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// Copyright (c) 2013 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 UI_GFX_SEQUENTIAL_ID_GENERATOR_H_
#define UI_GFX_SEQUENTIAL_ID_GENERATOR_H_
#include <map>
#include "base/basictypes.h"
#include "base/containers/hash_tables.h"
#include "ui/gfx/gfx_export.h"
namespace ui {
// This is used to generate a series of sequential ID numbers in a way that a
// new ID is always the lowest possible ID in the sequence.
class GFX_EXPORT SequentialIDGenerator {
public:
// Creates a new generator with the specified lower bound for the IDs.
explicit SequentialIDGenerator(uint32 min_id);
~SequentialIDGenerator();
// Generates a unique ID to represent |number|. The generated ID is the
// smallest available ID greater than or equal to the |min_id| specified
// during creation of the generator.
uint32 GetGeneratedID(uint32 number);
// Checks to see if the generator currently has a unique ID generated for
// |number|.
bool HasGeneratedIDFor(uint32 number) const;
// Removes the generated ID |id| from the internal mapping. Since the ID is
// no longer mapped to any number, subsequent calls to |GetGeneratedID()| can
// use this ID.
void ReleaseGeneratedID(uint32 id);
// Removes the ID previously generated for |number| by calling
// |GetGeneratedID()|.
void ReleaseNumber(uint32 number);
void ResetForTest();
private:
typedef base::hash_map<uint32, uint32> IDMap;
uint32 GetNextAvailableID();
void UpdateNextAvailableIDAfterRelease(uint32 id);
IDMap number_to_id_;
IDMap id_to_number_;
const uint32 min_id_;
uint32 min_available_id_;
DISALLOW_COPY_AND_ASSIGN(SequentialIDGenerator);
};
} // namespace ui
#endif // UI_GFX_SEQUENTIAL_ID_GENERATOR_H_
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