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// 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_
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