text: /****************************************************************************
  **
  ** Copyright (C) 2016 The Qt Company Ltd.
  ** Contact: https://www.qt.io/licensing/
  **
  ** This file is part of the QtQml module of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:LGPL$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
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  **
  ** GNU Lesser General Public License Usage
  ** Alternatively, this file may be used under the terms of the GNU Lesser
  ** General Public License version 3 as published by the Free Software
  ** Foundation and appearing in the file LICENSE.LGPL3 included in the
  ** packaging of this file. Please review the following information to
  ** ensure the GNU Lesser General Public License version 3 requirements
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  **
  ** GNU General Public License Usage
  ** Alternatively, this file may be used under the terms of the GNU
  ** General Public License version 2.0 or (at your option) the GNU General
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  ****************************************************************************/
  
  #ifndef QQMLBOUNDSIGNAL_P_H
  #define QQMLBOUNDSIGNAL_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 <QtCore/qmetaobject.h>
  
  #include <private/qqmljavascriptexpression_p.h>
  #include <private/qqmlboundsignalexpressionpointer_p.h>
  #include <private/qqmlnotifier_p.h>
  #include <private/qflagpointer_p.h>
  #include <private/qqmlrefcount_p.h>
  #include <private/qqmlglobal_p.h>
  #include <private/qbitfield_p.h>
  
  QT_BEGIN_NAMESPACE
  
  class Q_QML_PRIVATE_EXPORT QQmlBoundSignalExpression : public QQmlJavaScriptExpression, public QQmlRefCount
  {
  public:
      QQmlBoundSignalExpression(QObject *target, int index,
                                QQmlContextData *ctxt, QObject *scope, const QString &expression,
                                const QString &fileName, quint16 line, quint16 column,
                                const QString &handlerName = QString(),
                                const QString &parameterString = QString());
  
      QQmlBoundSignalExpression(QObject *target, int index,
                                QQmlContextData *ctxt, QObject *scopeObject, QV4::Function *function,
                                QV4::ExecutionContext *scope = nullptr);
  
      // inherited from QQmlJavaScriptExpression.
      QString expressionIdentifier() const override;
      void expressionChanged() override;
  
      // evaluation of a bound signal expression doesn't return any value
      void evaluate(void **a);
      void evaluate(const QList<QVariant> &args);
  
      QString expression() const;
      QObject *target() const { return m_target; }
  
      QQmlEngine *engine() const { return context() ? context()->engine : nullptr; }
  
  private:
      ~QQmlBoundSignalExpression() override;
  
      void init(QQmlContextData *ctxt, QObject *scope);
  
      bool expressionFunctionValid() const { return function() != nullptr; }
  
      int m_index;
      QObject *m_target;
  };
  
  class Q_QML_PRIVATE_EXPORT QQmlBoundSignal : public QQmlNotifierEndpoint
  {
  public:
      QQmlBoundSignal(QObject *target, int signal, QObject *owner, QQmlEngine *engine);
      ~QQmlBoundSignal();
  
      void removeFromObject();
  
      QQmlBoundSignalExpression *expression() const;
      void takeExpression(QQmlBoundSignalExpression *);
  
      void setEnabled(bool enabled);
  
  private:
      friend void QQmlBoundSignal_callback(QQmlNotifierEndpoint *, void **);
      friend class QQmlPropertyPrivate;
      friend class QQmlData;
      friend class QQmlEngineDebugService;
  
      void addToObject(QObject *owner);
  
      QQmlBoundSignal **m_prevSignal;
      QQmlBoundSignal  *m_nextSignal;
  
      bool m_enabled;
  
      QQmlBoundSignalExpressionPointer m_expression;
  };
  
  QT_END_NAMESPACE
  
  #endif // QQMLBOUNDSIGNAL_P_H
  