Fixed rotater.
use ast::*;
pub fn rotate(rule: Rule) -> Rule {
- match rule {
- Rule { name, ty, expr } => Rule {
- name,
- ty,
+ fn rotate_internal(expr: Expr) -> Expr {
+ match expr {
// TODO: Use box syntax when it gets stabilized.
- expr: expr.map_bottom_up(|expr| match expr {
Expr::Seq(lhs, rhs) => {
let lhs = *lhs;
match lhs {
- Expr::Seq(ll, lr) => Expr::Seq(ll, Box::new(Expr::Seq(lr, rhs))),
+ Expr::Seq(ll, lr) => {
+ rotate_internal(Expr::Seq(ll, Box::new(Expr::Seq(lr, rhs))))
+ },
lhs => Expr::Seq(Box::new(lhs), rhs)
}
}
@@ -27,13 +26,20 @@ pub fn rotate(rule: Rule) -> Rule {
let lhs = *lhs;
match lhs {
Expr::Choice(ll, lr) => {
- Expr::Choice(ll, Box::new(Expr::Choice(lr, rhs)))
+ rotate_internal(Expr::Choice(ll, Box::new(Expr::Choice(lr, rhs))))
}
lhs => Expr::Choice(Box::new(lhs), rhs)
}
}
expr => expr
- })
+ }
+ }
+
+ match rule {
+ Rule { name, ty, expr } => Rule {
+ name,
+ ty,
+ expr: expr.map_top_down(rotate_internal)
}
}
}
