File	Doc	Category	Size	Date	Package
DisjunctionMaxScorer.java	API Doc	Apache Lucene 2.1.0	7970	Wed Feb 14 10:46:40 GMT 2007	org.apache.lucene.search

DisjunctionMaxScorer

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

Fields Summary
private ArrayList	subScorers
private float	tieBreakerMultiplier
private boolean	more
private boolean	firstTime

Constructors Summary

public DisjunctionMaxScorer(float tieBreakerMultiplier, Similarity similarity) Creates a new instance of DisjunctionMaxScorer param tieBreakerMultiplier Multiplier applied to non-maximum-scoring subqueries for a document as they are summed into the result. param similarity -- not used since our definition involves neither coord nor terms directly // True iff next() has not yet been called super(similarity); this.tieBreakerMultiplier = tieBreakerMultiplier;

Methods Summary
public void	add(org.apache.lucene.search.Scorer scorer) Add the scorer for a subquery param scorer the scorer of a subquery of our associated DisjunctionMaxQuery if (scorer.next()) { // Initialize and retain only if it produces docs subScorers.add(scorer); more = true; }
public int	doc() Determine the current document number. Initially invalid, until {@link #next()} is called the first time. return the document number of the currently generated document return ((Scorer) subScorers.get(0)).doc();
public org.apache.lucene.search.Explanation	explain(int doc) Explain a score that we computed. UNSUPPORTED -- see explanation capability in DisjunctionMaxQuery. param doc the number of a document we scored return the Explanation for our score throw new UnsupportedOperationException();
private void	heapAdjust(int root) Scorer scorer=(Scorer)subScorers.get(root); int doc=scorer.doc(); int i=root, size=subScorers.size(); while (i<=(size>>1)-1) { int lchild=(i<<1)+1; Scorer lscorer=(Scorer)subScorers.get(lchild); int ldoc=lscorer.doc(); int rdoc=Integer.MAX_VALUE, rchild=(i<<1)+2; Scorer rscorer=null; if (rchild<size) { rscorer=(Scorer)subScorers.get(rchild); rdoc=rscorer.doc(); } if (ldoc<doc) { if (rdoc<ldoc) { subScorers.set(i, rscorer); subScorers.set(rchild, scorer); i=rchild; } else { subScorers.set(i, lscorer); subScorers.set(lchild, scorer); i=lchild; } } else if (rdoc<doc) { subScorers.set(i, rscorer); subScorers.set(rchild, scorer); i=rchild; } else return; }
private void	heapRemoveRoot() int size=subScorers.size(); if (size==1) subScorers.remove(0); else { subScorers.set(0, subScorers.get(size-1)); subScorers.remove(size-1); heapAdjust(0); }
private void	heapify() int size = subScorers.size(); for (int i=(size>>1)-1; i>=0; i--) heapAdjust(i);
public boolean	next() Generate the next document matching our associated DisjunctionMaxQuery. return true iff there is a next document if (!more) return false; if (firstTime) { heapify(); firstTime = false; return true; // more would have been false if no subScorers had any docs } // Increment all generators that generated the last doc and adjust the heap. int lastdoc = ((Scorer) subScorers.get(0)).doc(); do { if (((Scorer) subScorers.get(0)).next()) heapAdjust(0); else { heapRemoveRoot(); if (subScorers.isEmpty()) return (more = false); } } while ( ((Scorer) subScorers.get(0)).doc()==lastdoc ); return true;
public float	score() Determine the current document score. Initially invalid, until {@link #next()} is called the first time. return the score of the current generated document int doc = ((Scorer) subScorers.get(0)).doc(); float[] sum = {((Scorer) subScorers.get(0)).score()}, max = {sum[0]}; int size = subScorers.size(); scoreAll(1, size, doc, sum, max); scoreAll(2, size, doc, sum, max); return max[0] + (sum[0] - max[0])*tieBreakerMultiplier;
private void	scoreAll(int root, int size, int doc, float[] sum, float[] max) if (root<size && ((Scorer) subScorers.get(root)).doc() == doc) { float sub = ((Scorer) subScorers.get(root)).score(); sum[0] += sub; max[0] = Math.max(max[0], sub); scoreAll((root<<1)+1, size, doc, sum, max); scoreAll((root<<1)+2, size, doc, sum, max); }
public boolean	skipTo(int target) Advance to the first document beyond the current whose number is greater than or equal to target. param target the minimum number of the next desired document return true iff there is a document to be generated whose number is at least target if (firstTime) { if (!more) return false; heapify(); firstTime = false; return true; // more would have been false if no subScorers had any docs } while (subScorers.size()>0 && ((Scorer)subScorers.get(0)).doc()<target) { if (((Scorer)subScorers.get(0)).skipTo(target)) heapAdjust(0); else heapRemoveRoot(); } if ((subScorers.size()==0)) return (more = false); return true;