/*
* 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.Comparator;
import java.util.Objects;
import org.apache.lucene.util.BytesRef;
/**
* Stores information about how to sort documents by terms in an individual
* field. Fields must be indexed in order to sort by them.
*
* <p>Created: Feb 11, 2004 1:25:29 PM
*
* @since lucene 1.4
* @see Sort
*/
public class SortField {
/**
* Specifies the type of the terms to be sorted, or special types such as CUSTOM
*/
public static enum Type {
/** Sort by document score (relevance). Sort values are Float and higher
* values are at the front. */
SCORE,
/** Sort by document number (index order). Sort values are Integer and lower
* values are at the front. */
DOC,
/** Sort using term values as Strings. Sort values are String and lower
* values are at the front. */
STRING,
/** Sort using term values as encoded Integers. Sort values are Integer and
* lower values are at the front. */
INT,
/** Sort using term values as encoded Floats. Sort values are Float and
* lower values are at the front. */
FLOAT,
/** Sort using term values as encoded Longs. Sort values are Long and
* lower values are at the front. */
LONG,
/** Sort using term values as encoded Doubles. Sort values are Double and
* lower values are at the front. */
DOUBLE,
/** Sort using a custom Comparator. Sort values are any Comparable and
* sorting is done according to natural order. */
CUSTOM,
/** Sort using term values as Strings, but comparing by
* value (using String.compareTo) for all comparisons.
* This is typically slower than {@link #STRING}, which
* uses ordinals to do the sorting. */
STRING_VAL,
/** Force rewriting of SortField using {@link SortField#rewrite(IndexSearcher)}
* before it can be used for sorting */
REWRITEABLE
}
/** Represents sorting by document score (relevance). */
public static final SortField FIELD_SCORE = new SortField(null, Type.SCORE);
/** Represents sorting by document number (index order). */
public static final SortField FIELD_DOC = new SortField(null, Type.DOC);
private String field;
private Type type; // defaults to determining type dynamically
boolean reverse = false; // defaults to natural order
// Used for CUSTOM sort
private FieldComparatorSource comparatorSource;
// Used for 'sortMissingFirst/Last'
protected Object missingValue = null;
/** Creates a sort by terms in the given field with the type of term
* values explicitly given.
* @param field Name of field to sort by. Can be <code>null</code> if
* <code>type</code> is SCORE or DOC.
* @param type Type of values in the terms.
*/
public SortField(String field, Type type) {
initFieldType(field, type);
}
/** Creates a sort, possibly in reverse, by terms in the given field with the
* type of term values explicitly given.
* @param field Name of field to sort by. Can be <code>null</code> if
* <code>type</code> is SCORE or DOC.
* @param type Type of values in the terms.
* @param reverse True if natural order should be reversed.
*/
public SortField(String field, Type type, boolean reverse) {
initFieldType(field, type);
this.reverse = reverse;
}
/** Pass this to {@link #setMissingValue} to have missing
* string values sort first. */
public final static Object STRING_FIRST = new Object() {
@Override
public String toString() {
return "SortField.STRING_FIRST";
}
};
/** Pass this to {@link #setMissingValue} to have missing
* string values sort last. */
public final static Object STRING_LAST = new Object() {
@Override
public String toString() {
return "SortField.STRING_LAST";
}
};
/** Return the value to use for documents that don't have a value.
* A value of {@code null} indicates that default should be used. */
public Object getMissingValue() {
return missingValue;
}
/** Set the value to use for documents that don't have a value. */
public void setMissingValue(Object missingValue) {
if (type == Type.STRING || type == Type.STRING_VAL) {
if (missingValue != STRING_FIRST && missingValue != STRING_LAST) {
throw new IllegalArgumentException("For STRING type, missing value must be either STRING_FIRST or STRING_LAST");
}
} else if (type == Type.INT) {
if (missingValue != null && missingValue.getClass() != Integer.class)
throw new IllegalArgumentException("Missing values for Type.INT can only be of type java.lang.Integer, but got " + missingValue.getClass());
} else if (type == Type.LONG) {
if (missingValue != null && missingValue.getClass() != Long.class)
throw new IllegalArgumentException("Missing values for Type.LONG can only be of type java.lang.Long, but got " + missingValue.getClass());
} else if (type == Type.FLOAT) {
if (missingValue != null && missingValue.getClass() != Float.class)
throw new IllegalArgumentException("Missing values for Type.FLOAT can only be of type java.lang.Float, but got " + missingValue.getClass());
} else if (type == Type.DOUBLE) {
if (missingValue != null && missingValue.getClass() != Double.class)
throw new IllegalArgumentException("Missing values for Type.DOUBLE can only be of type java.lang.Double, but got " + missingValue.getClass());
} else {
throw new IllegalArgumentException("Missing value only works for numeric or STRING types");
}
this.missingValue = missingValue;
}
/** Creates a sort with a custom comparison function.
* @param field Name of field to sort by; cannot be <code>null</code>.
* @param comparator Returns a comparator for sorting hits.
*/
public SortField(String field, FieldComparatorSource comparator) {
initFieldType(field, Type.CUSTOM);
this.comparatorSource = comparator;
}
/** Creates a sort, possibly in reverse, with a custom comparison function.
* @param field Name of field to sort by; cannot be <code>null</code>.
* @param comparator Returns a comparator for sorting hits.
* @param reverse True if natural order should be reversed.
