Everywhere: Hoist the Libraries folder to the top-level

Author: https://github.com/trflynn89
Commit: 93712b24bf
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2256
Reviewed-by: https://github.com/sideshowbarker

Libraries/LibWeb/CSS/CountersSet.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2024, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Checked.h>
+#include <AK/FlyString.h>
+#include <AK/Optional.h>
+#include <LibWeb/Forward.h>
+
+namespace Web::CSS {
+
+// "UAs may have implementation-specific limits on the maximum or minimum value of a counter.
+// If a counter reset, set, or increment would push the value outside of that range, the value
+// must be clamped to that range." - https://drafts.csswg.org/css-lists-3/#auto-numbering
+// So, we use a Checked<i32> and saturating addition/subtraction.
+using CounterValue = Checked<i32>;
+
+// https://drafts.csswg.org/css-lists-3/#counter
+struct Counter {
+    FlyString name;
+    UniqueNodeID originating_element_id; // "creator"
+    bool reversed { false };
+    Optional<CounterValue> value;
+};
+
+// https://drafts.csswg.org/css-lists-3/#css-counters-set
+class CountersSet {
+public:
+    CountersSet() = default;
+    ~CountersSet() = default;
+
+    Counter& instantiate_a_counter(FlyString name, UniqueNodeID originating_element_id, bool reversed, Optional<CounterValue>);
+    void set_a_counter(FlyString name, UniqueNodeID originating_element_id, CounterValue value);
+    void increment_a_counter(FlyString name, UniqueNodeID originating_element_id, CounterValue amount);
+    void append_copy(Counter const&);
+
+    Optional<Counter&> last_counter_with_name(FlyString const& name);
+    Optional<Counter&> counter_with_same_name_and_creator(FlyString const& name, UniqueNodeID originating_element_id);
+
+    Vector<Counter> const& counters() const { return m_counters; }
+    bool is_empty() const { return m_counters.is_empty(); }
+
+private:
+    Vector<Counter> m_counters;
+};
+
+}