| // Copyright (c) 2012 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 CHROME_COMMON_EXTENSIONS_VALUE_COUNTER_H_ |
| #define CHROME_COMMON_EXTENSIONS_VALUE_COUNTER_H_ |
| |
| #include "base/memory/linked_ptr.h" |
| |
| #include <vector> |
| |
| namespace base { |
| class Value; |
| } |
| |
| namespace extensions { |
| |
| // Keeps a running count of Values, like map<Value, int>. Adding / removing |
| // values increments / decrements the count associated with a given Value. |
| // |
| // Add() and Remove() are linear in the number of Values in the ValueCounter, |
| // because there is no operator<() defined on Value, so we must iterate to find |
| // whether a Value is equal to an existing one. |
| class ValueCounter { |
| public: |
| ValueCounter(); |
| ~ValueCounter(); |
| |
| // Adds |value| to the set and returns how many equal values are in the set |
| // after. Does not take ownership of |value|. In the case where a Value equal |
| // to |value| doesn't already exist in this map, this function makes a |
| // DeepCopy() of |value|. |
| int Add(const base::Value& value); |
| |
| // Removes |value| from the set and returns how many equal values are in |
| // the set after. |
| int Remove(const base::Value& value); |
| |
| // Same as Add() but only performs the add if the value isn't present. |
| int AddIfMissing(const base::Value& value); |
| |
| private: |
| class Entry { |
| public: |
| explicit Entry(const base::Value& value); |
| ~Entry(); |
| |
| int Increment(); |
| int Decrement(); |
| |
| const base::Value* value() const { return value_.get(); } |
| int count() const { return count_; } |
| |
| private: |
| linked_ptr<base::Value> value_; |
| int count_; |
| |
| DISALLOW_COPY_AND_ASSIGN(Entry); |
| }; |
| typedef std::vector<linked_ptr<Entry> > EntryList; |
| |
| int AddImpl(const base::Value& value, bool increment); |
| |
| EntryList entries_; |
| |
| DISALLOW_COPY_AND_ASSIGN(ValueCounter); |
| }; |
| |
| } // namespace extensions |
| |
| #endif // CHROME_COMMON_EXTENSIONS_VALUE_COUNTER_H_ |