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style: Refactor grid types to preserve repeat() at computed value time and use cbindgen.

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I'm _really_ sorry for the size of the patch. I tried to do this in two steps
but it was a lot of work and pretty ugly.

This patch makes us use cbindgen for grid-template-{rows,columns}, in order to:

 * Make us preserve repeat() at computed-value time. This is per spec since
   interpolation needs to know about repeat(). Except for subgrid, which did the
   repeat expansion at parse-time and was a bit more annoying (plus it doesn't
   really animate yet so we don't need it to comply with the spec).

 * Tweaks the WPT tests for interpolation to adopt the resolution at:
   https://github.com/w3c/csswg-drafts/issues/3503.

Trade-off here, as this patch stands, is that this change makes us use less
long-living memory, since we expand repeat() during layout, but at the cost of a
bit of CPU time during layout (conditional on the property applying though,
which wasn't the case before). It should be very easy to store a cached version
of the template, should this be too hot (I expect it isn't), or to change the
representation in other ways to optimize grid layout code if it's worth it.

Another trade-off: I've used SmallPointerArray to handle line-name merging,
pointing to the individual arrays in the style data, rather than actually
heap-allocating the merged lists. This would also be pretty easy to change
should we measure and see that it's not worth it.

This patch also opens the gate to potentially improving memory usage in some
other ways, by reference-counting line-name lists for example, though I don't
have data that suggests it is worth it.

In general, this patch makes much easier to tweak the internal representation of
the grid style data structures. Overall, I think it's a win, the amount of magic
going on in that mako code was a bit huge; it took a bit to wrap my head around
it.

This patch comments out the style struct size assertions. They will be
uncommented in a follow-up patch which contains some improvements for this type,
which are worth getting reviewed separately.

Also, this patch doesn't remove as much code as I would've hoped for because of
I tried not to change most of the dom/grid code for inspector, but I think a
fair bit of the nsGridContainerFrame.cpp code that collects information for it
can be simplified / de-copy-pasted to some extent. But that was a pre-existing
problem and this patch is already quite massive.

Differential Revision: https://phabricator.services.mozilla.com/D36598
This commit is contained in:
Emilio Cobos Álvarez 2019-06-28 13:27:19 +02:00
parent 0e8b1853a7
commit 3e39998068
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GPG key ID: E1152D0994E4BF8A
8 changed files with 142 additions and 505 deletions
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198
components/style/values/generics/grid.rs
View file

