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/*------------------------------------------------------------------------------
* 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.
------------------------------------------------------------------------------*/
#include "CLucene/StdHeader.h"
#include "ExactPhraseScorer.h"
#include "PhraseScorer.h"
#include "CLucene/index/Terms.h"
CL_NS_USE(index)
CL_NS_DEF(search)
ExactPhraseScorer::ExactPhraseScorer(Weight* weight, TermPositions** tps,
int32_t* positions, Similarity* similarity, uint8_t* norms):
PhraseScorer(weight, tps, positions, similarity, norms){
//Func - Constructor
//Pre - tps != NULL
// tpsLength >= 0
// n != NULL
//Post - Instance has been created
CND_PRECONDITION(tps != NULL,"tps is NULL");
CND_PRECONDITION(tps[0] != NULL,"tps is NULL");
//CND_PRECONDITION(n != NULL,"n is NULL") =this is checked already in PhraseScorer
}
qreal ExactPhraseScorer::phraseFreq(){
//Func - Returns the freqency of the phrase
//Pre - first != NULL
// last != NULL
// pq != NULL
// size of the PhraseQueue pq is 0
//Post - The frequency of the phrase has been returned
CND_PRECONDITION(first != NULL,"first is NULL");
CND_PRECONDITION(last != NULL,"last is NULL");
CND_PRECONDITION(pq != NULL,"pq is NULL");
CND_PRECONDITION(pq->size()==0,"pq is not empty");
//build pq from list
//Add the nodes of the list of PhrasePositions and store them
//into the PhraseQueue pq so it can used to build
//a list of sorted nodes
for (PhrasePositions* pp = first; pp != NULL; pp = pp->_next) {
//Read the first TermPosition of the current PhrasePositions pp
pp->firstPosition();
//Store the current PhrasePositions pp into the PhraseQueue pq
pq->put(pp);
}
//pqToList requires that first and last be NULL when it's called.
//This is done at the beginning of pqToList()
//In this case, the nodes of the linked list are referenced by pq (see
//above loop), so we can clear our pointers to the head and tail of the
//linked list without fear of leaking the nodes.
//rebuild list from pq
pqToList();
//Initialize freq at 0
int32_t freq = 0;
//find position with all terms
do {
//scan forward in first
while (first->position < last->position){
do{
if (!first->nextPosition()){
return (qreal)freq;
}
} while (first->position < last->position);
//Make the current first node the last node in the list
firstToLast();
}
//all equal: a match has been found
freq++;
} while (last->nextPosition());
return (qreal)freq;
}
CL_NS_END
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