*/
public SortField(String field, FieldComparatorSource comparator, boolean reverse) {
initFieldType(field, Type.CUSTOM);
this.reverse = reverse;
this.comparatorSource = comparator;
}
// Sets field & type, and ensures field is not NULL unless
// type is SCORE or DOC
private void initFieldType(String field, Type type) {
this.type = type;
if (field == null) {
if (type != Type.SCORE && type != Type.DOC) {
throw new IllegalArgumentException("field can only be null when type is SCORE or DOC");
}
} else {
this.field = field;
}
}
/** Returns the name of the field. Could return <code>null</code>
* if the sort is by SCORE or DOC.
* @return Name of field, possibly <code>null</code>.
*/
public String getField() {
return field;
}
/** Returns the type of contents in the field.
* @return One of the constants SCORE, DOC, STRING, INT or FLOAT.
*/
public Type getType() {
return type;
}
/** Returns whether the sort should be reversed.
* @return True if natural order should be reversed.
*/
public boolean getReverse() {
return reverse;
}
/** Returns the {@link FieldComparatorSource} used for
* custom sorting
*/
public FieldComparatorSource getComparatorSource() {
return comparatorSource;
}
@Override
public String toString() {
StringBuilder buffer = new StringBuilder();
switch (type) {
case SCORE:
buffer.append("<score>");
break;
case DOC:
buffer.append("<doc>");
break;
case STRING:
buffer.append("<string" + ": \"").append(field).append("\">");
break;
case STRING_VAL:
buffer.append("<string_val" + ": \"").append(field).append("\">");
break;
case INT:
buffer.append("<int" + ": \"").append(field).append("\">");
break;
case LONG:
buffer.append("<long: \"").append(field).append("\">");
break;
case FLOAT:
buffer.append("<float" + ": \"").append(field).append("\">");
break;
case DOUBLE:
buffer.append("<double" + ": \"").append(field).append("\">");
break;
case CUSTOM:
buffer.append("<custom:\"").append(field).append("\": ").append(comparatorSource).append('>');
break;
case REWRITEABLE:
buffer.append("<rewriteable: \"").append(field).append("\">");
break;
default:
buffer.append("<???: \"").append(field).append("\">");
break;
}
if (reverse) buffer.append('!');
if (missingValue != null) {
buffer.append(" missingValue=");
buffer.append(missingValue);
}
return buffer.toString();
}
/** Returns true if <code>o</code> is equal to this. If a
* {@link FieldComparatorSource} was provided, it must properly
* implement equals (unless a singleton is always used). */
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof SortField)) return false;
final SortField other = (SortField)o;
return (
Objects.equals(other.field, this.field)
&& other.type == this.type
&& other.reverse == this.reverse
&& Objects.equals(this.comparatorSource, other.comparatorSource)
&& Objects.equals(this.missingValue, other.missingValue)
);
}
/** Returns a hash code for this {@link SortField} instance. If a
* {@link FieldComparatorSource} was provided, it must properly
* implement hashCode (unless a singleton is always used). */
@Override
public int hashCode() {
return Objects.hash(field, type, reverse, comparatorSource, missingValue);
}
private Comparator<BytesRef> bytesComparator = Comparator.naturalOrder();
public void setBytesComparator(Comparator<BytesRef> b) {
bytesComparator = b;
}
public Comparator<BytesRef> getBytesComparator() {
return bytesComparator;
}
/** Returns the {@link FieldComparator} to use for
* sorting.
*
* @lucene.experimental
*
* @param numHits number of top hits the queue will store
* @param sortPos position of this SortField within {@link
* Sort}. The comparator is primary if sortPos==0,
* secondary if sortPos==1, etc. Some comparators can
* optimize themselves when they are the primary sort.
* @return {@link FieldComparator} to use when sorting
*/
public FieldComparator<?> getComparator(final int numHits, final int sortPos) {
switch (type) {
case SCORE:
return new FieldComparator.RelevanceComparator(numHits);
case DOC:
return new FieldComparator.DocComparator(numHits);
case INT:
return new FieldComparator.IntComparator(numHits, field, (Integer) missingValue);
case FLOAT:
return new FieldComparator.FloatComparator(numHits, field, (Float) missingValue);
case LONG:
return new FieldComparator.LongComparator(numHits, field, (Long) missingValue);
case DOUBLE:
return new FieldComparator.DoubleComparator(numHits, field, (Double) missingValue);
case CUSTOM:
assert comparatorSource != null;
return comparatorSource.newComparator(field, numHits, sortPos, reverse);
case STRING:
return new FieldComparator.TermOrdValComparator(numHits, field, missingValue == STRING_LAST);
case STRING_VAL:
return new FieldComparator.TermValComparator(numHits, field, missingValue == STRING_LAST);
case REWRITEABLE:
throw new IllegalStateException("SortField needs to be rewritten through Sort.rewrite(..) and SortField.rewrite(..)");
default:
throw new IllegalStateException("Illegal sort type: " + type);
}
}
/**
* Rewrites this SortField, returning a new SortField if a change is made.
* Subclasses should override this define their rewriting behavior when this
* SortField is of type {@link SortField.Type#REWRITEABLE}
*
* @param searcher IndexSearcher to use during rewriting
* @return New rewritten SortField, or {@code this} if nothing has changed.
* @throws IOException Can be thrown by the rewriting
* @lucene.experimental
*/
public SortField rewrite(IndexSearcher searcher) throws IOException {
return this;
}
/** Whether the relevance score is needed to sort documents. */
public boolean needsScores() {
return type == Type.SCORE;
}
}