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fune/servo/components/layout/construct.rs
Emilio Cobos Álvarez 80e92561e4 servo: Merge #17025 - script/layout: Stop doing unsafe transmutes between refcell references (from emilio:layout-data); r=jdm 
This commit splits the style and layout data in two separate refcells.

These transmutes have been a source of trouble (for example on Android), and
they feel like a hack anyway.

Fixes #16982

Source-Repo: https://github.com/servo/servo
Source-Revision: 764da7ba39c0ccbaf807c6131418761f70584322

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 8c76908f751b0f628da00bd0aa46e7c1548b1b66
2017-05-25 19:58:47 -05:00

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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/. */
//! Creates flows and fragments from a DOM tree via a bottom-up, incremental traversal of the DOM.
//!
//! Each step of the traversal considers the node and existing flow, if there is one. If a node is
//! not dirty and an existing flow exists, then the traversal reuses that flow. Otherwise, it
//! proceeds to construct either a flow or a `ConstructionItem`. A construction item is a piece of
//! intermediate data that goes with a DOM node and hasn't found its "home" yet-maybe it's a box,
//! maybe it's an absolute or fixed position thing that hasn't found its containing block yet.
//! Construction items bubble up the tree from children to parents until they find their homes.
#![deny(unsafe_code)]
use StyleArc;
use app_units::Au;
use block::BlockFlow;
use context::{LayoutContext, with_thread_local_font_context};
use data::{HAS_NEWLY_CONSTRUCTED_FLOW, LayoutData};
use flex::FlexFlow;
use floats::FloatKind;
use flow::{self, AbsoluteDescendants, Flow, FlowClass, ImmutableFlowUtils};
use flow::{CAN_BE_FRAGMENTED, IS_ABSOLUTELY_POSITIONED, MARGINS_CANNOT_COLLAPSE};
use flow::{MutableFlowUtils, MutableOwnedFlowUtils};
use flow_ref::FlowRef;
use fragment::{CanvasFragmentInfo, ImageFragmentInfo, InlineAbsoluteFragmentInfo, SvgFragmentInfo};
use fragment::{Fragment, GeneratedContentInfo, IframeFragmentInfo};
use fragment::{IS_INLINE_FLEX_ITEM, IS_BLOCK_FLEX_ITEM};
use fragment::{InlineAbsoluteHypotheticalFragmentInfo, TableColumnFragmentInfo};
use fragment::{InlineBlockFragmentInfo, SpecificFragmentInfo, UnscannedTextFragmentInfo};
use fragment::WhitespaceStrippingResult;
use gfx::display_list::OpaqueNode;
use inline::{FIRST_FRAGMENT_OF_ELEMENT, InlineFlow};
use inline::{InlineFragmentNodeInfo, LAST_FRAGMENT_OF_ELEMENT};
use linked_list::prepend_from;
use list_item::{ListItemFlow, ListStyleTypeContent};
use multicol::{MulticolColumnFlow, MulticolFlow};
use parallel;
use script_layout_interface::{LayoutElementType, LayoutNodeType, is_image_data};
use script_layout_interface::wrapper_traits::{PseudoElementType, ThreadSafeLayoutElement, ThreadSafeLayoutNode};
use servo_config::opts;
use servo_url::ServoUrl;
use std::borrow::ToOwned;
use std::collections::LinkedList;
use std::marker::PhantomData;
use std::mem;
use std::sync::Arc;
use std::sync::atomic::Ordering;
use style::computed_values::{caption_side, display, empty_cells, float, list_style_position};
use style::computed_values::content::ContentItem;
use style::computed_values::position;
use style::context::SharedStyleContext;
use style::logical_geometry::Direction;
use style::properties::ServoComputedValues;
use style::properties::longhands::list_style_image;
use style::selector_parser::{PseudoElement, RestyleDamage};
use style::servo::restyle_damage::{BUBBLE_ISIZES, RECONSTRUCT_FLOW};
use style::values::Either;
use table::TableFlow;
use table_caption::TableCaptionFlow;
use table_cell::TableCellFlow;
use table_colgroup::TableColGroupFlow;
use table_row::TableRowFlow;
use table_rowgroup::TableRowGroupFlow;
use table_wrapper::TableWrapperFlow;
use text::TextRunScanner;
use traversal::PostorderNodeMutTraversal;
use wrapper::{LayoutNodeLayoutData, TextContent, ThreadSafeLayoutNodeHelpers};
/// The results of flow construction for a DOM node.
#[derive(Clone)]
pub enum ConstructionResult {
/// This node contributes nothing at all (`display: none`). Alternately, this is what newly
/// created nodes have their `ConstructionResult` set to.
None,
/// This node contributed a flow at the proper position in the tree.
/// Nothing more needs to be done for this node. It has bubbled up fixed
/// and absolute descendant flows that have a containing block above it.
Flow(FlowRef, AbsoluteDescendants),
/// This node contributed some object or objects that will be needed to construct a proper flow
/// later up the tree, but these objects have not yet found their home.
ConstructionItem(ConstructionItem),
}
impl ConstructionResult {
pub fn get(&mut self) -> ConstructionResult {
// FIXME(pcwalton): Stop doing this with inline fragments. Cloning fragments is very
// inefficient!
(*self).clone()
}
pub fn debug_id(&self) -> usize {
match *self {
ConstructionResult::None => 0,
ConstructionResult::ConstructionItem(_) => 0,
ConstructionResult::Flow(ref flow_ref, _) => flow::base(&**flow_ref).debug_id(),
}
}
}
/// Represents the output of flow construction for a DOM node that has not yet resulted in a
/// complete flow. Construction items bubble up the tree until they find a `Flow` to be attached
/// to.
#[derive(Clone)]
pub enum ConstructionItem {
/// Inline fragments and associated {ib} splits that have not yet found flows.
InlineFragments(InlineFragmentsConstructionResult),
/// Potentially ignorable whitespace.
Whitespace(OpaqueNode, PseudoElementType<()>, StyleArc<ServoComputedValues>, RestyleDamage),
/// TableColumn Fragment
TableColumnFragment(Fragment),
}
/// Represents inline fragments and {ib} splits that are bubbling up from an inline.
#[derive(Clone)]
pub struct InlineFragmentsConstructionResult {
/// Any {ib} splits that we're bubbling up.
pub splits: LinkedList<InlineBlockSplit>,
/// Any fragments that succeed the {ib} splits.
pub fragments: IntermediateInlineFragments,
}
/// Represents an {ib} split that has not yet found the containing block that it belongs to. This
/// is somewhat tricky. An example may be helpful. For this DOM fragment:
///
/// ```html
/// <span>
/// A
/// <div>B</div>
/// C
/// </span>
/// ```
///
/// The resulting `ConstructionItem` for the outer `span` will be:
///
/// ```ignore
/// ConstructionItem::InlineFragments(
/// InlineFragmentsConstructionResult{
/// splits: linked_list![
/// InlineBlockSplit{
/// predecessors: IntermediateInlineFragments{
/// fragments: linked_list![A],
/// absolute_descendents: AbsoluteDescendents{
/// descendant_links: vec![]
/// }
/// },
/// flow: B
/// }
/// ],
/// fragments: linked_list![C],
/// }
/// )
/// ```
#[derive(Clone)]
pub struct InlineBlockSplit {
/// The inline fragments that precede the flow.
pub predecessors: IntermediateInlineFragments,
/// The flow that caused this {ib} split.
pub flow: FlowRef,
}
impl InlineBlockSplit {
/// Flushes the given accumulator to the new split and makes a new accumulator to hold any
/// subsequent fragments.
fn new<ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>(fragment_accumulator: &mut InlineFragmentsAccumulator,
node: &ConcreteThreadSafeLayoutNode,
style_context: &SharedStyleContext,
flow: FlowRef)
-> InlineBlockSplit {
fragment_accumulator.enclosing_node.as_mut().expect(
"enclosing_node is None; Are {ib} splits being generated outside of an inline node?"
).flags.remove(LAST_FRAGMENT_OF_ELEMENT);
let split = InlineBlockSplit {
predecessors: mem::replace(
fragment_accumulator,
InlineFragmentsAccumulator::from_inline_node(
node, style_context)).to_intermediate_inline_fragments(style_context),
flow: flow,
};
fragment_accumulator.enclosing_node.as_mut().unwrap().flags.remove(FIRST_FRAGMENT_OF_ELEMENT);
split
}
}
/// Holds inline fragments and absolute descendants.
#[derive(Clone)]
pub struct IntermediateInlineFragments {
/// The list of fragments.
pub fragments: LinkedList<Fragment>,
/// The list of absolute descendants of those inline fragments.
pub absolute_descendants: AbsoluteDescendants,
}
impl IntermediateInlineFragments {
fn new() -> IntermediateInlineFragments {
IntermediateInlineFragments {
fragments: LinkedList::new(),
absolute_descendants: AbsoluteDescendants::new(),
}
}
fn is_empty(&self) -> bool {
self.fragments.is_empty() && self.absolute_descendants.is_empty()
}
fn push_all(&mut self, mut other: IntermediateInlineFragments) {
self.fragments.append(&mut other.fragments);
self.absolute_descendants.push_descendants(other.absolute_descendants);
}
}
/// Holds inline fragments that we're gathering for children of an inline node.
struct InlineFragmentsAccumulator {
/// The list of fragments.
fragments: IntermediateInlineFragments,
/// Information about the inline box directly enclosing the fragments being gathered, if any.
