Fix CSS step timing functions jump-both, jump-start, start at timestamp 0; Early return when possible

.github/workflows/main.yml

@@ -0,0 +1,75 @@
+name: CI
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+  workflow_dispatch:
+  merge_group:
+    types: [checks_requested]
+
+
+jobs:
+  linux-debug:
+    name: Linux (Debug)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+      - name: Run Tests
+        run: cargo build --features servo
+        env:
+          RUST_BACKTRACE: 1
+
+  linux-release:
+    name: Linux (Release)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+      - name: Run Tests
+        run: cargo build --release --features servo
+        env:
+          RUST_BACKTRACE: 1
+
+  macos-debug:
+    name: macOS (Debug)
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+      - name: Run Tests
+        run: cargo build --features servo
+        env:
+          RUST_BACKTRACE: 1
+
+  windows-debug:
+    name: Windows (Debug)
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+      - name: Run Tests
+        run: cargo build --features servo
+        env:
+          RUST_BACKTRACE: 1
+
+  build-result:
+    name: Result
+    runs-on: ubuntu-latest
+    if: ${{ always() }}
+    needs:
+      - linux-debug
+      - linux-release
+    steps:
+      - name: Success
+        if: ${{ !contains(needs.*.result, 'failure') && !contains(needs.*.result, 'cancelled') }}
+        run: exit 0
+      - name: Failure
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
+        run: exit 1
+

.github/workflows/mirror-to-release-branch.yml

@@ -0,0 +1,26 @@
+name: 🪞 Mirror `main`
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  mirror:
+    name: Mirror
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+    - name: Get branch name
+      id: branch-name
+      run: |
+        first_commit=$(git log --pretty=\%H --grep='Servo initial downstream commit')
+        upstream_base="$first_commit~"
+        echo BRANCH_NAME=$(git log -n1 --pretty='%as' $upstream_base) >> $GITHUB_OUTPUT
+    - uses: google/mirror-branch-action@v1.0
+      name: Mirror to ${{ steps.branch-name.outputs.BRANCH_NAME }}
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        source: main
+        dest: ${{ steps.branch-name.outputs.BRANCH_NAME }}

.github/workflows/sync-upstream.yml

@@ -0,0 +1,23 @@
+name: Sync upstream with mozilla-central
+
+on:
+  schedule:
+    - cron: '0 13 * * *'
+  workflow_dispatch:
+
+jobs:
+  sync:
+    name: Sync
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 1
+      - uses: actions/cache@v3
+        with:
+          path: _cache/upstream
+          key: upstream
+      - run: |
+          ./sync.sh _filtered
+          git fetch -f --progress ./_filtered main:upstream
+          git push -fu --progress origin upstream

.gitignore

@@ -0,0 +1,5 @@
+/_cache/
+/_filtered/
+/target/
+/style/properties/__pycache__/
+Cargo.lock

Cargo.toml

@@ -0,0 +1,36 @@
+[workspace]
+resolver = "2"
+members = [
+    "stylo_atoms",
+    "stylo_dom",
+    "malloc_size_of",
+    "rustfmt.toml",
+    "selectors",
+    "servo_arc",
+    "style",
+    "style_derive",
+    "stylo_static_prefs",
+    "style_traits",
+    "to_shmem",
+    "to_shmem_derive",
+]
+default-members = ["style"]
+
+[workspace.package]
+version = "0.14.0"
+
+[workspace.dependencies]
+# in-repo dependencies (separately versioned)
+servo_arc       = { version = "0.4.3",  path = "./servo_arc" }
+selectors       = { version = "0.36.1", path = "./selectors" }
+to_shmem        = { version = "0.3.0",  path = "./to_shmem", features = ["servo"] }
+to_shmem_derive = { version = "0.1.0",  path = "./to_shmem_derive" }
+
+# in-repo dependencies (main version)
+malloc_size_of  = { version = "0.14.0", path = "./malloc_size_of", package = "stylo_malloc_size_of", features = ["servo"] }
+static_prefs    = { version = "0.14.0", path = "./stylo_static_prefs", package = "stylo_static_prefs" }
+stylo_atoms     = { version = "0.14.0", path = "./stylo_atoms" }
+dom             = { version = "0.14.0", path = "./stylo_dom", package = "stylo_dom" }
+style_traits    = { version = "0.14.0", path = "./style_traits", features = ["servo"], package = "stylo_traits"}
+style_derive    = { version = "0.14.0", path = "./style_derive", package = "stylo_derive"}
+stylo           = { version = "0.14.0", path = "./style" }

