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use {
SyntaxNodeRef,
algo::generate,
};
pub fn preorder<'a>(root: SyntaxNodeRef<'a>) -> impl Iterator<Item = SyntaxNodeRef<'a>> {
walk(root).filter_map(|event| match event {
WalkEvent::Enter(node) => Some(node),
WalkEvent::Exit(_) => None,
})
}
#[derive(Debug, Copy, Clone)]
pub enum WalkEvent<'a> {
Enter(SyntaxNodeRef<'a>),
Exit(SyntaxNodeRef<'a>),
}
pub fn walk<'a>(root: SyntaxNodeRef<'a>) -> impl Iterator<Item = WalkEvent<'a>> {
generate(Some(WalkEvent::Enter(root)), move |pos| {
let next = match *pos {
WalkEvent::Enter(node) => match node.first_child() {
Some(child) => WalkEvent::Enter(child),
None => WalkEvent::Exit(node),
},
WalkEvent::Exit(node) => {
if node == root {
return None;
}
match node.next_sibling() {
Some(sibling) => WalkEvent::Enter(sibling),
None => WalkEvent::Exit(node.parent().unwrap()),
}
}
};
Some(next)
})
}
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