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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Implements sequential traversal over the DOM tree.
#![deny(missing_docs)]
use context::{StyleContext, ThreadLocalStyleContext};
use dom::{TElement, TNode};
use std::collections::VecDeque;
use time;
use traversal::{DomTraversal, PerLevelTraversalData, PreTraverseToken};
struct WorkItem<N: TNode>(N, usize);
/// Do a sequential DOM traversal for layout or styling, generic over `D`.
pub fn traverse_dom<E, D>(traversal: &D,
root: E,
token: PreTraverseToken)
where E: TElement,
D: DomTraversal<E>,
{
let dump_stats = traversal.shared_context().options.dump_style_statistics;
let start_time = if dump_stats { Some(time::precise_time_s()) } else { None };
debug_assert!(!traversal.is_parallel());
debug_assert!(token.should_traverse());
let mut discovered = VecDeque::<WorkItem<E::ConcreteNode>>::with_capacity(16);
let mut tlc = ThreadLocalStyleContext::new(traversal.shared_context());
let mut context = StyleContext {
shared: traversal.shared_context(),
thread_local: &mut tlc,
};
let root_depth = root.depth();
if token.traverse_unstyled_children_only() {
for kid in root.as_node().traversal_children() {
if kid.as_element().map_or(false, |el| el.get_data().is_none()) {
discovered.push_back(WorkItem(kid, root_depth + 1));
}
}
} else {
discovered.push_back(WorkItem(root.as_node(), root_depth));
}
// Process the nodes breadth-first, just like the parallel traversal does.
// This helps keep similar traversal characteristics for the style sharing
// cache.
while let Some(WorkItem(node, depth)) = discovered.pop_front() {
let mut children_to_process = 0isize;
let traversal_data = PerLevelTraversalData { current_dom_depth: depth };
traversal.process_preorder(&traversal_data, &mut context, node, |n| {
children_to_process += 1;
discovered.push_back(WorkItem(n, depth + 1));
});
traversal.handle_postorder_traversal(&mut context, root.as_node().opaque(),
node, children_to_process);
}
// Dump statistics to stdout if requested.
if dump_stats {
context.thread_local.statistics.finish(traversal, start_time.unwrap());
if context.thread_local.statistics.is_large_traversal() {
println!("{}", context.thread_local.statistics);
}
}
}
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