README.md

@@ -0,0 +1,105 @@
+Stylo
+=====
+
+**High-Performance CSS Style Engine**
+
+[![Build Status](https://github.com/servo/stylo/actions/workflows/main.yml/badge.svg)](https://github.com/servo/stylo/actions)
+[![Crates.io](https://img.shields.io/crates/v/stylo.svg)](https://crates.io/crates/stylo)
+[![Docs](https://docs.rs/stylo/badge.svg)](https://docs.rs/stylo)
+![Crates.io License](https://img.shields.io/crates/l/stylo)
+
+Stylo is a high-performance, browser-grade CSS style engine written in Rust that powers [Servo](https://servo.org) and [Firefox](https://firefox.com). This repo contains Servo’s downstream version of Stylo. The upstream version lives in mozilla-central with the rest of the Gecko/Firefox codebase.
+
+Coordination of Stylo development happens:
+
+- Here in Github Issues
+- In the [#stylo](https://servo.zulipchat.com/#narrow/channel/417109-stylo) channel of the [Servo Zulip](https://servo.zulipchat.com/)
+- In the [#layout](https://chat.mozilla.org/#/room/#layout:mozilla.org) room of the Mozilla Matrix instance (matrix.mozilla.org)
+
+## High-Level Documentation
+
+- This [Mozilla Hacks article](https://hacks.mozilla.org/2017/08/inside-a-super-fast-css-engine-quantum-css-aka-stylo) contains a high-level overview of the Stylo architecture.
+- There is a [chapter](https://book.servo.org/architecture/style.html) in the Servo Book (although it is a little out of date).
+
+## Branches
+
+The branches are as follows:
+
+- [**upstream**](https://github.com/servo/style/tree/upstream) has upstream [mozilla-central](https://searchfox.org/mozilla-central/source/servo) filtered to the paths we care about ([style.paths](style.paths)), but is otherwise unmodified.
+- [**main**](https://github.com/servo/style/tree/ci) adds our downstream patches, plus the scripts and workflows for syncing with mozilla-central on top of **upstream**.
+
+> [!WARNING]
+> This repo syncs from upstream by creating a new branch and then rebasing our changes on top of it. This means that `git pull` will not work across syncs (you will need to use `git fetch`, `git reset` and `git rebase`).
+
+More information on the syncing process is available in [SYNCING.md](SYNCING.md)
+
+## Crates
+
+A guide to the crates contained within this repo
+
+### Stylo Crates
+
+These crates are largely implementation details of Stylo, although you may need to use some of them directly if you use Stylo.
+
+| Directory          | Crate                                                                                                               | Notes                                                                                                             |
+| ---                | ---                                                                                                                 | ---                                                                                                               |
+| style              | [![Crates.io](https://img.shields.io/crates/v/stylo.svg)](https://crates.io/crates/stylo)                           | The main Stylo crate containing the entire CSS engine                                                             |
+| style_traits       | [![Crates.io](https://img.shields.io/crates/v/stylo_traits.svg)](https://crates.io/crates/stylo_traits)             | Types and traits which allow other code to interoperate with Stylo without depending on the main crate directly.  |
+| stylo_dom          | [![Crates.io](https://img.shields.io/crates/v/stylo_dom.svg)](https://crates.io/crates/stylo_dom)                   | Similar to stylo_traits (but much smaller)                                                                        |