@ -12,7 +12,7 @@ use crate::values::{CSSFloat, CustomIdent};
use crate::{Atom, Zero};
use cssparser::Parser;
use std::fmt::{self, Write};
use std::{cmp, mem, usize};
use std::{cmp, usize};
use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
/// These are the limits that we choose to clamp grid line numbers to.
@ -366,6 +366,7 @@ where
#[derive(
Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue, ToCss, ToResolvedValue, ToShmem,
)]
#[repr(C, u8)]
pub enum RepeatCount<Integer> {
/// A positive integer. This is allowed only for `<track-repeat>` and `<fixed-repeat>`
Number(Integer),
@ -380,18 +381,15 @@ impl Parse for RepeatCount<specified::Integer> {
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
// Maximum number of repeat is 10000. The greater numbers should be clamped.
const MAX_LINE: i32 = 10000;
if let Ok(mut i) = input.try(|i| specified::Integer::parse_positive(context, i)) {
if i.value() > MAX_LINE {
i = specified::Integer::new(MAX_LINE);
}
Ok(RepeatCount::Number(i))
} else {
try_match_ident_ignore_ascii_case! { input,
"auto-fill" => Ok(RepeatCount::AutoFill),
"auto-fit" => Ok(RepeatCount::AutoFit),
if i.value() > MAX_GRID_LINE {
i = specified::Integer::new(MAX_GRID_LINE);
}
return Ok(RepeatCount::Number(i))
}
try_match_ident_ignore_ascii_case! { input,
"auto-fill" => Ok(RepeatCount::AutoFill),
"auto-fit" => Ok(RepeatCount::AutoFit),
}
}
}
@ -411,7 +409,8 @@ impl Parse for RepeatCount<specified::Integer> {
ToShmem,
)]
#[css(function = "repeat")]
pub struct TrackRepeat<L, I> {
#[repr(C)]
pub struct GenericTrackRepeat<L, I> {
/// The number of times for the value to be repeated (could also be `auto-fit` or `auto-fill`)
pub count: RepeatCount<I>,
/// `<line-names>` accompanying `<track_size>` values.
@ -419,11 +418,13 @@ pub struct TrackRepeat<L, I> {
/// If there's no `<line-names>`, then it's represented by an empty vector.
/// For N `<track-size>` values, there will be N+1 `<line-names>`, and so this vector's
/// length is always one value more than that of the `<track-size>`.
pub line_names: Box<[Box<[CustomIdent]>]>,
pub line_names: crate::OwnedSlice<crate::OwnedSlice<CustomIdent>>,
/// `<track-size>` values.
pub track_sizes: Vec<TrackSize<L>>,
pub track_sizes: crate::OwnedSlice<GenericTrackSize<L>>,
}
pub use self::GenericTrackRepeat as TrackRepeat;
impl<L: ToCss, I: ToCss> ToCss for TrackRepeat<L, I> {
fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
where
@ -457,46 +458,10 @@ impl<L: ToCss, I: ToCss> ToCss for TrackRepeat<L, I> {
Ok(())
}
}
impl<L: Clone> TrackRepeat<L, specified::Integer> {
/// If the repeat count is numeric, then expand the values and merge accordingly.
pub fn expand(&self) -> Self {
if let RepeatCount::Number(num) = self.count {
let mut line_names = vec![];
let mut track_sizes = vec![];
let mut prev_names = vec![];
for _ in 0..num.value() {
let mut names_iter = self.line_names.iter();
for (size, names) in self.track_sizes.iter().zip(&mut names_iter) {
prev_names.extend_from_slice(&names);
let vec = mem::replace(&mut prev_names, vec![]);
line_names.push(vec.into_boxed_slice());
track_sizes.push(size.clone());
}
if let Some(names) = names_iter.next() {
prev_names.extend_from_slice(&names);
}
}
line_names.push(prev_names.into_boxed_slice());
TrackRepeat {
count: self.count,
track_sizes: track_sizes,
line_names: line_names.into_boxed_slice(),
}
} else {
// if it's auto-fit/auto-fill, then it's left to the layout.
TrackRepeat {
count: self.count,
track_sizes: self.track_sizes.clone(),
line_names: self.line_names.clone(),
}
}
}
}
/// Track list values. Can be <track-size> or <track-repeat>
///
/// cbindgen:derive-tagged-enum-copy-constructor=true
#[derive(
Animate,
Clone,
@ -509,56 +474,54 @@ impl<L: Clone> TrackRepeat<L, specified::Integer> {
ToResolvedValue,
ToShmem,
)]
pub enum TrackListValue<LengthPercentage, Integer> {
#[repr(C, u8)]
pub enum GenericTrackListValue<LengthPercentage, Integer> {
/// A <track-size> value.
