(4);
- private int maxPosition = 0;
- private int slop = 0;
-
- /** Constructs an empty phrase query. */
- public PhraseQuery() {}
-
- /** Sets the number of other words permitted between words in query phrase.
- If zero, then this is an exact phrase search. For larger values this works
- like a WITHIN or NEAR operator.
-
- The slop is in fact an edit-distance, where the units correspond to
- moves of terms in the query phrase out of position. For example, to switch
- the order of two words requires two moves (the first move places the words
- atop one another), so to permit re-orderings of phrases, the slop must be
- at least two.
-
-
More exact matches are scored higher than sloppier matches, thus search
- results are sorted by exactness.
-
-
The slop is zero by default, requiring exact matches.*/
- public void setSlop(int s) { slop = s; }
- /** Returns the slop. See setSlop(). */
- public int getSlop() { return slop; }
-
- /**
- * Adds a term to the end of the query phrase.
- * The relative position of the term is the one immediately after the last term added.
- */
- public void add(Term term) {
- int position = 0;
- if(positions.size() > 0)
- position = positions.get(positions.size()-1).intValue() + 1;
-
- add(term, position);
- }
-
- /**
- * Adds a term to the end of the query phrase.
- * The relative position of the term within the phrase is specified explicitly.
- * This allows e.g. phrases with more than one term at the same position
- * or phrases with gaps (e.g. in connection with stopwords).
- *
- * @param term
- * @param position
- */
- public void add(Term term, int position) {
- if (terms.size() == 0)
- field = term.field();
- else if (term.field() != field)
- throw new IllegalArgumentException("All phrase terms must be in the same field: " + term);
-
- terms.add(term);
- positions.add(Integer.valueOf(position));
- if (position > maxPosition) maxPosition = position;
- }
-
- /** Returns the set of terms in this phrase. */
- public Term[] getTerms() {
- return terms.toArray(new Term[0]);
- }
-
- /**
- * Returns the relative positions of terms in this phrase.
- */
- public int[] getPositions() {
- int[] result = new int[positions.size()];
- for(int i = 0; i < positions.size(); i++)
- result[i] = positions.get(i).intValue();
- return result;
- }
-
- @Override
- public Query rewrite(IndexReader reader) throws IOException {
- if (terms.size() == 1) {
- TermQuery tq = new TermQuery(terms.get(0));
- tq.setBoost(getBoost());
- return tq;
- } else
- return super.rewrite(reader);
- }
-
- static class PostingsAndFreq implements Comparable {
- final TermPositions postings;
- final int docFreq;
- final int position;
- final Term term;
-
- public PostingsAndFreq(TermPositions postings, int docFreq, int position, Term term) {
- this.postings = postings;
- this.docFreq = docFreq;
- this.position = position;
- this.term = term;
- }
-
- public int compareTo(PostingsAndFreq other) {
- if (docFreq == other.docFreq) {
- if (position == other.position) {
- return term.compareTo(other.term);
- }
- return position - other.position;
- }
- return docFreq - other.docFreq;
- }
-
- @Override
- public int hashCode() {
- final int prime = 31;
- int result = 1;
- result = prime * result + docFreq;
- result = prime * result + position;
- result = prime * result + ((term == null) ? 0 : term.hashCode());
- return result;
- }
-
- @Override
- public boolean equals(Object obj) {
- if (this == obj) return true;
- if (obj == null) return false;
- if (getClass() != obj.getClass()) return false;
- PostingsAndFreq other = (PostingsAndFreq) obj;
- if (docFreq != other.docFreq) return false;
- if (position != other.position) return false;
- if (term == null) {
- if (other.term != null) return false;
- } else if (!term.equals(other.term)) return false;
- return true;
- }
- }
-
- private class PhraseWeight extends Weight {
- private final Similarity similarity;
- private float value;
- private float idf;
- private float queryNorm;
- private float queryWeight;
- private IDFExplanation idfExp;
-
- public PhraseWeight(Searcher searcher)
- throws IOException {
- this.similarity = getSimilarity(searcher);
-
- idfExp = similarity.idfExplain(terms, searcher);
- idf = idfExp.getIdf();
- }
-
- @Override
- public String toString() { return "weight(" + PhraseQuery.this + ")"; }
-
- @Override
- public Query getQuery() { return PhraseQuery.this; }
-
- @Override
- public float getValue() { return value; }
-
- @Override
- public float sumOfSquaredWeights() {
- queryWeight = idf * getBoost(); // compute query weight
- return queryWeight * queryWeight; // square it
- }
-
- @Override
- public void normalize(float queryNorm) {
- this.queryNorm = queryNorm;
- queryWeight *= queryNorm; // normalize query weight
- value = queryWeight * idf; // idf for document
- }
-
- @Override
- public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException {
- if (terms.size() == 0) // optimize zero-term case
- return null;
-
- PostingsAndFreq[] postingsFreqs = new PostingsAndFreq[terms.size()];
- for (int i = 0; i < terms.size(); i++) {
