Optimize BidiParagraphs with ASCII fast path (#408)

* Optimize BidiParagraphs with ASCII fast path - Added fast path for ASCII text that avoids BidiInfo allocation - Added some text shaping benchmarks

* refactor: fix clippy warnings and cleanup imports

benches/text_shaping_benchmarks.rs

@@ -0,0 +1,121 @@
+use cosmic_text as ct;
+use cosmic_text::BidiParagraphs;
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+
+fn bench_ascii_fast_path(c: &mut Criterion) {
+    let mut fs = ct::FontSystem::new();
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0));
+    buffer.set_size(&mut fs, Some(500.0), None);
+
+    let ascii_text = "Pure ASCII text for BidiParagraphs optimization testing.\n".repeat(50);
+
+    c.bench_function("ShapeLine/ASCII Fast Path", |b| {
+        b.iter(|| {
+            buffer.set_text(
+                &mut fs,
+                black_box(&ascii_text),
+                &ct::Attrs::new(),
+                ct::Shaping::Advanced,
+            );
+            buffer.shape_until_scroll(&mut fs, false);
+        });
+    });
+}
+
+fn bench_bidi_processing(c: &mut Criterion) {
+    let mut fs = ct::FontSystem::new();
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0));
+    buffer.set_size(&mut fs, Some(500.0), None);
+
+    let bidi_text = "Mixed English and العربية النص العربي text for BiDi testing.\nThis tests adjust_levels and combined BiDi optimizations.\n".repeat(30);
+
+    c.bench_function("ShapeLine/BiDi Processing", |b| {
+        b.iter(|| {
+            buffer.set_text(
+                &mut fs,
+                black_box(&bidi_text),
+                &ct::Attrs::new(),
+                ct::Shaping::Advanced,
+            );
+            buffer.shape_until_scroll(&mut fs, false);
+        });
+    });
+}
+
+fn bench_layout_heavy(c: &mut Criterion) {
+    let mut fs = ct::FontSystem::new();
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0));
+    buffer.set_size(&mut fs, Some(500.0), None);
+
+    let layout_text = "This is a very long line that will wrap multiple times and stress the reorder optimization through intensive layout processing with comprehensive buffer reuse testing. ".repeat(30);
+
+    c.bench_function("ShapeLine/Layout Heavy", |b| {
+        b.iter(|| {
+            buffer.set_text(
+                &mut fs,
+                black_box(&layout_text),
+                &ct::Attrs::new(),
+                ct::Shaping::Advanced,
+            );
+            buffer.shape_until_scroll(&mut fs, false);
+        });
+    });
+}
+
+fn bench_combined_stress(c: &mut Criterion) {
+    let mut fs = ct::FontSystem::new();
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0));
+    buffer.set_size(&mut fs, Some(500.0), None);
+
+    let stress_text = format!("{}\n{}\n{}\n{}\n",
+        "ASCII line for BidiParagraphs optimization. ".repeat(15),
+        "Mixed English + العربية for BiDi optimizations. ".repeat(12),
+        "Very long wrapping line that will trigger reorder optimizations multiple times through intensive layout processing. ".repeat(8),
+        "Cache key generation line for ShapeRunKey optimization testing. ".repeat(10)
+    ).repeat(10);
+
+    c.bench_function("ShapeLine/Combined Stress", |b| {
+        b.iter(|| {
+            buffer.set_text(
+                &mut fs,
+                black_box(&stress_text),
+                &ct::Attrs::new(),
+                ct::Shaping::Advanced,
+            );
+            buffer.shape_until_scroll(&mut fs, false);
+        });
+    });
+}
+
+fn bench_bidi_paragraphs_ascii(c: &mut Criterion) {
+    let ascii_text = "Simple ASCII text\nwith multiple lines\n".repeat(50);
+
+    c.bench_function("BidiParagraphs/ASCII", |b| {
+        b.iter(|| {
+            let paras = BidiParagraphs::new(black_box(&ascii_text));
+            black_box(paras.count());
+        });
+    });
+}
+
+fn bench_bidi_paragraphs_mixed(c: &mut Criterion) {
+    let mixed_text = "Mixed English and العربية text\nwith multiple lines\n".repeat(30);
+
+    c.bench_function("BidiParagraphs/Mixed", |b| {
+        b.iter(|| {
+            let paras = BidiParagraphs::new(black_box(&mixed_text));
+            black_box(paras.count());
+        });
+    });
+}
+
+criterion_group!(
+    benches,
+    bench_ascii_fast_path,
+    bench_bidi_processing,
+    bench_layout_heavy,
+    bench_combined_stress,
+    bench_bidi_paragraphs_ascii,
+    bench_bidi_paragraphs_mixed
+);
+criterion_main!(benches);