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refactor: Make consumer tree traversals iterative #717

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228 changes: 172 additions & 56 deletions consumer/src/node.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ use accesskit::{
};
use alloc::{
string::{String, ToString},
vec,
vec::Vec,
};
use core::{fmt, iter::FusedIterator};
Expand Down Expand Up @@ -121,13 +122,13 @@ impl<'a> Node<'a> {
}

pub fn filtered_parent(&self, filter: &impl Fn(&Node) -> FilterResult) -> Option<Node<'a>> {
self.parent().and_then(move |parent| {
if filter(&parent) == FilterResult::Include {
Some(parent)
} else {
parent.filtered_parent(filter)
let mut current = self.parent()?;
loop {
if filter(&current) == FilterResult::Include {
return Some(current);
}
})
current = current.parent()?;
}
}

pub fn parent_and_index(self) -> Option<(Node<'a>, usize)> {
Expand Down Expand Up @@ -283,13 +284,16 @@ impl<'a> Node<'a> {
}

pub fn is_descendant_of(&self, ancestor: &Node) -> bool {
if self.id() == ancestor.id() {
return true;
}
if let Some(parent) = self.parent() {
return parent.is_descendant_of(ancestor);
let mut current = *self;
loop {
if current.id() == ancestor.id() {
return true;
}
match current.parent() {
Some(parent) => current = parent,
None => return false,
}
}
false
}

/// Returns the transform defined directly on this node, or the identity
Expand All @@ -303,22 +307,26 @@ impl<'a> Node<'a> {
/// Returns the combined affine transform of this node and its ancestors,
/// up to and including the root of this node's tree.
pub fn transform(&self) -> Affine {
self.parent()
.map_or(Affine::IDENTITY, |parent| parent.transform())
* self.direct_transform()
let mut acc = self.direct_transform();
let mut current = *self;
while let Some(parent) = current.parent() {
acc = parent.direct_transform() * acc;
current = parent;
}
acc
}

pub(crate) fn relative_transform(&self, stop_at: &Node) -> Affine {
let parent_transform = if let Some(parent) = self.parent() {
let mut acc = self.direct_transform();
let mut current = *self;
while let Some(parent) = current.parent() {
if parent.id() == stop_at.id() {
Affine::IDENTITY
} else {
parent.relative_transform(stop_at)
break;
}
} else {
Affine::IDENTITY
};
parent_transform * self.direct_transform()
acc = parent.direct_transform() * acc;
current = parent;
}
acc
}

pub fn raw_bounds(&self) -> Option<Rect> {
Expand Down Expand Up @@ -348,23 +356,37 @@ impl<'a> Node<'a> {
point: Point,
filter: &impl Fn(&Node) -> FilterResult,
) -> Option<(Node<'a>, Point)> {
let filter_result = filter(self);

if filter_result == FilterResult::ExcludeSubtree {
return None;
// A node's `Test` frame is pushed before its children, then children in
// forward order, so that children are searched last-to-first and the
// node's own bounds are tested only after all descendants miss.
enum Frame<'n> {
Visit(Node<'n>, Point),
Test(Node<'n>, Point),
}

for child in self.children().rev() {
let point = child.direct_transform().inverse() * point;
if let Some(result) = child.hit_test(point, filter) {
return Some(result);
}
}