///
/// `inline::InlineFragmentNodeInfo` also stores flags indicating whether a fragment is the
/// first and/or last of the corresponding inline box. This `InlineFragmentsAccumulator` may
/// represent only one side of an {ib} split, so we store these flags as if it represented only
/// one fragment. `to_intermediate_inline_fragments` later splits this hypothetical fragment
/// into pieces, leaving the `FIRST_FRAGMENT_OF_ELEMENT` and `LAST_FRAGMENT_OF_ELEMENT` flags,
/// if present, on the first and last fragments of the output.
enclosing_node: Option<InlineFragmentNodeInfo>,
/// Restyle damage to use for fragments created in this node.
restyle_damage: RestyleDamage,
/// Bidi control characters to insert before and after these fragments.
bidi_control_chars: Option<(&'static str, &'static str)>,
}
impl InlineFragmentsAccumulator {
fn new() -> InlineFragmentsAccumulator {
InlineFragmentsAccumulator {
fragments: IntermediateInlineFragments::new(),
enclosing_node: None,
bidi_control_chars: None,
restyle_damage: RestyleDamage::empty(),
}
}
fn from_inline_node<N>(node: &N, style_context: &SharedStyleContext) -> InlineFragmentsAccumulator
where N: ThreadSafeLayoutNode {
InlineFragmentsAccumulator {
fragments: IntermediateInlineFragments::new(),
enclosing_node: Some(InlineFragmentNodeInfo {
address: node.opaque(),
pseudo: node.get_pseudo_element_type().strip(),
style: node.style(style_context),
selected_style: node.selected_style(),
flags: FIRST_FRAGMENT_OF_ELEMENT | LAST_FRAGMENT_OF_ELEMENT,
}),
bidi_control_chars: None,
restyle_damage: node.restyle_damage(),
}
}
fn push(&mut self, fragment: Fragment) {
self.fragments.fragments.push_back(fragment)
}
fn push_all(&mut self, mut fragments: IntermediateInlineFragments) {
self.fragments.fragments.append(&mut fragments.fragments);
self.fragments.absolute_descendants.push_descendants(fragments.absolute_descendants);
}
fn to_intermediate_inline_fragments(self, context: &SharedStyleContext)
-> IntermediateInlineFragments {
let InlineFragmentsAccumulator {
mut fragments,
enclosing_node,
bidi_control_chars,
restyle_damage,
} = self;
if let Some(mut enclosing_node) = enclosing_node {
let fragment_count = fragments.fragments.len();
for (index, fragment) in fragments.fragments.iter_mut().enumerate() {
let mut enclosing_node = enclosing_node.clone();
if index != 0 {
enclosing_node.flags.remove(FIRST_FRAGMENT_OF_ELEMENT)
}
if index != fragment_count - 1 {
enclosing_node.flags.remove(LAST_FRAGMENT_OF_ELEMENT)
}
fragment.add_inline_context_style(enclosing_node);
}
// Control characters are later discarded in transform_text, so they don't affect the
// is_first/is_last styles above.
enclosing_node.flags.remove(FIRST_FRAGMENT_OF_ELEMENT | LAST_FRAGMENT_OF_ELEMENT);
if let Some((start, end)) = bidi_control_chars {
fragments.fragments.push_front(
control_chars_to_fragment(&enclosing_node, context, start, restyle_damage));
fragments.fragments.push_back(
control_chars_to_fragment(&enclosing_node, context, end, restyle_damage));
}
}
fragments
}
}
/// An object that knows how to create flows.
pub struct FlowConstructor<'a, N: ThreadSafeLayoutNode> {
/// The layout context.
pub layout_context: &'a LayoutContext<'a>,
/// Satisfy the compiler about the unused parameters, which we use to improve the ergonomics of
/// the ensuing impl {} by removing the need to parameterize all the methods individually.
phantom2: PhantomData<N>,
}
impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
FlowConstructor<'a, ConcreteThreadSafeLayoutNode> {
/// Creates a new flow constructor.
pub fn new(layout_context: &'a LayoutContext<'a>) -> Self {
FlowConstructor {
layout_context: layout_context,
phantom2: PhantomData,
}
}
#[inline]
fn style_context(&self) -> &SharedStyleContext {
self.layout_context.shared_context()
}
#[inline]
fn set_flow_construction_result(&self,
node: &ConcreteThreadSafeLayoutNode,
result: ConstructionResult) {
node.set_flow_construction_result(result);
}
/// Builds the fragment for the given block or subclass thereof.
fn build_fragment_for_block(&self, node: &ConcreteThreadSafeLayoutNode) -> Fragment {
let specific_fragment_info = match node.type_id() {
Some(LayoutNodeType::Element(LayoutElementType::HTMLIFrameElement)) => {
SpecificFragmentInfo::Iframe(IframeFragmentInfo::new(node))
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLImageElement)) => {
let image_info = box ImageFragmentInfo::new(node.image_url(),
node,
&self.layout_context);
SpecificFragmentInfo::Image(image_info)
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLObjectElement)) => {
let image_info = box ImageFragmentInfo::new(node.object_data(),
node,
&self.layout_context);
SpecificFragmentInfo::Image(image_info)
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableElement)) => {
SpecificFragmentInfo::TableWrapper
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableColElement)) => {
SpecificFragmentInfo::TableColumn(TableColumnFragmentInfo::new(node))
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableCellElement)) => {
SpecificFragmentInfo::TableCell
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableRowElement)) |
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableSectionElement)) => {
SpecificFragmentInfo::TableRow
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLCanvasElement)) => {
let data = node.canvas_data().unwrap();
SpecificFragmentInfo::Canvas(box CanvasFragmentInfo::new(data))
}
Some(LayoutNodeType::Element(LayoutElementType::SVGSVGElement)) => {
let data = node.svg_data().unwrap();
SpecificFragmentInfo::Svg(box SvgFragmentInfo::new(data))
}
_ => {
// This includes pseudo-elements.
SpecificFragmentInfo::Generic
}
};
Fragment::new(node, specific_fragment_info, self.layout_context)
}
/// Creates an inline flow from a set of inline fragments, then adds it as a child of the given
/// flow or pushes it onto the given flow list.
///
/// `#[inline(always)]` because this is performance critical and LLVM will not inline it
/// otherwise.
#[inline(always)]
fn flush_inline_fragments_to_flow(&mut self,
fragment_accumulator: InlineFragmentsAccumulator,
flow: &mut FlowRef,
absolute_descendants: &mut AbsoluteDescendants,
legalizer: &mut Legalizer,
node: &ConcreteThreadSafeLayoutNode) {
let mut fragments = fragment_accumulator.to_intermediate_inline_fragments(self.style_context());
if fragments.is_empty() {
return
};
strip_ignorable_whitespace_from_start(&mut fragments.fragments);
strip_ignorable_whitespace_from_end(&mut fragments.fragments);
if fragments.fragments.is_empty() {
absolute_descendants.push_descendants(fragments.absolute_descendants);
return
}
// Build a list of all the inline-block fragments before fragments is moved.
let mut inline_block_flows = vec!();
for fragment in &fragments.fragments {
match fragment.specific {
SpecificFragmentInfo::InlineBlock(ref info) => {
inline_block_flows.push(info.flow_ref.clone())
}
SpecificFragmentInfo::InlineAbsoluteHypothetical(ref info) => {
inline_block_flows.push(info.flow_ref.clone())
}
SpecificFragmentInfo::InlineAbsolute(ref info) => {
inline_block_flows.push(info.flow_ref.clone())
}
_ => {}
}
}
// We must scan for runs before computing minimum ascent and descent because scanning
// for runs might collapse so much whitespace away that only hypothetical fragments
// remain. In that case the inline flow will compute its ascent and descent to be zero.
let scanned_fragments =
with_thread_local_font_context(self.layout_context, |font_context| {
TextRunScanner::new().scan_for_runs(font_context,
mem::replace(&mut fragments.fragments, LinkedList::new()))
});
let mut inline_flow_ref =
FlowRef::new(Arc::new(InlineFlow::from_fragments(scanned_fragments,
node.style(self.style_context()).writing_mode)));
// Add all the inline-block fragments as children of the inline flow.
for inline_block_flow in &inline_block_flows {
inline_flow_ref.add_new_child(inline_block_flow.clone());
}
// Set up absolute descendants as necessary.
//
// The inline flow itself may need to become the containing block for absolute descendants
// in order to handle cases like:
//
// <div>
// <span style="position: relative">
// <span style="position: absolute; ..."></span>
// </span>
// </div>
//
// See the comment above `flow::AbsoluteDescendantInfo` for more information.
inline_flow_ref.take_applicable_absolute_descendants(&mut fragments.absolute_descendants);
absolute_descendants.push_descendants(fragments.absolute_descendants);
{
// FIXME(#6503): Use Arc::get_mut().unwrap() here.
let inline_flow = FlowRef::deref_mut(&mut inline_flow_ref).as_mut_inline();
inline_flow.minimum_line_metrics =
with_thread_local_font_context(self.layout_context, |font_context| {
inline_flow.minimum_line_metrics(font_context, &node.style(self.style_context()))
});
}
inline_flow_ref.finish();
legalizer.add_child(self.style_context(), flow, inline_flow_ref)
}
fn build_block_flow_using_construction_result_of_child(
&mut self,
flow: &mut FlowRef,
node: &ConcreteThreadSafeLayoutNode,
kid: ConcreteThreadSafeLayoutNode,
inline_fragment_accumulator: &mut InlineFragmentsAccumulator,
abs_descendants: &mut AbsoluteDescendants,
legalizer: &mut Legalizer) {
match kid.get_construction_result() {
ConstructionResult::None => {}
ConstructionResult::Flow(kid_flow, kid_abs_descendants) => {
// If kid_flow is TableCaptionFlow, kid_flow should be added under
// TableWrapperFlow.
if flow.is_table() && kid_flow.is_table_caption() {
let construction_result =
ConstructionResult::Flow(kid_flow, AbsoluteDescendants::new());
self.set_flow_construction_result(&kid, construction_result)
} else {
if !flow::base(&*kid_flow).flags.contains(IS_ABSOLUTELY_POSITIONED) {
// Flush any inline fragments that we were gathering up. This allows us to
// handle {ib} splits.
