package org.apache.lucene.index;
/**
* 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 org.apache.lucene.util.BitVector;
import org.apache.lucene.store.IndexInput;
class SegmentTermDocs implements TermDocs {
protected SegmentReader parent;
protected IndexInput freqStream;
protected int count;
protected int df;
protected BitVector deletedDocs;
int doc = 0;
int freq;
private int skipInterval;
private int numSkips;
private int skipCount;
private IndexInput skipStream;
private int skipDoc;
private long freqPointer;
private long proxPointer;
private long skipPointer;
private boolean haveSkipped;
protected SegmentTermDocs(SegmentReader parent) {
this.parent = parent;
this.freqStream = (IndexInput) parent.freqStream.clone();
this.deletedDocs = parent.deletedDocs;
this.skipInterval = parent.tis.getSkipInterval();
}
public void seek(Term term) throws IOException {
TermInfo ti = parent.tis.get(term);
seek(ti);
}
public void seek(TermEnum termEnum) throws IOException {
TermInfo ti;
// use comparison of fieldinfos to verify that termEnum belongs to the same segment as this SegmentTermDocs
if (termEnum instanceof SegmentTermEnum && ((SegmentTermEnum) termEnum).fieldInfos == parent.fieldInfos) // optimized case
ti = ((SegmentTermEnum) termEnum).termInfo();
else // punt case
ti = parent.tis.get(termEnum.term());
seek(ti);
}
void seek(TermInfo ti) throws IOException {
count = 0;
if (ti == null) {
df = 0;
} else {
df = ti.docFreq;
doc = 0;
skipDoc = 0;
skipCount = 0;
numSkips = df / skipInterval;
freqPointer = ti.freqPointer;
proxPointer = ti.proxPointer;
skipPointer = freqPointer + ti.skipOffset;
freqStream.seek(freqPointer);
haveSkipped = false;
}
}
public void close() throws IOException {
freqStream.close();
if (skipStream != null)
skipStream.close();
}
public final int doc() { return doc; }
public final int freq() { return freq; }
protected void skippingDoc() throws IOException {
}
public boolean next() throws IOException {
while (true) {
if (count == df)
return false;
int docCode = freqStream.readVInt();
doc += docCode >>> 1; // shift off low bit
if ((docCode & 1) != 0) // if low bit is set
freq = 1; // freq is one
else
freq = freqStream.readVInt(); // else read freq
count++;
if (deletedDocs == null || !deletedDocs.get(doc))
break;
skippingDoc();
}
return true;
}
/** Optimized implementation. */
public int read(final int[] docs, final int[] freqs)
throws IOException {
final int length = docs.length;
int i = 0;
while (i < length && count < df) {
// manually inlined call to next() for speed
final int docCode = freqStream.readVInt();
doc += docCode >>> 1; // shift off low bit
if ((docCode & 1) != 0) // if low bit is set
freq = 1; // freq is one
else
freq = freqStream.readVInt(); // else read freq
count++;
if (deletedDocs == null || !deletedDocs.get(doc)) {
docs[i] = doc;
freqs[i] = freq;
++i;
}
}
return i;
}
/** Overridden by SegmentTermPositions to skip in prox stream. */
protected void skipProx(long proxPointer) throws IOException {}
/** Optimized implementation. */
public boolean skipTo(int target) throws IOException {
if (df >= skipInterval) { // optimized case
if (skipStream == null)
skipStream = (IndexInput) freqStream.clone(); // lazily clone
if (!haveSkipped) { // lazily seek skip stream
skipStream.seek(skipPointer);
haveSkipped = true;
}
// scan skip data
int lastSkipDoc = skipDoc;
long lastFreqPointer = freqStream.getFilePointer();
long lastProxPointer = -1;
int numSkipped = -1 - (count % skipInterval);
while (target > skipDoc) {
lastSkipDoc = skipDoc;
lastFreqPointer = freqPointer;
lastProxPointer = proxPointer;
if (skipDoc != 0 && skipDoc >= doc)
numSkipped += skipInterval;
if(skipCount >= numSkips)
break;
skipDoc += skipStream.readVInt();
freqPointer += skipStream.readVInt();
proxPointer += skipStream.readVInt();
skipCount++;
}
// if we found something to skip, then skip it
if (lastFreqPointer > freqStream.getFilePointer()) {
freqStream.seek(lastFreqPointer);
skipProx(lastProxPointer);
doc = lastSkipDoc;
count += numSkipped;
}
}
// done skipping, now just scan
do {
if (!next())
return false;
} while (target > doc);
return true;
}
}
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