style: Add a class-selector-matching benchmark

style/BUILD

@@ -5,7 +5,10 @@ cc_library(
     name = "style",
     srcs = glob(
         include = ["*.cpp"],
-        exclude = ["*_test.cpp"],
+        exclude = [
+            "*_test.cpp",
+            "*_bench.cpp",
+        ],
     ),
     hdrs = glob(["*.h"]),
     copts = HASTUR_COPTS,
@@ -33,3 +36,16 @@ cc_library(
         "//gfx",
     ],
 ) for src in glob(["*_test.cpp"])]
+
+[cc_test(
+    name = src.removesuffix(".cpp"),
+    size = "small",
+    srcs = [src],
+    copts = HASTUR_COPTS,
+    deps = [
+        ":style",
+        "//dom",
+        "//etest",
+        "@nanobench",
+    ],
+) for src in glob(["*_bench.cpp"])]

style/style_bench.cpp

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: 2025 Robin Lindén <[email protected]>
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include "style/style.h"
+
+#include "style/styled_node.h"
+
+#include "dom/dom.h"
+#include "etest/etest2.h"
+
+#include <nanobench.h>
+
+int main() {
+    etest::Suite s;
+
+    s.add_test("is_match: class", [](etest::IActions const &) {
+        ankerl::nanobench::Bench bench;
+        bench.title("is_match: class");
+
+        dom::Node few_classes_dom = dom::Element{"div", {{"class", "first second"}}};
+        auto few_classes = style::StyledNode{.node = few_classes_dom};
+        bench.run("match, few classes", [&] {
+            style::is_match(few_classes, ".first.second"); //
+        });
+
+        bench.run("no match, few classes", [&] {
+            style::is_match(few_classes, ".first.second.third.fourth"); //
+        });
+
+        dom::Node many_classes_dom = dom::Element{
+                "div",
+                {{"class", "one two three four five six seven eight nine ten"}},
+        };
+        auto many_classes = style::StyledNode{.node = many_classes_dom};
+        bench.run("match, many classes", [&] {
+            style::is_match(many_classes, ".eight.two.seven.ten"); //
+        });
+
+        bench.run("no match, many classes", [&] {
+            style::is_match(many_classes, ".eight.two.seve.ten"); //
+        });
+    });
+
+    return s.run();
+}