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      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 // This class enumerates the media transfer protocol (MTP) device objects from
      6 // a given object entry list.
      7 
      8 #ifndef CHROME_BROWSER_MEDIA_GALLERIES_WIN_MTP_DEVICE_OBJECT_ENUMERATOR_H_
      9 #define CHROME_BROWSER_MEDIA_GALLERIES_WIN_MTP_DEVICE_OBJECT_ENUMERATOR_H_
     10 
     11 #include "base/files/file_path.h"
     12 #include "base/threading/thread_checker.h"
     13 #include "base/time/time.h"
     14 #include "chrome/browser/media_galleries/win/mtp_device_object_entry.h"
     15 
     16 // MTPDeviceObjectEnumerator is used to enumerate the media transfer protocol
     17 // (MTP) device objects from a given object entry list.
     18 // MTPDeviceObjectEnumerator supports MTP device file operations.
     19 // MTPDeviceObjectEnumerator may only be used on a single thread.
     20 class MTPDeviceObjectEnumerator {
     21  public:
     22   explicit MTPDeviceObjectEnumerator(const MTPDeviceObjectEntries& entries);
     23   ~MTPDeviceObjectEnumerator();
     24 
     25   base::FilePath Next();
     26   int64 Size();
     27   bool IsDirectory();
     28   base::Time LastModifiedTime();
     29 
     30   // If the current file object entry is valid, returns an non-empty object id.
     31   // Returns an empty string otherwise.
     32   base::string16 GetObjectId() const;
     33 
     34  private:
     35   // Returns true if the enumerator has more entries to traverse, false
     36   // otherwise.
     37   bool HasMoreEntries() const;
     38 
     39   // Returns true if Next() has been called at least once, and the enumerator
     40   // has more entries to traverse.
     41   bool IsIndexReadyAndInRange() const;
     42 
     43   // List of directory file object entries.
     44   MTPDeviceObjectEntries object_entries_;
     45 
     46   // Index into |object_entries_|.
     47   // Should only be used when |is_index_ready_| is true.
     48   size_t index_;
     49 
     50   // Initially false. Set to true after Next() has been called.
     51   bool is_index_ready_;
     52 
     53   base::ThreadChecker thread_checker_;
     54 
     55   DISALLOW_COPY_AND_ASSIGN(MTPDeviceObjectEnumerator);
     56 };
     57 
     58 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_WIN_MTP_DEVICE_OBJECT_ENUMERATOR_H_
     59