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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef EXTENSIONS_COMMON_VALUE_COUNTER_H_
#define EXTENSIONS_COMMON_VALUE_COUNTER_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(const ValueCounter&) = delete;
ValueCounter& operator=(const ValueCounter&) = delete;
~ValueCounter();
// Adds `value` to the set. In the case where a Value equal to `value`
// doesn't already exist in this map, this function makes a copy of `value`
// and returns true. Otherwise, it returns false.
bool Add(const base::Value& value);
// Removes `value` from the set, and returns true if it removed the last
// value equal to `value`. If there are more equal values, or if there
// weren't any in the first place, returns false.
bool Remove(const base::Value& value);
// Returns true if there are no values of any type being counted.
bool is_empty() const { return entries_.empty(); }
private:
struct Entry;
std::vector<Entry> entries_;
};
} // namespace extensions
#endif // EXTENSIONS_COMMON_VALUE_COUNTER_H_
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