/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.search;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import org.apache.lucene.codecs.lucene50.Lucene50PostingsFormat;
import org.apache.lucene.codecs.lucene50.Lucene50PostingsReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexReaderContext;
import org.apache.lucene.index.LeafReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.PostingsEnum;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermContext;
import org.apache.lucene.index.TermState;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.search.similarities.Similarity.SimScorer;
import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.BytesRef;
/** A Query that matches documents containing a particular sequence of terms.
* A PhraseQuery is built by QueryParser for input like <code>"new york"</code>.
*
* <p>This query may be combined with other terms or queries with a {@link BooleanQuery}.
*
* <p><b>NOTE</b>:
* All terms in the phrase must match, even those at the same position. If you
* have terms at the same position, perhaps synonyms, you probably want {@link MultiPhraseQuery}
* instead which only requires one term at a position to match.
* <br >Also, Leading holes don't have any particular meaning for this query
* and will be ignored. For instance this query:
* <pre class="prettyprint">
* PhraseQuery.Builder builder = new PhraseQuery.Builder();
* builder.add(new Term("body", "one"), 4);
* builder.add(new Term("body", "two"), 5);
* PhraseQuery pq = builder.build();
* </pre>
* is equivalent to the below query:
* <pre class="prettyprint">
* PhraseQuery.Builder builder = new PhraseQuery.Builder();
* builder.add(new Term("body", "one"), 0);
* builder.add(new Term("body", "two"), 1);
* PhraseQuery pq = builder.build();
* </pre>
*/
public class PhraseQuery extends Query {
/** A builder for phrase queries. */
public static class Builder {
private int slop;
private final List<Term> terms;
private final List<Integer> positions;
/** Sole constructor. */
public Builder() {
slop = 0;
terms = new ArrayList<>();
positions = new ArrayList<>();
}
/**
* Set the slop.
* @see PhraseQuery#getSlop()
*/
public Builder setSlop(int slop) {
this.slop = slop;
return this;
}
/**
* 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 Builder add(Term term) {
return add(term, positions.isEmpty() ? 0 : 1 + positions.get(positions.size() - 1));
}
/**
* Adds a term to the end of the query phrase.
* The relative position of the term within the phrase is specified explicitly, but must be greater than
* or equal to that of the previously added term.
* A greater position allows phrases with gaps (e.g. in connection with stopwords).
* If the position is equal, you most likely should be using
* {@link MultiPhraseQuery} instead which only requires one term at each position to match; this class requires
* all of them.
*/
public Builder add(Term term, int position) {
if (position < 0) {
throw new IllegalArgumentException("Positions must be >= 0, got " + position);
}
if (positions.isEmpty() == false) {
final int lastPosition = positions.get(positions.size() - 1);
if (position < lastPosition) {
throw new IllegalArgumentException("Positions must be added in order, got " + position + " after " + lastPosition);
}
}
if (terms.isEmpty() == false && term.field().equals(terms.get(0).field()) == false) {
throw new IllegalArgumentException("All terms must be on the same field, got " + term.field() + " and " + terms.get(0).field());
}
terms.add(term);
positions.add(position);
return this;
}
/**
* Build a phrase query based on the terms that have been added.