+| stylo_atoms        | [![Crates.io](https://img.shields.io/crates/v/stylo_atoms.svg)](https://crates.io/crates/stylo_atoms)               | [Atoms](https://docs.rs/string_cache/latest/string_cache/struct.Atom.html) for CSS and HTML event related strings |
+| stylo_static_prefs | [![Crates.io](https://img.shields.io/crates/v/stylo_static_prefs.svg)](https://crates.io/crates/stylo_static_prefs) | Configuration for Stylo. Can be used to set runtime preferences (enabling/disabling properties, etc)              |
+| style_derive       | [![Crates.io](https://img.shields.io/crates/v/stylo_derive.svg)](https://crates.io/crates/stylo_derive)             | Internal derive macro for stylo crate                                                                             |
+
+### Standalone Crates
+
+These crates form part of Stylo but are also be useful standalone.
+
+| Directory | Crate                                                                                             | Notes                   |
+| ---       | ---                                                                                               | ---                     |
+| selectors | [![Crates.io](https://img.shields.io/crates/v/selectors.svg)](https://crates.io/crates/selectors) | CSS Selector matching   |
+| servo_arc | [![Crates.io](https://img.shields.io/crates/v/servo_arc.svg)](https://crates.io/crates/servo_arc) | A variant on `std::Arc` |
+
+You may also be interested in the `cssparser` crate which lives in the [servo/rust-cssparser](https://github.com/servo/rust-cssparser) repo.
+
+### Support Crates
+
+Low-level crates which could technically be used standalone but are unlikely to be generally useful in practice.
+
+| Directory       | Crate                                                                                                                   | Notes                                                       |
+| ---             | ---                                                                                                                     | ---                                                         |
+| malloc_size_of  | [![Crates.io](https://img.shields.io/crates/v/stylo_malloc_size_of.svg)](https://crates.io/crates/stylo_malloc_size_of) | Heap size measurement for Stylo values                      |
+| to_shmem        | [![Crates.io](https://img.shields.io/crates/v/to_shmem.svg)](https://crates.io/crates/to_shmem)                         | Internal utility crate for sharing memory across processes. |
+| to_shmem_derive | [![Crates.io](https://img.shields.io/crates/v/to_shmem_derive.svg)](https://crates.io/crates/to_shmem_derive)           | Internal derive macro for to_shmem crate                    |
+
+## Building Servo Against a Local Copy of Stylo
+
+Assuming your local `servo` and `stylo` directories are siblings, you can build `servo` against `stylo` by adding the following to `servo/Cargo.toml`:
+
+```toml
+[patch."https://github.com/servo/stylo"]
+selectors = { path = "../stylo/selectors" }
+servo_arc = { path = "../stylo/servo_arc" }
+stylo = { path = "../stylo/style" }
+stylo_atoms = { path = "../stylo/stylo_atoms" }
+stylo_dom = { path = "../stylo/stylo_dom" }
+stylo_malloc_size_of = { path = "../stylo/malloc_size_of" }
+stylo_static_prefs = { path = "../stylo/stylo_static_prefs" }
+stylo_traits = { path = "../stylo/style_traits" }
+```
+
+## Releases
+
+Releases are made every time this repository rebases its changes on top of the latest version of upstream Stylo. There are a lot of crates here. In order to publish them, they must be done in order. One order that works is:
+
+- selectors
+- stylo_static_prefs
+- stylo_atoms
+- stylo_malloc_size_of
+- stylo_dom
+- stylo_derive
+- stylo_traits
+- stylo
+
+## License
+
+Stylo is licensed under MPL 2.0