- final Term t = terms.get(i);
- TermPositions p = reader.termPositions(t);
- if (p == null)
- return null;
- postingsFreqs[i] = new PostingsAndFreq(p, reader.docFreq(t), positions.get(i).intValue(), t);
- }
-
- // sort by increasing docFreq order
- if (slop == 0) {
- ArrayUtil.mergeSort(postingsFreqs);
- }
-
- if (slop == 0) { // optimize exact case
- ExactPhraseScorer s = new ExactPhraseScorer(this, postingsFreqs, similarity,
- reader.norms(field));
- if (s.noDocs) {
- return null;
- } else {
- return s;
- }
- } else {
- return
- new SloppyPhraseScorer(this, postingsFreqs, similarity, slop,
- reader.norms(field));
- }
- }
-
- @Override
- public Explanation explain(IndexReader reader, int doc)
- throws IOException {
-
- ComplexExplanation result = new ComplexExplanation();
- result.setDescription("weight("+getQuery()+" in "+doc+"), product of:");
-
- StringBuilder docFreqs = new StringBuilder();
- StringBuilder query = new StringBuilder();
- query.append('\"');
- docFreqs.append(idfExp.explain());
- for (int i = 0; i < terms.size(); i++) {
- if (i != 0) {
- query.append(" ");
- }
-
- Term term = terms.get(i);
-
- query.append(term.text());
- }
- query.append('\"');
-
- Explanation idfExpl =
- new Explanation(idf, "idf(" + field + ":" + docFreqs + ")");
-
- // explain query weight
- Explanation queryExpl = new Explanation();
- queryExpl.setDescription("queryWeight(" + getQuery() + "), product of:");
-
- Explanation boostExpl = new Explanation(getBoost(), "boost");
- if (getBoost() != 1.0f)
- queryExpl.addDetail(boostExpl);
- queryExpl.addDetail(idfExpl);
-
- Explanation queryNormExpl = new Explanation(queryNorm,"queryNorm");
- queryExpl.addDetail(queryNormExpl);
-
- queryExpl.setValue(boostExpl.getValue() *
- idfExpl.getValue() *
- queryNormExpl.getValue());
-
- result.addDetail(queryExpl);
-
- // explain field weight
- Explanation fieldExpl = new Explanation();
- fieldExpl.setDescription("fieldWeight("+field+":"+query+" in "+doc+
- "), product of:");
-
- Scorer scorer = scorer(reader, true, false);
- if (scorer == null) {
- return new Explanation(0.0f, "no matching docs");
- }
- Explanation tfExplanation = new Explanation();
- int d = scorer.advance(doc);
- float phraseFreq;
- if (d == doc) {
- phraseFreq = scorer.freq();
- } else {
- phraseFreq = 0.0f;
- }
-
- tfExplanation.setValue(similarity.tf(phraseFreq));
- tfExplanation.setDescription("tf(phraseFreq=" + phraseFreq + ")");
-
- fieldExpl.addDetail(tfExplanation);
- fieldExpl.addDetail(idfExpl);
-
- Explanation fieldNormExpl = new Explanation();
- byte[] fieldNorms = reader.norms(field);
- float fieldNorm =
- fieldNorms!=null ? similarity.decodeNormValue(fieldNorms[doc]) : 1.0f;
- fieldNormExpl.setValue(fieldNorm);
- fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
- fieldExpl.addDetail(fieldNormExpl);
-
- fieldExpl.setValue(tfExplanation.getValue() *
- idfExpl.getValue() *
- fieldNormExpl.getValue());
-
- result.addDetail(fieldExpl);
-
- // combine them
- result.setValue(queryExpl.getValue() * fieldExpl.getValue());
- result.setMatch(tfExplanation.isMatch());
- return result;
- }
- }
-
- @Override
- public Weight createWeight(Searcher searcher) throws IOException {
- if (terms.size() == 1) { // optimize one-term case
- Term term = terms.get(0);
- Query termQuery = new TermQuery(term);
- termQuery.setBoost(getBoost());
- return termQuery.createWeight(searcher);
- }
- return new PhraseWeight(searcher);
- }
-
- /**
- * @see org.apache.lucene.search.Query#extractTerms(Set)
- */
- @Override
- public void extractTerms(Set queryTerms) {
- queryTerms.addAll(terms);
- }
-
- /** Prints a user-readable version of this query. */
- @Override
- public String toString(String f) {
- StringBuilder buffer = new StringBuilder();
- if (field != null && !field.equals(f)) {
- buffer.append(field);
- buffer.append(":");
- }
-
- buffer.append("\"");
- String[] pieces = new String[maxPosition + 1];
- for (int i = 0; i < terms.size(); i++) {
- int pos = positions.get(i).intValue();
- String s = pieces[pos];
- if (s == null) {
- s = (terms.get(i)).text();
- } else {
- s = s + "|" + (terms.get(i)).text();
- }
- pieces[pos] = s;
- }
- for (int i = 0; i < pieces.length; i++) {
- if (i > 0) {
- buffer.append(' ');
- }
- String s = pieces[i];
- if (s == null) {
- buffer.append('?');
- } else {
- buffer.append(s);
- }
- }
- buffer.append("\"");
-
- if (slop != 0) {
- buffer.append("~");
- buffer.append(slop);
- }
-
- buffer.append(ToStringUtils.boost(getBoost()));
-
- return buffer.toString();
- }
-
- /** Returns true iff o is equal to this. */
- @Override
- public boolean equals(Object o) {
- if (!(o instanceof PhraseQuery))
- return false;
- PhraseQuery other = (PhraseQuery)o;
- return (this.getBoost() == other.getBoost())
- && (this.slop == other.slop)
- && this.terms.equals(other.terms)
- && this.positions.equals(other.positions);
- }
-
- /** Returns a hash code value for this object.*/
- @Override
- public int hashCode() {
- return Float.floatToIntBits(getBoost())
- ^ slop
- ^ terms.hashCode()
- ^ positions.hashCode();
- }
-
-}