package org.apache.lucene.search;
/**
* 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.text.Collator;
import java.util.Locale;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.FieldCache.DoubleParser;
import org.apache.lucene.search.FieldCache.LongParser;
import org.apache.lucene.search.FieldCache.ByteParser;
import org.apache.lucene.search.FieldCache.FloatParser;
import org.apache.lucene.search.FieldCache.IntParser;
import org.apache.lucene.search.FieldCache.ShortParser;
import org.apache.lucene.search.FieldCache.StringIndex;
/**
* Expert: a FieldComparator compares hits so as to determine their
* sort order when collecting the top results with {@link
* TopFieldCollector}. The concrete public FieldComparator
* classes here correspond to the SortField types.
*
* <p>This API is designed to achieve high performance
* sorting, by exposing a tight interaction with {@link
* FieldValueHitQueue} as it visits hits. Whenever a hit is
* competitive, it's enrolled into a virtual slot, which is
* an int ranging from 0 to numHits-1. The {@link
* FieldComparator} is made aware of segment transitions
* during searching in case any internal state it's tracking
* needs to be recomputed during these transitions.</p>
*
* <p>A comparator must define these functions:</p>
*
* <ul>
*
* <li> {@link #compare} Compare a hit at 'slot a'
* with hit 'slot b'.
*
* <li> {@link #setBottom} This method is called by
* {@link FieldValueHitQueue} to notify the
* FieldComparator of the current weakest ("bottom")
* slot. Note that this slot may not hold the weakest
* value according to your comparator, in cases where
* your comparator is not the primary one (ie, is only
* used to break ties from the comparators before it).
*
* <li> {@link #compareBottom} Compare a new hit (docID)
* against the "weakest" (bottom) entry in the queue.
*
* <li> {@link #copy} Installs a new hit into the
* priority queue. The {@link FieldValueHitQueue}
* calls this method when a new hit is competitive.
*
* <li> {@link #setNextReader} Invoked
* when the search is switching to the next segment.
* You may need to update internal state of the
* comparator, for example retrieving new values from
* the {@link FieldCache}.
*
* <li> {@link #value} Return the sort value stored in
* the specified slot. This is only called at the end
* of the search, in order to populate {@link
* FieldDoc#fields} when returning the top results.
* </ul>
*
* <b>NOTE:</b> This API is experimental and might change in
* incompatible ways in the next release.
*/
public abstract class FieldComparator {
/**
* Compare hit at slot1 with hit at slot2.
*
* @param slot1 first slot to compare
* @param slot2 second slot to compare
* @return any N < 0 if slot2's value is sorted after
* slot1, any N > 0 if the slot2's value is sorted before
* slot1 and 0 if they are equal
*/
public abstract int compare(int slot1, int slot2);
/**
* Set the bottom slot, ie the "weakest" (sorted last)
* entry in the queue. When {@link #compareBottom} is
* called, you should compare against this slot. This
* will always be called before {@link #compareBottom}.
*
* @param slot the currently weakest (sorted last) slot in the queue
*/
public abstract void setBottom(final int slot);
/**
* Compare the bottom of the queue with doc. This will
* only invoked after setBottom has been called. This
* should return the same result as {@link
* #compare(int,int)}} as if bottom were slot1 and the new
* document were slot 2.
*
* <p>For a search that hits many results, this method
* will be the hotspot (invoked by far the most
* frequently).</p>
*
* @param doc that was hit
* @return any N < 0 if the doc's value is sorted after
* the bottom entry (not competitive), any N > 0 if the
* doc's value is sorted before the bottom entry and 0 if
* they are equal.
*/
public abstract int compareBottom(int doc) throws IOException;
/**
* This method is called when a new hit is competitive.
* You should copy any state associated with this document
* that will be required for future comparisons, into the
* specified slot.
*
* @param slot which slot to copy the hit to
* @param doc docID relative to current reader
*/
public abstract void copy(int slot, int doc) throws IOException;
/**
* Set a new Reader. All doc correspond to the current Reader.
*
* @param reader current reader
* @param docBase docBase of this reader
* @throws IOException
* @throws IOException
*/
public abstract void setNextReader(IndexReader reader, int docBase) throws IOException;
/** Sets the Scorer to use in case a document's score is
* needed.
*
* @param scorer Scorer instance that you should use to
* obtain the current hit's score, if necessary. */
public void setScorer(Scorer scorer) {
// Empty implementation since most comparators don't need the score. This
// can be overridden by those that need it.
}
/**
* Return the actual value in the slot.
