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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_REVOCABLE_STORE_H_
#define BASE_REVOCABLE_STORE_H_
#include "base/basictypes.h"
#include "nsISupportsImpl.h"
#include "nsAutoPtr.h"
// |RevocableStore| is a container of items that can be removed from the store.
class RevocableStore {
public:
// A |StoreRef| is used to link the |RevocableStore| to its items. There is
// one StoreRef per store, and each item holds a reference to it. If the
// store wishes to revoke its items, it sets |store_| to null. Items are
// permitted to release their reference to the |StoreRef| when they no longer
// require the store.
class StoreRef final {
public:
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(StoreRef)
explicit StoreRef(RevocableStore* aStore) : store_(aStore) { }
void set_store(RevocableStore* aStore) { store_ = aStore; }
RevocableStore* store() const { return store_; }
protected:
~StoreRef() {}
private:
RevocableStore* store_;
DISALLOW_EVIL_CONSTRUCTORS(StoreRef);
};
// An item in the store. On construction, the object adds itself to the
// store.
class Revocable {
public:
explicit Revocable(RevocableStore* store);
~Revocable();
// This item has been revoked if it no longer has a pointer to the store.
bool revoked() const { return !store_reference_->store(); }
private:
// We hold a reference to the store through this ref pointer. We release
// this reference on destruction.
RefPtr<StoreRef> store_reference_;
DISALLOW_EVIL_CONSTRUCTORS(Revocable);
};
RevocableStore();
~RevocableStore();
// Revokes all the items in the store.
void RevokeAll();
// Returns true if there are no items in the store.
bool empty() const { return count_ == 0; }
private:
friend class Revocable;
// Adds an item to the store. To add an item to the store, construct it
// with a pointer to the store.
void Add(Revocable* item);
// This is the reference the unrevoked items in the store hold.
RefPtr<StoreRef> owning_reference_;
// The number of unrevoked items in the store.
int count_;
DISALLOW_EVIL_CONSTRUCTORS(RevocableStore);
};
#endif // BASE_REVOCABLE_STORE_H_
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