// |RevocableStore| is a container of items that can be removed from the store.
Revoke: 撤销
RevocableStore 是个items容器,items可以从store中删除。
还是老样子,看看头文件
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 : public base::RefCounted<StoreRef> { public: StoreRef(RevocableStore* store) : store_(store) { } void set_store(RevocableStore* store) { store_ = store; } RevocableStore* store() const { return store_; } private: RevocableStore* store_; DISALLOW_EVIL_CONSTRUCTORS(StoreRef); }; // An item in the store. On construction, the object adds itself to the // store. class Revocable { public: Revocable(RevocableStore* store); ~Revocable(); // This item has been revoked if it no longer has a pointer to the store.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. scoped_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. scoped_refptr<StoreRef> owning_reference_; // The number of unrevoked items in the store. int count_; DISALLOW_EVIL_CONSTRUCTORS(RevocableStore); };
想一想怎么用
总共有3个类,RevocableStore,StoreRef,Revocable,其中两个嵌套类,StoreRef,Revocable
头文件的开头说,这是个items容器,猜测RevocableStore是容器,Revocable对应items
RevocableStore *store = new RevocableStore(); Revocable *item = new Revocable(store); ... store->RevokeAll();
Revocable构造函数传递了一个store进去,应该会调用store的Add方法,瞄一下实现
RevocableStore::Revocable::Revocable(RevocableStore* store) : store_reference_(store->owning_reference_) { // We AddRef() the owning reference. DCHECK(store_reference_->store()); store_reference_->store()->Add(this); }