*
* @param slot the value
* @return value in this slot upgraded to Comparable
*/
public abstract Comparable value(int slot);
/** Parses field's values as byte (using {@link
* FieldCache#getBytes} and sorts by ascending value */
public static final class ByteComparator extends FieldComparator {
private final byte[] values;
private byte[] currentReaderValues;
private final String field;
private ByteParser parser;
private byte bottom;
ByteComparator(int numHits, String field, FieldCache.Parser parser) {
values = new byte[numHits];
this.field = field;
this.parser = (ByteParser) parser;
}
@Override
public int compare(int slot1, int slot2) {
return values[slot1] - values[slot2];
}
@Override
public int compareBottom(int doc) {
return bottom - currentReaderValues[doc];
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getBytes(reader, field, parser);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return Byte.valueOf(values[slot]);
}
}
/** Sorts by ascending docID */
public static final class DocComparator extends FieldComparator {
private final int[] docIDs;
private int docBase;
private int bottom;
DocComparator(int numHits) {
docIDs = new int[numHits];
}
@Override
public int compare(int slot1, int slot2) {
// No overflow risk because docIDs are non-negative
return docIDs[slot1] - docIDs[slot2];
}
@Override
public int compareBottom(int doc) {
// No overflow risk because docIDs are non-negative
return bottom - (docBase + doc);
}
@Override
public void copy(int slot, int doc) {
docIDs[slot] = docBase + doc;
}
@Override
public void setNextReader(IndexReader reader, int docBase) {
// TODO: can we "map" our docIDs to the current
// reader? saves having to then subtract on every
// compare call
this.docBase = docBase;
}
@Override
public void setBottom(final int bottom) {
this.bottom = docIDs[bottom];
}
@Override
public Comparable value(int slot) {
return Integer.valueOf(docIDs[slot]);
}
}
/** Parses field's values as double (using {@link
* FieldCache#getDoubles} and sorts by ascending value */
public static final class DoubleComparator extends FieldComparator {
private final double[] values;
private double[] currentReaderValues;
private final String field;
private DoubleParser parser;
private double bottom;
DoubleComparator(int numHits, String field, FieldCache.Parser parser) {
values = new double[numHits];
this.field = field;
this.parser = (DoubleParser) parser;
}
@Override
public int compare(int slot1, int slot2) {
final double v1 = values[slot1];
final double v2 = values[slot2];
if (v1 > v2) {
return 1;
} else if (v1 < v2) {
return -1;
} else {
return 0;
}
}
@Override
public int compareBottom(int doc) {
final double v2 = currentReaderValues[doc];
if (bottom > v2) {
return 1;
} else if (bottom < v2) {
return -1;
} else {
return 0;
}
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getDoubles(reader, field, parser);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return Double.valueOf(values[slot]);
}
}
/** Parses field's values as float (using {@link
* FieldCache#getFloats} and sorts by ascending value */
public static final class FloatComparator extends FieldComparator {
private final float[] values;
private float[] currentReaderValues;
private final String field;
private FloatParser parser;
private float bottom;
FloatComparator(int numHits, String field, FieldCache.Parser parser) {
values = new float[numHits];
this.field = field;
this.parser = (FloatParser) parser;
}
@Override
public int compare(int slot1, int slot2) {
// TODO: are there sneaky non-branch ways to compute
// sign of float?
final float v1 = values[slot1];
final float v2 = values[slot2];
if (v1 > v2) {
return 1;
} else if (v1 < v2) {
return -1;
} else {
return 0;
}
}
@Override
public int compareBottom(int doc) {
// TODO: are there sneaky non-branch ways to compute
// sign of float?
final float v2 = currentReaderValues[doc];
if (bottom > v2) {
return 1;
} else if (bottom < v2) {
return -1;
} else {
return 0;
}
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getFloats(reader, field, parser);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return Float.valueOf(values[slot]);
}
}
/** Parses field's values as int (using {@link
* FieldCache#getInts} and sorts by ascending value */
public static final class IntComparator extends FieldComparator {
private final int[] values;
private int[] currentReaderValues;
private final String field;
private IntParser parser;
private int bottom; // Value of bottom of queue
IntComparator(int numHits, String field, FieldCache.Parser parser) {
values = new int[numHits];
this.field = field;
this.parser = (IntParser) parser;
}
@Override
public int compare(int slot1, int slot2) {
// TODO: there are sneaky non-branch ways to compute
// -1/+1/0 sign
// Cannot return values[slot1] - values[slot2] because that
// may overflow
final int v1 = values[slot1];
final int v2 = values[slot2];
if (v1 > v2) {
return 1;
} else if (v1 < v2) {
return -1;
} else {
return 0;
}
}
@Override
public int compareBottom(int doc) {
// TODO: there are sneaky non-branch ways to compute
