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package org.apache.lucene.search;
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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import java.io.IOException;
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import java.io.Serializable;
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import java.util.Locale;
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import org.apache.lucene.util.StringHelper;
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* Stores information about how to sort documents by terms in an individual
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* field. Fields must be indexed in order to sort by them.
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* <p>Created: Feb 11, 2004 1:25:29 PM
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public class SortField
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implements Serializable {
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/** Sort by document score (relevance). Sort values are Float and higher
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* values are at the front. */
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public static final int SCORE = 0;
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/** Sort by document number (index order). Sort values are Integer and lower
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* values are at the front. */
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public static final int DOC = 1;
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// reserved, in Lucene 2.9, there was a constant: AUTO = 2;
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/** Sort using term values as Strings. Sort values are String and lower
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* values are at the front. */
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public static final int STRING = 3;
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/** Sort using term values as encoded Integers. Sort values are Integer and
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* lower values are at the front. */
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public static final int INT = 4;
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/** Sort using term values as encoded Floats. Sort values are Float and
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* lower values are at the front. */
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public static final int FLOAT = 5;
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/** Sort using term values as encoded Longs. Sort values are Long and
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* lower values are at the front. */
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public static final int LONG = 6;
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/** Sort using term values as encoded Doubles. Sort values are Double and
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* lower values are at the front. */
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public static final int DOUBLE = 7;
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/** Sort using term values as encoded Shorts. Sort values are Short and
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* lower values are at the front. */
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public static final int SHORT = 8;
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/** Sort using a custom Comparator. Sort values are any Comparable and
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* sorting is done according to natural order. */
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public static final int CUSTOM = 9;
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/** Sort using term values as encoded Bytes. Sort values are Byte and
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* lower values are at the front. */
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public static final int BYTE = 10;
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/** Sort using term values as Strings, but comparing by
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* value (using String.compareTo) for all comparisons.
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* This is typically slower than {@link #STRING}, which
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* uses ordinals to do the sorting. */
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public static final int STRING_VAL = 11;
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// IMPLEMENTATION NOTE: the FieldCache.STRING_INDEX is in the same "namespace"
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// as the above static int values. Any new values must not have the same value
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// as FieldCache.STRING_INDEX.
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/** Represents sorting by document score (relevance). */
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public static final SortField FIELD_SCORE = new SortField(null, SCORE);
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/** Represents sorting by document number (index order). */
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public static final SortField FIELD_DOC = new SortField(null, DOC);
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private int type; // defaults to determining type dynamically
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private Locale locale; // defaults to "natural order" (no Locale)
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boolean reverse = false; // defaults to natural order
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private FieldCache.Parser parser;
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// Used for CUSTOM sort
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private FieldComparatorSource comparatorSource;
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private Object missingValue;
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/** Creates a sort by terms in the given field with the type of term
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* values explicitly given.
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* @param field Name of field to sort by. Can be <code>null</code> if
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* <code>type</code> is SCORE or DOC.
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* @param type Type of values in the terms.
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public SortField(String field, int type) {
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initFieldType(field, type);
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/** Creates a sort, possibly in reverse, by terms in the given field with the
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* type of term values explicitly given.
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* @param field Name of field to sort by. Can be <code>null</code> if
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* <code>type</code> is SCORE or DOC.
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* @param type Type of values in the terms.
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* @param reverse True if natural order should be reversed.
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public SortField(String field, int type, boolean reverse) {
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initFieldType(field, type);
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this.reverse = reverse;
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/** Creates a sort by terms in the given field, parsed
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* to numeric values using a custom {@link FieldCache.Parser}.
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* @param field Name of field to sort by. Must not be null.
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* @param parser Instance of a {@link FieldCache.Parser},
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* which must subclass one of the existing numeric
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* parsers from {@link FieldCache}. Sort type is inferred
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* by testing which numeric parser the parser subclasses.
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* @throws IllegalArgumentException if the parser fails to
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* subclass an existing numeric parser, or field is null
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public SortField(String field, FieldCache.Parser parser) {
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this(field, parser, false);
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/** Creates a sort, possibly in reverse, by terms in the given field, parsed
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* to numeric values using a custom {@link FieldCache.Parser}.
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* @param field Name of field to sort by. Must not be null.
