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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
#ifndef mozilla_SimpleEnumerator_h
#define mozilla_SimpleEnumerator_h
#include "nsCOMPtr.h"
#include "nsISimpleEnumerator.h"
namespace mozilla {
/**
* A wrapper class around nsISimpleEnumerator to support ranged iteration. This
* requires every element in the enumeration to implement the same interface, T.
* If any element does not implement this interface, the enumeration ends at
* that element, and triggers an assertion in debug builds.
*
* Typical usage looks something like:
*
* for (auto& docShell : SimpleEnumerator<nsIDocShell>(docShellEnum)) {
* docShell.LoadURI(...);
* }
*/
template <typename T>
class SimpleEnumerator final {
public:
explicit SimpleEnumerator(nsISimpleEnumerator* aEnum) : mEnum(aEnum) {}
class Entry {
public:
explicit Entry(T* aPtr) : mPtr(aPtr) {}
explicit Entry(nsISimpleEnumerator& aEnum) : mEnum(&aEnum) { ++*this; }
const nsCOMPtr<T>& operator*() {
MOZ_ASSERT(mPtr);
return mPtr;
}
Entry& operator++() {
MOZ_ASSERT(mEnum);
nsCOMPtr<nsISupports> next;
if (NS_SUCCEEDED(mEnum->GetNext(getter_AddRefs(next)))) {
mPtr = do_QueryInterface(next);
MOZ_ASSERT(mPtr);
} else {
mPtr = nullptr;
}
return *this;
}
bool operator!=(const Entry& aOther) const { return mPtr != aOther.mPtr; }
private:
nsCOMPtr<T> mPtr;
nsCOMPtr<nsISimpleEnumerator> mEnum;
};
Entry begin() { return Entry(*mEnum); }
Entry end() { return Entry(nullptr); }
private:
nsCOMPtr<nsISimpleEnumerator> mEnum;
};
} // namespace mozilla
#endif // mozilla_SimpleEnumerator_h