/****************************************************************************
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** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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** contained in the Technology Preview License Agreement accompanying
** this package.
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** Foundation and appearing in the file LICENSE.LGPL included in the
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****************************************************************************/

//
//  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.

#ifndef QPatternist_ResourceDelegator_p_H
#define QPatternist_ResourceDelegator_p_H

#include <QSet>
#include <QUrl>

#include "qdeviceresourceloader_p.h"

QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short Delegates to another ResourceLoader, but in case a URI is in an
     * exception list, it delegates to a different loader.
     *
     * This is used for handling device variables, since when a device variable
     * is rebound, a resource loader needs to carry that binding, while the
     * resource loader for the other query remains as is.
     *
     * @since 4.5
     * @author Frans Englich <frans.englich@nokia.com>
     */
    class ResourceDelegator : public DeviceResourceLoader
    {
    public:
        ResourceDelegator(const QSet<QUrl> &needsOverride,
                          const ResourceLoader::Ptr &parentLoader,
                          const ResourceLoader::Ptr &forDeviceLoader) : m_needsOverride(needsOverride)
                                                                      , m_parentLoader(parentLoader)
                                                                      , m_forDeviceLoader(forDeviceLoader)

        {
            Q_ASSERT(m_parentLoader);
        }

        virtual bool isUnparsedTextAvailable(const QUrl &uri,
                                             const QString &encoding);
        virtual ItemType::Ptr announceUnparsedText(const QUrl &uri);
        virtual Item openUnparsedText(const QUrl &uri,
                                      const QString &encoding,
                                      const ReportContext::Ptr &context,
                                      const SourceLocationReflection *const where);
        virtual Item openDocument(const QUrl &uri,
                                  const ReportContext::Ptr &context);
        virtual SequenceType::Ptr announceDocument(const QUrl &uri, const Usage usageHint);
        virtual bool isDocumentAvailable(const QUrl &uri);
        virtual Item::Iterator::Ptr openCollection(const QUrl &uri);
        virtual SequenceType::Ptr announceCollection(const QUrl &uri);

        /**
         * Returns the union of the deviceURIs() that ResourceDelegator's two
         * resource loaders has.
         */
        virtual QSet<QUrl> deviceURIs() const;

    private:
        const QSet<QUrl> m_needsOverride;
        const ResourceLoader::Ptr m_parentLoader;
        const ResourceDelegator::Ptr m_forDeviceLoader;
    };
}

QT_END_NAMESPACE
QT_END_HEADER

#endif