treeclimber 0.0.1

An iterator that climbs trees.
Documentation 
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use crate::IndexedClimber;

pub struct Postorder<C: IndexedClimber> {
    climber: C,
    stack: Vec<(C::Index, bool)>,
}
impl<C: IndexedClimber> Postorder<C> {
    pub fn new(climber: C) -> Self {
        let index = climber.index();
        Self {
            climber,
            stack: vec![(index, false)],
        }
    }
}
impl<C: IndexedClimber> Iterator for Postorder<C> {
    type Item = C::Item;
    fn next(&mut self) -> Option<Self::Item> {
        loop {
            let (index, visited) = self.stack.pop()?;
            let item = self.climber.go_to(&index)?;
            if visited {
                return Some(item);
            }
            self.stack.push((index, true));
            self.stack.extend(
                self.climber
                    .child_indices()
                    .rev()
                    .map(|index| (index, false)),
            );
        }
    }
}