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Elasticsearch - Open Source, Distributed, RESTful Search Engine
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.search.lookup;
import org.apache.lucene.index.Fields;
import org.apache.lucene.index.FilterLeafReader.FilterPostingsEnum;
import org.apache.lucene.index.LeafReader;
import org.apache.lucene.index.PostingsEnum;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermContext;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.TermStatistics;
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.ElasticsearchException;
import java.io.IOException;
import java.util.Iterator;
/**
* Holds all information on a particular term in a field.
* */
public class IndexFieldTerm implements Iterable {
// The posting list for this term. Is null if the term or field does not
// exist.
PostingsEnum postings;
// Stores if positions, offsets and payloads are requested.
private final int flags;
private final String fieldName;
private final String term;
private final PositionIterator iterator;
// for lucene calls
private final Term identifier;
private final TermStatistics termStats;
// get the document frequency of the term
public long df() throws IOException {
return termStats.docFreq();
}
// get the total term frequency of the term, that is, how often does the
// term appear in any document?
public long ttf() throws IOException {
return termStats.totalTermFreq();
}
// when the reader changes, we have to get the posting list for this term
// and reader
private void setReader(LeafReader reader) {
try {
postings = getPostings(convertToLuceneFlags(flags), reader);
if (postings == null) {
// no term or field for this segment, fake out the postings...
final DocIdSetIterator empty = DocIdSetIterator.empty();
postings = new PostingsEnum() {
@Override
public int docID() {
return empty.docID();
}
@Override
public int nextDoc() throws IOException {
return empty.nextDoc();
}
@Override
public int advance(int target) throws IOException {
return empty.advance(target);
}
@Override
public long cost() {
return empty.cost();
}
@Override
public int freq() throws IOException {
return 1;
}
@Override
public int nextPosition() throws IOException {
return -1;
}
@Override
public int startOffset() throws IOException {
return -1;
}
@Override
public int endOffset() throws IOException {
return -1;
}
@Override
public BytesRef getPayload() throws IOException {
return null;
}
};
}
} catch (IOException e) {
throw new ElasticsearchException("Unable to get postings for field " + fieldName + " and term " + term, e);
}
}
private int convertToLuceneFlags(int flags) {
int lucenePositionsFlags = PostingsEnum.NONE;
lucenePositionsFlags |= (flags & IndexLookup.FLAG_FREQUENCIES) > 0 ? PostingsEnum.FREQS : 0x0;
lucenePositionsFlags |= (flags & IndexLookup.FLAG_POSITIONS) > 0 ? PostingsEnum.POSITIONS : 0x0;
lucenePositionsFlags |= (flags & IndexLookup.FLAG_PAYLOADS) > 0 ? PostingsEnum.PAYLOADS : 0x0;
lucenePositionsFlags |= (flags & IndexLookup.FLAG_OFFSETS) > 0 ? PostingsEnum.OFFSETS : 0x0;
return lucenePositionsFlags;
}
private PostingsEnum getPostings(int luceneFlags, LeafReader reader) throws IOException {
assert identifier.field() != null;
assert identifier.bytes() != null;
final Fields fields = reader.fields();
PostingsEnum newPostings = null;
if (fields != null) {
final Terms terms = fields.terms(identifier.field());
if (terms != null) {
TermsEnum termsEnum = terms.iterator();
if (termsEnum.seekExact(identifier.bytes())) {
newPostings = termsEnum.postings(postings, luceneFlags);
final Bits liveDocs = reader.getLiveDocs();
if (liveDocs != null) {
newPostings = new FilterPostingsEnum(newPostings) {
private int doNext(int d) throws IOException {
for (; d != NO_MORE_DOCS; d = super.nextDoc()) {
if (liveDocs.get(d)) {
return d;
}
}
return NO_MORE_DOCS;
}
@Override
public int nextDoc() throws IOException {
return doNext(super.nextDoc());
}
@Override
public int advance(int target) throws IOException {
return doNext(super.advance(target));
}
};
}
}
}
}
return newPostings;
}
private int freq = 0;
public void setDocument(int docId) {
assert (postings != null);
try {
// we try to advance to the current document.