let old_inline_fragment_accumulator =
mem::replace(inline_fragment_accumulator,
InlineFragmentsAccumulator::new());
self.flush_inline_fragments_to_flow(old_inline_fragment_accumulator,
flow,
abs_descendants,
legalizer,
node);
}
legalizer.add_child(self.style_context(), flow, kid_flow)
}
abs_descendants.push_descendants(kid_abs_descendants);
}
ConstructionResult::ConstructionItem(ConstructionItem::InlineFragments(
InlineFragmentsConstructionResult {
splits,
fragments: successor_fragments,
})) => {
// Add any {ib} splits.
for split in splits {
// Pull apart the {ib} split object and push its predecessor fragments
// onto the list.
let InlineBlockSplit {
predecessors,
flow: kid_flow
} = split;
inline_fragment_accumulator.push_all(predecessors);
// Flush any inline fragments that we were gathering up.
debug!("flushing {} inline box(es) to flow A",
inline_fragment_accumulator.fragments.fragments.len());
let old_inline_fragment_accumulator =
mem::replace(inline_fragment_accumulator,
InlineFragmentsAccumulator::new());
let absolute_descendants =
&mut inline_fragment_accumulator.fragments.absolute_descendants;
self.flush_inline_fragments_to_flow(old_inline_fragment_accumulator,
flow,
absolute_descendants,
legalizer,
node);
// Push the flow generated by the {ib} split onto our list of flows.
legalizer.add_child(self.style_context(), flow, kid_flow)
}
// Add the fragments to the list we're maintaining.
inline_fragment_accumulator.push_all(successor_fragments);
}
ConstructionResult::ConstructionItem(ConstructionItem::Whitespace(
whitespace_node,
whitespace_pseudo,
whitespace_style,
whitespace_damage)) => {
// Add whitespace results. They will be stripped out later on when
// between block elements, and retained when between inline elements.
let fragment_info = SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(" ".to_owned(), None));
let fragment = Fragment::from_opaque_node_and_style(whitespace_node,
whitespace_pseudo,
whitespace_style,
node.selected_style(),
whitespace_damage,
fragment_info);
inline_fragment_accumulator.fragments.fragments.push_back(fragment);
}
ConstructionResult::ConstructionItem(ConstructionItem::TableColumnFragment(_)) => {
// TODO: Implement anonymous table objects for missing parents
// CSS 2.1 § 17.2.1, step 3-2
}
}
}
/// Constructs a block flow, beginning with the given `initial_fragments` if present and then
/// appending the construction results of children to the child list of the block flow. {ib}
/// splits and absolutely-positioned descendants are handled correctly.
fn build_flow_for_block_starting_with_fragments(
&mut self,
mut flow: FlowRef,
node: &ConcreteThreadSafeLayoutNode,
initial_fragments: IntermediateInlineFragments)
-> ConstructionResult {
// Gather up fragments for the inline flows we might need to create.
let mut inline_fragment_accumulator = InlineFragmentsAccumulator::new();
inline_fragment_accumulator.fragments.push_all(initial_fragments);
// List of absolute descendants, in tree order.
let mut abs_descendants = AbsoluteDescendants::new();
let mut legalizer = Legalizer::new();
if !node.is_replaced_content() {
for kid in node.children() {
if kid.get_pseudo_element_type() != PseudoElementType::Normal {
self.process(&kid);
}
self.build_block_flow_using_construction_result_of_child(
&mut flow,
node,
kid,
&mut inline_fragment_accumulator,
&mut abs_descendants,
&mut legalizer);
}
}
// Perform a final flush of any inline fragments that we were gathering up to handle {ib}
// splits, after stripping ignorable whitespace.
self.flush_inline_fragments_to_flow(inline_fragment_accumulator,
&mut flow,
&mut abs_descendants,
&mut legalizer,
node);
// The flow is done.
legalizer.finish(&mut flow);
flow.finish();
// Set up the absolute descendants.
let contains_positioned_fragments = flow.contains_positioned_fragments();
let is_absolutely_positioned = flow::base(&*flow).flags.contains(IS_ABSOLUTELY_POSITIONED);
if contains_positioned_fragments {
// This is the containing block for all the absolute descendants.
flow.set_absolute_descendants(abs_descendants);
abs_descendants = AbsoluteDescendants::new();
if is_absolutely_positioned {
// This is now the only absolute flow in the subtree which hasn't yet
// reached its CB.
abs_descendants.push(flow.clone());
}
}
ConstructionResult::Flow(flow, abs_descendants)
}
/// Constructs a flow for the given block node and its children. This method creates an
/// initial fragment as appropriate and then dispatches to
/// `build_flow_for_block_starting_with_fragments`. Currently the following kinds of flows get
/// initial content:
///
/// * Generated content gets the initial content specified by the `content` attribute of the
/// CSS.
/// * `<input>` and `<textarea>` elements get their content.
///
/// FIXME(pcwalton): It is not clear to me that there isn't a cleaner way to handle
/// `<textarea>`.
fn build_flow_for_block_like(&mut self, flow: FlowRef, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let mut fragments = IntermediateInlineFragments::new();
let node_is_input_or_text_area =
node.type_id() == Some(LayoutNodeType::Element(LayoutElementType::HTMLInputElement)) ||
node.type_id() == Some(LayoutNodeType::Element(LayoutElementType::HTMLTextAreaElement));
if node.get_pseudo_element_type().is_replaced_content() ||
node_is_input_or_text_area {
// A TextArea's text contents are displayed through the input text
// box, so don't construct them.
if node.type_id() == Some(LayoutNodeType::Element(LayoutElementType::HTMLTextAreaElement)) {
for kid in node.children() {
self.set_flow_construction_result(&kid, ConstructionResult::None)
}
}
let context = self.style_context();
let mut style = node.style(context);
style = context.stylist.style_for_anonymous(
&context.guards, &PseudoElement::ServoText, &style);
if node_is_input_or_text_area {
style = context.stylist.style_for_anonymous(
&context.guards, &PseudoElement::ServoInputText, &style)
}
self.create_fragments_for_node_text_content(&mut fragments, node, &style)
}
self.build_flow_for_block_starting_with_fragments(flow, node, fragments)
}
/// Pushes fragments appropriate for the content of the given node onto the given list.
fn create_fragments_for_node_text_content(&self,
fragments: &mut IntermediateInlineFragments,
node: &ConcreteThreadSafeLayoutNode,
style: &StyleArc<ServoComputedValues>) {
// Fast path: If there is no text content, return immediately.
let text_content = node.text_content();
if text_content.is_empty() {
return
}
let style = (*style).clone();
let selected_style = node.selected_style();
match text_content {
TextContent::Text(string) => {
let info = box UnscannedTextFragmentInfo::new(string, node.selection());
let specific_fragment_info = SpecificFragmentInfo::UnscannedText(info);
fragments.fragments.push_back(Fragment::from_opaque_node_and_style(
node.opaque(),
node.get_pseudo_element_type().strip(),
style,
selected_style,
node.restyle_damage(),
specific_fragment_info))
}
TextContent::GeneratedContent(content_items) => {
for content_item in content_items.into_iter() {
let specific_fragment_info = match content_item {
ContentItem::String(string) => {
let info = box UnscannedTextFragmentInfo::new(string, None);
SpecificFragmentInfo::UnscannedText(info)
}
content_item => {
let content_item = box GeneratedContentInfo::ContentItem(content_item);
SpecificFragmentInfo::GeneratedContent(content_item)
}
};
fragments.fragments.push_back(Fragment::from_opaque_node_and_style(
node.opaque(),
node.get_pseudo_element_type().strip(),
style.clone(),
selected_style.clone(),
node.restyle_damage(),
specific_fragment_info))
}
}
}
}
/// Builds a flow for a node with `display: block`. This yields a `BlockFlow` with possibly
/// other `BlockFlow`s or `InlineFlow`s underneath it, depending on whether {ib} splits needed
/// to happen.
fn build_flow_for_block(&mut self, node: &ConcreteThreadSafeLayoutNode, float_kind: Option<FloatKind>)
-> ConstructionResult {
if node.style(self.style_context()).is_multicol() {
return self.build_flow_for_multicol(node, float_kind)
}
let fragment = self.build_fragment_for_block(node);
let flow =
FlowRef::new(Arc::new(BlockFlow::from_fragment_and_float_kind(fragment, float_kind)));
self.build_flow_for_block_like(flow, node)
}
/// Bubbles up {ib} splits.
fn accumulate_inline_block_splits(&mut self,
splits: LinkedList<InlineBlockSplit>,
node: &ConcreteThreadSafeLayoutNode,
fragment_accumulator: &mut InlineFragmentsAccumulator,
opt_inline_block_splits: &mut LinkedList<InlineBlockSplit>) {
for split in splits {
let InlineBlockSplit {
predecessors,
flow: kid_flow
} = split;
fragment_accumulator.push_all(predecessors);
opt_inline_block_splits.push_back(
InlineBlockSplit::new(fragment_accumulator, node, self.style_context(), kid_flow));
}
}
/// Concatenates the fragments of kids, adding in our own borders/padding/margins if necessary.