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* @param parser Instance of a {@link FieldCache.Parser},
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* which must subclass one of the existing numeric
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* parsers from {@link FieldCache}. Sort type is inferred
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* by testing which numeric parser the parser subclasses.
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* @param reverse True if natural order should be reversed.
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* @throws IllegalArgumentException if the parser fails to
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* subclass an existing numeric parser, or field is null
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public SortField(String field, FieldCache.Parser parser, boolean reverse) {
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if (parser instanceof FieldCache.IntParser) initFieldType(field, INT);
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else if (parser instanceof FieldCache.FloatParser) initFieldType(field, FLOAT);
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else if (parser instanceof FieldCache.ShortParser) initFieldType(field, SHORT);
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else if (parser instanceof FieldCache.ByteParser) initFieldType(field, BYTE);
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else if (parser instanceof FieldCache.LongParser) initFieldType(field, LONG);
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else if (parser instanceof FieldCache.DoubleParser) initFieldType(field, DOUBLE);
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throw new IllegalArgumentException("Parser instance does not subclass existing numeric parser from FieldCache (got " + parser + ")");
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this.reverse = reverse;
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this.parser = parser;
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/** Creates a sort by terms in the given field sorted
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* according to the given locale.
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* @param field Name of field to sort by, cannot be <code>null</code>.
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* @param locale Locale of values in the field.
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public SortField (String field, Locale locale) {
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initFieldType(field, STRING);
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this.locale = locale;
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/** Creates a sort, possibly in reverse, by terms in the given field sorted
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* according to the given locale.
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* @param field Name of field to sort by, cannot be <code>null</code>.
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* @param locale Locale of values in the field.
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public SortField (String field, Locale locale, boolean reverse) {
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initFieldType(field, STRING);
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this.locale = locale;
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this.reverse = reverse;
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/** Creates a sort with a custom comparison function.
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* @param field Name of field to sort by; cannot be <code>null</code>.
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* @param comparator Returns a comparator for sorting hits.
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public SortField(String field, FieldComparatorSource comparator) {
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initFieldType(field, CUSTOM);
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this.comparatorSource = comparator;
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/** Creates a sort, possibly in reverse, with a custom comparison function.
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* @param field Name of field to sort by; cannot be <code>null</code>.
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* @param comparator Returns a comparator for sorting hits.
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* @param reverse True if natural order should be reversed.
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public SortField(String field, FieldComparatorSource comparator, boolean reverse) {
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initFieldType(field, CUSTOM);
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this.reverse = reverse;
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this.comparatorSource = comparator;
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/** Set a default sorting value for documents which lacks one */
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public SortField setMissingValue(Object missingValue) {
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if (type != BYTE && type != SHORT && type != INT && type != FLOAT && type != LONG && type != DOUBLE) {
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throw new IllegalArgumentException( "Missing value only works for numeric types" );
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this.missingValue = missingValue;
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// Sets field & type, and ensures field is not NULL unless
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// type is SCORE or DOC
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private void initFieldType(String field, int type) {
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if (type != SCORE && type != DOC)
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throw new IllegalArgumentException("field can only be null when type is SCORE or DOC");
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this.field = StringHelper.intern(field);
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/** Returns the name of the field. Could return <code>null</code>
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* if the sort is by SCORE or DOC.
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* @return Name of field, possibly <code>null</code>.
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public String getField() {
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/** Returns the type of contents in the field.
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* @return One of the constants SCORE, DOC, STRING, INT or FLOAT.
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public int getType() {
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/** Returns the Locale by which term values are interpreted.
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* May return <code>null</code> if no Locale was specified.
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* @return Locale, or <code>null</code>.
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public Locale getLocale() {
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/** Returns the instance of a {@link FieldCache} parser that fits to the given sort type.
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* May return <code>null</code> if no parser was specified. Sorting is using the default parser then.
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* @return An instance of a {@link FieldCache} parser, or <code>null</code>.
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public FieldCache.Parser getParser() {
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/** Returns whether the sort should be reversed.
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* @return True if natural order should be reversed.
