tawasuyu/taffy

* test: add benchmarks for mixed Flexbox and CSS Grid layouts

Signed-off-by: WaterWhisperer <waterwhisperer24@qq.com>

* take the `benches` crate out of the workspace to solve the MSRV issue

* fix: update related ci

---------

Signed-off-by: WaterWhisperer <waterwhisperer24@qq.com>

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2eaec37ca..a4b38921b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -273,13 +273,15 @@ jobs:
             exit 1
           fi
 
+  # benches is excluded from the workspace as it depends on cosmic-text which breaks compilation
+  # of all crates in the workspace with our MSRV compiler
   benchmarks:
     name: Build Benchmarks
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
-      - run: cargo bench -p taffy_benchmarks --no-run
+      - run: cd benches && cargo bench --no-run
         name: Build benchmarks
         env:
           RUSTFLAGS: "-C opt-level=0"
@@ -290,7 +292,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
-      - run: cargo bench -p taffy_benchmarks --no-run --features yoga
+      - run: cd benches && cargo bench --no-run --features yoga
         name: Build benchmarks (w/yoga)
         env:
           RUSTFLAGS: "-C opt-level=0"
diff --git a/.gitignore b/.gitignore
index d625633e1..97ad0a970 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 /target
 /scripts/gentest/target
+/benches/target
 /examples/cosmic_text/target
 /yoga_test_fixtures
 /yoga_test_fixtures_grouped
diff --git a/Cargo.toml b/Cargo.toml
index bc569a5fe..459e332ff 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -105,9 +105,8 @@ members = [
     "scripts/gentest",
     "scripts/format-fixtures",
     "scripts/import-yoga-tests",
-    "benches",
     "tests/common",
 ]
-# The cosmic_text example is excluded from the workspace as including it breaks compilation
+# The cosmic_text example and benches are excluded from the workspace as including them breaks compilation
 # of all crates in the workspace with our MSRV compiler
-exclude = ["examples/cosmic_text"]
+exclude = ["examples/cosmic_text", "benches"]
diff --git a/benches/Cargo.toml b/benches/Cargo.toml
index 2404d1c58..0ba4b8245 100644
--- a/benches/Cargo.toml
+++ b/benches/Cargo.toml
@@ -21,6 +21,7 @@ taffy_03 = { package = "taffy", version = "0.3", optional = true }
 yoga = { version = "0.5.0", optional = true }
 ordered-float = { version = "4", optional = true }
 slotmap = { version = "1.0.6", optional = true }
+cosmic-text = "0.13"
 