if filter_result == FilterResult::Include {
if let Some(rect) = &self.raw_bounds() {
if rect.contains(point) {
return Some((*self, point));
let mut stack = Vec::with_capacity(self.children().len() + 1);
stack.push(Frame::Visit(*self, point));
while let Some(frame) = stack.pop() {
match frame {
Frame::Test(node, point) => {
if let Some(rect) = &node.raw_bounds() {
if rect.contains(point) {
return Some((node, point));
}
}
}
Frame::Visit(node, point) => {
let filter_result = filter(&node);
if filter_result == FilterResult::ExcludeSubtree {
continue;
}
if filter_result == FilterResult::Include {
stack.push(Frame::Test(node, point));
}
for child in node.children() {
let child_point = child.direct_transform().inverse() * point;
stack.push(Frame::Visit(child, child_point));
}
}
}
}
Expand Down Expand Up @@ -1000,15 +1022,16 @@ impl<'a> Node<'a> {
&self,
filter: &impl Fn(&Node) -> FilterResult,
) -> Option<Node<'a>> {
for child in self.children() {
let result = filter(&child);
if result == FilterResult::Include {
return Some(child);
}
if result == FilterResult::ExcludeNode {
if let Some(descendant) = child.first_filtered_child(filter) {
return Some(descendant);
let mut stack = vec![self.children()];
while let Some(iter) = stack.last_mut() {
if let Some(child) = iter.next() {
match filter(&child) {
FilterResult::Include => return Some(child),
FilterResult::ExcludeNode => stack.push(child.children()),
FilterResult::ExcludeSubtree => {}
}
} else {
stack.pop();
}
}
None
Expand All @@ -1018,15 +1041,16 @@ impl<'a> Node<'a> {
&self,
filter: &impl Fn(&Node) -> FilterResult,
) -> Option<Node<'a>> {
for child in self.children().rev() {
let result = filter(&child);
if result == FilterResult::Include {
return Some(child);
}
if result == FilterResult::ExcludeNode {
if let Some(descendant) = child.last_filtered_child(filter) {
return Some(descendant);
let mut stack = vec![self.children().rev()];
while let Some(iter) = stack.last_mut() {
if let Some(child) = iter.next() {
match filter(&child) {
FilterResult::Include => return Some(child),
FilterResult::ExcludeNode => stack.push(child.children().rev()),
FilterResult::ExcludeSubtree => {}
}
} else {
stack.pop();
}
}
None
Expand Down Expand Up @@ -1085,8 +1109,8 @@ impl<W: fmt::Write> fmt::Write for SpacePrefixingWriter<W> {
#[cfg(test)]
mod tests {
use accesskit::{
Action, Node, NodeId, Point, Rect, Role, TextDirection, TextPosition, TextSelection, Tree,
TreeId, TreeUpdate,
Action, Affine, Node, NodeId, Point, Rect, Role, TextDirection, TextPosition,
TextSelection, Tree, TreeId, TreeUpdate, Vec2,
};
use alloc::vec;

Expand Down Expand Up @@ -1405,6 +1429,98 @@ mod tests {
);
}

#[test]
fn first_filtered_child() {
let tree = test_tree();
assert_eq!(
Some(PARAGRAPH_0_ID),
tree.state()
.root()
.first_filtered_child(&test_tree_filter)
.map(|node| node.id().to_components().0)
);
// Descends through ExcludeNode children (EMPTY_CONTAINER_3_0 then into
// LINK_3_1) to find the first included descendant.
assert_eq!(
Some(LABEL_3_1_0_ID),
tree.state()
.node_by_id(nid(PARAGRAPH_3_IGNORED_ID))
.unwrap()
.first_filtered_child(&test_tree_filter)
.map(|node| node.id().to_components().0)
);
assert!(
tree.state()
.node_by_id(nid(LABEL_2_0_ID))
.unwrap()
.first_filtered_child(&test_tree_filter)
.is_none()
);
}

#[test]
fn last_filtered_child() {
let tree = test_tree();
// Reverse order: skips the trailing ExcludeNode container, returns the
// included button.
assert_eq!(
Some(BUTTON_3_2_ID),
tree.state()
.node_by_id(nid(PARAGRAPH_3_IGNORED_ID))
.unwrap()
.last_filtered_child(&test_tree_filter)
.map(|node| node.id().to_components().0)
);
assert!(
tree.state()
.node_by_id(nid(LABEL_2_0_ID))
.unwrap()
.last_filtered_child(&test_tree_filter)
.is_none()
);
}

