/* 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/. */
//! An iterator over a list of rules.
use crate::context::QuirksMode;
use crate::media_queries::Device;
use crate::shared_lock::SharedRwLockReadGuard;
use crate::stylesheets::{CssRule, DocumentRule, ImportRule, MediaRule, SupportsRule};
use smallvec::SmallVec;
use std::slice;
/// An iterator over a list of rules.
pub struct RulesIterator<'a, 'b, C>
where
'b: 'a,
C: NestedRuleIterationCondition + 'static,
{
device: &'a Device,
quirks_mode: QuirksMode,
guard: &'a SharedRwLockReadGuard<'b>,
stack: SmallVec<[slice::Iter<'a, CssRule>; 3]>,
_phantom: ::std::marker::PhantomData<C>,
}
impl<'a, 'b, C> RulesIterator<'a, 'b, C>
where
'b: 'a,
C: NestedRuleIterationCondition + 'static,
{
/// Creates a new `RulesIterator` to iterate over `rules`.
pub fn new(
device: &'a Device,
quirks_mode: QuirksMode,
guard: &'a SharedRwLockReadGuard<'b>,
rules: slice::Iter<'a, CssRule>,
) -> Self {
let mut stack = SmallVec::new();
stack.push(rules);
Self {
device,
quirks_mode,
guard,
stack,
_phantom: ::std::marker::PhantomData,
}
}
/// Skips all the remaining children of the last nested rule processed.
pub fn skip_children(&mut self) {
self.stack.pop();
}
/// Returns the children of `rule`, and whether `rule` is effective.
pub fn children(
rule: &'a CssRule,
device: &'a Device,
quirks_mode: QuirksMode,
guard: &'a SharedRwLockReadGuard<'_>,
effective: &mut bool,
) -> Option<slice::Iter<'a, CssRule>> {
*effective = true;
match *rule {
CssRule::Namespace(_) |
CssRule::FontFace(_) |
CssRule::CounterStyle(_) |
CssRule::Keyframes(_) |
CssRule::Margin(_) |
CssRule::Property(_) |
CssRule::LayerStatement(_) |
CssRule::FontFeatureValues(_) |
CssRule::FontPaletteValues(_) |
CssRule::NestedDeclarations(_) |
CssRule::PositionTry(_) => None,
CssRule::Page(ref page_rule) => {
let page_rule = page_rule.read_with(guard);
let rules = page_rule.rules.read_with(guard);
Some(rules.0.iter())
},
CssRule::Style(ref style_rule) => {
let style_rule = style_rule.read_with(guard);
style_rule
.rules
.as_ref()
.map(|r| r.read_with(guard).0.iter())
},
CssRule::Import(ref import_rule) => {
let import_rule = import_rule.read_with(guard);
if !C::process_import(guard, device, quirks_mode, import_rule) {
*effective = false;
return None;
}
Some(import_rule.stylesheet.rules(guard).iter())
},
CssRule::Document(ref doc_rule) => {
if !C::process_document(guard, device, quirks_mode, doc_rule) {
*effective = false;
return None;
}
Some(doc_rule.rules.read_with(guard).0.iter())
},
CssRule::Container(ref container_rule) => {
Some(container_rule.rules.read_with(guard).0.iter())
},
CssRule::Media(ref media_rule) => {
if !C::process_media(guard, device, quirks_mode, media_rule) {
*effective = false;
return None;
}
Some(media_rule.rules.read_with(guard).0.iter())
},
CssRule::Supports(ref supports_rule) => {
if !C::process_supports(guard, device, quirks_mode, supports_rule) {
*effective = false;
return None;
}
Some(supports_rule.rules.read_with(guard).0.iter())
},
CssRule::LayerBlock(ref layer_rule) => Some(layer_rule.rules.read_with(guard).0.iter
()),
CssRule::Scope(ref rule) => Some(rule.rules.read_with(guard).0.iter()),
CssRule::StartingStyle(ref rule) => Some(rule.rules.read_with(guard).0.iter()),
}
}
}
impl<'a, 'b, C> Iterator for RulesIterator<'a, 'b, C>
where
'b: 'a,
C: NestedRuleIterationCondition + 'static,
{
type Item = &'a CssRule;
fn next(&mut self) -> Option<Self::Item> {
while !self.stack.is_empty() {
let rule = {
let nested_iter = self.stack.last_mut().unwrap();
match nested_iter.next() {
Some(r) => r,
None => {
self.stack.pop();
continue;
},
}
};
let mut effective = true;
let children = Self::children(
rule,
self.device,
self.quirks_mode,
self.guard,
&mut effective,
);
if !effective {
continue;
}
if let Some(children) = children {
// NOTE: It's important that `children` gets pushed even if
// empty, so that `skip_children()` works as expected.