/// Returns the `InlineFragmentsConstructionResult`, if any. There will be no
/// `InlineFragmentsConstructionResult` if this node consisted entirely of ignorable
/// whitespace.
fn build_fragments_for_nonreplaced_inline_content(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let mut opt_inline_block_splits: LinkedList<InlineBlockSplit> = LinkedList::new();
let mut fragment_accumulator = InlineFragmentsAccumulator::from_inline_node(node, self.style_context());
fragment_accumulator.bidi_control_chars = bidi_control_chars(&node.style(self.style_context()));
let mut abs_descendants = AbsoluteDescendants::new();
// Concatenate all the fragments of our kids, creating {ib} splits as necessary.
let mut is_empty = true;
for kid in node.children() {
is_empty = false;
if kid.get_pseudo_element_type() != PseudoElementType::Normal {
self.process(&kid);
}
match kid.get_construction_result() {
ConstructionResult::None => {}
ConstructionResult::Flow(flow, kid_abs_descendants) => {
if !flow::base(&*flow).flags.contains(IS_ABSOLUTELY_POSITIONED) {
opt_inline_block_splits.push_back(InlineBlockSplit::new(
&mut fragment_accumulator, node, self.style_context(), flow));
abs_descendants.push_descendants(kid_abs_descendants);
} else {
// Push the absolutely-positioned kid as an inline containing block.
let kid_node = flow.as_block().fragment.node;
let kid_pseudo = flow.as_block().fragment.pseudo.clone();
let kid_style = flow.as_block().fragment.style.clone();
let kid_selected_style = flow.as_block().fragment.selected_style.clone();
let kid_restyle_damage = flow.as_block().fragment.restyle_damage;
let fragment_info = SpecificFragmentInfo::InlineAbsolute(
InlineAbsoluteFragmentInfo::new(flow));
fragment_accumulator.push(Fragment::from_opaque_node_and_style(
kid_node,
kid_pseudo,
kid_style,
kid_selected_style,
kid_restyle_damage,
fragment_info));
fragment_accumulator.fragments
.absolute_descendants
.push_descendants(kid_abs_descendants);
}
}
ConstructionResult::ConstructionItem(ConstructionItem::InlineFragments(
InlineFragmentsConstructionResult {
splits,
fragments: successors,
})) => {
// Bubble up {ib} splits.
self.accumulate_inline_block_splits(splits,
node,
&mut fragment_accumulator,
&mut opt_inline_block_splits);
// Push residual fragments.
fragment_accumulator.push_all(successors);
}
ConstructionResult::ConstructionItem(ConstructionItem::Whitespace(
whitespace_node,
whitespace_pseudo,
whitespace_style,
whitespace_damage)) => {
// Instantiate the whitespace fragment.
let fragment_info = SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(" ".to_owned(), None));
let fragment =
Fragment::from_opaque_node_and_style(whitespace_node,
whitespace_pseudo,
whitespace_style,
node.selected_style(),
whitespace_damage,
fragment_info);
fragment_accumulator.fragments.fragments.push_back(fragment)
}
ConstructionResult::ConstructionItem(ConstructionItem::TableColumnFragment(_)) => {
// TODO: Implement anonymous table objects for missing parents
// CSS 2.1 § 17.2.1, step 3-2
}
}
}
let node_style = node.style(self.style_context());
if is_empty && node_style.has_padding_or_border() {
// An empty inline box needs at least one fragment to draw its background and borders.
let info = SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(String::new(), None));
let fragment = Fragment::from_opaque_node_and_style(node.opaque(),
node.get_pseudo_element_type().strip(),
node_style.clone(),
node.selected_style(),
node.restyle_damage(),
info);
fragment_accumulator.fragments.fragments.push_back(fragment)
}
// Finally, make a new construction result.
if opt_inline_block_splits.len() > 0 || !fragment_accumulator.fragments.is_empty()
|| abs_descendants.len() > 0 {
fragment_accumulator.fragments.absolute_descendants.push_descendants(abs_descendants);
// If the node is positioned, then it's the containing block for all absolutely-
// positioned descendants.
if node_style.get_box().position != position::T::static_ {
fragment_accumulator.fragments
.absolute_descendants
.mark_as_having_reached_containing_block();
}
let construction_item = ConstructionItem::InlineFragments(
InlineFragmentsConstructionResult {
splits: opt_inline_block_splits,
fragments: fragment_accumulator.to_intermediate_inline_fragments(self.style_context()),
});
ConstructionResult::ConstructionItem(construction_item)
} else {
ConstructionResult::None
}
}
/// Creates an `InlineFragmentsConstructionResult` for replaced content. Replaced content
/// doesn't render its children, so this just nukes a child's fragments and creates a
/// `Fragment`.
fn build_fragments_for_replaced_inline_content(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
for kid in node.children() {
self.set_flow_construction_result(&kid, ConstructionResult::None)
}
let context = self.style_context();
let style = node.style(context);
// If this node is ignorable whitespace, bail out now.
if node.is_ignorable_whitespace(context) {
return ConstructionResult::ConstructionItem(ConstructionItem::Whitespace(
node.opaque(),
node.get_pseudo_element_type().strip(),
context.stylist.style_for_anonymous(
&context.guards, &PseudoElement::ServoText, &style),
node.restyle_damage()))
}
// If this is generated content, then we need to initialize the accumulator with the
// fragment corresponding to that content. Otherwise, just initialize with the ordinary
// fragment that needs to be generated for this inline node.
let mut fragments = IntermediateInlineFragments::new();
match (node.get_pseudo_element_type(), node.type_id()) {
(_, Some(LayoutNodeType::Text)) => {
let text_style = context.stylist.style_for_anonymous(
&context.guards, &PseudoElement::ServoText, &style);
self.create_fragments_for_node_text_content(&mut fragments, node, &text_style)
}
(PseudoElementType::Normal, _) => {
fragments.fragments.push_back(self.build_fragment_for_block(node));
}
(_, _) => self.create_fragments_for_node_text_content(&mut fragments, node, &style),
}
let construction_item =
ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
splits: LinkedList::new(),
fragments: fragments,
});
ConstructionResult::ConstructionItem(construction_item)
}
/// Build the fragment for an inline-block or inline-flex, based on the `display` flag
fn build_fragment_for_inline_block_or_inline_flex(&mut self, node: &ConcreteThreadSafeLayoutNode,
display: display::T) -> ConstructionResult {
let block_flow_result = match display {
display::T::inline_block => self.build_flow_for_block(node, None),
display::T::inline_flex => self.build_flow_for_flex(node, None),
_ => panic!("The flag should be inline-block or inline-flex")
};
let (block_flow, abs_descendants) = match block_flow_result {
ConstructionResult::Flow(block_flow, abs_descendants) => (block_flow, abs_descendants),
_ => unreachable!()
};
let context = self.style_context();
let style = node.style(context);
let style = context.stylist.style_for_anonymous(
&context.guards, &PseudoElement::ServoInlineBlockWrapper, &style);
let fragment_info = SpecificFragmentInfo::InlineBlock(InlineBlockFragmentInfo::new(
block_flow));
let fragment = Fragment::from_opaque_node_and_style(node.opaque(),
node.get_pseudo_element_type().strip(),
style,
node.selected_style(),
node.restyle_damage(),
fragment_info);
let mut fragment_accumulator = InlineFragmentsAccumulator::new();
fragment_accumulator.fragments.fragments.push_back(fragment);
fragment_accumulator.fragments.absolute_descendants.push_descendants(abs_descendants);
let construction_item =
ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
splits: LinkedList::new(),
fragments: fragment_accumulator.to_intermediate_inline_fragments(context),
});
ConstructionResult::ConstructionItem(construction_item)
}
/// This is an annoying case, because the computed `display` value is `block`, but the
/// hypothetical box is inline.
fn build_fragment_for_absolutely_positioned_inline(&mut self,
node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let block_flow_result = self.build_flow_for_block(node, None);
let (block_flow, abs_descendants) = match block_flow_result {
ConstructionResult::Flow(block_flow, abs_descendants) => (block_flow, abs_descendants),
_ => unreachable!()
};
let fragment_info = SpecificFragmentInfo::InlineAbsoluteHypothetical(
InlineAbsoluteHypotheticalFragmentInfo::new(block_flow));
let style_context = self.style_context();
let style = node.style(style_context);
let style = style_context.stylist.style_for_anonymous(
&style_context.guards, &PseudoElement::ServoInlineAbsolute, &style);
let fragment = Fragment::from_opaque_node_and_style(node.opaque(),
PseudoElementType::Normal,
style,
node.selected_style(),
node.restyle_damage(),
fragment_info);
let mut fragment_accumulator = InlineFragmentsAccumulator::from_inline_node(node, self.style_context());
fragment_accumulator.fragments.fragments.push_back(fragment);
fragment_accumulator.fragments.absolute_descendants.push_descendants(abs_descendants);
let construction_item =
ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
splits: LinkedList::new(),
fragments: fragment_accumulator.to_intermediate_inline_fragments(style_context),
});
ConstructionResult::ConstructionItem(construction_item)
}
/// Builds one or more fragments for a node with `display: inline`. This yields an
/// `InlineFragmentsConstructionResult`.
fn build_fragments_for_inline(&mut self, node: &ConcreteThreadSafeLayoutNode) -> ConstructionResult {
// Is this node replaced content?
if !node.is_replaced_content() {
// Go to a path that concatenates our kids' fragments.
self.build_fragments_for_nonreplaced_inline_content(node)
} else {
// Otherwise, just nuke our kids' fragments, create our fragment if any, and be done
// with it.
self.build_fragments_for_replaced_inline_content(node)
}
}
/// Places any table captions found under the given table wrapper, if the value of their
/// `caption-side` property is equal to the given `side`.
fn place_table_caption_under_table_wrapper_on_side(&mut self,
table_wrapper_flow: &mut FlowRef,
node: &ConcreteThreadSafeLayoutNode,
side: caption_side::T) {
// Only flows that are table captions are matched here.
for kid in node.children() {
match kid.get_construction_result() {
ConstructionResult::Flow(kid_flow, _) => {
if kid_flow.is_table_caption() &&
kid_flow.as_block()
.fragment
.style()
.get_inheritedtable()
.caption_side == side {
table_wrapper_flow.add_new_child(kid_flow);
}
}
ConstructionResult::None | ConstructionResult::ConstructionItem(_) => {}
}
}
}
/// Builds a flow for a node with `column-count` or `column-width` non-`auto`.
