Question

I’m working on an container class that looks something like this:

class hexFile {
public:
    HANDLE theFile;
    unsigned __int64 fileLength;
    hexFile(const std::wstring& fileName)
    {
        theFile = CreateFile(fileName.c_str(), GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_DELETE | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL);
        if (theFile == INVALID_HANDLE_VALUE);
        {
            throw std::runtime_error(eAsciiMsg("Could not open file!"));
        }
        BY_HANDLE_FILE_INFORMATION sizeFinder;
        GetFileInformationByHandle(theFile, &sizeFinder);
        fileLength = sizeFinder.nFileSizeHigh;
        fileLength <<= 32;
        fileLength += sizeFinder.nFileSizeLow;
    };
    ~hexFile()
    {
        CloseHandle(theFile);
    };
    hexIterator begin()
    {
        hexIterator theIterator(this, true);
        return theIterator;
    };
    hexIterator end()
    {
        hexIterator theIterator(this, false);
        return theIterator;
    };
};

And an iterator class to match that looks like this:

class hexIterator : public std::iterator<std::bidirectional_iterator_tag, wchar_t>
{
    hexFile *parent;
public:
    bool highCharacter;
    __int64 filePosition;
    hexIterator(hexFile* file, bool begin);
    hexIterator(const hexIterator& toCopy);
    ~hexIterator();
    hexIterator& operator++()
    {
        return ++this;
    }
    hexIterator& operator++(hexIterator& toPlus);
    hexIterator& operator--()
    {
        return --this;
    }
    hexIterator& operator--(hexIterator& toMinus);
    hexIterator& operator=(const hexIterator& toCopy);
    bool operator==(const hexIterator& toCompare) const;
    bool operator!=(const hexIterator& toCompare) const;
    wchar_t& operator*();
    wchar_t* operator->();
};

My problem is… both classes need to implemented in terms of the other. I’m unsure how to reference the container inside the iterator, for example, because when the iterator is defined, the container hasn’t been defined yet.

How might one accomplish this?

Billy3

Answer 1

Forward declare one before the other. You can use references to a forward declared class in the declaration of another class, so this should work:

class hexFile; // forward

class hexIterator : ,,, {
   ...
};

class hexFile {
   ...
};