Previously, we would only invalidate style when setting the `media` IDL
attribute; changing the attribute via `setAttribute()` and
`removeAttribute()` had no immediate effect.
There are two changes happening here: a correctness fix, and an
optimization. In theory they are unrelated, but the optimization
actually paves the way for the correctness fix.
Before this commit, the HTML tokenizer would attempt to look for named
character references by checking from after the `&` until the end of
m_decoded_input, which meant that it was unable to recognize things like
named character references that are inserted via `document.write` one
byte at a time. For example, if `∉` was written one-byte-at-a-time
with `document.write`, then the tokenizer would only check against `n`
since that's all that would exist at the time of the check and therefore
erroneously conclude that it was an invalid named character reference.
This commit modifies the approach taken for named character reference
matching by using a trie-like structure (specifically, a deterministic
acyclic finite state automaton or DAFSA), which allows for efficiently
matching one-character-at-a-time and therefore it is able to pick up
matching where it left off after each code point is consumed.
Note: Because it's possible for a partial match to not actually develop
into a full match (e.g. `¬indo` which could lead to `⋵̸`),
some backtracking is performed after-the-fact in order to only consume
the code points within the longest match found (e.g. `¬indo` would
backtrack back to `¬`).
With this new approach, `document.write` being called one-byte-at-a-time
is handled correctly, which allows for passing more WPT tests, with the
most directly relevant tests being
`/html/syntax/parsing/html5lib_entities01.html`
and
`/html/syntax/parsing/html5lib_entities02.html`
when run with `?run_type=write_single`. Additionally, the implementation
now better conforms to the language of the spec (and resolves a FIXME)
because exactly the matched characters are consumed and nothing more, so
SWITCH_TO is able to be used as the spec says instead of RECONSUME_IN.
The new approach is also an optimization:
- Instead of a linear search using `starts_with`, the usage of a DAFSA
means that it is always aware of which characters can lead to a match
at any given point, and will bail out whenever a match is no longer
possible.
- The DAFSA is able to take advantage of the note in the section
`13.5 Named character references` that says "This list is static and
will not be expanded or changed in the future." and tailor its Node
struct accordingly to tightly pack each node's data into 32-bits.
Together with the inherent DAFSA property of redundant node
deduplication, the amount of data stored for named character reference
matching is minimized.
In my testing:
- A benchmark tokenizing an arbitrary set of HTML test files was about
1.23x faster (2070ms to 1682ms).
- A benchmark tokenizing a file with tens of thousands of named
character references mixed in with truncated named character
references and arbitrary ASCII characters/ampersands runs about 8x
faster (758ms to 93ms).
- The size of `liblagom-web.so` was reduced by 94.96KiB.
Some technical details:
A DAFSA (deterministic acyclic finite state automaton) is essentially a
trie flattened into an array, but it also uses techniques to minimize
redundant nodes. This provides fast lookups while minimizing the
required data size, but normally does not allow for associating data
related to each word. However, by adding a count of the number of
possible words from each node, it becomes possible to also use it to
achieve minimal perfect hashing for the set of words (which allows going
from word -> unique index as well as unique index -> word). This allows
us to store a second array of data so that the DAFSA can be used as a
lookup for e.g. the associated code points.
For the Swift implementation, the new NamedCharacterReferenceMatcher
was used to satisfy the previous API and the tokenizer was left alone
otherwise. In the future, the Swift implementation should be updated to
use the same implementation for its NamedCharacterReference state as
the updated C++ implementation.
...boxes with non-auto height.
We know for sure that by the time we layout abspos boxes, their
containing block has definite height, so it's possible to resolve
non-auto heights and mark it as definite before doing inner layout.
Big step towards having reasonable performance on
https://demo.immich.app/photos because now we avoid a bunch of work
initiated by mistakenly invoked intersection observer callbacks.
Co-Authored-By: Andreas Kling <andreas@ladybird.org>
It was annoying to maintain two separate but almost identical functions
that gradually accumulated small differences over time. This change
replaces them with a single function that resolves either width or
height, depending on the specified dimension.
This avoids emitting TDZ checks for multiple bindings declared and
referenced within one variable declaration, i.e:
var foo = 0, bar = foo;
In the above case, we'd emit an unnecessary TDZ check for the second
reference to `foo`.
Before this change, we would enumerate all the keys with
[[OwnPropertyKeys]], and then do [[GetOwnPropertyDescriptor]] twice for
each key as we went through them.
We now only do one [[GetOwnPropertyDescriptor]] per key, which
drastically reduces the number of proxy traps when those are involved.
The new trap sequence matches what you get with V8, so I don't think
anyone will be unpleasantly surprised here.
If all the parameter default values end up in locals, the lexical
environment we create to hold them would never be used for anything,
and so we can elide it and avoid the GC work.
Instead of creating a new iterator result Object for every step of
for..in iteration, we can create a single object up front and reuse it
for every step. This avoids generating a bunch of garbage that isn't
observable by author code anyway.
We can also reuse the existing premade shape for these objects.
Instead of pruning as-we-go, which means a ton of hash lookups,
we now only do a single pass to prune all non-enumerable keys when
setting up for for..in iteration.
This fixes a compile warning on GCC 13.3.0 where it warns about the
use of Variant within this class with no key function. Since the class
was almost a CRTP base class, make it a real one.
Previously, when serializing an angle value, we would always convert it
to degrees. We now canonicalize the angle value only when serializing
its computed value.
Previously, when serializing a time value, we would always convert it
to seconds. We now canonicalize the time value only when serializing
its computed value.
GIF loader was completely failing when encountering errors with
frame descriptors or individual frames, even when some frames were
successfully loaded. Now we attempt to decode at least some frames
and fail only when no frames can be decoded at all.
When we inspect a DOM node, we currently serialize many properties for
that node, including its layout, computed style, used fonts, etc. Now
that we aren't piggy-backing on the Inspector interface, we can instead
only serialize the specific information required by DevTools.
Now that we aren't piggy-backing on the Inspector interface, we can make
our box-model serialization provide exactly the values that DevTools
requires.
With this change we no longer stretch "width: auto" for replaced
elements and also use "width calculation rules for block-level replaced
elements", like suggested by the spec.
The intent is that this will replace the separate Task Manager window.
This will allow us to more easily add features such as actual process
management, better rendering of the process table, etc. Included in this
page is the ability to sort table rows.
This also lays the ground work for more internal `about` pages, such as
about:config.
CSSStyleDeclaration is a base class that's used by various collections
of style properties or descriptors. This commit moves all
style-property-related code into CSSStyleProperties, where it belongs.
As noted in the previous commit, we also apply the CSSStyleProperties
prototype now.
