File	Doc	Category	Size	Date	Package
PhraseScorer.java	API Doc	Apache Lucene 2.2.0	6013	Sat Jun 16 22:20:34 BST 2007	org.apache.lucene.search

PhraseScorer

• java.lang.Object
  • org.apache.lucene.search.Scorer

Fields Summary
private Weight	weight
protected byte[]	norms
protected float	value
private boolean	firstTime
private boolean	more
protected PhraseQueue	pq
protected PhrasePositions	first
protected PhrasePositions	last
private float	freq

Constructors Summary

PhraseScorer(Weight weight, TermPositions[] tps, int[] offsets, Similarity similarity, byte[] norms) //prhase frequency in current doc as computed by phraseFreq(). super(similarity); this.norms = norms; this.weight = weight; this.value = weight.getValue(); // convert tps to a list of phrase positions. // note: phrase-position differs from term-position in that its position // reflects the phrase offset: pp.pos = tp.pos - offset. // this allows to easily identify a matching (exact) phrase // when all PhrasePositions have exactly the same position. for (int i = 0; i < tps.length; i++) { PhrasePositions pp = new PhrasePositions(tps[i], offsets[i]); if (last != null) { // add next to end of list last.next = pp; } else first = pp; last = pp; } pq = new PhraseQueue(tps.length); // construct empty pq

Methods Summary
private boolean	doNext() while (more) { while (more && first.doc < last.doc) { // find doc w/ all the terms more = first.skipTo(last.doc); // skip first upto last firstToLast(); // and move it to the end } if (more) { // found a doc with all of the terms freq = phraseFreq(); // check for phrase if (freq == 0.0f) // no match more = last.next(); // trigger further scanning else return true; // found a match } } return false; // no more matches
public int	doc() return first.doc;
public org.apache.lucene.search.Explanation	explain(int doc) Explanation tfExplanation = new Explanation(); while (next() && doc() < doc) {} float phraseFreq = (doc() == doc) ? freq : 0.0f; tfExplanation.setValue(getSimilarity().tf(phraseFreq)); tfExplanation.setDescription("tf(phraseFreq=" + phraseFreq + ")"); return tfExplanation;
protected final void	firstToLast() last.next = first; // move first to end of list last = first; first = first.next; last.next = null;
private void	init() for (PhrasePositions pp = first; more && pp != null; pp = pp.next) more = pp.next(); if(more) sort();
public boolean	next() if (firstTime) { init(); firstTime = false; } else if (more) { more = last.next(); // trigger further scanning } return doNext();
protected abstract float	phraseFreq() For a document containing all the phrase query terms, compute the frequency of the phrase in that document. A non zero frequency means a match. Note, that containing all phrase terms does not guarantee a match - they have to be found in matching locations. return frequency of the phrase in current doc, 0 if not found.
protected final void	pqToList() last = first = null; while (pq.top() != null) { PhrasePositions pp = (PhrasePositions) pq.pop(); if (last != null) { // add next to end of list last.next = pp; } else first = pp; last = pp; pp.next = null; }
public float	score() //System.out.println("scoring " + first.doc); float raw = getSimilarity().tf(freq) * value; // raw score return raw * Similarity.decodeNorm(norms[first.doc]); // normalize
public boolean	skipTo(int target) firstTime = false; for (PhrasePositions pp = first; more && pp != null; pp = pp.next) { more = pp.skipTo(target); } if (more) sort(); // re-sort return doNext();
private void	sort() pq.clear(); for (PhrasePositions pp = first; pp != null; pp = pp.next) pq.put(pp); pqToList();
public java.lang.String	toString() return "scorer(" + weight + ")";