LibWeb: Move table grid slots functionality to separate module

Userland/Libraries/LibWeb/Layout/TableGrid.h

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2023, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <LibWeb/Layout/Box.h>
+
+namespace Web::Layout {
+
+class TableGrid {
+public:
+    struct GridPosition {
+        size_t x;
+        size_t y;
+        inline bool operator==(GridPosition const&) const = default;
+    };
+
+    struct Row {
+        JS::NonnullGCPtr<Box const> box;
+        CSSPixels base_height { 0 };
+        CSSPixels reference_height { 0 };
+        CSSPixels final_height { 0 };
+        CSSPixels baseline { 0 };
+        CSSPixels min_size { 0 };
+        CSSPixels max_size { 0 };
+        bool has_intrinsic_percentage { false };
+        double intrinsic_percentage { 0 };
+        // Store whether the row is constrained: https://www.w3.org/TR/css-tables-3/#constrainedness
+        bool is_constrained { false };
+    };
+
+    struct Cell {
+        JS::NonnullGCPtr<Box const> box;
+        size_t column_index;
+        size_t row_index;
+        size_t column_span;
+        size_t row_span;
+        CSSPixels baseline { 0 };
+        CSSPixels outer_min_width { 0 };
+        CSSPixels outer_max_width { 0 };
+        CSSPixels outer_min_height { 0 };
+        CSSPixels outer_max_height { 0 };
+    };
+
+    // Calculate and return the grid and also rows and cells as output parameters.
+    static TableGrid calculate_row_column_grid(Box const&, Vector<Cell>&, Vector<Row>&);
+    // Overload for callers that don't care about rows and cells (currently the layout tree builder).
+    static TableGrid calculate_row_column_grid(Box const& box);
+
+    size_t column_count() const { return m_column_count; }
+    HashMap<GridPosition, bool> const& occupancy_grid() const { return m_occupancy_grid; }
+
+    static bool is_table_row_group(Box const& box)
+    {
+        auto const& display = box.display();
+        return display.is_table_row_group() || display.is_table_header_group() || display.is_table_footer_group();
+    }
+
+    static bool is_table_row(Box const& box)
+    {
+        return box.display().is_table_row();
+    }
+
+    template<typename Matcher, typename Callback>
+    static void for_each_child_box_matching(Box const& parent, Matcher matcher, Callback callback)
+    {
+        parent.for_each_child_of_type<Box>([&](Box const& child_box) {
+            if (matcher(child_box))
+                callback(child_box);
+        });
+    }
+
+private:
+    size_t m_column_count { 0 };
+    HashMap<GridPosition, bool> m_occupancy_grid;
+};
+
+}
+
+namespace AK {
+
+template<>
+struct Traits<Web::Layout::TableGrid::GridPosition> : public GenericTraits<Web::Layout::TableGrid::GridPosition> {
+    static unsigned hash(Web::Layout::TableGrid::GridPosition const& key)
+    {
+        return pair_int_hash(key.x, key.y);
+    }
+};
+
+}