/*

  *  Index.h

  *  Ottoman

  *

  *  Created by Jens Alfke on 8/27/09.

  *  Copyright 2009 Jens Alfke. All rights reserved.

  *  BSD-Licensed: See the file "LICENSE.txt" for details.

  */

 #ifndef _MOOSEYARD_INDEX_

 #define _MOOSEYARD_INDEX_

 #include "Chunk.h"

 #include "Dictionary.h"

 namespace Mooseyard {

     class KeyValueChunk;

     /** An in-file hash table. This structure is stored directly in the file, memory-mapped.

         Index is normally only used internally by VersionDictionary. */

     class Index :public Chunk {

     public:

         class Entry;

         static const Index* indexMappedAt (const void*);

         static Index* create (int capacity);

         int count() const                                   {return _count;}

         Blob get (File *file, Key) const;

         bool put (File *file, Key, FilePosition valuePosition, FilePosition maxPosition);

         bool remove (File *file, Key, FilePosition maxPosition);

         void removeAll();

         void copyFrom (File *file, const Index *index);

         class Iterator;

         void validate() const  throw(File::Error);

         void validateEntries (const File *file) const  throw(File::Error);

         static const uint16_t kChunkType = 2;

     private:

         Index (uint32_t tableSize);

         const Entry* table (int index) const;

         Entry* table (int index);

         const KeyValueChunk* _find (File *file, Key) const;

         bool _put (File *file, Key, FilePosition, FilePosition maxPosition);

         // This is mapped to data in the file! Don't mess with it!

         LittleEndian<uint32_t>  _magicNumber;

         LittleEndian<uint32_t>  _count;

         LittleEndian<uint32_t>  _tableSize;

         char                    _table[0];      // Actually Entry[]

     };

     class Index::Iterator :public Dictionary::Iterator {

     public:

         Iterator (File*, const Index*);

         virtual Key key() const;

         virtual Blob value() const;

         virtual bool next();

         virtual bool hasValue() const;

         FilePosition valuePosition();

     private:

         File* const _file;

         const Index::Entry *_current, *_end;

     };

 }

 #endif //_MOOSEYARD_INDEX_