// -1/+1/0 sign
// Cannot return bottom - values[slot2] because that
// may overflow
final int v2 = currentReaderValues[doc];
if (bottom > v2) {
return 1;
} else if (bottom < v2) {
return -1;
} else {
return 0;
}
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getInts(reader, field, parser);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return Integer.valueOf(values[slot]);
}
}
/** Parses field's values as long (using {@link
* FieldCache#getLongs} and sorts by ascending value */
public static final class LongComparator extends FieldComparator {
private final long[] values;
private long[] currentReaderValues;
private final String field;
private LongParser parser;
private long bottom;
LongComparator(int numHits, String field, FieldCache.Parser parser) {
values = new long[numHits];
this.field = field;
this.parser = (LongParser) parser;
}
@Override
public int compare(int slot1, int slot2) {
// TODO: there are sneaky non-branch ways to compute
// -1/+1/0 sign
final long v1 = values[slot1];
final long v2 = values[slot2];
if (v1 > v2) {
return 1;
} else if (v1 < v2) {
return -1;
} else {
return 0;
}
}
@Override
public int compareBottom(int doc) {
// TODO: there are sneaky non-branch ways to compute
// -1/+1/0 sign
final long v2 = currentReaderValues[doc];
if (bottom > v2) {
return 1;
} else if (bottom < v2) {
return -1;
} else {
return 0;
}
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getLongs(reader, field, parser);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return Long.valueOf(values[slot]);
}
}
/** Sorts by descending relevance. NOTE: if you are
* sorting only by descending relevance and then
* secondarily by ascending docID, performance is faster
* using {@link TopScoreDocCollector} directly (which {@link
* IndexSearcher#search} uses when no {@link Sort} is
* specified). */
public static final class RelevanceComparator extends FieldComparator {
private final float[] scores;
private float bottom;
private Scorer scorer;
RelevanceComparator(int numHits) {
scores = new float[numHits];
}
@Override
public int compare(int slot1, int slot2) {
final float score1 = scores[slot1];
final float score2 = scores[slot2];
return score1 > score2 ? -1 : (score1 < score2 ? 1 : 0);
}
@Override
public int compareBottom(int doc) throws IOException {
float score = scorer.score();
return bottom > score ? -1 : (bottom < score ? 1 : 0);
}
@Override
public void copy(int slot, int doc) throws IOException {
scores[slot] = scorer.score();
}
@Override
public void setNextReader(IndexReader reader, int docBase) {
}
@Override
public void setBottom(final int bottom) {
this.bottom = scores[bottom];
}
@Override
public void setScorer(Scorer scorer) {
// wrap with a ScoreCachingWrappingScorer so that successive calls to
// score() will not incur score computation over and over again.
this.scorer = new ScoreCachingWrappingScorer(scorer);
}
@Override
public Comparable value(int slot) {
return Float.valueOf(scores[slot]);
}
}
/** Parses field's values as short (using {@link
* FieldCache#getShorts} and sorts by ascending value */
public static final class ShortComparator extends FieldComparator {
private final short[] values;
private short[] currentReaderValues;
private final String field;
private ShortParser parser;
private short bottom;
ShortComparator(int numHits, String field, FieldCache.Parser parser) {
values = new short[numHits];
this.field = field;
this.parser = (ShortParser) parser;
}
@Override
public int compare(int slot1, int slot2) {
return values[slot1] - values[slot2];
}
@Override
public int compareBottom(int doc) {
return bottom - currentReaderValues[doc];
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getShorts(reader, field, parser);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return Short.valueOf(values[slot]);
}
}
/** Sorts by a field's value using the Collator for a
* given Locale.*/
public static final class StringComparatorLocale extends FieldComparator {
private final String[] values;
private String[] currentReaderValues;
private final String field;
final Collator collator;
private String bottom;
StringComparatorLocale(int numHits, String field, Locale locale) {
values = new String[numHits];
this.field = field;
collator = Collator.getInstance(locale);
}
@Override
public int compare(int slot1, int slot2) {
final String val1 = values[slot1];
final String val2 = values[slot2];
if (val1 == null) {
if (val2 == null) {
return 0;
}
return -1;
} else if (val2 == null) {
return 1;
}
return collator.compare(val1, val2);
}
@Override
public int compareBottom(int doc) {
final String val2 = currentReaderValues[doc];
if (bottom == null) {
if (val2 == null) {
return 0;
}
return -1;
} else if (val2 == null) {
return 1;
}
return collator.compare(bottom, val2);
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getStrings(reader, field);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return values[slot];
}
}
/** Sorts by field's natural String sort order, using
* ordinals. This is functionally equivalent to {@link
* StringValComparator}, but it first resolves the string
