/
declaration_block.rs
1227 lines (1098 loc) · 43.3 KB
/
declaration_block.rs
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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/. */
//! A property declaration block.
#![deny(missing_docs)]
use context::QuirksMode;
use cssparser::{DeclarationListParser, parse_important, ParserInput, CowRcStr};
use cssparser::{Parser, AtRuleParser, DeclarationParser, Delimiter, ParseErrorKind};
use custom_properties::CustomPropertiesBuilder;
use error_reporting::{ParseErrorReporter, ContextualParseError};
use parser::{ParserContext, ParserErrorContext};
use properties::animated_properties::AnimationValue;
use shared_lock::Locked;
use smallbitvec::{self, SmallBitVec};
use smallvec::SmallVec;
use std::fmt::{self, Write};
use std::iter::{DoubleEndedIterator, Zip};
use std::slice::Iter;
use str::{CssString, CssStringBorrow, CssStringWriter};
use style_traits::{CssWriter, ParseError, ParsingMode, StyleParseErrorKind, ToCss};
use stylesheets::{CssRuleType, Origin, UrlExtraData};
use super::*;
use values::computed::Context;
#[cfg(feature = "gecko")] use properties::animated_properties::AnimationValueMap;
/// The animation rules.
///
/// The first one is for Animation cascade level, and the second one is for
/// Transition cascade level.
pub struct AnimationRules(pub Option<Arc<Locked<PropertyDeclarationBlock>>>,
pub Option<Arc<Locked<PropertyDeclarationBlock>>>);
impl AnimationRules {
/// Returns whether these animation rules represents an actual rule or not.
pub fn is_empty(&self) -> bool {
self.0.is_none() && self.1.is_none()
}
}
/// Whether a given declaration comes from CSS parsing, or from CSSOM.
#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq)]
pub enum DeclarationSource {
/// The declaration was obtained from CSS parsing of sheets and such.
Parsing,
/// The declaration was obtained from CSSOM.
CssOm,
}
/// A declaration [importance][importance].
///
/// [importance]: https://drafts.csswg.org/css-cascade/#importance
#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq)]
pub enum Importance {
/// Indicates a declaration without `!important`.
Normal,
/// Indicates a declaration with `!important`.
Important,
}
impl Importance {
/// Return whether this is an important declaration.
pub fn important(self) -> bool {
match self {
Importance::Normal => false,
Importance::Important => true,
}
}
}
/// Overridden declarations are skipped.
#[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
#[derive(Clone)]
pub struct PropertyDeclarationBlock {
/// The group of declarations, along with their importance.
///
/// Only deduplicated declarations appear here.
declarations: Vec<PropertyDeclaration>,
/// The "important" flag for each declaration in `declarations`.
declarations_importance: SmallBitVec,
longhands: LonghandIdSet,
}
/// Iterator over `(PropertyDeclaration, Importance)` pairs.
pub struct DeclarationImportanceIterator<'a> {
iter: Zip<Iter<'a, PropertyDeclaration>, smallbitvec::Iter<'a>>,
}
impl<'a> DeclarationImportanceIterator<'a> {
/// Constructor.
pub fn new(declarations: &'a [PropertyDeclaration], important: &'a SmallBitVec) -> Self {
DeclarationImportanceIterator {
iter: declarations.iter().zip(important.iter()),
}
}
}
impl<'a> Iterator for DeclarationImportanceIterator<'a> {
type Item = (&'a PropertyDeclaration, Importance);
#[inline]
fn next(&mut self) -> Option<Self::Item> {
self.iter.next().map(|(decl, important)|
(decl, if important { Importance::Important } else { Importance::Normal }))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a> DoubleEndedIterator for DeclarationImportanceIterator<'a> {
#[inline(always)]
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.next_back().map(|(decl, important)|
(decl, if important { Importance::Important } else { Importance::Normal }))
}
}
/// Iterator over `PropertyDeclaration` for Importance::Normal.
pub struct NormalDeclarationIterator<'a>(DeclarationImportanceIterator<'a>);
impl<'a> NormalDeclarationIterator<'a> {
/// Constructor.
