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Simplify walk

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This commit is contained in:
Aleksey Kladov 2018-08-15 21:25:29 +03:00
parent 9f6cf42c5f
commit a7d31b55a4
1 changed files with 13 additions and 20 deletions
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33
crates/libsyntax2/src/algo/walk.rs
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@ -1,4 +1,7 @@
use SyntaxNodeRef;
use {
SyntaxNodeRef,
algo::generate,
};
pub fn preorder<'a>(root: SyntaxNodeRef<'a>) -> impl Iterator<Item = SyntaxNodeRef<'a>> {
walk(root).filter_map(|event| match event {
@ -14,32 +17,22 @@ pub enum WalkEvent<'a> {
}
pub fn walk<'a>(root: SyntaxNodeRef<'a>) -> impl Iterator<Item = WalkEvent<'a>> {
let mut done = false;
::itertools::unfold(WalkEvent::Enter(root), move |pos| {
if done {
return None;
}
let res = *pos;
*pos = match *pos {
generate(Some(WalkEvent::Enter(root)), |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 {
done = true;
WalkEvent::Exit(node)
} else {
match node.next_sibling() {
Some(sibling) => WalkEvent::Enter(sibling),
None => match node.parent() {
Some(node) => WalkEvent::Exit(node),
None => WalkEvent::Exit(node),
},
}
match node.next_sibling() {
Some(sibling) => WalkEvent::Enter(sibling),
None => match node.parent() {
Some(node) => WalkEvent::Exit(node),
None => return None,
},
}
}
};
Some(res)
Some(next)
})
}