* to their relative ordinal positions (using the index
* returned by {@link FieldCache#getStringIndex}), and
* does most comparisons using the ordinals. For medium
* to large results, this comparator will be much faster
* than {@link StringValComparator}. For very small
* result sets it may be slower. */
public static final class StringOrdValComparator extends FieldComparator {
private final int[] ords;
private final String[] values;
private final int[] readerGen;
private int currentReaderGen = -1;
private String[] lookup;
private int[] order;
private final String field;
private int bottomSlot = -1;
private int bottomOrd;
private String bottomValue;
private final boolean reversed;
private final int sortPos;
public StringOrdValComparator(int numHits, String field, int sortPos, boolean reversed) {
ords = new int[numHits];
values = new String[numHits];
readerGen = new int[numHits];
this.sortPos = sortPos;
this.reversed = reversed;
this.field = field;
}
@Override
public int compare(int slot1, int slot2) {
if (readerGen[slot1] == readerGen[slot2]) {
int cmp = ords[slot1] - ords[slot2];
if (cmp != 0) {
return cmp;
}
}
final String val1 = values[slot1];
final String val2 = values[slot2];
if (val1 == null) {
if (val2 == null) {
return 0;
}
return -1;
} else if (val2 == null) {
return 1;
}
return val1.compareTo(val2);
}
@Override
public int compareBottom(int doc) {
assert bottomSlot != -1;
int order = this.order[doc];
final int cmp = bottomOrd - order;
if (cmp != 0) {
return cmp;
}
final String val2 = lookup[order];
if (bottomValue == null) {
if (val2 == null) {
return 0;
}
// bottom wins
return -1;
} else if (val2 == null) {
// doc wins
return 1;
}
return bottomValue.compareTo(val2);
}
private void convert(int slot) {
readerGen[slot] = currentReaderGen;
int index = 0;
String value = values[slot];
if (value == null) {
ords[slot] = 0;
return;
}
if (sortPos == 0 && bottomSlot != -1 && bottomSlot != slot) {
// Since we are the primary sort, the entries in the
// queue are bounded by bottomOrd:
assert bottomOrd < lookup.length;
if (reversed) {
index = binarySearch(lookup, value, bottomOrd, lookup.length-1);
} else {
index = binarySearch(lookup, value, 0, bottomOrd);
}
} else {
// Full binary search
index = binarySearch(lookup, value);
}
if (index < 0) {
index = -index - 2;
}
ords[slot] = index;
}
@Override
public void copy(int slot, int doc) {
final int ord = order[doc];
ords[slot] = ord;
assert ord >= 0;
values[slot] = lookup[ord];
readerGen[slot] = currentReaderGen;
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
StringIndex currentReaderValues = FieldCache.DEFAULT.getStringIndex(reader, field);
currentReaderGen++;
order = currentReaderValues.order;
lookup = currentReaderValues.lookup;
assert lookup.length > 0;
if (bottomSlot != -1) {
convert(bottomSlot);
bottomOrd = ords[bottomSlot];
}
}
@Override
public void setBottom(final int bottom) {
bottomSlot = bottom;
if (readerGen[bottom] != currentReaderGen) {
convert(bottomSlot);
}
bottomOrd = ords[bottom];
assert bottomOrd >= 0;
assert bottomOrd < lookup.length;
bottomValue = values[bottom];
}
@Override
public Comparable value(int slot) {
return values[slot];
}
public String[] getValues() {
return values;
}
public int getBottomSlot() {
return bottomSlot;
}
public String getField() {
return field;
}
}
/** Sorts by field's natural String sort order. All
* comparisons are done using String.compareTo, which is
* slow for medium to large result sets but possibly
* very fast for very small results sets. */
public static final class StringValComparator extends FieldComparator {
private String[] values;
private String[] currentReaderValues;
private final String field;
private String bottom;
StringValComparator(int numHits, String field) {
values = new String[numHits];
this.field = field;
}
@Override
public int compare(int slot1, int slot2) {
final String val1 = values[slot1];
final String val2 = values[slot2];
if (val1 == null) {
if (val2 == null) {
return 0;
}
return -1;
} else if (val2 == null) {
return 1;
}
return val1.compareTo(val2);
}
@Override
public int compareBottom(int doc) {
final String val2 = currentReaderValues[doc];
if (bottom == null) {
if (val2 == null) {
return 0;
}
return -1;
} else if (val2 == null) {
return 1;
}
return bottom.compareTo(val2);
}
@Override
public void copy(int slot, int doc) {
values[slot] = currentReaderValues[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
currentReaderValues = FieldCache.DEFAULT.getStrings(reader, field);
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Comparable value(int slot) {
return values[slot];
}
}
final protected static int binarySearch(String[] a, String key) {
return binarySearch(a, key, 0, a.length-1);
}
final protected static int binarySearch(String[] a, String key, int low, int high) {
while (low <= high) {
int mid = (low + high) >>> 1;
String midVal = a[mid];
int cmp;
if (midVal != null) {
cmp = midVal.compareTo(key);
} else {
cmp = -1;
}
if (cmp < 0)
low = mid + 1;
else if (cmp > 0)
high = mid - 1;
else
return mid;
}
return -(low + 1);
}
}