#[inline]
pub fn new(declarations: &'a [PropertyDeclaration], important: &'a SmallBitVec) -> Self {
NormalDeclarationIterator(
DeclarationImportanceIterator::new(declarations, important)
)
}
}
impl<'a> Iterator for NormalDeclarationIterator<'a> {
type Item = &'a PropertyDeclaration;
fn next(&mut self) -> Option<Self::Item> {
loop {
let (decl, importance) = self.0.iter.next()?;
if !importance {
return Some(decl);
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.0.iter.size_hint()
}
}
/// Iterator for AnimationValue to be generated from PropertyDeclarationBlock.
pub struct AnimationValueIterator<'a, 'cx, 'cx_a:'cx> {
iter: NormalDeclarationIterator<'a>,
context: &'cx mut Context<'cx_a>,
default_values: &'a ComputedValues,
/// Custom properties in a keyframe if exists.
extra_custom_properties: Option<&'a Arc<::custom_properties::CustomPropertiesMap>>,
}
impl<'a, 'cx, 'cx_a:'cx> AnimationValueIterator<'a, 'cx, 'cx_a> {
fn new(
declarations: &'a PropertyDeclarationBlock,
context: &'cx mut Context<'cx_a>,
default_values: &'a ComputedValues,
extra_custom_properties: Option<&'a Arc<::custom_properties::CustomPropertiesMap>>,
) -> AnimationValueIterator<'a, 'cx, 'cx_a> {
AnimationValueIterator {
iter: declarations.normal_declaration_iter(),
context,
default_values,
extra_custom_properties,
}
}
}
impl<'a, 'cx, 'cx_a:'cx> Iterator for AnimationValueIterator<'a, 'cx, 'cx_a> {
type Item = AnimationValue;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
loop {
let decl = self.iter.next()?;
let animation = AnimationValue::from_declaration(
decl,
&mut self.context,
self.extra_custom_properties,
self.default_values,
);
if let Some(anim) = animation {
return Some(anim);
}
}
}
}
impl fmt::Debug for PropertyDeclarationBlock {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.declarations.fmt(f)
}
}
impl PropertyDeclarationBlock {
/// Returns the number of declarations in the block.
#[inline]
pub fn len(&self) -> usize {
self.declarations.len()
}
/// Create an empty block
#[inline]
pub fn new() -> Self {
PropertyDeclarationBlock {
declarations: Vec::new(),
declarations_importance: SmallBitVec::new(),
longhands: LonghandIdSet::new(),
}
}
/// Create a block with a single declaration
pub fn with_one(declaration: PropertyDeclaration, importance: Importance) -> Self {
let mut longhands = LonghandIdSet::new();
if let PropertyDeclarationId::Longhand(id) = declaration.id() {
longhands.insert(id);
}
PropertyDeclarationBlock {
declarations: vec![declaration],
declarations_importance: SmallBitVec::from_elem(1, importance.important()),
longhands,
}
}
/// The declarations in this block
#[inline]
pub fn declarations(&self) -> &[PropertyDeclaration] {
&self.declarations
}
/// The `important` flags for declarations in this block
#[inline]
pub fn declarations_importance(&self) -> &SmallBitVec {
&self.declarations_importance
}
/// Iterate over `(PropertyDeclaration, Importance)` pairs
#[inline]
pub fn declaration_importance_iter(&self) -> DeclarationImportanceIterator {
DeclarationImportanceIterator::new(&self.declarations, &self.declarations_importance)
}
/// Iterate over `PropertyDeclaration` for Importance::Normal
#[inline]
pub fn normal_declaration_iter(&self) -> NormalDeclarationIterator {
NormalDeclarationIterator::new(&self.declarations, &self.declarations_importance)
}
/// Return an iterator of (AnimatableLonghand, AnimationValue).