TrackSize(#[animation(field_bound)] TrackSize<LengthPercentage>),
TrackSize(#[animation(field_bound)] GenericTrackSize<LengthPercentage>),
/// A <track-repeat> value.
TrackRepeat(#[animation(field_bound)] TrackRepeat<LengthPercentage, Integer>),
TrackRepeat(#[animation(field_bound)] GenericTrackRepeat<LengthPercentage, Integer>),
}
/// The type of a `<track-list>` as determined during parsing.
///
/// <https://drafts.csswg.org/css-grid/#typedef-track-list>
#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue, ToResolvedValue, ToShmem)]
pub enum TrackListType {
/// [`<auto-track-list>`](https://drafts.csswg.org/css-grid/#typedef-auto-track-list)
///
/// If this type exists, then the value at the index in `line_names` field in `TrackList`
/// has the `<line-names>?` list that comes before `<auto-repeat>`. If it's a specified value,
/// then the `repeat()` function (that follows the line names list) is also at the given index
/// in `values` field. On the contrary, if it's a computed value, then the `repeat()` function
/// is in the `auto_repeat` field.
Auto(u16),
/// [`<track-list>`](https://drafts.csswg.org/css-grid/#typedef-track-list)
Normal,
/// [`<explicit-track-list>`](https://drafts.csswg.org/css-grid/#typedef-explicit-track-list)
///
/// Note that this is a subset of the normal `<track-list>`, and so it could be used in place
/// of the latter.
Explicit,
pub use self::GenericTrackListValue as TrackListValue;
impl<L, I> TrackListValue<L, I> {
fn is_repeat(&self) -> bool {
matches!(*self, TrackListValue::TrackRepeat(..))
}
}
/// A grid `<track-list>` type.
///
/// <https://drafts.csswg.org/css-grid/#typedef-track-list>
#[derive(Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToResolvedValue, ToShmem)]
pub struct TrackList<LengthPercentage, Integer> {
/// The type of this `<track-list>` (auto, explicit or general).
///
/// In order to avoid parsing the same value multiple times, this does a single traversal
/// and arrives at the type of value it has parsed (or bails out gracefully with an error).
#[derive(Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToComputedValue, ToResolvedValue, ToShmem)]
#[repr(C)]
pub struct GenericTrackList<LengthPercentage, Integer> {
/// The index in `values` where our `<auto-repeat>` value is, if in bounds.
#[css(skip)]
pub list_type: TrackListType,
pub auto_repeat_index: usize,
/// A vector of `<track-size> | <track-repeat>` values.
pub values: Vec<TrackListValue<LengthPercentage, Integer>>,
pub values: crate::OwnedSlice<GenericTrackListValue<LengthPercentage, Integer>>,
/// `<line-names>` accompanying `<track-size> | <track-repeat>` values.
///
/// If there's no `<line-names>`, then it's represented by an empty vector.
/// For N values, there will be N+1 `<line-names>`, and so this vector's
/// length is always one value more than that of the `<track-size>`.
pub line_names: Box<[Box<[CustomIdent]>]>,
/// `<auto-repeat>` value. There can only be one `<auto-repeat>` in a TrackList.
pub auto_repeat: Option<TrackRepeat<LengthPercentage, Integer>>,
pub line_names: crate::OwnedSlice<crate::OwnedSlice<CustomIdent>>,
}
pub use self::GenericTrackList as TrackList;
impl<L, I> TrackList<L, I> {
/// Whether this track list is an explicit track list (that is, doesn't have
/// any repeat values).
pub fn is_explicit(&self) -> bool {
!self.values.iter().any(|v| v.is_repeat())
}
/// Whether this track list has an `<auto-repeat>` value.
pub fn has_auto_repeat(&self) -> bool {
self.auto_repeat_index < self.values.len()
}
}
impl<L: ToCss, I: ToCss> ToCss for TrackList<L, I> {
@ -566,11 +529,6 @@ impl<L: ToCss, I: ToCss> ToCss for TrackList<L, I> {
where
W: Write,
{
let auto_idx = match self.list_type {
TrackListType::Auto(i) => i as usize,
_ => usize::MAX,
};
let mut values_iter = self.values.iter().peekable();
let mut line_names_iter = self.line_names.iter().peekable();
@ -578,29 +536,20 @@ impl<L: ToCss, I: ToCss> ToCss for TrackList<L, I> {
let names = line_names_iter.next().unwrap(); // This should exist!
