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extern crate proc_macro;
#[macro_use]
extern crate syn;
#[macro_use]
extern crate quote;
use self::proc_macro::TokenStream;
use syn::{
fold::Fold,
parse::{Parse, ParseStream, Result as ParseResult},
punctuated::Punctuated,
Block, FnDecl, ItemFn, LitStr,
};
struct Args {
roles: Vec<String>,
}
impl Parse for Args {
fn parse(input: ParseStream) -> ParseResult<Self> {
let roles = Punctuated::<LitStr, Token![,]>::parse_terminated(input)?;
Ok(Args {
roles: roles.iter().map(|lit| lit.value()).collect(),
})
}
}
impl Fold for Args {
fn fold_fn_decl(&mut self, mut i: FnDecl) -> FnDecl {
i.inputs.push(parse_quote!(user_roles: UserRoles));
i
}
fn fold_block(&mut self, i: Block) -> Block {
let roles = &self.roles; parse_quote!({
if user_roles.has_roles(&[#(#roles),*]) {
#i } else {
Err(Status::Unauthorized.into()) }
})
}
}
#[proc_macro_attribute]
pub fn auth(args: TokenStream, input: TokenStream) -> TokenStream {
let mut args = parse_macro_input!(args as Args);
let input = parse_macro_input!(input as ItemFn);
let output = args.fold_item_fn(input);
TokenStream::from(quote!(#output))
}