/// This yields a `MulticolFlow` with a single `MulticolColumnFlow` underneath it.
fn build_flow_for_multicol(&mut self,
node: &ConcreteThreadSafeLayoutNode,
float_kind: Option<FloatKind>)
-> ConstructionResult {
let fragment = Fragment::new(node, SpecificFragmentInfo::Multicol, self.layout_context);
let mut flow = FlowRef::new(Arc::new(MulticolFlow::from_fragment(fragment, float_kind)));
let column_fragment = Fragment::new(node, SpecificFragmentInfo::MulticolColumn, self.layout_context);
let column_flow = FlowRef::new(Arc::new(MulticolColumnFlow::from_fragment(column_fragment)));
// First populate the column flow with its children.
let construction_result = self.build_flow_for_block_like(column_flow, node);
let mut abs_descendants = AbsoluteDescendants::new();
if let ConstructionResult::Flow(column_flow, column_abs_descendants) = construction_result {
flow.add_new_child(column_flow);
abs_descendants.push_descendants(column_abs_descendants);
}
// The flow is done.
flow.finish();
let contains_positioned_fragments = flow.contains_positioned_fragments();
if contains_positioned_fragments {
// This is the containing block for all the absolute descendants.
flow.set_absolute_descendants(abs_descendants);
abs_descendants = AbsoluteDescendants::new();
let is_absolutely_positioned =
flow::base(&*flow).flags.contains(IS_ABSOLUTELY_POSITIONED);
if is_absolutely_positioned {
// This is now the only absolute flow in the subtree which hasn't yet
// reached its containing block.
abs_descendants.push(flow.clone());
}
}
ConstructionResult::Flow(flow, abs_descendants)
}
/// Builds a flow for a node with `display: table`. This yields a `TableWrapperFlow` with
/// possibly other `TableCaptionFlow`s or `TableFlow`s underneath it.
fn build_flow_for_table(&mut self, node: &ConcreteThreadSafeLayoutNode, float_value: float::T)
-> ConstructionResult {
let mut legalizer = Legalizer::new();
let table_style;
let wrapper_style;
{
let context = self.style_context();
table_style = node.style(context);
wrapper_style = context.stylist.style_for_anonymous(
&context.guards, &PseudoElement::ServoTableWrapper, &table_style);
}
let wrapper_fragment =
Fragment::from_opaque_node_and_style(node.opaque(),
PseudoElementType::Normal,
wrapper_style,
node.selected_style(),
node.restyle_damage(),
SpecificFragmentInfo::TableWrapper);
let wrapper_float_kind = FloatKind::from_property(float_value);
let mut wrapper_flow =
FlowRef::new(Arc::new(TableWrapperFlow::from_fragment_and_float_kind(wrapper_fragment,
wrapper_float_kind)));
let table_fragment = Fragment::new(node, SpecificFragmentInfo::Table, self.layout_context);
let table_flow = FlowRef::new(Arc::new(TableFlow::from_fragment(table_fragment)));
// First populate the table flow with its children.
let construction_result = self.build_flow_for_block_like(table_flow, node);
let mut abs_descendants = AbsoluteDescendants::new();
// The order of the caption and the table are not necessarily the same order as in the DOM
// tree. All caption blocks are placed before or after the table flow, depending on the
// value of `caption-side`.
self.place_table_caption_under_table_wrapper_on_side(&mut wrapper_flow,
node,
caption_side::T::top);
if let ConstructionResult::Flow(table_flow, table_abs_descendants) = construction_result {
legalizer.add_child(self.style_context(), &mut wrapper_flow, table_flow);
abs_descendants.push_descendants(table_abs_descendants);
}
// If the value of `caption-side` is `bottom`, place it now.
self.place_table_caption_under_table_wrapper_on_side(&mut wrapper_flow,
node,
caption_side::T::bottom);
// The flow is done.
legalizer.finish(&mut wrapper_flow);
wrapper_flow.finish();
let contains_positioned_fragments = wrapper_flow.contains_positioned_fragments();
if contains_positioned_fragments {
// This is the containing block for all the absolute descendants.
wrapper_flow.set_absolute_descendants(abs_descendants);
abs_descendants = AbsoluteDescendants::new();
let is_absolutely_positioned =
flow::base(&*wrapper_flow).flags.contains(IS_ABSOLUTELY_POSITIONED);
if is_absolutely_positioned {
// This is now the only absolute flow in the subtree which hasn't yet
// reached its containing block.
abs_descendants.push(wrapper_flow.clone());
}
}
ConstructionResult::Flow(wrapper_flow, abs_descendants)
}
/// Builds a flow for a node with `display: table-caption`. This yields a `TableCaptionFlow`
/// with possibly other `BlockFlow`s or `InlineFlow`s underneath it.
fn build_flow_for_table_caption(&mut self, node: &ConcreteThreadSafeLayoutNode) -> ConstructionResult {
let fragment = self.build_fragment_for_block(node);
let flow = FlowRef::new(Arc::new(TableCaptionFlow::from_fragment(fragment)));
self.build_flow_for_block_like(flow, node)
}
/// Builds a flow for a node with `display: table-row-group`. This yields a `TableRowGroupFlow`
/// with possibly other `TableRowFlow`s underneath it.
fn build_flow_for_table_rowgroup(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let fragment = Fragment::new(node, SpecificFragmentInfo::TableRow, self.layout_context);
let flow = FlowRef::new(Arc::new(TableRowGroupFlow::from_fragment(fragment)));
self.build_flow_for_block_like(flow, node)
}
/// Builds a flow for a node with `display: table-row`. This yields a `TableRowFlow` with
/// possibly other `TableCellFlow`s underneath it.
fn build_flow_for_table_row(&mut self, node: &ConcreteThreadSafeLayoutNode) -> ConstructionResult {
let fragment = Fragment::new(node, SpecificFragmentInfo::TableRow, self.layout_context);
let flow = FlowRef::new(Arc::new(TableRowFlow::from_fragment(fragment)));
self.build_flow_for_block_like(flow, node)
}
/// Builds a flow for a node with `display: table-cell`. This yields a `TableCellFlow` with
/// possibly other `BlockFlow`s or `InlineFlow`s underneath it.
fn build_flow_for_table_cell(&mut self, node: &ConcreteThreadSafeLayoutNode) -> ConstructionResult {
let fragment = Fragment::new(node, SpecificFragmentInfo::TableCell, self.layout_context);
// Determine if the table cell should be hidden. Per CSS 2.1 § 17.6.1.1, this will be true
// if the cell has any in-flow elements (even empty ones!) and has `empty-cells` set to
// `hide`.
let hide = node.style(self.style_context()).get_inheritedtable().empty_cells == empty_cells::T::hide &&
node.children().all(|kid| {
let position = kid.style(self.style_context()).get_box().position;
!kid.is_content() ||
position == position::T::absolute ||
position == position::T::fixed
});
let flow = FlowRef::new(Arc::new(
TableCellFlow::from_node_fragment_and_visibility_flag(node, fragment, !hide)));
self.build_flow_for_block_like(flow, node)
}
/// Builds a flow for a node with `display: list-item`. This yields a `ListItemFlow` with
/// possibly other `BlockFlow`s or `InlineFlow`s underneath it.
fn build_flow_for_list_item(&mut self,
node: &ConcreteThreadSafeLayoutNode,
flotation: float::T)
-> ConstructionResult {
let flotation = FloatKind::from_property(flotation);
let marker_fragments = match node.style(self.style_context()).get_list().list_style_image {
list_style_image::computed_value::T(Either::First(ref url_value)) => {
let image_info = box ImageFragmentInfo::new(url_value.url().map(|u| u.clone()),
node,
&self.layout_context);
vec![Fragment::new(node, SpecificFragmentInfo::Image(image_info), self.layout_context)]
}
list_style_image::computed_value::T(Either::Second(_none)) => {
match ListStyleTypeContent::from_list_style_type(node.style(self.style_context())
.get_list()
.list_style_type) {
ListStyleTypeContent::None => Vec::new(),
ListStyleTypeContent::StaticText(ch) => {
let text = format!("{}\u{a0}", ch);
let mut unscanned_marker_fragments = LinkedList::new();
unscanned_marker_fragments.push_back(Fragment::new(
node,
SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(text, None)),
self.layout_context));
let marker_fragments =
with_thread_local_font_context(self.layout_context, |mut font_context| {
TextRunScanner::new().scan_for_runs(&mut font_context,
unscanned_marker_fragments)
});
marker_fragments.fragments
}
ListStyleTypeContent::GeneratedContent(info) => {
vec![Fragment::new(node, SpecificFragmentInfo::GeneratedContent(info), self.layout_context)]
}
}
}
};
// If the list marker is outside, it becomes the special "outside fragment" that list item
// flows have. If it's inside, it's just a plain old fragment. Note that this means that
// we adopt Gecko's behavior rather than WebKit's when the marker causes an {ib} split,
// which has caused some malaise (Bugzilla #36854) but CSS 2.1 § 12.5.1 lets me do it, so
// there.
let mut initial_fragments = IntermediateInlineFragments::new();
let main_fragment = self.build_fragment_for_block(node);
let flow = match node.style(self.style_context()).get_list().list_style_position {
list_style_position::T::outside => {
Arc::new(ListItemFlow::from_fragments_and_flotation(
main_fragment, marker_fragments, flotation))
}
list_style_position::T::inside => {
for marker_fragment in marker_fragments {
initial_fragments.fragments.push_back(marker_fragment)
}
Arc::new(ListItemFlow::from_fragments_and_flotation(
main_fragment, vec![], flotation))
}
};
self.build_flow_for_block_starting_with_fragments(FlowRef::new(flow), node, initial_fragments)
}
/// Creates a fragment for a node with `display: table-column`.
fn build_fragments_for_table_column(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
// CSS 2.1 § 17.2.1. Treat all child fragments of a `table-column` as `display: none`.
for kid in node.children() {
self.set_flow_construction_result(&kid, ConstructionResult::None)
}
let specific = SpecificFragmentInfo::TableColumn(TableColumnFragmentInfo::new(node));
let construction_item = ConstructionItem::TableColumnFragment(Fragment::new(node,
specific,
self.layout_context));
ConstructionResult::ConstructionItem(construction_item)
}
/// Builds a flow for a node with `display: table-column-group`.