concat_serialize_idents("[", "]", names, " ", dest)?;
match self.auto_repeat {
Some(ref repeat) if idx == auto_idx => {
match values_iter.next() {
Some(value) => {
if !names.is_empty() {
dest.write_str(" ")?;
}
repeat.to_css(dest)?;
},
_ => match values_iter.next() {
Some(value) => {
if !names.is_empty() {
dest.write_str(" ")?;
}
value.to_css(dest)?;
},
None => break,
value.to_css(dest)?;
},
None => break,
}
if values_iter.peek().is_some() ||
line_names_iter.peek().map_or(false, |v| !v.is_empty()) ||
(idx + 1 == auto_idx)
(idx + 1 == self.auto_repeat_index)
{
dest.write_str(" ")?;
}
@ -613,7 +562,8 @@ impl<L: ToCss, I: ToCss> ToCss for TrackList<L, I> {
/// The `<line-name-list>` for subgrids.
///
/// `subgrid [ <line-names> | repeat(<positive-integer> | auto-fill, <line-names>+) ]+`
/// Old spec: https://www.w3.org/TR/2015/WD-css-grid-1-20150917/#typedef-line-name-list
///
/// https://drafts.csswg.org/css-grid-2/#typedef-line-name-list
#[derive(
Clone,
Debug,
@ -625,11 +575,12 @@ impl<L: ToCss, I: ToCss> ToCss for TrackList<L, I> {
ToResolvedValue,
ToShmem,
)]
#[repr(C)]
pub struct LineNameList {
/// The optional `<line-name-list>`
pub names: Box<[Box<[CustomIdent]>]>,
/// Indicates the line name that requires `auto-fill`
pub fill_idx: Option<u32>,
pub names: crate::OwnedSlice<crate::OwnedSlice<CustomIdent>>,
/// Indicates the line name that requires `auto-fill`, if in bounds.
pub fill_idx: usize,
}
impl Parse for LineNameList {
@ -652,13 +603,17 @@ impl Parse for LineNameList {
while let Ok(names) = input.try(parse_line_names) {
names_list.push(names);
}
Ok((names_list, count))
})
});
if let Ok((mut names_list, count)) = repeat_parse_result {
match count {
// FIXME(emilio): we probably shouldn't expand repeat() at
// parse time for subgrid.
//
// Also this doesn't have the merging semantics that
// non-subgrid has... But maybe that's ok?
RepeatCount::Number(num) => line_names.extend(
names_list
.iter()
@ -676,7 +631,7 @@ impl Parse for LineNameList {
let names = names_list.pop().unwrap();
line_names.push(names);
fill_idx = Some(line_names.len() as u32 - 1);
fill_idx = Some(line_names.len() - 1);
},
_ => return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError)),
}
@ -687,9 +642,13 @@ impl Parse for LineNameList {
}
}
if line_names.len() > MAX_GRID_LINE as usize {
line_names.truncate(MAX_GRID_LINE as usize);
}
Ok(LineNameList {
names: line_names.into_boxed_slice(),
fill_idx: fill_idx,
names: line_names.into(),
fill_idx: fill_idx.unwrap_or(usize::MAX),
})
}
}
@ -700,7 +659,7 @@ impl ToCss for LineNameList {
W: Write,
{
dest.write_str("subgrid")?;
let fill_idx = self.fill_idx.map(|v| v as usize).unwrap_or(usize::MAX);
let fill_idx = self.fill_idx;
for (i, names) in self.names.iter().enumerate() {
if i == fill_idx {
dest.write_str(" repeat(auto-fill,")?;
@ -727,8 +686,8 @@ impl ToCss for LineNameList {
}
/// Variants for `<grid-template-rows> | <grid-template-columns>`
/// Subgrid deferred to Level 2 spec due to lack of implementation.
/// But it's implemented in gecko, so we have to as well.
///
/// cbindgen:derive-tagged-enum-copy-constructor=true
#[derive(
Animate,
Clone,
@ -741,7 +700,8 @@ impl ToCss for LineNameList {
ToResolvedValue,
ToShmem,
)]
pub enum GridTemplateComponent<L, I> {
#[repr(C, u8)]
pub enum GenericGridTemplateComponent<L, I> {
/// `none` value.
None,
/// The grid `<track-list>`
@ -750,7 +710,7 @@ pub enum GridTemplateComponent<L, I> {
#[compute(field_bound)]
#[resolve(field_bound)]
#[shmem(field_bound)]
TrackList<L, I>,
GenericTrackList<L, I>,
),
/// A `subgrid <line-name-list>?`
/// TODO: Support animations for this after subgrid is addressed in [grid-2] spec.
@ -758,6 +718,8 @@ pub enum GridTemplateComponent<L, I> {
Subgrid(LineNameList),
}
pub use self::GenericGridTemplateComponent as GridTemplateComponent;
impl<L, I> GridTemplateComponent<L, I> {
/// Returns length of the <track-list>s <track-size>
pub fn track_list_len(&self) -> usize {