/****************************************************************************
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** Contact: Qt Software Information (qt-info@nokia.com)
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** This file is part of the QtDeclarative module of the Qt Toolkit.
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** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
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****************************************************************************/

#ifndef QMLEXPRESSION_H
#define QMLEXPRESSION_H

#include <QtCore/qobject.h>
#include <QtCore/qvariant.h>
#include <QtDeclarative/qmlerror.h>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

QT_MODULE(Declarative)

class QString;
class QmlRefCount;
class QmlEngine;
class QmlContext;
class QmlExpressionPrivate;
class QmlBasicScript;
class Q_DECLARATIVE_EXPORT QmlExpression : public QObject
{
    Q_OBJECT
public:
    QmlExpression();
    QmlExpression(QmlContext *, const QString &, QObject *);
    virtual ~QmlExpression();

    QmlEngine *engine() const;
    QmlContext *context() const;

    QString expression() const;
    void clearExpression();
    virtual void setExpression(const QString &);
    bool isConstant() const;

    bool trackChange() const;
    void setTrackChange(bool);

    QUrl sourceFile() const;
    int lineNumber() const;
    void setSourceLocation(const QUrl &fileName, int line);

    QObject *scopeObject() const;

    bool hasError() const;
    void clearError();
    QmlError error() const;

public Q_SLOTS:
    QVariant value(bool *isUndefined = 0);

Q_SIGNALS:
    virtual void valueChanged();

protected:
    QmlExpression(QmlContext *, const QString &, QObject *, 
                  QmlExpressionPrivate &dd);
    QmlExpression(QmlContext *, void *, QmlRefCount *rc, QObject *me, const QUrl &,
                  int, QmlExpressionPrivate &dd);

private Q_SLOTS:
    void __q_notify();

private:
    Q_DECLARE_PRIVATE(QmlExpression)
    friend class QmlDebugger;
    friend class QmlContext;
};

QT_END_NAMESPACE

QT_END_HEADER

#endif // QMLEXPRESSION_H