1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef UI_GFX_SEQUENTIAL_ID_GENERATOR_H_ 6 #define UI_GFX_SEQUENTIAL_ID_GENERATOR_H_ 7 8 #include <map> 9 10 #include "base/basictypes.h" 11 #include "base/containers/hash_tables.h" 12 #include "ui/gfx/gfx_export.h" 13 14 namespace ui { 15 16 // This is used to generate a series of sequential ID numbers in a way that a 17 // new ID is always the lowest possible ID in the sequence. 18 class GFX_EXPORT SequentialIDGenerator { 19 public: 20 // Creates a new generator with the specified lower bound for the IDs. 21 explicit SequentialIDGenerator(uint32 min_id); 22 ~SequentialIDGenerator(); 23 24 // Generates a unique ID to represent |number|. The generated ID is the 25 // smallest available ID greater than or equal to the |min_id| specified 26 // during creation of the generator. 27 uint32 GetGeneratedID(uint32 number); 28 29 // Checks to see if the generator currently has a unique ID generated for 30 // |number|. 31 bool HasGeneratedIDFor(uint32 number) const; 32 33 // Removes the generated ID |id| from the internal mapping. Since the ID is 34 // no longer mapped to any number, subsequent calls to |GetGeneratedID()| can 35 // use this ID. 36 void ReleaseGeneratedID(uint32 id); 37 38 // Removes the ID previously generated for |number| by calling 39 // |GetGeneratedID()|. 40 void ReleaseNumber(uint32 number); 41 42 void ResetForTest(); 43 44 private: 45 typedef base::hash_map<uint32, uint32> IDMap; 46 47 uint32 GetNextAvailableID(); 48 49 void UpdateNextAvailableIDAfterRelease(uint32 id); 50 51 IDMap number_to_id_; 52 IDMap id_to_number_; 53 54 const uint32 min_id_; 55 uint32 min_available_id_; 56 57 DISALLOW_COPY_AND_ASSIGN(SequentialIDGenerator); 58 }; 59 60 } // namespace ui 61 62 #endif // UI_GFX_SEQUENTIAL_ID_GENERATOR_H_ 63