*/
public PhraseQuery build() {
Term[] terms = this.terms.toArray(new Term[this.terms.size()]);
int[] positions = new int[this.positions.size()];
for (int i = 0; i < positions.length; ++i) {
positions[i] = this.positions.get(i);
}
return new PhraseQuery(slop, terms, positions);
}
}
private final int slop;
private final String field;
private final Term[] terms;
private final int[] positions;
private PhraseQuery(int slop, Term[] terms, int[] positions) {
if (terms.length != positions.length) {
throw new IllegalArgumentException("Must have as many terms as positions");
}
if (slop < 0) {
throw new IllegalArgumentException("Slop must be >= 0, got " + slop);
}
for (int i = 1; i < terms.length; ++i) {
if (terms[i-1].field().equals(terms[i].field()) == false) {
throw new IllegalArgumentException("All terms should have the same field");
}
}
for (int position : positions) {
if (position < 0) {
throw new IllegalArgumentException("Positions must be >= 0, got " + position);
}
}
for (int i = 1; i < positions.length; ++i) {
if (positions[i] < positions[i - 1]) {
throw new IllegalArgumentException("Positions should not go backwards, got "
+ positions[i-1] + " before " + positions[i]);
}
}
this.slop = slop;
this.terms = terms;
this.positions = positions;
this.field = terms.length == 0 ? null : terms[0].field();
}
private static int[] incrementalPositions(int length) {
int[] positions = new int[length];
for (int i = 0; i < length; ++i) {
positions[i] = i;
}
return positions;
}
private static Term[] toTerms(String field, String... termStrings) {
Term[] terms = new Term[termStrings.length];
for (int i = 0; i < terms.length; ++i) {
terms[i] = new Term(field, termStrings[i]);
}
return terms;
}
private static Term[] toTerms(String field, BytesRef... termBytes) {
Term[] terms = new Term[termBytes.length];
for (int i = 0; i < terms.length; ++i) {
terms[i] = new Term(field, termBytes[i]);
}
return terms;
}
/**
* Create a phrase query which will match documents that contain the given
* list of terms at consecutive positions in {@code field}, and at a
* maximum edit distance of {@code slop}. For more complicated use-cases,
* use {@link PhraseQuery.Builder}.
* @see #getSlop()
*/
public PhraseQuery(int slop, String field, String... terms) {
this(slop, toTerms(field, terms), incrementalPositions(terms.length));
}
/**
* Create a phrase query which will match documents that contain the given
* list of terms at consecutive positions in {@code field}.
*/
public PhraseQuery(String field, String... terms) {
this(0, field, terms);
}
/**
* Create a phrase query which will match documents that contain the given
* list of terms at consecutive positions in {@code field}, and at a
* maximum edit distance of {@code slop}. For more complicated use-cases,
* use {@link PhraseQuery.Builder}.
* @see #getSlop()
*/
public PhraseQuery(int slop, String field, BytesRef... terms) {
this(slop, toTerms(field, terms), incrementalPositions(terms.length));
}
/**
* Create a phrase query which will match documents that contain the given
* list of terms at consecutive positions in {@code field}.
*/
public PhraseQuery(String field, BytesRef... terms) {
this(0, field, terms);
}
/**
* Return the slop for this {@link PhraseQuery}.
*
* <p>The slop is an edit distance between respective positions of terms as
* defined in this {@link PhraseQuery} and the positions of terms in a
* document.
*
* <p>For instance, when searching for {@code "quick fox"}, it is expected that
* the difference between the positions of {@code fox} and {@code quick} is 1.
* So {@code "a quick brown fox"} would be at an edit distance of 1 since the
* difference of the positions of {@code fox} and {@code quick} is 2.
* Similarly, {@code "the fox is quick"} would be at an edit distance of 3
* since the difference of the positions of {@code fox} and {@code quick} is -2.
* The slop defines the maximum edit distance for a document to match.
*
* <p>More exact matches are scored higher than sloppier matches, thus search
* results are sorted by exactness.
*/
public int getSlop() { return slop; }
/** Returns the list of terms in this phrase. */
public Term[] getTerms() {
return terms;
}
/**
* Returns the relative positions of terms in this phrase.
