qqmlbinding_p.h

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// Copyright (C) 2016 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
 
#ifndef QQMLBINDING_P_H
#define QQMLBINDING_P_H
 
//
//  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.
//
 
#include "qqmlproperty.h"
#include "qqmlscriptstring.h"
 
#include <QtCore/QObject>
#include <QtCore/QMetaProperty>
 
#include <private/qqmlabstractbinding_p.h>
#include <private/qqmljavascriptexpression_p.h>
#include <private/qv4functionobject_p.h>
#include <private/qqmltranslation_p.h>
 
QT_BEGIN_NAMESPACE
 
class QQmlContext;
class Q_QML_EXPORT QQmlBinding : public QQmlJavaScriptExpression,
                                         public QQmlAbstractBinding
{
    friend class QQmlAbstractBinding;
public:
    typedef QExplicitlySharedDataPointer<QQmlBinding> Ptr;
 
    static QQmlBinding *create(const QQmlPropertyData *, const QQmlScriptString &, QObject *, QQmlContext *);
 
    static QQmlBinding *create(
            const QQmlPropertyData *, const QString &, QObject *,
            const QQmlRefPointer<QQmlContextData> &, const QString &url = QString(),
            quint16 lineNumber = 0);
 
    static QQmlBinding *create(
            const QQmlPropertyData *property, QV4::Function *function, QObject *obj,
            const QQmlRefPointer<QQmlContextData> &ctxt, QV4::ExecutionContext *scope);
 
    static QQmlBinding *create(QMetaType propertyType, QV4::Function *function, QObject *obj,
                               const QQmlRefPointer<QQmlContextData> &ctxt,
                               QV4::ExecutionContext *scope);
 
    static QQmlBinding *createTranslationBinding(
            const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
            const QV4::CompiledData::Binding *binding, QObject *obj,
            const QQmlRefPointer<QQmlContextData> &ctxt);
 
    static QQmlBinding *
    createTranslationBinding(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &unit,
                             const QQmlRefPointer<QQmlContextData> &ctxt,
                             const QString &propertyName, const QQmlTranslation &translationData,
                             const QQmlSourceLocation &location, QObject *obj);
 
    Kind kind() const final { return QQmlAbstractBinding::QmlBinding; }
 
    ~QQmlBinding() override;
 
    bool mustCaptureBindableProperty() const final {return true;}
    void refresh() override;
 
    void setEnabled(bool, QQmlPropertyData::WriteFlags flags = QQmlPropertyData::DontRemoveBinding) override;
    QString expression() const override;
    void update(QQmlPropertyData::WriteFlags flags = QQmlPropertyData::DontRemoveBinding);
 
    void printBindingLoopError(const QQmlProperty &prop) override;
 
    typedef int Identifier;
    enum {
        Invalid = -1
    };
 
    QVariant evaluate();
    bool evaluate(void *result, QMetaType type)
    {
        return QQmlJavaScriptExpression::evaluate(&result, &type, 0);
    }
 
    void expressionChanged() override;
 
    QQmlSourceLocation sourceLocation() const override;
    void setSourceLocation(const QQmlSourceLocation &location);
    void setBoundFunction(QV4::BoundFunction *boundFunction) {
        m_boundFunction.set(boundFunction->engine(), *boundFunction);
    }
    bool hasBoundFunction() const { return m_boundFunction.valueRef(); }
 
    /**
     * This method returns a snapshot of the currently tracked dependencies of
     * this binding. The dependencies can change upon reevaluation. This method is
     * used in GammaRay to visualize binding hierarchies.
     *
     * Call this method from the UI thread.
     */
    QVector<QQmlProperty> dependencies() const;
    // This method is used internally to check whether a binding is constant and can be removed
    virtual bool hasDependencies() const;
 
protected:
    virtual void doUpdate(const DeleteWatcher &watcher,
                  QQmlPropertyData::WriteFlags flags, QV4::Scope &scope);
 
    virtual bool write(const QV4::Value &result, bool isUndefined, QQmlPropertyData::WriteFlags flags) = 0;
    virtual bool write(void *result, QMetaType type, bool isUndefined, QQmlPropertyData::WriteFlags flags) = 0;
 
    int getPropertyType() const;
 
    bool slowWrite(const QQmlPropertyData &core, const QQmlPropertyData &valueTypeData,
                   const QV4::Value &result, bool isUndefined, QQmlPropertyData::WriteFlags flags);
    bool slowWrite(const QQmlPropertyData &core, const QQmlPropertyData &valueTypeData,
                   const void *result, QMetaType resultType, bool isUndefined,
                   QQmlPropertyData::WriteFlags flags);
 
    QV4::ReturnedValue evaluate(bool *isUndefined);
 
private:
    static QQmlBinding *newBinding(const QQmlPropertyData *property);
    static QQmlBinding *newBinding(QMetaType propertyType);
 
    QQmlSourceLocation *m_sourceLocation = nullptr; // used for Qt.binding() created functions
    QV4::PersistentValue m_boundFunction; // used for Qt.binding() that are created from a bound function object
    void handleWriteError(const void *result, QMetaType resultType, QMetaType metaType);
};
 
QT_END_NAMESPACE
 
Q_DECLARE_METATYPE(QQmlBinding*)
 
#endif // QQMLBINDING_P_H