/// This yields a `TableColGroupFlow`.
fn build_flow_for_table_colgroup(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let fragment =
Fragment::new(node,
SpecificFragmentInfo::TableColumn(TableColumnFragmentInfo::new(node)),
self.layout_context);
let mut col_fragments = vec!();
for kid in node.children() {
// CSS 2.1 § 17.2.1. Treat all non-column child fragments of `table-column-group`
// as `display: none`.
if let ConstructionResult::ConstructionItem(ConstructionItem::TableColumnFragment(fragment)) =
kid.get_construction_result() {
col_fragments.push(fragment)
}
}
if col_fragments.is_empty() {
debug!("add SpecificFragmentInfo::TableColumn for empty colgroup");
let specific = SpecificFragmentInfo::TableColumn(TableColumnFragmentInfo::new(node));
col_fragments.push(Fragment::new(node, specific, self.layout_context));
}
let mut flow = FlowRef::new(Arc::new(TableColGroupFlow::from_fragments(fragment, col_fragments)));
flow.finish();
ConstructionResult::Flow(flow, AbsoluteDescendants::new())
}
/// Builds a flow for a node with 'display: flex'.
fn build_flow_for_flex(&mut self,
node: &ConcreteThreadSafeLayoutNode,
float_kind: Option<FloatKind>)
-> ConstructionResult {
let fragment = self.build_fragment_for_block(node);
let flow = FlowRef::new(Arc::new(FlexFlow::from_fragment(fragment, float_kind)));
self.build_flow_for_block_like(flow, node)
}
/// Attempts to perform incremental repair to account for recent changes to this node. This
/// can fail and return false, indicating that flows will need to be reconstructed.
///
/// TODO(pcwalton): Add some more fast paths, like toggling `display: none`, adding block kids
/// to block parents with no {ib} splits, adding out-of-flow kids, etc.
pub fn repair_if_possible(&mut self, node: &ConcreteThreadSafeLayoutNode) -> bool {
// We can skip reconstructing the flow if we don't have to reconstruct and none of our kids
// did either.
//
// We visit the kids first and reset their HAS_NEWLY_CONSTRUCTED_FLOW flags after checking
// them. NOTE: Make sure not to bail out early before resetting all the flags!
let mut need_to_reconstruct = false;
// If the node has display: none, it's possible that we haven't even
// styled the children once, so we need to bailout early here.
if node.style(self.style_context()).get_box().clone_display() == display::T::none {
return false;
}
for kid in node.children() {
if kid.flags().contains(HAS_NEWLY_CONSTRUCTED_FLOW) {
kid.remove_flags(HAS_NEWLY_CONSTRUCTED_FLOW);
need_to_reconstruct = true
}
}
if need_to_reconstruct {
return false
}
if node.restyle_damage().contains(RECONSTRUCT_FLOW) {
return false
}
if node.can_be_fragmented() || node.style(self.style_context()).is_multicol() {
return false
}
let mut set_has_newly_constructed_flow_flag = false;
let result = {
let style = node.style(self.style_context());
let damage = node.restyle_damage();
let mut data = node.mutate_layout_data().unwrap();
match *node.construction_result_mut(&mut *data) {
ConstructionResult::None => true,
ConstructionResult::Flow(ref mut flow, _) => {
// The node's flow is of the same type and has the same set of children and can
// therefore be repaired by simply propagating damage and style to the flow.
if !flow.is_block_flow() {
return false
}
let flow = FlowRef::deref_mut(flow);
flow::mut_base(flow).restyle_damage.insert(damage);
flow.repair_style_and_bubble_inline_sizes(&style);
true
}
ConstructionResult::ConstructionItem(ConstructionItem::InlineFragments(
ref mut inline_fragments_construction_result)) => {
if !inline_fragments_construction_result.splits.is_empty() {
return false
}
for fragment in inline_fragments_construction_result.fragments
.fragments
.iter_mut() {
// Only mutate the styles of fragments that represent the dirty node (including
// pseudo-element).
if fragment.node != node.opaque() {
continue
}
if fragment.pseudo != node.get_pseudo_element_type().strip() {
continue
}
match fragment.specific {
SpecificFragmentInfo::InlineBlock(ref mut inline_block_fragment) => {
let flow_ref = FlowRef::deref_mut(&mut inline_block_fragment.flow_ref);
flow::mut_base(flow_ref).restyle_damage.insert(damage);
// FIXME(pcwalton): Fragment restyle damage too?
flow_ref.repair_style_and_bubble_inline_sizes(&style);
}
SpecificFragmentInfo::InlineAbsoluteHypothetical(
ref mut inline_absolute_hypothetical_fragment) => {
let flow_ref = FlowRef::deref_mut(
&mut inline_absolute_hypothetical_fragment.flow_ref);
flow::mut_base(flow_ref).restyle_damage.insert(damage);
// FIXME(pcwalton): Fragment restyle damage too?
flow_ref.repair_style_and_bubble_inline_sizes(&style);
}
SpecificFragmentInfo::InlineAbsolute(ref mut inline_absolute_fragment) => {
let flow_ref = FlowRef::deref_mut(
&mut inline_absolute_fragment.flow_ref);
flow::mut_base(flow_ref).restyle_damage.insert(damage);
// FIXME(pcwalton): Fragment restyle damage too?
flow_ref.repair_style_and_bubble_inline_sizes(&style);
}
SpecificFragmentInfo::ScannedText(_) => {
// Text fragments in ConstructionResult haven't been scanned yet
unreachable!()
}
SpecificFragmentInfo::GeneratedContent(_) |
SpecificFragmentInfo::UnscannedText(_) => {
// We can't repair this unscanned text; we need to update the
// scanned text fragments.
//
// TODO: Add code to find and repair the ScannedText fragments?
return false
}
_ => {
fragment.repair_style(&style);
set_has_newly_constructed_flow_flag = true;
}
}
}
true
}
ConstructionResult::ConstructionItem(_) => {
false
}
}
};
if set_has_newly_constructed_flow_flag {
node.insert_flags(HAS_NEWLY_CONSTRUCTED_FLOW);
}
return result;
}
}
impl<'a, ConcreteThreadSafeLayoutNode> PostorderNodeMutTraversal<ConcreteThreadSafeLayoutNode>
for FlowConstructor<'a, ConcreteThreadSafeLayoutNode>
where ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode {
// Construct Flow based on 'display', 'position', and 'float' values.
//
// CSS 2.1 Section 9.7
//
// TODO: This should actually consult the table in that section to get the
// final computed value for 'display'.
fn process(&mut self, node: &ConcreteThreadSafeLayoutNode) {
node.insert_flags(HAS_NEWLY_CONSTRUCTED_FLOW);
// Bail out if this node has an ancestor with display: none.
if node.style(self.style_context()).get_inheritedbox()._servo_under_display_none.0 {
self.set_flow_construction_result(node, ConstructionResult::None);
return;
}
// Get the `display` property for this node, and determine whether this node is floated.
let (display, float, positioning) = match node.type_id() {
None => {
// Pseudo-element.
let style = node.style(self.style_context());
let display = match node.get_pseudo_element_type() {
PseudoElementType::Normal
=> display::T::inline,
PseudoElementType::Before(maybe_display) |
PseudoElementType::After(maybe_display) |
PseudoElementType::DetailsContent(maybe_display) |
PseudoElementType::DetailsSummary(maybe_display)
=> maybe_display.unwrap_or(style.get_box().display),
};
(display, style.get_box().float, style.get_box().position)
}
Some(LayoutNodeType::Element(_)) => {
let style = node.style(self.style_context());
let original_display = style.get_box()._servo_display_for_hypothetical_box;
let munged_display = match original_display {
display::T::inline | display::T::inline_block => original_display,
_ => style.get_box().display,
};
(munged_display, style.get_box().float, style.get_box().position)
}
Some(LayoutNodeType::Text) =>
(display::T::inline, float::T::none, position::T::static_),
};
debug!("building flow for node: {:?} {:?} {:?} {:?}", display, float, positioning, node.type_id());
// Switch on display and floatedness.
match (display, float, positioning) {
// `display: none` contributes no flow construction result.
(display::T::none, _, _) => {
self.set_flow_construction_result(node, ConstructionResult::None);
}
// Table items contribute table flow construction results.
(display::T::table, float_value, _) => {
let construction_result = self.build_flow_for_table(node, float_value);
self.set_flow_construction_result(node, construction_result)
}
// Absolutely positioned elements will have computed value of
// `float` as 'none' and `display` as per the table.
// Only match here for block items. If an item is absolutely
// positioned, but inline we shouldn't try to construct a block
// flow here - instead, let it match the inline case
// below.
(display::T::block, _, position::T::absolute) |
(display::T::block, _, position::T::fixed) => {
let construction_result = self.build_flow_for_block(node, None);
self.set_flow_construction_result(node, construction_result)
}
// List items contribute their own special flows.
(display::T::list_item, float_value, _) => {
let construction_result = self.build_flow_for_list_item(node, float_value);
self.set_flow_construction_result(node, construction_result)
}
// Inline items that are absolutely-positioned contribute inline fragment construction
// results with a hypothetical fragment.
(display::T::inline, _, position::T::absolute) |
(display::T::inline_block, _, position::T::absolute) => {
let construction_result =
self.build_fragment_for_absolutely_positioned_inline(node);
self.set_flow_construction_result(node, construction_result)
}
// Inline items contribute inline fragment construction results.
//
// FIXME(pcwalton, #3307): This is not sufficient to handle floated generated content.
(display::T::inline, float::T::none, _) => {
let construction_result = self.build_fragments_for_inline(node);
self.set_flow_construction_result(node, construction_result)
}
// Inline-block items contribute inline fragment construction results.
(display::T::inline_block, float::T::none, _) => {
let construction_result = self.build_fragment_for_inline_block_or_inline_flex(node,
display::T::inline_block);
self.set_flow_construction_result(node, construction_result)
}
// Table items contribute table flow construction results.
