qqmlpreviewbindingpatchcontext_p.h

Go to the documentation of this file.

// Copyright (C) 2026 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant reason:default
#ifndef QQMLPREVIEWBINDINGPATCHCONTEXT_P_H
#define QQMLPREVIEWBINDINGPATCHCONTEXT_P_H
 
#include <private/qduplicatetracker_p.h>
#include <private/qqmlanybinding_p.h>
#include <private/qqmlboundsignal_p.h>
#include <private/qqmlcontextdata_p.h>
#include <private/qqmldata_p.h>
#include <private/qqmlpreviewdiff_p.h>
#include <private/qqmlvmemetaobject_p.h>
#include <private/qv4executablecompilationunit_p.h>
 
#include <QtCore/qpointer.h>
#include <QtCore/qvariant.h>
 
#include <unordered_map>
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
 
QT_BEGIN_NAMESPACE
 
namespace QQmlPreview {
 
struct CompositeLevel
{
    QQmlRefPointer<QV4::ExecutableCompilationUnit> oldCu;
    QQmlRefPointer<QV4::ExecutableCompilationUnit> newCu;
    int objectIndex = -1;
    QString icName;
 
    QQmlRefPointer<QQmlContextData> context;
};
 
// Maps a property name bound by the new compilation unit to the new binding. Used to
// recognize properties that repopulateBindings() will re-assign (so resetting them is
// redundant) and, for group/attached properties, to find the matching new sub-object.
using ReboundBindings = QHash<QString, const QV4::CompiledData::Binding *>;
 
class BindingPatchContext
{
    Q_DISABLE_COPY(BindingPatchContext)
public:
    static QString targetPropertyName(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                                      int objectIndex, const QV4::CompiledData::Binding *binding);
 
    BindingPatchContext(QObject *object, const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                        int objectIndex, const QString &prefix)
        : m_object(object), unit(unit), objectIndex(objectIndex), prefix(prefix + QLatin1Char('.'))
    {
    }
 
    BindingPatchContext(QObject *object, const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                        int objectIndex)
        : m_object(object), unit(unit), objectIndex(objectIndex)
    {
    }
 
    BindingPatchContext(BindingPatchContext &&) = default;
    BindingPatchContext &operator=(BindingPatchContext &&) = default;
 
    void reset(const std::vector<QQmlRefPointer<QV4::ExecutableCompilationUnit>> &unitsToUnparent,
               const std::vector<CompositeLevel> &internalUnits);
    void stashExternalState(
            const std::vector<CompositeLevel> &internalUnits,
            QDuplicateTracker<QObject *> *seenChildren);
    void refreshObjects();
    void restoreExternalState();
 
    BindingPatchContext *childContext(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                                      const QV4::CompiledData::Binding *binding,
                                      QDuplicateTracker<QObject *> *seenChildren);
    BindingPatchContext *childContext(const QString &name, QObject *object,
                                      const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                                      int objectIndex, QDuplicateTracker<QObject *> *seenChildren);
    BindingPatchContext *attachedContext(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                                         const QV4::CompiledData::Binding *binding,
                                         QDuplicateTracker<QObject *> *seenChildren);
 
    // Walk this object's group- and attached-property sub-object tree and find the right one to
    // apply the change to. Return true if the change was applied or false otherwise.
    bool applyBindingChange(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &newUnit,
                     const QV4::CompiledData::Change &change);
 
private:
    struct StoredBinding
    {
        QString propertyName;
        QQmlAnyBinding binding;
        QPointer<QObject> sourceGuard;
    };
 
    struct StoredValue
    {
        QString propertyName;
        QVariant value;
    };
 
    struct StoredSignalHandler
    {
        QString signature;
        std::unique_ptr<QQmlBoundSignal> handler;
    };
 
    void recordBindingValues(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                             int cuIndex, QHash<QString, QVariant> *constantValues,
                             QDuplicateTracker<QObject *> *seenChildren);
    void resetBinding(const QV4::CompiledData::Binding *binding, const QString &name,
                      const QQmlRefPointer<QV4::ExecutableCompilationUnit> &oldUnit,
                      const QQmlRefPointer<QV4::ExecutableCompilationUnit> &newUnit,
                      const ReboundBindings &rebound);
    void resetBindings(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit, int cuIndex,
                       const QQmlRefPointer<QV4::ExecutableCompilationUnit> &newUnit,
                       int newCuIndex);
    void patchBinding(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &newUnit,
                      const QV4::CompiledData::Change &change);
 
    static void retireObject(QObject *object);
    static void clearBindingsRecursive(QObject *object);
 
 
    QPointer<QObject> m_object;
    QQmlRefPointer<QV4::ExecutableCompilationUnit> unit;
    int objectIndex;
    QString prefix;
 
    std::vector<StoredBinding> m_storedBindings;
    std::vector<StoredValue> m_storedValues;
    std::vector<StoredSignalHandler> m_storedSignalHandlers;
    std::unordered_map<QString, std::unique_ptr<BindingPatchContext>> m_children;
};
 
} // namespace QQmlPreview
 
QT_END_NAMESPACE
 
#endif