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style: Document cascade_info.

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Emilio Cobos Álvarez 2016-12-31 14:55:48 +01:00
parent 7bf80e5d50
commit 4108ff8383
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1 changed files with 19 additions and 2 deletions
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21
components/style/cascade_info.rs
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@ -1,6 +1,11 @@
/* 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/. */
//! A structure to collect information about the cascade.
#![deny(missing_docs)]
use dom::TNode;
use properties::{DeclaredValue, PropertyDeclaration};
use values::HasViewportPercentage;
@ -12,12 +17,17 @@ use values::HasViewportPercentage;
/// non-inherited property is explicitly inherited, in order to cut-off the
/// traversal.
pub struct CascadeInfo {
/// Whether we've seen viewport units so far.
pub saw_viewport_units: bool,
/// Whether the cascade has been marked as finished. This is a debug-only
/// flag to ensure `finish` is called, given it's optional to not pass a
/// `CascadeInfo`.
#[cfg(debug_assertions)]
finished: bool,
}
impl CascadeInfo {
/// Construct a new `CascadeInfo`.
#[cfg(debug_assertions)]
pub fn new() -> Self {
CascadeInfo {
@ -26,6 +36,7 @@ impl CascadeInfo {
}
}
/// Construct a new `CascadeInfo`.
#[cfg(not(debug_assertions))]
pub fn new() -> Self {
CascadeInfo {
@ -40,7 +51,7 @@ impl CascadeInfo {
pub fn on_cascade_property<T>(&mut self,
_property_declaration: &PropertyDeclaration,
value: &DeclaredValue<T>)
where T: HasViewportPercentage
where T: HasViewportPercentage,
{
// TODO: we can be smarter and keep a property bitfield to keep track of
// the last applying rule.
@ -57,6 +68,11 @@ impl CascadeInfo {
#[cfg(not(debug_assertions))]
fn mark_as_finished_if_appropriate(&mut self) {}
/// Called when the cascade is finished, in order to use the information
/// we've collected.
///
/// Currently used for styling to mark a node as needing restyling when the
/// viewport size changes.
#[allow(unsafe_code)]
pub fn finish<N: TNode>(mut self, node: &N) {
self.mark_as_finished_if_appropriate();
@ -73,6 +89,7 @@ impl CascadeInfo {
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");
"Didn't use the result of CascadeInfo, if you don't need \
it, consider passing None");
}
}