(display::T::table_caption, _, _) => {
let construction_result = self.build_flow_for_table_caption(node);
self.set_flow_construction_result(node, construction_result)
}
// Table items contribute table flow construction results.
(display::T::table_column_group, _, _) => {
let construction_result = self.build_flow_for_table_colgroup(node);
self.set_flow_construction_result(node, construction_result)
}
// Table items contribute table flow construction results.
(display::T::table_column, _, _) => {
let construction_result = self.build_fragments_for_table_column(node);
self.set_flow_construction_result(node, construction_result)
}
// Table items contribute table flow construction results.
(display::T::table_row_group, _, _) |
(display::T::table_header_group, _, _) |
(display::T::table_footer_group, _, _) => {
let construction_result = self.build_flow_for_table_rowgroup(node);
self.set_flow_construction_result(node, construction_result)
}
// Table items contribute table flow construction results.
(display::T::table_row, _, _) => {
let construction_result = self.build_flow_for_table_row(node);
self.set_flow_construction_result(node, construction_result)
}
// Table items contribute table flow construction results.
(display::T::table_cell, _, _) => {
let construction_result = self.build_flow_for_table_cell(node);
self.set_flow_construction_result(node, construction_result)
}
// Flex items contribute flex flow construction results.
(display::T::flex, float_value, _) => {
let float_kind = FloatKind::from_property(float_value);
let construction_result = self.build_flow_for_flex(node, float_kind);
self.set_flow_construction_result(node, construction_result)
}
(display::T::inline_flex, _, _) => {
let construction_result = self.build_fragment_for_inline_block_or_inline_flex(node,
display::T::inline_flex);
self.set_flow_construction_result(node, construction_result)
}
// Block flows that are not floated contribute block flow construction results.
//
// TODO(pcwalton): Make this only trigger for blocks and handle the other `display`
// properties separately.
(_, float_value, _) => {
let float_kind = FloatKind::from_property(float_value);
let construction_result = self.build_flow_for_block(node, float_kind);
self.set_flow_construction_result(node, construction_result)
}
}
}
}
/// A utility trait with some useful methods for node queries.
trait NodeUtils {
/// Returns true if this node doesn't render its kids and false otherwise.
fn is_replaced_content(&self) -> bool;
fn construction_result_mut(self, layout_data: &mut LayoutData) -> &mut ConstructionResult;
/// Sets the construction result of a flow.
fn set_flow_construction_result(self, result: ConstructionResult);
/// Returns the construction result for this node.
fn get_construction_result(self) -> ConstructionResult;
}
impl<ConcreteThreadSafeLayoutNode> NodeUtils for ConcreteThreadSafeLayoutNode
where ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode {
fn is_replaced_content(&self) -> bool {
match self.type_id() {
Some(LayoutNodeType::Text) |
Some(LayoutNodeType::Element(LayoutElementType::HTMLImageElement)) |
Some(LayoutNodeType::Element(LayoutElementType::HTMLIFrameElement)) |
Some(LayoutNodeType::Element(LayoutElementType::HTMLCanvasElement)) |
Some(LayoutNodeType::Element(LayoutElementType::SVGSVGElement)) => true,
Some(LayoutNodeType::Element(LayoutElementType::HTMLObjectElement)) => self.has_object_data(),
Some(LayoutNodeType::Element(_)) => false,
None => self.get_pseudo_element_type().is_replaced_content(),
}
}
fn construction_result_mut(self, data: &mut LayoutData) -> &mut ConstructionResult {
match self.get_pseudo_element_type() {
PseudoElementType::Before(_) => &mut data.before_flow_construction_result,
PseudoElementType::After(_) => &mut data.after_flow_construction_result,
PseudoElementType::DetailsSummary(_) => &mut data.details_summary_flow_construction_result,
PseudoElementType::DetailsContent(_) => &mut data.details_content_flow_construction_result,
PseudoElementType::Normal => &mut data.flow_construction_result,
}
}
#[inline(always)]
fn set_flow_construction_result(self, mut result: ConstructionResult) {
if self.can_be_fragmented() {
if let ConstructionResult::Flow(ref mut flow, _) = result {
flow::mut_base(FlowRef::deref_mut(flow)).flags.insert(CAN_BE_FRAGMENTED);
}
}
let mut layout_data = self.mutate_layout_data().unwrap();
let dst = self.construction_result_mut(&mut *layout_data);
*dst = result;
}
#[inline(always)]
fn get_construction_result(self) -> ConstructionResult {
let mut layout_data = self.mutate_layout_data().unwrap();
self.construction_result_mut(&mut *layout_data).get()
}
}
/// Methods for interacting with HTMLObjectElement nodes
trait ObjectElement {
/// Returns true if this node has object data that is correct uri.
fn has_object_data(&self) -> bool;
/// Returns the "data" attribute value parsed as a URL
fn object_data(&self) -> Option<ServoUrl>;
}
impl<N> ObjectElement for N where N: ThreadSafeLayoutNode {
fn has_object_data(&self) -> bool {
let elem = self.as_element().unwrap();
let type_and_data = (
elem.get_attr(&ns!(), &local_name!("type")),
elem.get_attr(&ns!(), &local_name!("data")),
);
match type_and_data {
(None, Some(uri)) => is_image_data(uri),
_ => false
}
}
fn object_data(&self) -> Option<ServoUrl> {
let elem = self.as_element().unwrap();
let type_and_data = (
elem.get_attr(&ns!(), &local_name!("type")),
elem.get_attr(&ns!(), &local_name!("data")),
);
match type_and_data {
(None, Some(uri)) if is_image_data(uri) => ServoUrl::parse(uri).ok(),
_ => None
}
}
}
// This must not be public because only the layout constructor can call these
// methods.
trait FlowConstructionUtils {
/// Adds a new flow as a child of this flow. Removes the flow from the given leaf set if
/// it's present.
fn add_new_child(&mut self, new_child: FlowRef);
/// Finishes a flow. Once a flow is finished, no more child flows or boxes may be added to it.
/// This will normally run the bubble-inline-sizes (minimum and preferred -- i.e. intrinsic --
/// inline-size) calculation, unless the global `bubble_inline-sizes_separately` flag is on.
///
/// All flows must be finished at some point, or they will not have their intrinsic inline-
/// sizes properly computed. (This is not, however, a memory safety problem.)
fn finish(&mut self);
}
impl FlowConstructionUtils for FlowRef {
/// Adds a new flow as a child of this flow. Fails if this flow is marked as a leaf.
fn add_new_child(&mut self, mut new_child: FlowRef) {
{
let kid_base = flow::mut_base(FlowRef::deref_mut(&mut new_child));
kid_base.parallel.parent = parallel::mut_owned_flow_to_unsafe_flow(self);
}
let base = flow::mut_base(FlowRef::deref_mut(self));
base.children.push_back(new_child);
let _ = base.parallel.children_count.fetch_add(1, Ordering::Relaxed);
}
/// Finishes a flow. Once a flow is finished, no more child flows or fragments may be added to
/// it. This will normally run the bubble-inline-sizes (minimum and preferred -- i.e. intrinsic
/// -- inline-size) calculation, unless the global `bubble_inline-sizes_separately` flag is on.
///
/// All flows must be finished at some point, or they will not have their intrinsic inline-sizes
/// properly computed. (This is not, however, a memory safety problem.)
fn finish(&mut self) {
if !opts::get().bubble_inline_sizes_separately {
FlowRef::deref_mut(self).bubble_inline_sizes();
flow::mut_base(FlowRef::deref_mut(self)).restyle_damage.remove(BUBBLE_ISIZES);
}
}
}
/// Strips ignorable whitespace from the start of a list of fragments.
pub fn strip_ignorable_whitespace_from_start(this: &mut LinkedList<Fragment>) {
if this.is_empty() {
return // Fast path.
}
let mut leading_fragments_consisting_of_solely_bidi_control_characters = LinkedList::new();
while !this.is_empty() {
match this.front_mut().as_mut().unwrap().strip_leading_whitespace_if_necessary() {
WhitespaceStrippingResult::RetainFragment => break,
WhitespaceStrippingResult::FragmentContainedOnlyBidiControlCharacters => {
leading_fragments_consisting_of_solely_bidi_control_characters.push_back(
this.pop_front().unwrap())
}
WhitespaceStrippingResult::FragmentContainedOnlyWhitespace => {
let removed_fragment = this.pop_front().unwrap();
if let Some(ref mut remaining_fragment) = this.front_mut() {
remaining_fragment.meld_with_prev_inline_fragment(&removed_fragment);
}
}
}
}
prepend_from(this, &mut leading_fragments_consisting_of_solely_bidi_control_characters);
}
/// Strips ignorable whitespace from the end of a list of fragments.
pub fn strip_ignorable_whitespace_from_end(this: &mut LinkedList<Fragment>) {
if this.is_empty() {
return
}
let mut trailing_fragments_consisting_of_solely_bidi_control_characters = LinkedList::new();
while !this.is_empty() {
match this.back_mut().as_mut().unwrap().strip_trailing_whitespace_if_necessary() {
WhitespaceStrippingResult::RetainFragment => break,
WhitespaceStrippingResult::FragmentContainedOnlyBidiControlCharacters => {
trailing_fragments_consisting_of_solely_bidi_control_characters.push_front(
this.pop_back().unwrap())
}
WhitespaceStrippingResult::FragmentContainedOnlyWhitespace => {
let removed_fragment = this.pop_back().unwrap();
if let Some(ref mut remaining_fragment) = this.back_mut() {
remaining_fragment.meld_with_next_inline_fragment(&removed_fragment);
}
}
}
}
this.append(&mut trailing_fragments_consisting_of_solely_bidi_control_characters);
}
/// If the 'unicode-bidi' property has a value other than 'normal', return the bidi control codes
/// to inject before and after the text content of the element.