#[inline]
pub fn to_animation_value_iter<'a, 'cx, 'cx_a:'cx>(
&'a self,
context: &'cx mut Context<'cx_a>,
default_values: &'a ComputedValues,
extra_custom_properties: Option<&'a Arc<::custom_properties::CustomPropertiesMap>>,
) -> AnimationValueIterator<'a, 'cx, 'cx_a> {
AnimationValueIterator::new(self, context, default_values, extra_custom_properties)
}
/// Returns whether this block contains any declaration with `!important`.
///
/// This is based on the `declarations_importance` bit-vector,
/// which should be maintained whenever `declarations` is changed.
#[inline]
pub fn any_important(&self) -> bool {
!self.declarations_importance.all_false()
}
/// Returns whether this block contains any declaration without `!important`.
///
/// This is based on the `declarations_importance` bit-vector,
/// which should be maintained whenever `declarations` is changed.
#[inline]
pub fn any_normal(&self) -> bool {
!self.declarations_importance.all_true()
}
/// Returns whether this block contains a declaration of a given longhand.
#[inline]
pub fn contains(&self, id: LonghandId) -> bool {
self.longhands.contains(id)
}
/// Returns whether this block contains any reset longhand.
#[inline]
pub fn contains_any_reset(&self) -> bool {
self.longhands.contains_any_reset()
}
/// Get a declaration for a given property.
///
/// NOTE: This is linear time in the case of custom properties or in the
/// case the longhand is actually in the declaration block.
#[inline]
pub fn get(&self, property: PropertyDeclarationId) -> Option<(&PropertyDeclaration, Importance)> {
if let PropertyDeclarationId::Longhand(id) = property {
if !self.contains(id) {
return None;
}
}
self.declarations.iter().enumerate().find(|&(_, decl)| decl.id() == property).map(|(i, decl)| {
let importance = if self.declarations_importance[i] {
Importance::Important
} else {
Importance::Normal
};
(decl, importance)
})
}
fn shorthand_to_css(
&self,
shorthand: ShorthandId,
dest: &mut CssStringWriter,
) -> fmt::Result {
// Step 1.2.1 of
// https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-getpropertyvalue
let mut list = SmallVec::<[&_; 10]>::new();
let mut important_count = 0;
// Step 1.2.2
for longhand in shorthand.longhands() {
// Step 1.2.2.1
let declaration = self.get(PropertyDeclarationId::Longhand(longhand));
// Step 1.2.2.2 & 1.2.2.3
match declaration {
Some((declaration, importance)) => {
list.push(declaration);
if importance.important() {
important_count += 1;
}
},
None => return Ok(()),
}
}
// If there is one or more longhand with important, and one or more
// without important, we don't serialize it as a shorthand.
if important_count > 0 && important_count != list.len() {
return Ok(());
}
// Step 1.2.3
// We don't print !important when serializing individual properties,
// so we treat this as a normal-importance property
match shorthand.get_shorthand_appendable_value(list.iter().cloned()) {
Some(appendable_value) => {
append_declaration_value(dest, appendable_value)
}
None => return Ok(()),
}
}
/// Find the value of the given property in this block and serialize it
///
/// <https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-getpropertyvalue>
pub fn property_value_to_css(&self, property: &PropertyId, dest: &mut CssStringWriter) -> fmt::Result {
// Step 1.1: done when parsing a string to PropertyId
// Step 1.2
let longhand_or_custom = match property.as_shorthand() {
Ok(shorthand) => return self.shorthand_to_css(shorthand, dest),
Err(longhand_or_custom) => longhand_or_custom,
};
if let Some((value, _importance)) = self.get(longhand_or_custom) {
// Step 2
value.to_css(dest)
} else {
// Step 3
Ok(())
}
}
/// <https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-getpropertypriority>
pub fn property_priority(&self, property: &PropertyId) -> Importance {
// Step 1: done when parsing a string to PropertyId
// Step 2
match property.as_shorthand() {
Ok(shorthand) => {
// Step 2.1 & 2.2 & 2.3
if shorthand.longhands().all(|l| {
self.get(PropertyDeclarationId::Longhand(l))
.map_or(false, |(_, importance)| importance.important())
}) {
Importance::Important
} else {
Importance::Normal
}
}
Err(longhand_or_custom) => {
// Step 3
self.get(longhand_or_custom).map_or(Importance::Normal, |(_, importance)| importance)
}
}
}
/// Adds or overrides the declaration for a given property in this block.
