fileopener.h

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/*
* Copyright 2016 Autodesk, Inc. All rights reserved.
* Use of this software is subject to the terms of the Autodesk license agreement and any attachments or Appendices thereto provided at the time of installation or download,
* or which otherwise accompanies this software in either electronic or hard copy form, or which is signed by you and accepted by Autodesk.
*/


// A callback interface that is used for opening files.
// Must return either an open file or 0 value for failure.
// The caller of the function is responsible for Releasing
// the File interface.

#pragma once

#include "gwnavruntime/base/memory.h"
#include "gwnavruntime/kernel/SF_File.h"
#include "gwnavruntime/kernel/SF_SysFile.h"

namespace Kaim
{

enum FileOpenerMode
{
    OpenMode_Read = 0, 
    OpenMode_Write     
};

class FileOpenerBase : public NewOverrideBase<Stat_Default_Mem>
{
public:
    virtual ~FileOpenerBase() {}

    int GetFlagsFromMode(FileOpenerMode mode)
    {
        if (mode == OpenMode_Read)
            return FileConstants::Open_Read | FileConstants::Open_Buffered;

        else if (mode == OpenMode_Write)
            return FileConstants::Open_Write | FileConstants::Open_Truncate | FileConstants::Open_Create | FileConstants::Open_Buffered;

        else
            return 0;
    }

    virtual Ptr<File> OpenFile(const char* filename, FileOpenerMode mode) = 0;
};


class DefaultFileOpener : public FileOpenerBase
{
public:
    DefaultFileOpener(FileOpenerBase* primaryFileOpener = nullptr) : m_primaryFileOpener(primaryFileOpener) {}

    virtual Ptr<File> OpenFile(const char* filename, FileOpenerMode mode)
    {
        if (m_primaryFileOpener)
        {
            return m_primaryFileOpener->OpenFile(filename, mode);
        }
        else
        {
            Ptr<File> file = *KY_NEW Kaim::SysFile(filename, GetFlagsFromMode(mode), FileConstants::Mode_ReadWrite);
            if (file->IsValid() == false)
                return NULL;
            return file;
        }
    }

private:
    FileOpenerBase* m_primaryFileOpener;
};


}