Keyfile.hpp

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/*==========================================================================
 * Copyright (c) 2003 University of Massachusetts.  All Rights Reserved.
 *
 * Use of the Lemur Toolkit for Language Modeling and Information Retrieval
 * is subject to the terms of the software license set forth in the LICENSE
 * file included with this software, and also available at
 * http://www.lemurproject.org/license.html
 *
 *==========================================================================
 */


#ifndef _LEMUR_KEYFILE_H
#define _LEMUR_KEYFILE_H
#include <string>
namespace lemur 
{
  namespace file 
  {
    
    class Keyfile {
    public:
      Keyfile() : _handleSize(0), _handle(NULL) {
      }

      void put( const char* key, const void* value, int valueSize );

      void put( int key, const void* value, int valueSize );

      bool get( const char* key, void* value, int& actualSize, int maxSize ) const;

      bool get( const char* key, char** value, int& actualSize ) const;

      bool get( int key, void* value, int& actualSize, int maxSize ) const;

      bool get( int key, char** value, int& actualSize ) const;

      // redundant with getNext... combine.
      bool next( char* key, int& keyLength, char* value, int& valueLength );
      bool next( int& key, char* value, int& valueLength );

      bool previous( char* key, int& keyLength, char* value, int& valueLength );
      bool previous( int& key, char* value, int& valueLength );

      int getSize( const char* key ) const;

      int getSize( int key ) const;

      void remove( const char* key );

      void remove( int key );

      void open( const std::string& filename, int cacheSize = 1024 * 1024, bool readOnly = false);

      void open( const char* filename, int cacheSize = 1024 * 1024, bool readOnly = false );

      void openRead( const std::string& filename, int cacheSize = 1024 * 1024 );

      void create( const std::string& filename, int cacheSize = 1024 * 1024 );

      void create( const char* filename, int cacheSize = 1024 * 1024 );

      void close();

      void setFirst();

      bool getNext( int& key, void* value, int& actualSize, int maxSize ) const;

      bool getNext( char* key, int maxKeySize, void* value, 
                    int& actualSize, int maxSize ) const;

      bool getNext( char* key, int& actKeySize, int maxKeySize, void* value, 
                    int& actualSize, int maxSize ) const;

      enum {
        MAX_KEY_LENGTH = 512
      };
  
    private:
      char* _handle; // file control block of the keyfile
      int _handleSize; // sizeof _handle buffer

      void _buildHandle( int cacheSize );
      void _createKey( char* keyBuf, int number ) const;
      int _decodeKey( char* keyBuf ) const;
    };
  }
}

#endif // _LEMUR_KEYFILE_H

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