chromium/third_party/blink/renderer/core/layout/table/layout_table_column_visitor.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_TABLE_LAYOUT_TABLE_COLUMN_VISITOR_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_TABLE_LAYOUT_TABLE_COLUMN_VISITOR_H_

#include "third_party/blink/renderer/core/layout/block_node.h"
#include "third_party/blink/renderer/core/layout/table/layout_table_column.h"

namespace blink {

// Rules for computed spans of COLGROUP/COL elements are complicated.
// 1) Spans cannot protrude outside of table boundary.
// 2) Colgroup span is
//    a) sum of children COL spans if it has children.
//    b) span attribute if it has no children.
//
// This function implements a Visitor pattern for LayoutTableColumn
// traversal, and computes correct spans.
//
// class Visitor {
//   void VisitCol(const BlockNode& column,
//                 wtf_size_t start_column_index,
//                 wtf_size_t span);
//   void EnterColgroup(const BlockNode&  colgroup,
//                      wtf_size_t start_column_index);
//   void LeaveColgroup(const BlockNode& colgroup,
//                      wtf_size_t start_column_index,
//                      wtf_size_t span,
//                      bool has_children);
// }
template <typename Visitor>
void VisitLayoutTableColumn(const HeapVector<BlockNode>& columns,
                            wtf_size_t table_column_count,
                            Visitor* visitor) { … }

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_TABLE_LAYOUT_TABLE_COLUMN_VISITOR_H_