*/
public int[] getPositions() {
return positions;
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
if (terms.length == 0) {
return new MatchNoDocsQuery("empty PhraseQuery");
} else if (terms.length == 1) {
return new TermQuery(terms[0]);
} else if (positions[0] != 0) {
int[] newPositions = new int[positions.length];
for (int i = 0; i < positions.length; ++i) {
newPositions[i] = positions[i] - positions[0];
}
return new PhraseQuery(slop, terms, newPositions);
} else {
return super.rewrite(reader);
}
}
static class PostingsAndFreq implements Comparable<PostingsAndFreq> {
final PostingsEnum postings;
final int position;
final Term[] terms;
final int nTerms; // for faster comparisons
public PostingsAndFreq(PostingsEnum postings, int position, Term... terms) {
this.postings = postings;
this.position = position;
nTerms = terms==null ? 0 : terms.length;
if (nTerms>0) {
if (terms.length==1) {
this.terms = terms;
} else {
Term[] terms2 = new Term[terms.length];
System.arraycopy(terms, 0, terms2, 0, terms.length);
Arrays.sort(terms2);
this.terms = terms2;
}
} else {
this.terms = null;
}
}
@Override
public int compareTo(PostingsAndFreq other) {
if (position != other.position) {
return position - other.position;
}
if (nTerms != other.nTerms) {
return nTerms - other.nTerms;
}
if (nTerms == 0) {
return 0;
}
for (int i=0; i<terms.length; i++) {
int res = terms[i].compareTo(other.terms[i]);
if (res!=0) return res;
}
return 0;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + position;
for (int i=0; i<nTerms; i++) {
result = prime * result + terms[i].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 (position != other.position) return false;
if (terms == null) return other.terms == null;
return Arrays.equals(terms, other.terms);
}
}
private class PhraseWeight extends Weight {
private final Similarity similarity;
private final Similarity.SimWeight stats;
private final boolean needsScores;
private transient TermContext states[];
public PhraseWeight(IndexSearcher searcher, boolean needsScores, float boost)
throws IOException {
super(PhraseQuery.this);
final int[] positions = PhraseQuery.this.getPositions();
if (positions.length < 2) {
throw new IllegalStateException("PhraseWeight does not support less than 2 terms, call rewrite first");
} else if (positions[0] != 0) {
throw new IllegalStateException("PhraseWeight requires that the first position is 0, call rewrite first");
}
this.needsScores = needsScores;
this.similarity = searcher.getSimilarity(needsScores);
final IndexReaderContext context = searcher.getTopReaderContext();
states = new TermContext[terms.length];
TermStatistics termStats[] = new TermStatistics[terms.length];
for (int i = 0; i < terms.length; i++) {
final Term term = terms[i];
states[i] = TermContext.build(context, term);
termStats[i] = searcher.termStatistics(term, states[i]);
}
stats = similarity.computeWeight(boost, searcher.collectionStatistics(field), termStats);
}
@Override
public void extractTerms(Set<Term> queryTerms) {
Collections.addAll(queryTerms, terms);
}
@Override
public String toString() { return "weight(" + PhraseQuery.this + ")"; }
@Override
public Scorer scorer(LeafReaderContext context) throws IOException {
assert terms.length > 0;
final LeafReader reader = context.reader();
PostingsAndFreq[] postingsFreqs = new PostingsAndFreq[terms.length];
final Terms fieldTerms = reader.terms(field);
if (fieldTerms == null) {
return null;
}
if (fieldTerms.hasPositions() == false) {
throw new IllegalStateException("field \"" + field + "\" was indexed without position data; cannot run PhraseQuery (phrase=" + getQuery() + ")");
}
// Reuse single TermsEnum below:
final TermsEnum te = fieldTerms.iterator();
float totalMatchCost = 0;
for (int i = 0; i < terms.length; i++) {
final Term t = terms[i];
final TermState state = states[i].get(context.ord);
if (state == null) { /* term doesnt exist in this segment */
assert termNotInReader(reader, t): "no termstate found but term exists in reader";
return null;
}
te.seekExact(t.bytes(), state);
PostingsEnum postingsEnum = te.postings(null, PostingsEnum.POSITIONS);
postingsFreqs[i] = new PostingsAndFreq(postingsEnum, positions[i], t);
totalMatchCost += termPositionsCost(te);
}
// sort by increasing docFreq order
if (slop == 0) {
ArrayUtil.timSort(postingsFreqs);
}
if (slop == 0) { // optimize exact case
return new ExactPhraseScorer(this, postingsFreqs,
similarity.simScorer(stats, context),
needsScores, totalMatchCost);
} else {
return new SloppyPhraseScorer(this, postingsFreqs, slop,
similarity.simScorer(stats, context),
needsScores, totalMatchCost);
}
}
// only called from assert
private boolean termNotInReader(LeafReader reader, Term term) throws IOException {
return reader.docFreq(term) == 0;
}
@Override
public Explanation explain(LeafReaderContext context, int doc) throws IOException {
Scorer scorer = scorer(context);
if (scorer != null) {
int newDoc = scorer.iterator().advance(doc);
if (newDoc == doc) {
float freq = slop == 0 ? scorer.freq() : ((SloppyPhraseScorer)scorer).sloppyFreq();
SimScorer docScorer = similarity.simScorer(stats, context);
Explanation freqExplanation = Explanation.match(freq, "phraseFreq=" + freq);
Explanation scoreExplanation = docScorer.explain(doc, freqExplanation);
return Explanation.match(
scoreExplanation.getValue(),
"weight("+getQuery()+" in "+doc+") [" + similarity.getClass().getSimpleName() + "], result of:",
scoreExplanation);
}
}
return Explanation.noMatch("no matching term");
}
}
/** A guess of
* the average number of simple operations for the initial seek and buffer refill
* per document for the positions of a term.