///
/// See the documentation of `push` to see what impact `source` has when the
/// property is already there.
pub fn extend(
&mut self,
mut drain: SourcePropertyDeclarationDrain,
importance: Importance,
source: DeclarationSource,
) -> bool {
match source {
DeclarationSource::Parsing => {
let all_shorthand_len = match drain.all_shorthand {
AllShorthand::NotSet => 0,
AllShorthand::CSSWideKeyword(_) |
AllShorthand::WithVariables(_) => shorthands::ALL_SHORTHAND_MAX_LEN,
};
let push_calls_count =
drain.declarations.len() + all_shorthand_len;
// With deduplication the actual length increase may be less than this.
self.declarations.reserve(push_calls_count);
}
DeclarationSource::CssOm => {
// Don't bother reserving space, since it's usually the case
// that CSSOM just overrides properties and we don't need to use
// more memory. See bug 1424346 for an example where this
// matters.
//
// TODO: Would it be worth to call reserve() just if it's empty?
}
}
let mut changed = false;
for decl in &mut drain.declarations {
changed |= self.push(
decl,
importance,
source,
);
}
match drain.all_shorthand {
AllShorthand::NotSet => {}
AllShorthand::CSSWideKeyword(keyword) => {
for id in ShorthandId::All.longhands() {
let decl = PropertyDeclaration::CSSWideKeyword(
WideKeywordDeclaration { id, keyword },
);
changed |= self.push(
decl,
importance,
source,
);
}
}
AllShorthand::WithVariables(unparsed) => {
for id in ShorthandId::All.longhands() {
let decl = PropertyDeclaration::WithVariables(
VariableDeclaration { id, value: unparsed.clone() },
);
changed |= self.push(
decl,
importance,
source,
);
}
}
}
changed
}
/// Adds or overrides the declaration for a given property in this block.
///
/// Depending on the value of `source`, this has a different behavior in the
/// presence of another declaration with the same ID in the declaration
/// block.
///
/// * For `DeclarationSource::Parsing`, this will not override a
/// declaration with more importance, and will ensure that, if inserted,
/// it's inserted at the end of the declaration block.
///
/// * For `DeclarationSource::CssOm`, this will override importance and
/// will preserve the original position on the block.
///
pub fn push(
&mut self,
declaration: PropertyDeclaration,
importance: Importance,
source: DeclarationSource,
) -> bool {
let longhand_id = match declaration.id() {
PropertyDeclarationId::Longhand(id) => Some(id),
PropertyDeclarationId::Custom(..) => None,
};
let definitely_new = longhand_id.map_or(false, |id| {
!self.longhands.contains(id)
});
if !definitely_new {
let mut index_to_remove = None;
for (i, slot) in self.declarations.iter_mut().enumerate() {
if slot.id() != declaration.id() {
continue;
}
let important = self.declarations_importance[i];
// For declarations from parsing, non-important declarations
// shouldn't override existing important one.
if important && !importance.important() &&
matches!(source, DeclarationSource::Parsing) {
return true;
}
if matches!(source, DeclarationSource::Parsing) {
// As a compatibility hack, specially on Android,
// don't allow to override a prefixed webkit display
// value with an unprefixed version from parsing
// code.
//
// TODO(emilio): Unship.
if let PropertyDeclaration::Display(old_display) = *slot {
use properties::longhands::display::computed_value::T as display;
if let PropertyDeclaration::Display(new_display) = declaration {
if display::should_ignore_parsed_value(old_display, new_display) {
return false;
}
}
}
}
index_to_remove = Some(i);
break;
}
if let Some(index) = index_to_remove {
self.declarations.remove(index);
self.declarations_importance.remove(index);
self.declarations.push(declaration);
self.declarations_importance.push(importance.important());
return true;
}
}
if let Some(id) = longhand_id {
self.longhands.insert(id);
}
self.declarations.push(declaration);
self.declarations_importance.push(importance.important());
true
}
/// Set the declaration importance for a given property, if found.