int currentDocPos = postings.docID();
if (currentDocPos < docId) {
currentDocPos = postings.advance(docId);
}
if (currentDocPos == docId) {
freq = postings.freq();
} else {
freq = 0;
}
iterator.nextDoc();
} catch (IOException e) {
throw new ElasticsearchException("While trying to initialize term positions in IndexFieldTerm.setNextDoc() ", e);
}
}
public IndexFieldTerm(String term, String fieldName, LeafIndexLookup indexLookup, int flags) {
assert fieldName != null;
this.fieldName = fieldName;
assert term != null;
this.term = term;
assert indexLookup != null;
identifier = new Term(fieldName, (String) term);
this.flags = flags;
boolean doRecord = ((flags & IndexLookup.FLAG_CACHE) > 0);
if (!doRecord) {
iterator = new PositionIterator(this);
} else {
iterator = new CachedPositionIterator(this);
}
setReader(indexLookup.getReader());
setDocument(indexLookup.getDocId());
try {
termStats = indexLookup.getIndexSearcher().termStatistics(identifier,
TermContext.build(indexLookup.getReaderContext(), identifier));
} catch (IOException e) {
throw new ElasticsearchException("Cannot get term statistics: ", e);
}
}
public int tf() throws IOException {
return freq;
}
@Override
public Iterator iterator() {
return iterator.reset();
}
/*
* A user might decide inside a script to call get with _POSITIONS and then
* a second time with _PAYLOADS. If the positions were recorded but the
* payloads were not, the user will not have access to them. Therfore, throw
* exception here explaining how to call get().
*/
public void validateFlags(int flags2) {
if ((this.flags & flags2) < flags2) {
throw new ElasticsearchException("You must call get with all required flags! Instead of " + getCalledStatement(flags2)
+ "call " + getCallStatement(flags2 | this.flags) + " once");
}
}
private String getCalledStatement(int flags2) {
String calledFlagsCall1 = getFlagsString(flags);
String calledFlagsCall2 = getFlagsString(flags2);
String callStatement1 = getCallStatement(calledFlagsCall1);
String callStatement2 = getCallStatement(calledFlagsCall2);
return " " + callStatement1 + " and " + callStatement2 + " ";
}
private String getCallStatement(String calledFlags) {
return "_index['" + this.fieldName + "'].get('" + this.term + "', " + calledFlags + ")";
}
private String getFlagsString(int flags2) {
String flagsString = null;
if ((flags2 & IndexLookup.FLAG_FREQUENCIES) != 0) {
flagsString = anddToFlagsString(flagsString, "_FREQUENCIES");
}
if ((flags2 & IndexLookup.FLAG_POSITIONS) != 0) {
flagsString = anddToFlagsString(flagsString, "_POSITIONS");
}
if ((flags2 & IndexLookup.FLAG_OFFSETS) != 0) {
flagsString = anddToFlagsString(flagsString, "_OFFSETS");
}
if ((flags2 & IndexLookup.FLAG_PAYLOADS) != 0) {
flagsString = anddToFlagsString(flagsString, "_PAYLOADS");
}
if ((flags2 & IndexLookup.FLAG_CACHE) != 0) {
flagsString = anddToFlagsString(flagsString, "_CACHE");
}
return flagsString;
}
private String anddToFlagsString(String flagsString, String flag) {
if (flagsString != null) {
flagsString += " | ";
} else {
flagsString = "";
}
flagsString += flag;
return flagsString;
}
private String getCallStatement(int flags2) {
String calledFlags = getFlagsString(flags2);
String callStatement = getCallStatement(calledFlags);
return " " + callStatement + " ";
}
}