as a syntax tree
   8     // that we can manipulate
   9     let ast = syn::parse(input).unwrap();
  10
  11     // Build the trait implementation
  12     impl_hello_macro(&ast)
  13 }
  14
  15 fn impl_hello_macro(ast: &syn::DeriveInput) -> TokenStream {
  16     let name = &ast.ident;
  17     let gen = quote! {
  18         impl HelloMacro for #name {
  19             fn hello_macro() {
  20                 println!("Hello, Macro! My name is {}!", stringify!(#name));
  21             }
  22         }
  23     };
  24     gen.into()
  25 }