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93 lines
2.0 KiB
C++
93 lines
2.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_SimpleEnumerator_h
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#define mozilla_SimpleEnumerator_h
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#include "nsCOMPtr.h"
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#include "nsISimpleEnumerator.h"
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namespace mozilla {
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/**
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* A wrapper class around nsISimpleEnumerator to support ranged iteration. This
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* requires every element in the enumeration to implement the same interface, T.
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* If any element does not implement this interface, the enumeration ends at
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* that element, and triggers an assertion in debug builds.
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*
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* Typical usage looks something like:
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*
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* for (auto& docShell : SimpleEnumerator<nsIDocShell>(docShellEnum)) {
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* docShell.LoadURI(...);
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* }
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*/
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template <typename T>
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class SimpleEnumerator final
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{
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public:
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explicit SimpleEnumerator(nsISimpleEnumerator* aEnum)
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: mEnum(aEnum)
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{}
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class Entry
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{
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public:
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explicit Entry(T* aPtr)
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: mPtr(aPtr)
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{}
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explicit Entry(nsISimpleEnumerator& aEnum)
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: mEnum(&aEnum)
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{
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++*this;
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}
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const nsCOMPtr<T>& operator*()
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{
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MOZ_ASSERT(mPtr);
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return mPtr;
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}
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Entry& operator++()
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{
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MOZ_ASSERT(mEnum);
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nsCOMPtr<nsISupports> next;
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if (NS_SUCCEEDED(mEnum->GetNext(getter_AddRefs(next)))) {
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mPtr = do_QueryInterface(next);
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MOZ_ASSERT(mPtr);
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} else {
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mPtr = nullptr;
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}
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return *this;
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}
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bool operator!=(const Entry& aOther) const
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{
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return mPtr != aOther.mPtr;
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}
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private:
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nsCOMPtr<T> mPtr;
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nsCOMPtr<nsISimpleEnumerator> mEnum;
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};
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Entry begin() {
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return Entry(*mEnum);
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}
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Entry end() {
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return Entry(nullptr);
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}
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private:
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nsCOMPtr<nsISimpleEnumerator> mEnum;
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};
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} // namespace mozilla
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#endif // mozilla_SimpleEnumerator_h
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