fn bidi_control_chars(style: &StyleArc<ServoComputedValues>) -> Option<(&'static str, &'static str)> {
use style::computed_values::direction::T::*;
use style::computed_values::unicode_bidi::T::*;
let unicode_bidi = style.get_text().unicode_bidi;
let direction = style.get_inheritedbox().direction;
// See the table in http://dev.w3.org/csswg/css-writing-modes/#unicode-bidi
match (unicode_bidi, direction) {
(normal, _) => None,
(embed, ltr) => Some(("\u{202A}", "\u{202C}")),
(embed, rtl) => Some(("\u{202B}", "\u{202C}")),
(isolate, ltr) => Some(("\u{2066}", "\u{2069}")),
(isolate, rtl) => Some(("\u{2067}", "\u{2069}")),
(bidi_override, ltr) => Some(("\u{202D}", "\u{202C}")),
(bidi_override, rtl) => Some(("\u{202E}", "\u{202C}")),
(isolate_override, ltr) => Some(("\u{2068}\u{202D}", "\u{202C}\u{2069}")),
(isolate_override, rtl) => Some(("\u{2068}\u{202E}", "\u{202C}\u{2069}")),
(plaintext, _) => Some(("\u{2068}", "\u{2069}")),
}
}
fn control_chars_to_fragment(node: &InlineFragmentNodeInfo,
context: &SharedStyleContext,
text: &str,
restyle_damage: RestyleDamage)
-> Fragment {
let info = SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(String::from(text), None));
let text_style = context.stylist.style_for_anonymous(
&context.guards, &PseudoElement::ServoText, &node.style);
Fragment::from_opaque_node_and_style(node.address,
node.pseudo,
text_style,
node.selected_style.clone(),
restyle_damage,
info)
}
/// Convenience methods for computed CSS values
trait ComputedValueUtils {
/// Returns true if this node has non-zero padding or border.
fn has_padding_or_border(&self) -> bool;
}
impl ComputedValueUtils for ServoComputedValues {
fn has_padding_or_border(&self) -> bool {
let padding = self.get_padding();
let border = self.get_border();
!padding.padding_top.is_definitely_zero() ||
!padding.padding_right.is_definitely_zero() ||
!padding.padding_bottom.is_definitely_zero() ||
!padding.padding_left.is_definitely_zero() ||
border.border_top_width != Au(0) ||
border.border_right_width != Au(0) ||
border.border_bottom_width != Au(0) ||
border.border_left_width != Au(0)
}
}
/// Maintains a stack of anonymous boxes needed to ensure that the flow tree is *legal*. The tree
/// is legal if it follows the rules in CSS 2.1 § 17.2.1.
///
/// As an example, the legalizer makes sure that table row flows contain only table cells. If the
/// flow constructor attempts to place, say, a block flow directly underneath the table row, the
/// legalizer generates an anonymous table cell in between to hold the block.
///
/// Generally, the flow constructor should use `Legalizer::add_child()` instead of calling
/// `Flow::add_new_child()` directly. This ensures that the flow tree remains legal at all times
/// and centralizes the anonymous flow generation logic in one place.
struct Legalizer {
/// A stack of anonymous flows that have yet to be finalized (i.e. that still could acquire new
/// children).
stack: Vec<FlowRef>,
}
impl Legalizer {
/// Creates a new legalizer.
fn new() -> Legalizer {
Legalizer {
stack: vec![],
}
}
/// Makes the `child` flow a new child of `parent`. Anonymous flows are automatically inserted
/// to keep the tree legal.
fn add_child(&mut self, context: &SharedStyleContext, parent: &mut FlowRef, mut child: FlowRef) {
while !self.stack.is_empty() {
if self.try_to_add_child(context, parent, &mut child) {
return
}
self.flush_top_of_stack(parent)
}
while !self.try_to_add_child(context, parent, &mut child) {
self.push_next_anonymous_flow(context, parent)
}
}
/// Flushes all flows we've been gathering up.
fn finish(mut self, parent: &mut FlowRef) {
while !self.stack.is_empty() {
self.flush_top_of_stack(parent)
}
}
/// Attempts to make `child` a child of `parent`. On success, this returns true. If this would
/// make the tree illegal, this method does nothing and returns false.
///
/// This method attempts to create anonymous blocks in between `parent` and `child` if and only
/// if those blocks will only ever have `child` as their sole child. At present, this is only
/// true for anonymous block children of flex flows.
fn try_to_add_child(&mut self, context: &SharedStyleContext, parent: &mut FlowRef, child: &mut FlowRef)
-> bool {
let mut parent = self.stack.last_mut().unwrap_or(parent);
let (parent_class, child_class) = (parent.class(), child.class());
match (parent_class, child_class) {
(FlowClass::TableWrapper, FlowClass::Table) |
(FlowClass::Table, FlowClass::TableColGroup) |
(FlowClass::Table, FlowClass::TableRowGroup) |
(FlowClass::Table, FlowClass::TableRow) |
(FlowClass::Table, FlowClass::TableCaption) |
(FlowClass::TableRowGroup, FlowClass::TableRow) |
(FlowClass::TableRow, FlowClass::TableCell) => {
parent.add_new_child((*child).clone());
true
}
(FlowClass::TableWrapper, _) |
(FlowClass::Table, _) |
(FlowClass::TableRowGroup, _) |
(FlowClass::TableRow, _) |
(_, FlowClass::Table) |
(_, FlowClass::TableColGroup) |
(_, FlowClass::TableRowGroup) |
(_, FlowClass::TableRow) |
(_, FlowClass::TableCaption) |
(_, FlowClass::TableCell) => {
false
}
(FlowClass::Flex, FlowClass::Inline) => {
flow::mut_base(FlowRef::deref_mut(child)).flags.insert(MARGINS_CANNOT_COLLAPSE);
let mut block_wrapper =
Legalizer::create_anonymous_flow(context,
parent,
&[PseudoElement::ServoAnonymousBlock],
SpecificFragmentInfo::Generic,
BlockFlow::from_fragment);
{
let flag = if parent.as_flex().main_mode() == Direction::Inline {
IS_INLINE_FLEX_ITEM
} else {
IS_BLOCK_FLEX_ITEM
};
let mut block = FlowRef::deref_mut(&mut block_wrapper).as_mut_block();
block.base.flags.insert(MARGINS_CANNOT_COLLAPSE);
block.fragment.flags.insert(flag);
}
block_wrapper.add_new_child((*child).clone());
block_wrapper.finish();
parent.add_new_child(block_wrapper);
true
}
(FlowClass::Flex, _) => {
{
let flag = if parent.as_flex().main_mode() == Direction::Inline {
IS_INLINE_FLEX_ITEM
} else {
IS_BLOCK_FLEX_ITEM
};
let mut block = FlowRef::deref_mut(child).as_mut_block();
block.base.flags.insert(MARGINS_CANNOT_COLLAPSE);
block.fragment.flags.insert(flag);
}
parent.add_new_child((*child).clone());
true
}
_ => {
parent.add_new_child((*child).clone());
true
}
}
}
/// Finalizes the flow on the top of the stack.
fn flush_top_of_stack(&mut self, parent: &mut FlowRef) {
let mut child = self.stack.pop().expect("flush_top_of_stack(): stack empty");
child.finish();
self.stack.last_mut().unwrap_or(parent).add_new_child(child)
}
/// Adds the anonymous flow that would be necessary to make an illegal child of `parent` legal
/// to the stack.
fn push_next_anonymous_flow(&mut self, context: &SharedStyleContext, parent: &FlowRef) {
let parent_class = self.stack.last().unwrap_or(parent).class();
match parent_class {
FlowClass::TableRow => {
self.push_new_anonymous_flow(context,
parent,
&[PseudoElement::ServoAnonymousTableCell],
SpecificFragmentInfo::TableCell,
TableCellFlow::from_fragment)
}
FlowClass::Table | FlowClass::TableRowGroup => {
self.push_new_anonymous_flow(context,
parent,
&[PseudoElement::ServoAnonymousTableRow],
SpecificFragmentInfo::TableRow,
TableRowFlow::from_fragment)
}
FlowClass::TableWrapper => {
self.push_new_anonymous_flow(context,
parent,
&[PseudoElement::ServoAnonymousTable],
SpecificFragmentInfo::Table,
TableFlow::from_fragment)
}
_ => {
self.push_new_anonymous_flow(context,
parent,
&[PseudoElement::ServoTableWrapper,
PseudoElement::ServoAnonymousTableWrapper],
SpecificFragmentInfo::TableWrapper,
TableWrapperFlow::from_fragment)
}
}
}
/// Creates an anonymous flow and pushes it onto the stack.
fn push_new_anonymous_flow<F>(&mut self,
context: &SharedStyleContext,
reference: &FlowRef,
pseudos: &[PseudoElement],
specific_fragment_info: SpecificFragmentInfo,
constructor: extern "Rust" fn(Fragment) -> F)
where F: Flow {
let new_flow = Legalizer::create_anonymous_flow(context,
reference,
pseudos,
specific_fragment_info,
constructor);
self.stack.push(new_flow)
}
/// Creates a new anonymous flow. The new flow is identical to `reference` except with all
/// styles applying to every pseudo-element in `pseudos` applied.
///
/// This method invokes the supplied constructor function on the given specific fragment info
/// in order to actually generate the flow.
fn create_anonymous_flow<F>(context: &SharedStyleContext,
reference: &FlowRef,
pseudos: &[PseudoElement],
specific_fragment_info: SpecificFragmentInfo,
constructor: extern "Rust" fn(Fragment) -> F)
-> FlowRef
where F: Flow {
let reference_block = reference.as_block();
let mut new_style = reference_block.fragment.style.clone();
for pseudo in pseudos {
new_style = context.stylist.style_for_anonymous(&context.guards, pseudo, &new_style)
}
let fragment = reference_block.fragment
.create_similar_anonymous_fragment(new_style,
specific_fragment_info);
FlowRef::new(Arc::new(constructor(fragment)))
}
}
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