src/storage/tiny_storage.h

// Copyright 2010, Google Inc.
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#ifndef MOZC_STORAGE_TINY_STORAGE_H_
#define MOZC_STORAGE_TINY_STORAGE_H_

#include <map>
#include <string>
#include "base/base.h"

namespace mozc {
namespace storage {

class StorageInterface {
 public:
  // Open storage
  virtual bool Open(const string &filename) = 0;

  // Syncing into the disk
  virtual bool Sync() = 0;

  // Lookup key and return the value.
  // if key is not found, return false.
  // It is not guranteed that the data is synced to the disk.
  virtual bool Lookup(const string &key, string *value) const = 0;

  // Insert key and value
  // It is not guranteed that the data is synced to the disk.
  virtual bool Insert(const string &key, const string &value) = 0;

  // Erase key
  // It is not guranteed that the data is synced to the disk
  virtual bool Erase(const string &key) = 0;

  // clear internal keys and values
  // Sync() is automatically called.
  virtual bool Clear() = 0;

  // return the size of keys
  virtual size_t Size() const = 0;

  StorageInterface() {}
  virtual ~StorageInterface() {}
};

// Very simple and tiny key/value storage.
// Use it just for saving small data which
// are not updated frequently, like timestamp, auth_token, etc.
// We will replace it with faster and more robust implementation.
class TinyStorage: public StorageInterface {
 public:
  TinyStorage();
  virtual ~TinyStorage();

  bool Open(const string &filename);
  bool Sync();
  bool Lookup(const string &key, string *value) const;
  bool Insert(const string &key, const string &value);
  bool Erase(const string &key);
  bool Clear();
  size_t Size() const {
    return dic_.size();
  }

  // return TinyStorage instance
  static TinyStorage *Create(const char *filename);

 private:
  string filename_;
  bool should_sync_;
  map<string, string> dic_;
};
}  // storage
}  // mozc
#endif  // MOZC_STORAGE_TINY_STORAGE_H_