diff options
Diffstat (limited to 'servo/components/style_traits/dom.rs')
| -rw-r--r-- | servo/components/style_traits/dom.rs | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/servo/components/style_traits/dom.rs b/servo/components/style_traits/dom.rs new file mode 100644 index 0000000000..03d5264abf --- /dev/null +++ b/servo/components/style_traits/dom.rs @@ -0,0 +1,26 @@ +/* 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 https://mozilla.org/MPL/2.0/. */ + +//! Types used to access the DOM from style calculation. + +/// An opaque handle to a node, which, unlike UnsafeNode, cannot be transformed +/// back into a non-opaque representation. The only safe operation that can be +/// performed on this node is to compare it to another opaque handle or to another +/// OpaqueNode. +/// +/// Layout and Graphics use this to safely represent nodes for comparison purposes. +/// Because the script task's GC does not trace layout, node data cannot be safely stored in layout +/// data structures. Also, layout code tends to be faster when the DOM is not being accessed, for +/// locality reasons. Using `OpaqueNode` enforces this invariant. +#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq)] +#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))] +pub struct OpaqueNode(pub usize); + +impl OpaqueNode { + /// Returns the address of this node, for debugging purposes. + #[inline] + pub fn id(&self) -> usize { + self.0 + } +} |