gecko-dev/xpcom/ds/nsHashtableEnumerator.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: NPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Netscape Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/NPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Pierre Phaneuf <pp@ludusdesign.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the NPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the NPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Implementation of nsHashEnumerator.
* Use it to expose nsIEnumerator interfaces around nsHashtable objects.
* Contributed by Rob Ginda, rginda@ix.netcom.com
*/
#include "nscore.h"
#include "nsHashtableEnumerator.h"
class nsHashtableEnumerator : public nsIBidirectionalEnumerator
{
public:
NS_DECL_ISUPPORTS
NS_DECL_NSIENUMERATOR
NS_DECL_NSIBIDIRECTIONALENUMERATOR
public:
virtual ~nsHashtableEnumerator ();
nsHashtableEnumerator (nsHashtable *aHash,
NS_HASH_ENUMERATOR_CONVERTER aConverter,
void *aData);
nsHashtableEnumerator (); /* no implementation */
private:
NS_IMETHOD Reset(nsHashtable *aHash,
NS_HASH_ENUMERATOR_CONVERTER aConverter,
void *aData);
NS_IMETHOD ReleaseElements();
nsISupports **mElements;
PRInt16 mCount, mCurrent;
PRBool mDoneFlag;
};
struct nsHashEnumClosure
{
NS_HASH_ENUMERATOR_CONVERTER Converter;
nsISupports **Elements;
PRInt16 Current;
void *Data;
};
extern "C" NS_COM nsresult
NS_NewHashtableEnumerator (nsHashtable *aHash,
NS_HASH_ENUMERATOR_CONVERTER aConverter,
void *aData, nsIEnumerator **retval)
{
NS_PRECONDITION (retval, "null ptr");
*retval = nsnull;
nsHashtableEnumerator *hte = new nsHashtableEnumerator (aHash, aConverter,
aData);
if (!hte)
return NS_ERROR_OUT_OF_MEMORY;
return hte->QueryInterface (NS_GET_IID(nsIEnumerator),
(void **)retval);
}
nsHashtableEnumerator::nsHashtableEnumerator (nsHashtable *aHash,
NS_HASH_ENUMERATOR_CONVERTER aConverter,
void *aData)
: mElements(nsnull), mCount(0), mDoneFlag(PR_TRUE)
{
NS_INIT_REFCNT();
Reset (aHash, aConverter, aData);
}
PRBool PR_CALLBACK
hash_enumerator (nsHashKey *aKey, void *aObject, void *closure)
{
nsresult rv;
nsHashEnumClosure *c = (nsHashEnumClosure *)closure;
rv = c->Converter (aKey, (void *)aObject, (void *)c->Data,
&c->Elements[c->Current]);
if (NS_SUCCEEDED(rv))
c->Current++;
return PR_TRUE;
}
NS_IMETHODIMP
nsHashtableEnumerator::Reset (nsHashtable *aHash,
NS_HASH_ENUMERATOR_CONVERTER aConverter,
void *aData)
{
nsHashEnumClosure c;
ReleaseElements();
mCurrent = c.Current = 0;
mCount = aHash->Count();
if (mCount == 0)
return NS_ERROR_FAILURE;
mElements = c.Elements = new nsISupports*[mCount];
c.Data = aData;
c.Converter = aConverter;
aHash->Enumerate (&hash_enumerator, &c);
mCount = c.Current; /* some items may not have converted correctly */
mDoneFlag = PR_FALSE;
return NS_OK;
}
NS_IMETHODIMP
nsHashtableEnumerator::ReleaseElements()
{
for (; mCount > 0; mCount--)
if (mElements[mCount - 1])
NS_RELEASE(mElements[mCount - 1]);
delete[] mElements;
mElements = nsnull;
return NS_OK;
}
NS_IMPL_ISUPPORTS2(nsHashtableEnumerator, nsIBidirectionalEnumerator, nsIEnumerator)
nsHashtableEnumerator::~nsHashtableEnumerator()
{
ReleaseElements();
}
NS_IMETHODIMP
nsHashtableEnumerator::First ()
{
if (!mElements || (mCount == 0))
return NS_ERROR_FAILURE;
mCurrent = 0;
mDoneFlag = PR_FALSE;
return NS_OK;
}
NS_IMETHODIMP
nsHashtableEnumerator::Last ()
{
if (!mElements || (mCount == 0))
return NS_ERROR_FAILURE;
mCurrent = mCount - 1;
mDoneFlag = PR_FALSE;
return NS_OK;
}
NS_IMETHODIMP
nsHashtableEnumerator::Prev ()
{
if (!mElements || (mCount == 0) || (mCurrent == 0)) {
mDoneFlag = PR_TRUE;
return NS_ERROR_FAILURE;
}
mCurrent--;
mDoneFlag = PR_FALSE;
return NS_OK;
}
NS_IMETHODIMP
nsHashtableEnumerator::Next ()
{
if (!mElements || (mCount == 0) || (mCurrent == mCount - 1)) {
mDoneFlag = PR_TRUE;
return NS_ERROR_FAILURE;
}
mCurrent++;
mDoneFlag = PR_FALSE;
return NS_OK;
}
NS_IMETHODIMP
nsHashtableEnumerator::CurrentItem (nsISupports **retval)
{
NS_PRECONDITION (retval, "null ptr");
NS_PRECONDITION (mElements, "invalid state");
NS_ASSERTION (mCurrent >= 0, "mCurrent less than zero");
if (mCount == 0)
{
*retval = nsnull;
return NS_ERROR_FAILURE;
}
NS_ASSERTION (mCurrent <= mCount - 1, "mCurrent too high");
*retval = mElements[mCurrent];
/* who says the item can't be null? */
if (*retval)
NS_ADDREF(*retval);
return NS_OK;
}
NS_IMETHODIMP
nsHashtableEnumerator::IsDone ()
{
if ((!mElements) || (mCount == 0) || (mDoneFlag))
return NS_OK;
return NS_COMFALSE;
}