///
/// Returns whether any declaration was updated.
pub fn set_importance(&mut self, property: &PropertyId, new_importance: Importance) -> bool {
let mut updated_at_least_one = false;
for (i, declaration) in self.declarations.iter().enumerate() {
if declaration.id().is_or_is_longhand_of(property) {
let is_important = new_importance.important();
if self.declarations_importance[i] != is_important {
self.declarations_importance.set(i, is_important);
updated_at_least_one = true;
}
}
}
updated_at_least_one
}
/// <https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-removeproperty>
///
/// Returns whether any declaration was actually removed.
pub fn remove_property(&mut self, property: &PropertyId) -> bool {
let longhand_id = property.longhand_id();
if let Some(id) = longhand_id {
if !self.longhands.contains(id) {
return false
}
}
let mut removed_at_least_one = false;
let longhands = &mut self.longhands;
let declarations_importance = &mut self.declarations_importance;
let mut i = 0;
self.declarations.retain(|declaration| {
let id = declaration.id();
let remove = id.is_or_is_longhand_of(property);
if remove {
removed_at_least_one = true;
if let PropertyDeclarationId::Longhand(id) = id {
longhands.remove(id);
}
declarations_importance.remove(i);
} else {
i += 1;
}
!remove
});
if longhand_id.is_some() {
debug_assert!(removed_at_least_one);
}
removed_at_least_one
}
/// Take a declaration block known to contain a single property and serialize it.
pub fn single_value_to_css(
&self,
property: &PropertyId,
dest: &mut CssStringWriter,
computed_values: Option<&ComputedValues>,
custom_properties_block: Option<&PropertyDeclarationBlock>,
) -> fmt::Result {
if let Ok(shorthand) = property.as_shorthand() {
return self.shorthand_to_css(shorthand, dest);
}
// FIXME(emilio): Should this assert, or assert that the declaration is
// the property we expect?
let declaration = match self.declarations.get(0) {
Some(d) => d,
None => return Err(fmt::Error),
};
let custom_properties = if let Some(cv) = computed_values {
// If there are extra custom properties for this declaration block,
// factor them in too.
if let Some(block) = custom_properties_block {
// FIXME(emilio): This is not super-efficient here, and all this
// feels like a hack anyway...
block.cascade_custom_properties(cv.custom_properties())
} else {
cv.custom_properties().cloned()
}
} else {
None
};
match (declaration, computed_values) {
// If we have a longhand declaration with variables, those variables
// will be stored as unparsed values.
//
// As a temporary measure to produce sensible results in Gecko's
// getKeyframes() implementation for CSS animations, if
// |computed_values| is supplied, we use it to expand such variable
// declarations. This will be fixed properly in Gecko bug 1391537.
(
&PropertyDeclaration::WithVariables(ref declaration),
Some(ref _computed_values),
) => {
declaration.value.substitute_variables(
declaration.id,
custom_properties.as_ref(),
QuirksMode::NoQuirks,
).to_css(dest)
},
(ref d, _) => d.to_css(dest),
}
}
/// Convert AnimationValueMap to PropertyDeclarationBlock.
#[cfg(feature = "gecko")]
pub fn from_animation_value_map(animation_value_map: &AnimationValueMap) -> Self {
let len = animation_value_map.len();
let mut declarations = Vec::with_capacity(len);
let mut longhands = LonghandIdSet::new();
for (property, animation_value) in animation_value_map.iter() {
longhands.insert(*property);
declarations.push(animation_value.uncompute());
}
PropertyDeclarationBlock {
declarations,
longhands,
declarations_importance: SmallBitVec::from_elem(len, false),
}
}
/// Returns true if the declaration block has a CSSWideKeyword for the given
/// property.
