more efficient preorder DOM traversals

This commit is contained in:
Clark Gaebel 2014-10-20 14:36:31 -07:00
parent 156ca98236
commit a5bb2f299f
3 changed files with 94 additions and 97 deletions

View file

@ -381,6 +381,7 @@ impl<'a> PrivateNodeHelpers for JSRef<'a, Node> {
pub trait NodeHelpers<'a> {
fn ancestors(self) -> AncestorIterator<'a>;
fn children(self) -> AbstractNodeChildrenIterator<'a>;
fn rev_children(self) -> ReverseChildrenIterator<'a>;
fn child_elements(self) -> ChildElementIterator<'a>;
fn following_siblings(self) -> AbstractNodeChildrenIterator<'a>;
fn is_in_doc(self) -> bool;
@ -441,7 +442,6 @@ pub trait NodeHelpers<'a> {
fn debug_str(self) -> String;
fn traverse_preorder(self) -> TreeIterator<'a>;
fn sequential_traverse_postorder(self) -> TreeIterator<'a>;
fn inclusively_following_siblings(self) -> AbstractNodeChildrenIterator<'a>;
fn to_trusted_node_address(self) -> TrustedNodeAddress;
@ -658,21 +658,12 @@ impl<'a> NodeHelpers<'a> for JSRef<'a, Node> {
/// Iterates over this node and all its descendants, in preorder.
fn traverse_preorder(self) -> TreeIterator<'a> {
let mut nodes = vec!();
gather_abstract_nodes(self, &mut nodes, false);
TreeIterator::new(nodes)
}
/// Iterates over this node and all its descendants, in postorder.
fn sequential_traverse_postorder(self) -> TreeIterator<'a> {
let mut nodes = vec!();
gather_abstract_nodes(self, &mut nodes, true);
TreeIterator::new(nodes)
TreeIterator::new(self)
}
fn inclusively_following_siblings(self) -> AbstractNodeChildrenIterator<'a> {
AbstractNodeChildrenIterator {
current_node: Some(self.clone()),
current: Some(self.clone()),
}
}
@ -682,7 +673,7 @@ impl<'a> NodeHelpers<'a> for JSRef<'a, Node> {
fn following_siblings(self) -> AbstractNodeChildrenIterator<'a> {
AbstractNodeChildrenIterator {
current_node: self.next_sibling().root().map(|next| next.clone()),
current: self.next_sibling().root().map(|next| next.clone()),
}
}
@ -774,7 +765,13 @@ impl<'a> NodeHelpers<'a> for JSRef<'a, Node> {
fn children(self) -> AbstractNodeChildrenIterator<'a> {
AbstractNodeChildrenIterator {
current_node: self.first_child.get().map(|node| (*node.root()).clone()),
current: self.first_child.get().map(|node| (*node.root()).clone()),
}
}
fn rev_children(self) -> ReverseChildrenIterator<'a> {
ReverseChildrenIterator {
current: self.last_child.get().map(|node| *node.root().deref()),
}
}
@ -974,15 +971,25 @@ pub type ChildElementIterator<'a> = Map<'a, JSRef<'a, Node>,
Filter<'a, JSRef<'a, Node>, AbstractNodeChildrenIterator<'a>>>;
pub struct AbstractNodeChildrenIterator<'a> {
current_node: Option<JSRef<'a, Node>>,
current: Option<JSRef<'a, Node>>,
}
impl<'a> Iterator<JSRef<'a, Node>> for AbstractNodeChildrenIterator<'a> {
fn next(&mut self) -> Option<JSRef<'a, Node>> {
let node = self.current_node.clone();
self.current_node = node.clone().and_then(|node| {
node.next_sibling().map(|node| (*node.root()).clone())
});
let node = self.current;
self.current = node.and_then(|node| node.next_sibling().map(|node| *node.root().deref()));
node
}
}
pub struct ReverseChildrenIterator<'a> {
current: Option<JSRef<'a, Node>>,
}
impl<'a> Iterator<JSRef<'a, Node>> for ReverseChildrenIterator<'a> {
fn next(&mut self) -> Option<JSRef<'a, Node>> {
let node = self.current;
self.current = node.and_then(|node| node.prev_sibling().map(|node| *node.root().deref()));
node
}
}
@ -993,43 +1000,32 @@ pub struct AncestorIterator<'a> {
impl<'a> Iterator<JSRef<'a, Node>> for AncestorIterator<'a> {
fn next(&mut self) -> Option<JSRef<'a, Node>> {
if self.current.is_none() {
return None;
}
// FIXME: Do we need two clones here?
let x = self.current.as_ref().unwrap().clone();
self.current = x.parent_node().map(|node| (*node.root()).clone());
Some(x)
let node = self.current;
self.current = node.and_then(|node| node.parent_node().map(|node| *node.root().deref()));
node
}
}
// FIXME: Do this without precomputing a vector of refs.
// Easy for preorder; harder for postorder.
pub struct TreeIterator<'a> {
nodes: Vec<JSRef<'a, Node>>,
index: uint,
stack: Vec<JSRef<'a, Node>>,
}
impl<'a> TreeIterator<'a> {
fn new(nodes: Vec<JSRef<'a, Node>>) -> TreeIterator<'a> {
fn new(root: JSRef<'a, Node>) -> TreeIterator<'a> {
let mut stack = vec!();
stack.push(root);
TreeIterator {
nodes: nodes,
index: 0,
stack: stack,
}
}
}
impl<'a> Iterator<JSRef<'a, Node>> for TreeIterator<'a> {
fn next(&mut self) -> Option<JSRef<'a, Node>> {
if self.index >= self.nodes.len() {
None
} else {
let v = self.nodes[self.index];
let v = v.clone();
self.index += 1;
Some(v)
}
let ret = self.stack.pop();
ret.map(|node| self.stack.extend(node.rev_children()));
ret
}
}
@ -1116,18 +1112,6 @@ impl<'a> Iterator<JSRef<'a, Node>> for NodeIterator {
}
}
fn gather_abstract_nodes<'a>(cur: JSRef<'a, Node>, refs: &mut Vec<JSRef<'a, Node>>, postorder: bool) {
if !postorder {
refs.push(cur.clone());
}
for kid in cur.children() {
gather_abstract_nodes(kid, refs, postorder)
}
if postorder {
refs.push(cur.clone());
}
}
/// Specifies whether children must be recursively cloned or not.
#[deriving(PartialEq)]
pub enum CloneChildrenFlag {
@ -2209,6 +2193,16 @@ impl<'a> style::TNode<'a, JSRef<'a, Element>> for JSRef<'a, Node> {
first_child(self).map(|node| *node.root())
}
fn last_child(self) -> Option<JSRef<'a, Node>> {
// FIXME(zwarich): Remove this when UFCS lands and there is a better way
// of disambiguating methods.
fn last_child<'a, T: NodeHelpers<'a>>(this: T) -> Option<Temporary<Node>> {
this.last_child()
}
last_child(self).map(|node| *node.root())
}
fn prev_sibling(self) -> Option<JSRef<'a, Node>> {
// FIXME(zwarich): Remove this when UFCS lands and there is a better way
// of disambiguating methods.