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#ifndef nsEnumeratorUtils_h__
#define nsEnumeratorUtils_h__

#include "nsIEnumerator.h"
#include "nsISupportsArray.h"

class NS_COM nsArrayEnumerator : public nsISimpleEnumerator
{
public:
    // nsISupports interface
    NS_DECL_ISUPPORTS

    // nsISimpleEnumerator interface
    NS_IMETHOD HasMoreElements(PRBool* aResult);
    NS_IMETHOD GetNext(nsISupports** aResult);

    // nsArrayEnumerator methods
    nsArrayEnumerator(nsISupportsArray* aValueArray);

private:
    ~nsArrayEnumerator(void);

protected:
    nsISupportsArray* mValueArray;
    PRInt32 mIndex;
};

extern NS_COM nsresult
NS_NewArrayEnumerator(nsISimpleEnumerator* *result,
                      nsISupportsArray* array);

////////////////////////////////////////////////////////////////////////////////

class NS_COM nsSingletonEnumerator : public nsISimpleEnumerator
{
public:
    NS_DECL_ISUPPORTS

    // nsISimpleEnumerator methods
    NS_IMETHOD HasMoreElements(PRBool* aResult);
    NS_IMETHOD GetNext(nsISupports** aResult);

    nsSingletonEnumerator(nsISupports* aValue);

private:
    ~nsSingletonEnumerator();

protected:
    nsISupports* mValue;
    PRBool mConsumed;
};

extern "C" NS_COM nsresult
NS_NewSingletonEnumerator(nsISimpleEnumerator* *result,
                          nsISupports* singleton);

////////////////////////////////////////////////////////////////////////

class NS_COM nsUnionEnumerator : public nsISimpleEnumerator
{
public:
    NS_DECL_ISUPPORTS

    // nsISimpleEnumerator methods
    NS_IMETHOD HasMoreElements(PRBool* aResult);
    NS_IMETHOD GetNext(nsISupports** aResult);

    nsUnionEnumerator(nsISimpleEnumerator* firstEnumerator,
                      nsISimpleEnumerator* secondEnumerator);

private:
    ~nsUnionEnumerator();

protected:
    nsCOMPtr<nsISimpleEnumerator> mFirstEnumerator, mSecondEnumerator;
    PRBool mConsumed;
    PRBool mAtSecond;
};

extern "C" NS_COM nsresult
NS_NewUnionEnumerator(nsISimpleEnumerator* *result,
                      nsISimpleEnumerator* firstEnumerator,
                      nsISimpleEnumerator* secondEnumerator);

////////////////////////////////////////////////////////////////////////

#endif /* nsEnumeratorUtils_h__ */