package org.apache.lucene.util;
/**
* 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.
*/
import java.io.IOException;
import java.util.Arrays;
import org.apache.lucene.index.Fields;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermState;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.index.IndexReader.AtomicReaderContext;
import org.apache.lucene.index.IndexReader.ReaderContext;
import org.apache.lucene.index.TermsEnum.SeekStatus;
/**
* Maintains a {@link IndexReader} {@link TermState} view over
* {@link IndexReader} instances containing a single term. The
* {@link PerReaderTermState} doesn't track if the given {@link TermState}
* objects are valid, neither if the {@link TermState} instances refer to the
* same terms in the associated readers.
*
* @lucene.experimental
*/
public final class PerReaderTermState {
public final ReaderContext topReaderContext; // for asserting!
private final TermState[] states;
private int docFreq;
/**
* Creates an empty {@link PerReaderTermState} from a {@link ReaderContext}
*/
public PerReaderTermState(ReaderContext context) {
assert context != null && context.isTopLevel;
topReaderContext = context;
docFreq = 0;
final int len;
if (context.leaves() == null) {
len = 1;
} else {
len = context.leaves().length;
}
states = new TermState[len];
}
/**
* Creates a {@link PerReaderTermState} with an initial {@link TermState},
* {@link IndexReader} pair.
*/
public PerReaderTermState(ReaderContext context, TermState state, int ord, int docFreq) {
this(context);
register(state, ord, docFreq);
}
/**
* Creates a {@link PerReaderTermState} from a top-level {@link ReaderContext} and the
* given {@link Term}. This method will lookup the given term in all context's leaf readers
* and register each of the readers containing the term in the returned {@link PerReaderTermState}
* using the leaf reader's ordinal.
* <p>
* Note: the given context must be a top-level context.
*/
public static PerReaderTermState build(ReaderContext context, Term term, boolean cache)
throws IOException {
assert context != null && context.isTopLevel;
final String field = term.field();
final BytesRef bytes = term.bytes();
final PerReaderTermState perReaderTermState = new PerReaderTermState(context);
final AtomicReaderContext[] leaves = ReaderUtil.leaves(context);
for (int i = 0; i < leaves.length; i++) {
final Fields fields = leaves[i].reader.fields();
if (fields != null) {
final Terms terms = fields.terms(field);
if (terms != null) {
final TermsEnum termsEnum = terms.getThreadTermsEnum(); // thread-private don't share!
if (SeekStatus.FOUND == termsEnum.seek(bytes, cache)) {
final TermState termState = termsEnum.termState();
perReaderTermState.register(termState, leaves[i].ord, termsEnum.docFreq());
}
}
}
}
return perReaderTermState;
}
/**
* Clears the {@link PerReaderTermState} internal state and removes all
* registered {@link TermState}s
*/
public void clear() {
docFreq = 0;
Arrays.fill(states, null);
}
/**
* Registers and associates a {@link TermState} with an leaf ordinal. The leaf ordinal
* should be derived from a {@link ReaderContext}'s leaf ord.
*/
public void register(TermState state, final int ord, final int docFreq) {
assert state != null : "state must not be null";
assert ord >= 0 && ord < states.length;
assert states[ord] == null : "state for ord: " + ord
+ " already registered";
this.docFreq += docFreq;
states[ord] = state;
}
/**
* Returns the {@link TermState} for an leaf ordinal or <code>null</code> if no
* {@link TermState} for the ordinal was registered.
*
* @param ord
* the readers leaf ordinal to get the {@link TermState} for.
* @return the {@link TermState} for the given readers ord or <code>null</code> if no
* {@link TermState} for the reader was registered
*/
public TermState get(int ord) {
assert ord >= 0 && ord < states.length;
return states[ord];
}
/**
* Returns the accumulated document frequency of all {@link TermState}
* instances passed to {@link #register(TermState, int, int)}.
* @return the accumulated document frequency of all {@link TermState}
* instances passed to {@link #register(TermState, int, int)}.
*/
public int docFreq() {
return docFreq;
}
}