#[cfg(feature = "gecko")]
pub fn has_css_wide_keyword(&self, property: &PropertyId) -> bool {
if let Some(id) = property.longhand_id() {
if !self.longhands.contains(id) {
return false
}
}
self.declarations.iter().any(|decl|
decl.id().is_or_is_longhand_of(property) &&
decl.get_css_wide_keyword().is_some()
)
}
/// Returns a custom properties map which is the result of cascading custom
/// properties in this declaration block along with context's custom
/// properties.
pub fn cascade_custom_properties_with_context(
&self,
context: &Context,
) -> Option<Arc<::custom_properties::CustomPropertiesMap>> {
self.cascade_custom_properties(context.style().custom_properties())
}
/// Returns a custom properties map which is the result of cascading custom
/// properties in this declaration block along with the given custom
/// properties.
pub fn cascade_custom_properties(
&self,
inherited_custom_properties: Option<&Arc<::custom_properties::CustomPropertiesMap>>,
) -> Option<Arc<::custom_properties::CustomPropertiesMap>> {
let mut builder = CustomPropertiesBuilder::new(inherited_custom_properties);
for declaration in self.normal_declaration_iter() {
if let PropertyDeclaration::Custom(ref declaration) = *declaration {
builder.cascade(&declaration.name, declaration.value.borrow());
}
}
builder.build()
}
}
impl PropertyDeclarationBlock {
/// Like the method on ToCss, but without the type parameter to avoid
/// accidentally monomorphizing this large function multiple times for
/// different writers.
///
/// https://drafts.csswg.org/cssom/#serialize-a-css-declaration-block
pub fn to_css(&self, dest: &mut CssStringWriter) -> fmt::Result {
use std::iter::Cloned;
use std::slice;
let mut is_first_serialization = true; // trailing serializations should have a prepended space
// Step 1 -> dest = result list
// Step 2
//
// NOTE(emilio): We reuse this set for both longhands and shorthands
// with subtly different meaning. For longhands, only longhands that
// have actually been serialized (either by themselves, or as part of a
// shorthand) appear here. For shorthands, all the shorthands that we've
// attempted to serialize appear here.
let mut already_serialized = NonCustomPropertyIdSet::new();
// Step 3
for (declaration, importance) in self.declaration_importance_iter() {
// Step 3.1
let property = declaration.id();
let longhand_id = match property {
PropertyDeclarationId::Longhand(id) => id,
PropertyDeclarationId::Custom(..) => {
// Given the invariants that there are no duplicate
// properties in a declaration block, and that custom
// properties can't be part of a shorthand, we can just care
// about them here.
append_serialization::<Cloned<slice::Iter<_>>, _>(
dest,
&property,
AppendableValue::Declaration(declaration),
importance,
&mut is_first_serialization,
)?;
continue;
}
};
// Step 3.2
if already_serialized.contains(longhand_id.into()) {
continue;
}
// Step 3.3
// Step 3.3.1 is done by checking already_serialized while
// iterating below.
// Step 3.3.2
for shorthand in longhand_id.shorthands() {
// We already attempted to serialize this shorthand before.
if already_serialized.contains(shorthand.into()) {
continue;
}
already_serialized.insert(shorthand.into());
// Substep 2 & 3
let mut current_longhands = SmallVec::<[_; 10]>::new();
let mut important_count = 0;
let mut found_system = None;
let is_system_font =
shorthand == ShorthandId::Font &&
self.declarations.iter().any(|l| {
match l.id() {
PropertyDeclarationId::Longhand(id) => {
if already_serialized.contains(id.into()) {
return false;
}
l.get_system().is_some()
}
PropertyDeclarationId::Custom(..) => {
debug_assert!(l.get_system().is_none());
false
}
}
});
if is_system_font {
for (longhand, importance) in self.declaration_importance_iter() {
if longhand.get_system().is_some() || longhand.is_default_line_height() {
current_longhands.push(longhand);
if found_system.is_none() {
found_system = longhand.get_system();
}
if importance.important() {
important_count += 1;
}
}
}
} else {
let mut contains_all_longhands = true;
for longhand in shorthand.longhands() {
match self.get(PropertyDeclarationId::Longhand(longhand)) {
Some((declaration, importance)) => {
current_longhands.push(declaration);
if importance.important() {
important_count += 1;
}
}
None => {
contains_all_longhands = false;
break;
}
}
}
// Substep 1:
if !contains_all_longhands {
continue;
}
}
// Substep 4
let is_important = important_count > 0;
if is_important && important_count != current_longhands.len() {
continue;
}
let importance = if is_important {
Importance::Important
} else {
Importance::Normal
};
// Substep 5 - Let value be the result of invoking serialize
// a CSS value of current longhands.
