segmenttermenum.h

clucene是c++版的全文检索引擎,完全移植于lucene,采用 stl 编写.

/*------------------------------------------------------------------------------
* Copyright (C) 2003-2006 Ben van Klinken and the CLucene Team
* 
* Distributable under the terms of either the Apache License (Version 2.0) or 
* the GNU Lesser General Public License, as specified in the COPYING file.
------------------------------------------------------------------------------*/
#ifndef _lucene_index_SegmentTermEnum_
#define _lucene_index_SegmentTermEnum_

#if defined(_LUCENE_PRAGMA_ONCE)
# pragma once
#endif

#include "Terms.h"
#include "FieldInfos.h"
#include "TermInfo.h"

CL_NS_DEF(index)

    //SegmentTermEnum is an enumeration of all Terms and TermInfos

	class SegmentTermEnum:public TermEnum{
	private:
		Term* _term;             //points to the current Term in the enumeration
		TermInfo* termInfo;     //points to the TermInfo matching the current Term in the enumeration

		bool isIndex;           //Indicates if the Segment is a an index

		TCHAR* buffer;         //The buffer that contains the data read from the Term Infos File
	
		bool isClone;           //Indicates if SegmentTermEnum is an orignal instance or
		                        //a clone of another SegmentTermEnum
		uint32_t bufferLength;     //Length of the buffer

		int32_t format;
		int32_t formatM1SkipInterval;
		
		//Constructor. 
		//The instance is created by cloning all properties of clone
		SegmentTermEnum( const SegmentTermEnum& clone);

	public:
#ifndef LUCENE_HIDE_INTERNAL
		CL_NS(store)::IndexInput* input;     //The IndexInput that reads from the Term Infos File
		FieldInfos* fieldInfos; //contains the Field Infos for the segment
		int64_t size;             //The size of the enumeration
		int64_t position;         //The position of the current (term) in the enumeration
		int64_t indexPointer;    
		Term* prev;             //The previous current 
		int32_t indexInterval;
		int32_t skipInterval;
#endif

		//Constructor
		SegmentTermEnum(CL_NS(store)::IndexInput* i, FieldInfos* fis, const bool isi );

		
		//Destructor
		~SegmentTermEnum();

		//Moves the current of the set to the next in the set
		bool next();

		//Returns a pointer to the current term. 
		Term* term();
		//Returns the current term. 
		Term* term(bool pointer);

        //Scan for Term term without allocating new Terms
		void scanTo(const Term *term);

		//Closes the enumeration to further activity, freeing resources. 
		void close();

		//Returns the document frequency of the current term in the set
		int32_t docFreq() const;

		//Repositions term and termInfo within the enumeration
		void seek(const int64_t pointer, const int32_t p, Term* t, TermInfo* ti);
		
		//Returns a clone of the current termInfo
		TermInfo* getTermInfo()const;

		//Retrieves a clone of termInfo through the reference ti
		void getTermInfo(TermInfo* ti)const;

		// Returns the freqPointer from the current TermInfo in the enumeration.
		int64_t freqPointer() const;

		// Returns the proxPointer from the current TermInfo in the enumeration.
		int64_t proxPointer() const;

        //Returns a clone of this instance
		SegmentTermEnum* clone() const;

		const char* getObjectName(){ return SegmentTermEnum::getClassName(); }
		static const char* getClassName(){ return "SegmentTermEnum"; }

    private:
		//Reads the next term in the enumeration
		Term* readTerm(Term* reuse);
        //Instantiate a buffer of length length+1
		void growBuffer(const uint32_t length);

	};
CL_NS_END
#endif