* See also {@link Lucene50PostingsReader.BlockPostingsEnum#nextPosition()}.
* <p>
* Aside: Instead of being constant this could depend among others on
* {@link Lucene50PostingsFormat#BLOCK_SIZE},
* {@link TermsEnum#docFreq()},
* {@link TermsEnum#totalTermFreq()},
* {@link DocIdSetIterator#cost()} (expected number of matching docs),
* {@link LeafReader#maxDoc()} (total number of docs in the segment),
* and the seek time and block size of the device storing the index.
*/
private static final int TERM_POSNS_SEEK_OPS_PER_DOC = 128;
/** Number of simple operations in {@link Lucene50PostingsReader.BlockPostingsEnum#nextPosition()}
* when no seek or buffer refill is done.
*/
private static final int TERM_OPS_PER_POS = 7;
/** Returns an expected cost in simple operations
* of processing the occurrences of a term
* in a document that contains the term.
* This is for use by {@link TwoPhaseIterator#matchCost} implementations.
* <br>This may be inaccurate when {@link TermsEnum#totalTermFreq()} is not available.
* @param termsEnum The term is the term at which this TermsEnum is positioned.
*/
static float termPositionsCost(TermsEnum termsEnum) throws IOException {
int docFreq = termsEnum.docFreq();
assert docFreq > 0;
long totalTermFreq = termsEnum.totalTermFreq(); // -1 when not available
float expOccurrencesInMatchingDoc = (totalTermFreq < docFreq) ? 1 : (totalTermFreq / (float) docFreq);
return TERM_POSNS_SEEK_OPS_PER_DOC + expOccurrencesInMatchingDoc * TERM_OPS_PER_POS;
}
@Override
public Weight createWeight(IndexSearcher searcher, boolean needsScores, float boost) throws IOException {
return new PhraseWeight(searcher, needsScores, boost);
}
/** 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("\"");
final int maxPosition;
if (positions.length == 0) {
maxPosition = -1;
} else {
maxPosition = positions[positions.length - 1];
}
String[] pieces = new String[maxPosition + 1];
for (int i = 0; i < terms.length; i++) {
int pos = positions[i];
String s = pieces[pos];
if (s == null) {
s = (terms[i]).text();
} else {
s = s + "|" + (terms[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);
}
return buffer.toString();
}
/** Returns true iff <code>o</code> is equal to this. */
@Override
public boolean equals(Object other) {
return sameClassAs(other) &&
equalsTo(getClass().cast(other));
}
private boolean equalsTo(PhraseQuery other) {
return slop == other.slop &&
Arrays.equals(terms, other.terms) &&
Arrays.equals(positions, other.positions);
}
/** Returns a hash code value for this object.*/
@Override
public int hashCode() {
int h = classHash();
h = 31 * h + slop;
h = 31 * h + Arrays.hashCode(terms);
h = 31 * h + Arrays.hashCode(positions);
return h;
}
}