db.h

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//
// Copyright RIME Developers
// Distributed under the BSD License
//
// 2013-04-16 GONG Chen <chen.sst@gmail.com>
//
#ifndef RIME_DB_H_
#define RIME_DB_H_
 
#include <rime_api.h>
#include <rime/common.h>
#include <rime/component.h>
 
namespace rime {
 
class DbAccessor {
 public:
  DbAccessor() = default;
  explicit DbAccessor(const string& prefix) : prefix_(prefix) {}
  virtual ~DbAccessor() = default;
 
  virtual bool Reset() = 0;
  virtual bool Jump(const string& key) = 0;
  virtual bool GetNextRecord(string* key, string* value) = 0;
  virtual bool exhausted() = 0;
 
 protected:
  bool MatchesPrefix(const string& key);
 
  string prefix_;
};
 
class Db : public Class<Db, const string&> {
 public:
  Db(const path& file_path, const string& name);
  virtual ~Db() = default;
 
  RIME_DLL bool Exists() const;
  RIME_DLL virtual bool Remove();
 
  virtual bool Open() = 0;
  virtual bool OpenReadOnly() = 0;
  virtual bool Close() = 0;
 
  virtual bool Backup(const path& snapshot_file) = 0;
  virtual bool Restore(const path& snapshot_file) = 0;
 
  virtual bool CreateMetadata();
  virtual bool MetaFetch(const string& key, string* value) = 0;
  virtual bool MetaUpdate(const string& key, const string& value) = 0;
 
  virtual an<DbAccessor> QueryMetadata() = 0;
  virtual an<DbAccessor> QueryAll() = 0;
  virtual an<DbAccessor> Query(const string& key) = 0;
  virtual bool Fetch(const string& key, string* value) = 0;
  virtual bool Update(const string& key, const string& value) = 0;
  virtual bool Erase(const string& key) = 0;
 
  const string& name() const { return name_; }
  const path& file_path() const { return file_path_; }
  bool loaded() const { return loaded_; }
  bool readonly() const { return readonly_; }
  bool disabled() const { return disabled_; }
  void disable() { disabled_ = true; }
  void enable() { disabled_ = false; }
 
 protected:
  string name_;
  path file_path_;
  bool loaded_ = false;
  bool readonly_ = false;
  bool disabled_ = false;
};
 
class Transactional {
 public:
  Transactional() = default;
  virtual ~Transactional() = default;
  virtual bool BeginTransaction() { return false; }
  virtual bool AbortTransaction() { return false; }
  virtual bool CommitTransaction() { return false; }
  bool in_transaction() const { return in_transaction_; }
 
 protected:
  bool in_transaction_ = false;
};
 
class Recoverable {
 public:
  virtual ~Recoverable() = default;
  virtual bool Recover() = 0;
};
 
class ResourceResolver;
 
class RIME_DLL DbComponentBase {
 public:
  DbComponentBase();
  virtual ~DbComponentBase();
 
  path DbFilePath(const string& name, const string& extension) const;
 
 protected:
  the<ResourceResolver> db_resource_resolver_;
};
 
template <class DbClass>
class DbComponent : public DbClass::Component, protected DbComponentBase {
 public:
  virtual string extension() const;
 
  DbClass* Create(const string& name) override {
    return new DbClass(DbFilePath(name, extension()), name);
  }
};
 
}  // namespace rime
 
#endif  // RIME_DB_H_