SYNCING.md

@@ -0,0 +1,63 @@
+# Syncing
+
+This file documents the process of syncing this repository with the upstream copy of Stylo in mozilla-central.
+
+## Syncing `upstream` with mozilla-central
+
+Start by generating a filtered copy of mozilla-central. This will cache the raw mozilla-central in `_cache/upstream`, storing the result in `_filtered`:
+
+```sh
+$ ./sync.sh _filtered
+```
+
+If `_filtered` already exists, you will need to delete it and try again:
+
+```sh
+$ rm -Rf _filtered
+```
+
+Now overwrite our `upstream` with those commits and push:
+
+```sh
+$ git fetch -f --progress ./_filtered main:upstream
+$ git push -fu --progress origin upstream
+```
+
+## Rebasing `main` onto `upstream`
+
+Start by fetching `upstream` into your local repo:
+
+```sh
+$ git fetch -f origin upstream:upstream
+```
+
+In general, the filtering process is deterministic, yielding the same commit hashes each time, so we can rebase normally:
+
+```sh
+$ git rebase upstream
+```
+
+But if the filtering config changes or Mozilla moves to GitHub, the commit hashes on `upstream` may change. In this case, we need to tell git where the old upstream ends and our own commits start (notice the `~`):
+
+```sh
+$ git log --pretty=\%H --grep='Servo initial downstream commit'
+e62d7f0090941496e392e1dc91df103a38e3f488
+
+$ git rebase --onto upstream e62d7f0090941496e392e1dc91df103a38e3f488~
+Successfully rebased and updated refs/heads/main.
+```
+
+`start-rebase.sh` takes care of this automatically, but you should still use `git rebase` for subsequent steps like `--continue` and `--abort`:
+
+```sh
+$ ./start-rebase.sh upstream
+$ ./start-rebase.sh upstream -i     # interactive
+$ git rebase --continue             # not ./start-rebase.sh --continue
+$ git rebase --abort                # not ./start-rebase.sh --abort
+```
+
+Or if we aren’t ready to rebase onto the tip of upstream:
+
+```sh
+$ ./start-rebase.sh upstream~10 -i
+```

commit-from-merge.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+# Usage: commit-from-merge.sh <path/to/servo/servo> <merge commit> [extra git-commit(1) arguments ...]
+# Given a merge commit made by bors, runs git-commit(1) with your local changes
+# while borrowing the author name/email from the right-hand parent of the merge,
+# and the author date from the committer date of the merge.
+set -eu
+
+lookup_repo=$1; shift
+merge_commit=$1; shift
+author_name_email=$(git -C "$lookup_repo" log -n1 --pretty='%aN <%aE>' "$merge_commit"\^2)
+committer_date=$(git -C "$lookup_repo" log -n1 --pretty='%cd' "$merge_commit")
+
+set -- git commit --author="$author_name_email" --date="$committer_date" "$@"
+echo "$@"
+"$@"

commit-from-squashed.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+# Usage: commit-from-squashed.sh <squashed commit> [extra git-commit(1) arguments ...]
+# Given a squashed commit made by the GitHub merge queue, runs git-commit(1) with your local changes
+# while borrowing our author name/email from that commit, our author date from its committer date,
+# and our commit message from that commit.
+set -eu
+
+squashed_commit=$1; shift
+committer_date=$(git log -n1 --pretty='%cd' "$squashed_commit")
+
+# -c is equivalent to --author=$(...'%aN <%aE>') -m $(...'%B'), but allows editing
+set -- git commit -c "$squashed_commit" --date="$committer_date" "$@"
+echo "$@"
+"$@"

malloc_size_of/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
-name = "malloc_size_of"
-version = "0.0.1"
+name = "stylo_malloc_size_of"
+version.workspace = true
 authors = ["The Servo Project Developers"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/servo/stylo"
@@ -18,10 +18,10 @@ servo = ["string_cache"]
 app_units = "0.7"
 cssparser = "0.36"
 euclid = "0.22"
-selectors = { path = "../selectors" }
-servo_arc = { path = "../servo_arc" }
+selectors = { workspace = true }
+servo_arc = { workspace = true }
 smallbitvec = "2.3.0"
-smallvec = "1.0"
-string_cache = { version = "0.8", optional = true }
-thin-vec = { version = "0.2.1" }
+smallvec = "1.13"
+string_cache = { version = "0.9", optional = true }
+thin-vec = { version = "0.2.13" }
 void = "1.0.2"