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/*
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* VersionDictionary.h
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* Ottoman
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*
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* Created by Jens Alfke on 8/21/09.
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* Copyright 2009 Jens Alfke. All rights reserved.
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* BSD-Licensed: See the file "LICENSE.txt" for details.
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*/
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#ifndef _MOOSEYARD_VERSIONDICTIONARY_
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#define _MOOSEYARD_VERSIONDICTIONARY_
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#include "Dictionary.h"
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namespace Mooseyard {
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class File;
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class Index;
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/** A persistent Dictionary embedded in a memory-mapped file,
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representing one complete version of an Ottoman dictionary. */
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class VersionDictionary :public Dictionary {
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public:
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/** The generation number. The first version in a new file is zero. */
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int generation() const;
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/** The absolute time at which this version was written to the file. */
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time_t timestamp() const;
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/** The previous version, before this one was saved. */
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const VersionDictionary* previousVersion() const;
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/** Is this the latest version in the file? */
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bool isLatestVersion() const;
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virtual int count() const;
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virtual Blob get (Key) const;
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class Iterator;
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virtual Dictionary::Iterator* iterate() const;
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class ChangeIterator;
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/** Iterates over the changes between this dictionary and the previous version. */
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virtual ChangeIterator* iterateChanges() const;
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// Stuff you probably won't need to use:
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File* file() const {return _file;}
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explicit VersionDictionary (File*);
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VersionDictionary (File *file, FilePosition trailerPosition);
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private:
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/** The type of the trailer chunk that's used as the position of the dictionary. */
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static const uint16_t kChunkType = 3;
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struct IndexPositions {
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LittleEndian<FilePosition> position[256];
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LittleEndian<FilePosition>& operator[] (int i) {return position[i];}
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LittleEndian<FilePosition> const& operator[] (int i) const {return position[i];}
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};
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class Trailer;
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const Trailer* _trailer() const;
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const Index* _index (int i) const;
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void _read (FilePosition trailerPosition =0);
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static FilePosition _append (const VersionDictionary *baseDict,
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const Dictionary *addDict,
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File *dstFile,
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bool replace);
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File *_file;
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FilePosition _trailerPosition, _previousTrailerPosition;
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IndexPositions _indexPositions;
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int _count;
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mutable const VersionDictionary *_previousVersion;
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#if VERSIONDICTIONARY_TESTING
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public:
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#endif
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static VersionDictionary* create (File *file, const Dictionary *srcDict);
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VersionDictionary* byAppending (const Dictionary* d) const {return _appendAndOpen(d,_file,false);}
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VersionDictionary* byReplacing (const Dictionary* d) const {return _appendAndOpen(d,_file,true);}
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VersionDictionary* _appendAndOpen (const Dictionary *addDict, File *dstFile, bool replace) const;
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friend class Ottoman;
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UNCOPYABLE(VersionDictionary);
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};
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class VersionDictionary::Iterator :public Dictionary::Iterator {
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public:
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explicit Iterator (const VersionDictionary*);
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virtual ~Iterator();
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virtual Key key() const;
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virtual Blob value() const;
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virtual bool next();
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virtual bool hasValue() const;
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private:
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bool nextIndex();
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const VersionDictionary *_file;
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int _bucket;
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Dictionary::Iterator *_iter;
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UNCOPYABLE(Iterator);
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};
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class VersionDictionary::ChangeIterator :public Dictionary::Iterator {
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public:
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explicit ChangeIterator (const VersionDictionary*);
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virtual ~ChangeIterator();
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virtual Key key() const;
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virtual Blob value() const;
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virtual bool next();
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virtual bool hasValue() const;
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private:
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bool nextIndex();
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const VersionDictionary *_file;
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int _bucket;
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Dictionary::Iterator *_iter;
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UNCOPYABLE(ChangeIterator);
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};
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}
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#endif //_MOOSEYARD_VERSIONDICTIONARY_
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