let appendable_value =
match shorthand.get_shorthand_appendable_value(current_longhands.iter().cloned()) {
None => continue,
Some(appendable_value) => appendable_value,
};
// We avoid re-serializing if we're already an
// AppendableValue::Css.
let mut v = CssString::new();
let value = match (appendable_value, found_system) {
(AppendableValue::Css { css, with_variables }, _) => {
debug_assert!(!css.is_empty());
AppendableValue::Css {
css: css,
with_variables: with_variables,
}
}
#[cfg(feature = "gecko")]
(_, Some(sys)) => {
sys.to_css(&mut CssWriter::new(&mut v))?;
AppendableValue::Css {
css: CssStringBorrow::from(&v),
with_variables: false,
}
}
(other, _) => {
append_declaration_value(&mut v, other)?;
// Substep 6
if v.is_empty() {
continue;
}
AppendableValue::Css {
css: CssStringBorrow::from(&v),
with_variables: false,
}
}
};
// Substeps 7 and 8
append_serialization::<Cloned<slice::Iter<_>>, _>(
dest,
&shorthand,
value,
importance,
&mut is_first_serialization,
)?;
for current_longhand in ¤t_longhands {
let longhand_id = match current_longhand.id() {
PropertyDeclarationId::Longhand(id) => id,
PropertyDeclarationId::Custom(..) => unreachable!(),
};
// Substep 9
already_serialized.insert(longhand_id.into());
}
// FIXME(https://github.com/w3c/csswg-drafts/issues/1774)
// The specification does not include an instruction to abort
// the shorthand loop at this point, but doing so both matches
// Gecko and makes sense since shorthands are checked in
// preferred order.
break;
}
// Step 3.3.4
if already_serialized.contains(longhand_id.into()) {
continue;
}
// Steps 3.3.5, 3.3.6 & 3.3.7
// Need to specify an iterator type here even though it’s unused to work around
// "error: unable to infer enough type information about `_`;
// type annotations or generic parameter binding required [E0282]"
// Use the same type as earlier call to reuse generated code.
append_serialization::<Cloned<slice::Iter<_>>, _>(
dest,
&property,
AppendableValue::Declaration(declaration),
importance,
&mut is_first_serialization,
)?;
// Step 3.3.8
already_serialized.insert(longhand_id.into());
}
// Step 4
Ok(())
}
}
/// A convenient enum to represent different kinds of stuff that can represent a
/// _value_ in the serialization of a property declaration.
pub enum AppendableValue<'a, I>
where I: Iterator<Item=&'a PropertyDeclaration>,
{
/// A given declaration, of which we'll serialize just the value.
Declaration(&'a PropertyDeclaration),
/// A set of declarations for a given shorthand.
///
/// FIXME: This needs more docs, where are the shorthands expanded? We print
/// the property name before-hand, don't we?
DeclarationsForShorthand(ShorthandId, I),
/// A raw CSS string, coming for example from a property with CSS variables,
/// or when storing a serialized shorthand value before appending directly.
Css {
/// The raw CSS string.
css: CssStringBorrow<'a>,
/// Whether the original serialization contained variables or not.
with_variables: bool,
}
}
/// Potentially appends whitespace after the first (property: value;) pair.
fn handle_first_serialization<W>(
dest: &mut W,
is_first_serialization: &mut bool,
) -> fmt::Result
where
W: Write,
{
if !*is_first_serialization {
dest.write_str(" ")
} else {
*is_first_serialization = false;
Ok(())
}
}