schala/schala-codegen/src/lib.rs

#![feature(proc_macro)]
extern crate proc_macro;
#[macro_use]
extern crate syn;
#[macro_use]
extern crate quote;

use proc_macro::TokenStream;
use syn::{Expr, Lit, ExprLit};
use syn::punctuated::Punctuated;
use syn::synom::Synom;


fn get_string_args(input: Expr) -> Vec<String> {
  let mut contained_strings = Vec::new();
  match input {
    Expr::Array(array) => {
      for item in array.elems {
        if let Expr::Lit(ExprLit { lit: Lit::Str(s), ..}) = item {
          contained_strings.push(s.value());
        } else {
          panic!("Non-string-literal input to compiler_pass_sequence");
        }
      }
    },
    _ => panic!("Non-array input to compiler_pass_sequence"),
  }
  contained_strings
}

#[proc_macro]
pub fn compiler_pass_sequence(input: TokenStream) -> TokenStream {
  /*
  for token_tree in input {
    //println!("ITEM: {:?}", token_tree.kind);
    match token_tree.kind {
      TokenNode::Literal(l) => println!("{:?}", l),
      _ => ()
    }
  }
  */

  let input: Expr = syn::parse(input).unwrap();
  let stages = get_string_args(input);
  let from_macro = format!("{:?}", stages);

  let output = quote! {
    fn new_execute(&mut self, input: &str, _options: &EvalOptions) -> FinishedComputation {
      let evaluation = UnfinishedComputation::default();
      evaluation.output(Err(#from_macro.to_string()))
    }
  };
  output.into()
}

/* #[compiler_pass(<name of pass>*/
#[proc_macro_attribute]
pub fn compiler_pass(metadata: TokenStream, function: TokenStream) -> TokenStream {
  //println!("FROM MACRO: {}", function);
  println!("Compiler pass metadata: {}", metadata);
  function
}

#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
        assert_eq!(2 + 2, 4);
    }
}


/* in Rocket
 *

 #[get("/")]
 fn hi() -> &'static str {
 "hello"
 }

 GETS MAPPED TO:

 static hi_info = RouteInfo {
  name: "hi",
  method: Method::Get,
  path: "/",
  handler: hi_route,
  }

  fn hi_route(req: &Request) -> Outcome {
  let responder = hi();
  Outcome::from(req, responder);
  }

 */