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/*
* Copyright (C) 2025 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <WebCore/AXID.h>
#include <wtf/FixedVector.h>
namespace WebCore {
// This class represents a stitch-group. All members in a stitch-group will not
// be exposed in the outwardly facing accessibility tree except for the group
// representative (m_representativeID), who will respond to accessibility APIs
// using the stitched representation of all members of the group.
//
// The intention of this is to expose a simpler accessibility tree, making
// the job of assistive technologies easier, and the lives of users better, e.g.
// by reducing the number of navigation stops an AT user has to make.
//
// Stitch groups are per-block-flow element, so only nodes within the same flow
// can be stitched together. Stitch group membership is maintained by the
// AXObjectCache on the main-thread, and stored as an AXProperty on each block-flow
// AXIsolatedObject on the accessibility thread. A stitch group is only valid if it
// has 2 or more elements within it — a group of one makes no sense.
class AXStitchGroup {
public:
explicit AXStitchGroup(const Vector<AXID>& members, AXID representativeID)
: m_members(members)
, m_representativeID(representativeID)
{
ASSERT(isValid());
}
explicit AXStitchGroup(Vector<AXID>&& members, AXID representativeID)
: m_members(WTFMove(members))
, m_representativeID(representativeID)
{
ASSERT(isValid());
}
bool isEmpty() const { return m_members.isEmpty(); }
bool isValid() const
{
// Some usages of this class intentionally create an instance containing only
// the representativeID to avoid an unneeded copy of m_members, so empty m_members
// can be a valid state.
return m_members.isEmpty() || m_members.contains(representativeID());
}
const FixedVector<AXID>& members() const { return m_members; }
AXID representativeID() const { return m_representativeID; }
private:
FixedVector<AXID> m_members;
// The ID of the object that will be exposed in the accessibility tree.
AXID m_representativeID;
};
} // namespace WebCore
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