db_utils.h

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//
// Copyright RIME Developers
// Distributed under the BSD License
//
// 2013-04-18 GONG Chen <chen.sst@gmail.com>
//
#ifndef RIME_DB_UTILS_H_
#define RIME_DB_UTILS_H_
 
#include <rime/common.h>
 
namespace rime {
 
class Sink {
 public:
  virtual ~Sink() = default;
  virtual bool MetaPut(const string& key, const string& value) = 0;
  virtual bool Put(const string& key, const string& value) = 0;
 
  template <class SourceType>
  int operator<<(SourceType& source);
};
 
class Source {
 public:
  virtual ~Source() = default;
  virtual bool MetaGet(string* key, string* value) = 0;
  virtual bool Get(string* key, string* value) = 0;
 
  template <class SinkType>
  int operator>>(SinkType& sink);
 
  int Dump(Sink* sink);
};
 
template <class SourceType>
int Sink::operator<<(SourceType& source) {
  return source.Dump(this);
}
 
template <class SinkType>
int Source::operator>>(SinkType& sink) {
  return Dump(&sink);
}
 
class Db;
class DbAccessor;
 
class DbSink : public Sink {
 public:
  explicit DbSink(Db* db);
 
  virtual bool MetaPut(const string& key, const string& value);
  virtual bool Put(const string& key, const string& value);
 
 protected:
  Db* db_;
};
 
class DbSource : public Source {
 public:
  explicit DbSource(Db* db);
 
  virtual bool MetaGet(string* key, string* value);
  virtual bool Get(string* key, string* value);
 
 protected:
  Db* db_;
  an<DbAccessor> metadata_;
  an<DbAccessor> data_;
};
 
}  // namespace rime
 
#endif  // RIME_DB_UTILS_H_