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public boolean getReverse() {
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/** Returns the {@link FieldComparatorSource} used for
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public FieldComparatorSource getComparatorSource() {
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return comparatorSource;
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public String toString() {
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StringBuilder buffer = new StringBuilder();
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buffer.append("<score>");
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buffer.append("<doc>");
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buffer.append("<string: \"").append(field).append("\">");
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buffer.append("<string_val: \"").append(field).append("\">");
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buffer.append("<byte: \"").append(field).append("\">");
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buffer.append("<short: \"").append(field).append("\">");
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buffer.append("<int: \"").append(field).append("\">");
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buffer.append("<long: \"").append(field).append("\">");
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buffer.append("<float: \"").append(field).append("\">");
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buffer.append("<double: \"").append(field).append("\">");
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buffer.append("<custom:\"").append(field).append("\": ").append(comparatorSource).append('>');
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buffer.append("<???: \"").append(field).append("\">");
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if (locale != null) buffer.append('(').append(locale).append(')');
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if (parser != null) buffer.append('(').append(parser).append(')');
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if (reverse) buffer.append('!');
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return buffer.toString();
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/** Returns true if <code>o</code> is equal to this. If a
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* {@link FieldComparatorSource} or {@link
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* FieldCache.Parser} was provided, it must properly
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* implement equals (unless a singleton is always used). */
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public boolean equals(Object o) {
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if (this == o) return true;
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if (!(o instanceof SortField)) return false;
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final SortField other = (SortField)o;
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other.field == this.field // field is always interned
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&& other.type == this.type
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&& other.reverse == this.reverse
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&& (other.locale == null ? this.locale == null : other.locale.equals(this.locale))
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&& (other.comparatorSource == null ? this.comparatorSource == null : other.comparatorSource.equals(this.comparatorSource))
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&& (other.parser == null ? this.parser == null : other.parser.equals(this.parser))
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/** Returns true if <code>o</code> is equal to this. If a
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* {@link FieldComparatorSource} or {@link
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* FieldCache.Parser} was provided, it must properly
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* implement hashCode (unless a singleton is always
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public int hashCode() {
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int hash=type^0x346565dd + Boolean.valueOf(reverse).hashCode()^0xaf5998bb;
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if (field != null) hash += field.hashCode()^0xff5685dd;
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if (locale != null) hash += locale.hashCode()^0x08150815;
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if (comparatorSource != null) hash += comparatorSource.hashCode();
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if (parser != null) hash += parser.hashCode()^0x3aaf56ff;
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// field must be interned after reading from stream
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private void readObject(java.io.ObjectInputStream in) throws java.io.IOException, ClassNotFoundException {
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in.defaultReadObject();
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field = StringHelper.intern(field);
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/** Returns the {@link FieldComparator} to use for
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* @lucene.experimental
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* @param numHits number of top hits the queue will store
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* @param sortPos position of this SortField within {@link
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* Sort}. The comparator is primary if sortPos==0,
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* secondary if sortPos==1, etc. Some comparators can
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* optimize themselves when they are the primary sort.
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* @return {@link FieldComparator} to use when sorting
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public FieldComparator getComparator(final int numHits, final int sortPos) throws IOException {
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if (locale != null) {
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// TODO: it'd be nice to allow FieldCache.getStringIndex
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// to optionally accept a Locale so sorting could then use
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// the faster StringComparator impls
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return new FieldComparator.StringComparatorLocale(numHits, field, locale);
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case SortField.SCORE:
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return new FieldComparator.RelevanceComparator(numHits);
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return new FieldComparator.DocComparator(numHits);
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return new FieldComparator.IntComparator(numHits, field, parser, (Integer) missingValue);
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case SortField.FLOAT:
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return new FieldComparator.FloatComparator(numHits, field, parser, (Float) missingValue);
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return new FieldComparator.LongComparator(numHits, field, parser, (Long) missingValue);
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case SortField.DOUBLE:
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return new FieldComparator.DoubleComparator(numHits, field, parser, (Double) missingValue);
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return new FieldComparator.ByteComparator(numHits, field, parser, (Byte) missingValue);
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case SortField.SHORT:
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return new FieldComparator.ShortComparator(numHits, field, parser, (Short) missingValue);
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case SortField.CUSTOM:
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assert comparatorSource != null;
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return comparatorSource.newComparator(field, numHits, sortPos, reverse);
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case SortField.STRING:
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return new FieldComparator.StringOrdValComparator(numHits, field, sortPos, reverse);
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case SortField.STRING_VAL:
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return new FieldComparator.StringValComparator(numHits, field);
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throw new IllegalStateException("Illegal sort type: " + type);