gecko-dev/xpcom/glue/nsEnumeratorUtils.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2012-05-21 11:12:37 +00:00
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/Attributes.h"
#include "nsEnumeratorUtils.h"
#include "nsISimpleEnumerator.h"
#include "nsIStringEnumerator.h"
#include "nsCOMPtr.h"
class EmptyEnumeratorImpl : public nsISimpleEnumerator,
public nsIUTF8StringEnumerator,
public nsIStringEnumerator
{
public:
EmptyEnumeratorImpl() {}
// nsISupports interface
NS_DECL_ISUPPORTS_INHERITED // not really inherited, but no mRefCnt
// nsISimpleEnumerator
NS_DECL_NSISIMPLEENUMERATOR
NS_DECL_NSIUTF8STRINGENUMERATOR
// can't use NS_DECL_NSISTRINGENUMERATOR because they share the
// HasMore() signature
NS_IMETHOD GetNext(nsAString& aResult);
static EmptyEnumeratorImpl* GetInstance() {
static const EmptyEnumeratorImpl kInstance;
return const_cast<EmptyEnumeratorImpl*>(&kInstance);
}
};
// nsISupports interface
NS_IMETHODIMP_(MozExternalRefCountType) EmptyEnumeratorImpl::AddRef(void)
{
return 2;
}
NS_IMETHODIMP_(MozExternalRefCountType) EmptyEnumeratorImpl::Release(void)
{
return 1;
}
NS_IMPL_QUERY_INTERFACE3(EmptyEnumeratorImpl, nsISimpleEnumerator,
nsIUTF8StringEnumerator, nsIStringEnumerator)
// nsISimpleEnumerator interface
NS_IMETHODIMP EmptyEnumeratorImpl::HasMoreElements(bool* aResult)
{
*aResult = false;
return NS_OK;
}
NS_IMETHODIMP EmptyEnumeratorImpl::HasMore(bool* aResult)
{
*aResult = false;
return NS_OK;
}
NS_IMETHODIMP EmptyEnumeratorImpl::GetNext(nsISupports** aResult)
{
return NS_ERROR_UNEXPECTED;
}
NS_IMETHODIMP EmptyEnumeratorImpl::GetNext(nsACString& aResult)
{
return NS_ERROR_UNEXPECTED;
}
NS_IMETHODIMP EmptyEnumeratorImpl::GetNext(nsAString& aResult)
{
return NS_ERROR_UNEXPECTED;
}
nsresult
NS_NewEmptyEnumerator(nsISimpleEnumerator** aResult)
{
*aResult = EmptyEnumeratorImpl::GetInstance();
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////
class nsSingletonEnumerator MOZ_FINAL : public nsISimpleEnumerator
{
public:
NS_DECL_ISUPPORTS
// nsISimpleEnumerator methods
NS_IMETHOD HasMoreElements(bool* aResult);
NS_IMETHOD GetNext(nsISupports** aResult);
nsSingletonEnumerator(nsISupports* aValue);
private:
~nsSingletonEnumerator();
protected:
nsISupports* mValue;
bool mConsumed;
};
nsSingletonEnumerator::nsSingletonEnumerator(nsISupports* aValue)
: mValue(aValue)
{
NS_IF_ADDREF(mValue);
mConsumed = (mValue ? false : true);
}
nsSingletonEnumerator::~nsSingletonEnumerator()
{
NS_IF_RELEASE(mValue);
}
NS_IMPL_ISUPPORTS1(nsSingletonEnumerator, nsISimpleEnumerator)
NS_IMETHODIMP
nsSingletonEnumerator::HasMoreElements(bool* aResult)
{
NS_PRECONDITION(aResult != 0, "null ptr");
if (! aResult)
return NS_ERROR_NULL_POINTER;
*aResult = !mConsumed;
return NS_OK;
}
NS_IMETHODIMP
nsSingletonEnumerator::GetNext(nsISupports** aResult)
{
NS_PRECONDITION(aResult != 0, "null ptr");
if (! aResult)
return NS_ERROR_NULL_POINTER;
if (mConsumed)
return NS_ERROR_UNEXPECTED;
mConsumed = true;
*aResult = mValue;
NS_ADDREF(*aResult);
return NS_OK;
}
nsresult
NS_NewSingletonEnumerator(nsISimpleEnumerator* *result,
nsISupports* singleton)
{
nsSingletonEnumerator* enumer = new nsSingletonEnumerator(singleton);
if (enumer == nullptr)
return NS_ERROR_OUT_OF_MEMORY;
*result = enumer;
NS_ADDREF(*result);
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////
class nsUnionEnumerator MOZ_FINAL : public nsISimpleEnumerator
{
public:
NS_DECL_ISUPPORTS
// nsISimpleEnumerator methods
NS_IMETHOD HasMoreElements(bool* aResult);
NS_IMETHOD GetNext(nsISupports** aResult);
nsUnionEnumerator(nsISimpleEnumerator* firstEnumerator,
nsISimpleEnumerator* secondEnumerator);
private:
~nsUnionEnumerator();
protected:
nsCOMPtr<nsISimpleEnumerator> mFirstEnumerator, mSecondEnumerator;
bool mConsumed;
bool mAtSecond;
};
nsUnionEnumerator::nsUnionEnumerator(nsISimpleEnumerator* firstEnumerator,
nsISimpleEnumerator* secondEnumerator)
: mFirstEnumerator(firstEnumerator),
mSecondEnumerator(secondEnumerator),
mConsumed(false), mAtSecond(false)
{
}
nsUnionEnumerator::~nsUnionEnumerator()
{
}
NS_IMPL_ISUPPORTS1(nsUnionEnumerator, nsISimpleEnumerator)
NS_IMETHODIMP
nsUnionEnumerator::HasMoreElements(bool* aResult)
{
NS_PRECONDITION(aResult != 0, "null ptr");
if (! aResult)
return NS_ERROR_NULL_POINTER;
nsresult rv;
if (mConsumed) {
*aResult = false;
return NS_OK;
}
if (! mAtSecond) {
rv = mFirstEnumerator->HasMoreElements(aResult);
if (NS_FAILED(rv)) return rv;
if (*aResult)
return NS_OK;
mAtSecond = true;
}
rv = mSecondEnumerator->HasMoreElements(aResult);
if (NS_FAILED(rv)) return rv;
if (*aResult)
return NS_OK;
*aResult = false;
mConsumed = true;
return NS_OK;
}
NS_IMETHODIMP
nsUnionEnumerator::GetNext(nsISupports** aResult)
{
NS_PRECONDITION(aResult != 0, "null ptr");
if (! aResult)
return NS_ERROR_NULL_POINTER;
if (mConsumed)
return NS_ERROR_UNEXPECTED;
if (! mAtSecond)
return mFirstEnumerator->GetNext(aResult);
return mSecondEnumerator->GetNext(aResult);
}
nsresult
NS_NewUnionEnumerator(nsISimpleEnumerator* *result,
nsISimpleEnumerator* firstEnumerator,
nsISimpleEnumerator* secondEnumerator)
{
*result = nullptr;
if (! firstEnumerator) {
*result = secondEnumerator;
} else if (! secondEnumerator) {
*result = firstEnumerator;
} else {
nsUnionEnumerator* enumer = new nsUnionEnumerator(firstEnumerator, secondEnumerator);
if (enumer == nullptr)
return NS_ERROR_OUT_OF_MEMORY;
*result = enumer;
}
NS_ADDREF(*result);
return NS_OK;
}