#[test]
fn transform() {
let tree = test_tree();
assert_eq!(Affine::IDENTITY, tree.state().root().transform());
// PARAGRAPH_1_IGNORED defines a translation.
let expected = Affine::translate(Vec2::new(10.0, 40.0));
assert_eq!(
expected,
tree.state()
.node_by_id(nid(PARAGRAPH_1_IGNORED_ID))
.unwrap()
.transform()
);
// LABEL_1_1 inherits its parent's translation (it has none of its own).
assert_eq!(
expected,
tree.state()
.node_by_id(nid(LABEL_1_1_ID))
.unwrap()
.transform()
);
}

#[test]
fn relative_transform() {
let tree = test_tree();
let label = tree.state().node_by_id(nid(LABEL_1_1_ID)).unwrap();
let paragraph = tree
.state()
.node_by_id(nid(PARAGRAPH_1_IGNORED_ID))
.unwrap();
// Relative to its immediate (transformed) parent: identity, since the
// parent's transform is excluded.
assert_eq!(Affine::IDENTITY, label.relative_transform(&paragraph));
// Relative to the root: includes the parent's translation.
assert_eq!(
Affine::translate(Vec2::new(10.0, 40.0)),
label.relative_transform(&tree.state().root())
);
}

#[test]
fn no_label_or_labelled_by() {
let update = TreeUpdate {
Expand Down
77 changes: 35 additions & 42 deletions consumer/src/tree.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -348,29 +348,25 @@ impl State {
changes: &mut Option<&mut InternalChanges>,
seen_child_ids: &HashSet<NodeId>,
new_tree_root: Option<NodeId>,
id: NodeId,
root: NodeId,
) {
if let Some(changes) = changes {
changes.removed_node_ids.insert(id);
}
let node = nodes.remove(&id).unwrap();
if let Some(subtree_id) = node.data.tree_id() {
grafts_to_remove.insert(subtree_id);
}
let (_, tree_index) = id.to_components();
for child_id in node.data.children().iter() {
let child_node_id = NodeId::new(*child_id, tree_index);
if !seen_child_ids.contains(&child_node_id)
&& new_tree_root != Some(child_node_id)
{
traverse_unreachable(
nodes,
grafts_to_remove,
changes,
seen_child_ids,
new_tree_root,
child_node_id,
);
let mut stack = vec![root];
while let Some(id) = stack.pop() {
if let Some(changes) = changes {
changes.removed_node_ids.insert(id);
}
let node = nodes.remove(&id).unwrap();
if let Some(subtree_id) = node.data.tree_id() {
grafts_to_remove.insert(subtree_id);
}
let (_, tree_index) = id.to_components();
for child_id in node.data.children().iter() {
let child_node_id = NodeId::new(*child_id, tree_index);
if !seen_child_ids.contains(&child_node_id)
&& new_tree_root != Some(child_node_id)
{
stack.push(child_node_id);
}
}
}
}
Expand All @@ -392,28 +388,25 @@ impl State {
subtrees_to_remove: &mut Vec<TreeId>,
subtrees_queued: &mut HashSet<TreeId>,
changes: &mut Option<&mut InternalChanges>,
id: NodeId,
root: NodeId,
) {
let Some(node) = nodes.remove(&id) else {
return;
};
if let Some(changes) = changes {
changes.removed_node_ids.insert(id);
}
if let Some(nested_subtree_id) = node.data.tree_id() {
if subtrees_queued.insert(nested_subtree_id) {
subtrees_to_remove.push(nested_subtree_id);
let mut stack = vec![root];
while let Some(id) = stack.pop() {
let Some(node) = nodes.remove(&id) else {
continue;
};
if let Some(changes) = changes {
changes.removed_node_ids.insert(id);
}
if let Some(nested_subtree_id) = node.data.tree_id() {
if subtrees_queued.insert(nested_subtree_id) {
subtrees_to_remove.push(nested_subtree_id);
}
}
let (_, tree_index) = id.to_components();
for child_id in node.data.children().iter() {
stack.push(NodeId::new(*child_id, tree_index));
}
}
let (_, tree_index) = id.to_components();
for child_id in node.data.children().iter() {
traverse_subtree(
nodes,
subtrees_to_remove,
subtrees_queued,
changes,
NodeId::new(*child_id, tree_index),
);
}
}

Expand Down
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