nom::preceded!

macro_rules! preceded(
  ($i:expr, $submac:ident!( $($args:tt)* ), $submac2:ident!( $($args2:tt)* )) => (
    {
      match $submac!($i, $($args)*) {
        $crate::IResult::Error(a)      => $crate::IResult::Error(a),
        $crate::IResult::Incomplete(i) => $crate::IResult::Incomplete(i),
        $crate::IResult::Done(i1,_)    => {
          match $submac2!(i1, $($args2)*) {
            $crate::IResult::Error(a)      => $crate::IResult::Error(a),
            $crate::IResult::Incomplete(i) => $crate::IResult::Incomplete(i),
            $crate::IResult::Done(i2,o2)   => {
              $crate::IResult::Done(i2, o2)
            }
          }
        },
      }
    }
  );

  ($i:expr, $submac:ident!( $($args:tt)* ), $g:expr) => (
    preceded!($i, $submac!($($args)*), call!($g));
  );

  ($i:expr, $f:expr, $submac:ident!( $($args:tt)* )) => (
    preceded!($i, call!($f), $submac!($($args)*));
  );

  ($i:expr, $f:expr, $g:expr) => (
    preceded!($i, call!($f), call!($g));
  );
);

preceded!(I -> IResult<I,T>, I -> IResult<I,O>) => I -> IResult<I, O> preceded(opening, X) returns X