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extern crate proc_macro;
extern crate syn;
use proc_macro::TokenStream;
use quote::ToTokens;
use syn::*;
extern crate quote;
use syn::fold::Fold;
#[proc_macro_attribute]
pub fn greenify(_args: TokenStream, input: TokenStream) -> TokenStream {
let input: ItemFn = parse_macro_input!(input as ItemFn);
let new_stmt: Stmt = parse(TokenStream::from(quote::quote!(greenie::thread_yield();))).unwrap();
let f = GreenFolder::new(new_stmt).fold_item_fn(input);
TokenStream::from(f.to_token_stream())
}
struct GreenFolder {
#[allow(dead_code)]
stmt: Stmt,
}
impl GreenFolder {
pub fn new(s: Stmt) -> GreenFolder {
Self { stmt: s }
}
fn gen_block(&self, old_block: &Block) -> Block {
parse_quote! {
{
greenie::yield_thread();
#old_block
}
}
}
}
impl syn::fold::Fold for GreenFolder {
fn fold_expr(&mut self, mut expr: Expr) -> Expr {
let new_expr = match expr {
Expr::Loop(ExprLoop {
body,
attrs,
label,
loop_token,
}) => Expr::Loop(ExprLoop {
body: self.gen_block(&body),
attrs,
label,
loop_token,
}),
Expr::ForLoop(ExprForLoop { ref mut body, .. }) => {
*body = self.gen_block(&body);
expr
}
Expr::While(ExprWhile { ref mut body, .. }) => {
*body = self.gen_block(&body);
expr
}
Expr::Closure(ExprClosure { ref mut body, .. }) => {
*body = Box::new(self.fold_expr(*body.clone()));
expr
}
_ => syn::fold::fold_expr(self, expr),
};
new_expr
}
fn fold_block(&mut self, i: Block) -> Block {
self.gen_block(&i)
}
fn fold_item_fn(&mut self, mut i: ItemFn) -> ItemFn {
let mut stmts = vec![];
for stmt in i.block.stmts.iter() {
stmts.push(syn::fold::fold_stmt(self, stmt.clone()));
}
i.block.stmts = stmts;
i.block = Box::new(self.gen_block(&*i.block));
i
}
}