self.stack.push(children);
}
return Some(rule);
}
None
}
}
/// RulesIterator.
pub trait NestedRuleIterationCondition {
/// Whether we should process the nested rules in a given `@import` rule.
fn process_import(
guard: &SharedRwLockReadGuard,
device: &Device,
quirks_mode: QuirksMode,
rule: &ImportRule,
) -> bool;
/// Whether we should process the nested rules in a given `@media` rule.
fn process_media(
guard: &SharedRwLockReadGuard,
device: &Device,
quirks_mode: QuirksMode,
rule: &MediaRule,
) -> bool;
/// Whether we should process the nested rules in a given `@-moz-document`
/// rule.
fn process_document(
guard: &SharedRwLockReadGuard,
device: &Device,
quirks_mode: QuirksMode,
rule: &DocumentRule,
) -> bool;
/// Whether we should process the nested rules in a given `@supports` rule.
fn process_supports(
guard: &SharedRwLockReadGuard,
device: &Device,
quirks_mode: QuirksMode,
rule: &SupportsRule,
) -> bool;
}
/// A struct that represents the condition that a rule applies to the document.
pub struct EffectiveRules;
impl EffectiveRules {
/// Returns whether a given rule is effective.
pub fn is_effective(
guard: &SharedRwLockReadGuard,
device: &Device,
quirks_mode: QuirksMode,
rule: &CssRule,
) -> bool {
match *rule {
CssRule::Import(ref import_rule) => {
let import_rule = import_rule.read_with(guard);
Self::process_import(guard, device, quirks_mode, import_rule)
},
CssRule::Document(ref doc_rule) => {
Self::process_document(guard, device, quirks_mode, doc_rule)
},
CssRule::Media(ref media_rule) => {
Self::process_media(guard, device, quirks_mode, media_rule)
},
CssRule::Supports(ref supports_rule) => {
Self::process_supports(guard, device, quirks_mode, supports_rule)
},
_ => true,
}
}
}
impl NestedRuleIterationCondition for EffectiveRules {
fn process_import(
guard: &SharedRwLockReadGuard,
device: &Device,
quirks_mode: QuirksMode,
rule: &ImportRule,
) -> bool {
match rule.stylesheet.media(guard) {
Some(m) => m.evaluate(device, quirks_mode),
None => true,
}
}
fn process_media(
guard: &SharedRwLockReadGuard,
device: &Device,
quirks_mode: QuirksMode,
rule: &MediaRule,
) -> bool {
rule.media_queries
.read_with(guard)
.evaluate(device, quirks_mode)
}
fn process_document(
_: &SharedRwLockReadGuard,
device: &Device,
_: QuirksMode,
rule: &DocumentRule,
) -> bool {
rule.condition.evaluate(device)
}
fn process_supports(
_: &SharedRwLockReadGuard,
_: &Device,
_: QuirksMode,
rule: &SupportsRule,
) -> bool {
rule.enabled
}
}
/// A filter that processes all the rules in a rule list.
pub struct AllRules;
impl NestedRuleIterationCondition for AllRules {
fn process_import(
_: &SharedRwLockReadGuard,
_: &Device,
_: QuirksMode,
_: &ImportRule,
) -> bool {
true
}
fn process_media(_: &SharedRwLockReadGuard, _: &Device, _: QuirksMode, _: &MediaRule) -> bool {
true
}
fn process_document(
_: &SharedRwLockReadGuard,
_: &Device,
_: QuirksMode,
_: &DocumentRule,
) -> bool {
true
}
fn process_supports(
_: &SharedRwLockReadGuard,
_: &Device,
_: QuirksMode,
_: &SupportsRule,
) -> bool {
true
}
}
/// An iterator over all the effective rules of a stylesheet.
///
/// NOTE: This iterator recurses into `@import` rules.
pub type EffectiveRulesIterator<'a, 'b> = RulesIterator<'a, 'b, EffectiveRules>;
impl<'a, 'b> EffectiveRulesIterator<'a, 'b> {
/// Returns an iterator over the effective children of a rule, even if
/// `rule` itself is not effective.
pub fn effective_children(
device: &'a Device,
quirks_mode: QuirksMode,
guard: &'a SharedRwLockReadGuard<'b>,
rule: &'a CssRule,
) -> Self {
let children =
RulesIterator::<AllRules>::children(rule, device, quirks_mode, guard, &mut false);
EffectiveRulesIterator::new(device, quirks_mode, guard, children.unwrap_or([].iter()))
}
}