 [features]
 yoga = ["dep:yoga", "dep:slotmap", "dep:ordered-float"]
@@ -45,3 +46,8 @@ harness = false
 name = "grid"
 path = "benches/grid.rs"
 harness = false
+
+[[bench]]
+name = "mixed"
+path = "benches/mixed.rs"
+harness = false
diff --git a/benches/benches/mixed.rs b/benches/benches/mixed.rs
new file mode 100644
index 000000000..e3c327a0a
--- /dev/null
+++ b/benches/benches/mixed.rs
@@ -0,0 +1,171 @@
+use cosmic_text::{Attrs, Buffer, FontSystem, Metrics, Shaping};
+use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
+use rand::prelude::*;
+use rand_chacha::ChaCha8Rng;
+use std::iter;
+use taffy::prelude::*;
+use taffy::style::Style;
+
+pub const LOREM_IPSUM : &str = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
+
+struct CosmicTextContext {
+    buffer: cosmic_text::Buffer,
+}
+
+impl CosmicTextContext {
+    fn new(metrics: Metrics, text: &str, attrs: Attrs, font_system: &mut FontSystem) -> Self {
+        let mut buffer = Buffer::new_empty(metrics);
+        buffer.set_size(font_system, None, None);
+        buffer.set_text(font_system, text, attrs, Shaping::Advanced);
+        Self { buffer }
+    }
+
+    fn measure(
+        &mut self,
+        known_dimensions: taffy::Size<Option<f32>>,
+        available_space: taffy::Size<taffy::AvailableSpace>,
+        font_system: &mut FontSystem,
+    ) -> taffy::Size<f32> {
+        let width_constraint = known_dimensions.width.or(match available_space.width {
+            AvailableSpace::MinContent => Some(0.0),
+            AvailableSpace::MaxContent => None,
+            AvailableSpace::Definite(width) => Some(width),
+        });
+        self.buffer.set_size(font_system, width_constraint, None);
+
+        self.buffer.shape_until_scroll(font_system, false);
+
+        let (width, total_lines) = self
+            .buffer
+            .layout_runs()
+            .fold((0.0, 0usize), |(width, total_lines), run| (run.line_w.max(width), total_lines + 1));
+        let height = total_lines as f32 * self.buffer.metrics().line_height;
+
+        taffy::Size { width, height }
+    }
+}
+
+fn measure_function(
+    known_dimensions: taffy::Size<Option<f32>>,
+    available_space: taffy::Size<taffy::AvailableSpace>,
+    node_context: Option<&mut CosmicTextContext>,
+    font_system: &mut FontSystem,
+) -> Size<f32> {
+    if let Size { width: Some(width), height: Some(height) } = known_dimensions {
+        return Size { width, height };
+    }
+
+    match node_context {
+        None => Size::ZERO,
+        Some(text_context) => text_context.measure(known_dimensions, available_space, font_system),
+    }
+}
+
+fn random_grid_track<R: Rng>(rng: &mut R) -> GridTemplateComponent<String> {
+    let switch: f32 = rng.random_range(0.0..=1.0);
+    if switch < 0.1 {
+        auto()
+    } else if switch < 0.2 {
+        min_content()
+    } else if switch < 0.3 {
+        max_content()
+    } else if switch < 0.5 {
+        fr(1.0)
+    } else if switch < 0.6 {
+        minmax(length(0.0), fr(1.0))
+    } else if switch < 0.8 {
+        length(40.0)
+    } else {
+        percent(0.3)
+    }
+}
+
+fn random_nxn_grid_style<R: Rng>(rng: &mut R, track_count: usize) -> Style {
+    Style {
+        display: Display::Grid,
+        grid_template_columns: iter::from_fn(|| Some(random_grid_track(rng))).take(track_count).collect(),
+        grid_template_rows: iter::from_fn(|| Some(random_grid_track(rng))).take(track_count).collect(),
+        ..Default::default()
+    }
+}
+
+fn random_flex_style<R: Rng>(rng: &mut R) -> Style {
+    Style {
+        display: Display::Flex,
+        flex_direction: if rng.random_bool(0.5) { FlexDirection::Row } else { FlexDirection::Column },
+        flex_wrap: if rng.random_bool(0.5) { FlexWrap::Wrap } else { FlexWrap::NoWrap },
+        ..Default::default()
+    }
+}
+
+fn build_mixed_tree(
+    taffy: &mut TaffyTree<CosmicTextContext>,
+    font_system: &mut FontSystem,
+    depth: usize,
+    width: usize,
+    rng: &mut ChaCha8Rng,
+    is_grid: bool,
+) -> NodeId {
+    if depth == 0 {
+        let metrics = Metrics { font_size: 14.0, line_height: 16.0 };
+        let context = CosmicTextContext::new(metrics, LOREM_IPSUM, Attrs::new(), font_system);
+        return taffy.new_leaf_with_context(Style::default(), context).unwrap();
+    }
+
+    let children: Vec<NodeId> =
+        (0..width).map(|_| build_mixed_tree(taffy, font_system, depth - 1, width, rng, !is_grid)).collect();
+
+    let style = if is_grid {
+        random_nxn_grid_style(rng, (width as f32).sqrt().ceil() as usize)
+    } else {
+        random_flex_style(rng)
+    };
+
+    taffy.new_with_children(style, &children).unwrap()
+}
+
+fn mixed_benchmark(c: &mut Criterion) {
+    let font_system = std::cell::RefCell::new(FontSystem::new());
+    let mut group = c.benchmark_group("mixed_flex_grid");
+
+    let depths = [2, 4];
+    let widths = [4, 8];
+
+    for &depth in &depths {
+        for &width in &widths {
+            let benchmark_id = BenchmarkId::new("mixed", format!("depth_{}_width_{}", depth, width));
+            group.bench_with_input(benchmark_id, &(depth, width), |b, &(depth, width)| {
+                b.iter_batched(
+                    || {
+                        let mut taffy = TaffyTree::new();
+                        let mut rng = ChaCha8Rng::seed_from_u64(12345);
+                        let root =
+                            build_mixed_tree(&mut taffy, &mut font_system.borrow_mut(), depth, width, &mut rng, true);
+                        (taffy, root)
+                    },
+                    |(mut taffy, root)| {
+                        taffy
+                            .compute_layout_with_measure(
+                                root,
+                                Size::MAX_CONTENT,
+                                |known_dimensions, available_space, _node_id, node_context, _style| {
+                                    measure_function(
+                                        known_dimensions,
+                                        available_space,
+                                        node_context,
+                                        &mut font_system.borrow_mut(),
+                                    )
+                                },
+                            )
+                            .unwrap();
+                    },
+                    criterion::BatchSize::SmallInput,
+                )
+            });
+        }
+    }
+    group.finish();
+}
+
+criterion_group!(benches, mixed_benchmark);
+criterion_main!(benches);