Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.h

/*
 * Copyright (C) 2019 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. ``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
 * 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

#if ENABLE(ACCESSIBILITY_ISOLATED_TREE)

#include "AccessibilityObjectInterface.h"
#include "PageIdentifier.h"
#include <wtf/HashMap.h>
#include <wtf/RefPtr.h>
#include <wtf/ThreadSafeRefCounted.h>

namespace WebCore {

class AXIsolatedObject;
class AXObjectCache;
class Page;

typedef unsigned AXIsolatedTreeID;

class AXIsolatedTree : public ThreadSafeRefCounted<AXIsolatedTree> {
    WTF_MAKE_NONCOPYABLE(AXIsolatedTree); WTF_MAKE_FAST_ALLOCATED;

public:
    static Ref<AXIsolatedTree> create();
    virtual ~AXIsolatedTree();

    static Ref<AXIsolatedTree> createTreeForPageID(PageIdentifier);
    static void removeTreeForPageID(PageIdentifier);

    WEBCORE_EXPORT static RefPtr<AXIsolatedTree> treeForPageID(PageIdentifier);
    WEBCORE_EXPORT static RefPtr<AXIsolatedTree> treeForID(AXIsolatedTreeID);
    AXObjectCache* axObjectCache() const { return m_axObjectCache; }
    void setAXObjectCache(AXObjectCache* axObjectCache) { m_axObjectCache = axObjectCache; }

    WEBCORE_EXPORT RefPtr<AXIsolatedObject> rootNode();
    WEBCORE_EXPORT RefPtr<AXIsolatedObject> focusedUIElement();
    RefPtr<AXIsolatedObject> nodeForID(AXID) const;
    static RefPtr<AXIsolatedObject> nodeInTreeForID(AXIsolatedTreeID, AXID);

    struct NodeChange {
        Ref<AXIsolatedObject> m_isolatedObject;
        AccessibilityObjectWrapper* m_wrapper;
        NodeChange(const Ref<AXIsolatedObject>&, AccessibilityObjectWrapper*);
        NodeChange(const NodeChange&);
    };

    // Call on main thread
    void appendNodeChanges(const Vector<NodeChange>&);
    void removeNode(AXID);

    void setRootNode(Ref<AXIsolatedObject>&);
    void setFocusedNodeID(AXID);
    
    // Call on AX thread
    void applyPendingChanges();

    AXIsolatedTreeID treeIdentifier() const { return m_treeID; }

private:
    AXIsolatedTree();

    static HashMap<AXIsolatedTreeID, Ref<AXIsolatedTree>>& treeIDCache();
    static HashMap<PageIdentifier, Ref<AXIsolatedTree>>& treePageCache();

    AXObjectCache* m_axObjectCache { nullptr };

    // Only access on AX thread requesting data.
    HashMap<AXID, Ref<AXIsolatedObject>> m_readerThreadNodeMap;

    // Written to by main thread under lock, accessed and applied by AX thread.
    Vector<NodeChange> m_pendingAppends;
    Vector<AXID> m_pendingRemovals;
    AXID m_pendingFocusedNodeID;
    Lock m_changeLogLock;

    AXIsolatedTreeID m_treeID;
    AXID m_rootNodeID { InvalidAXID };
    AXID m_focusedNodeID { InvalidAXID };
};

} // namespace WebCore

#endif