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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/. */
use dom::TNode;
use properties::{DeclaredValue, PropertyDeclaration};
use values::HasViewportPercentage;
/// A structure to collect information about the cascade.
///
/// This is useful to gather information about what an element is affected by,
/// and can be used in the future to track optimisations like when a
/// non-inherited property is explicitly inherited, in order to cut-off the
/// traversal.
pub struct CascadeInfo {
pub saw_viewport_units: bool,
#[cfg(debug_assertions)]
finished: bool,
}
impl CascadeInfo {
#[cfg(debug_assertions)]
pub fn new() -> Self {
CascadeInfo {
saw_viewport_units: false,
finished: false,
}
}
#[cfg(not(debug_assertions))]
pub fn new() -> Self {
CascadeInfo {
saw_viewport_units: false,
}
}
/// Called when a property is cascaded.
///
/// NOTE: We can add a vast amount of information here.
#[inline]
pub fn on_cascade_property<T>(&mut self,
_property_declaration: &PropertyDeclaration,
value: &DeclaredValue<T>)
where T: HasViewportPercentage
{
// TODO: we can be smarter and keep a property bitfield to keep track of
// the last applying rule.
if value.has_viewport_percentage() {
self.saw_viewport_units = true;
}
}
#[cfg(debug_assertions)]
fn mark_as_finished_if_appropriate(&mut self) {
self.finished = true;
}
#[cfg(not(debug_assertions))]
fn mark_as_finished_if_appropriate(&mut self) {}
#[allow(unsafe_code)]
pub fn finish<N: TNode>(mut self, node: &N) {
self.mark_as_finished_if_appropriate();
if self.saw_viewport_units {
unsafe {
node.set_dirty_on_viewport_size_changed();
}
}
}
}
#[cfg(debug_assertions)]
impl Drop for CascadeInfo {
fn drop(&mut self) {
debug_assert!(self.finished,
"Didn't use the result of CascadeInfo, if you don't need it, consider passing None");
}
}
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