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Lucene example source code file (SortField.java)

This example Lucene source code file (SortField.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

custom, doc, doc, fieldcomparatorsource, float, int, io, locale, locale, long, score, sortfield, sortfield, string, string, util

The Lucene SortField.java source code

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.io.Serializable;
import java.util.Locale;

import org.apache.lucene.util.StringHelper;

/**
 * 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
implements Serializable {

  /** Sort by document score (relevance).  Sort values are Float and higher
   * values are at the front. */
  public static final int SCORE = 0;

  /** Sort by document number (index order).  Sort values are Integer and lower
   * values are at the front. */
  public static final int DOC = 1;

  // reserved, in Lucene 2.9, there was a constant: AUTO = 2;

  /** Sort using term values as Strings.  Sort values are String and lower
   * values are at the front. */
  public static final int STRING = 3;

  /** Sort using term values as encoded Integers.  Sort values are Integer and
   * lower values are at the front. */
  public static final int INT = 4;

  /** Sort using term values as encoded Floats.  Sort values are Float and
   * lower values are at the front. */
  public static final int FLOAT = 5;

  /** Sort using term values as encoded Longs.  Sort values are Long and
   * lower values are at the front. */
  public static final int LONG = 6;

  /** Sort using term values as encoded Doubles.  Sort values are Double and
   * lower values are at the front. */
  public static final int DOUBLE = 7;

  /** Sort using term values as encoded Shorts.  Sort values are Short and
   * lower values are at the front. */
  public static final int SHORT = 8;

  /** Sort using a custom Comparator.  Sort values are any Comparable and
   * sorting is done according to natural order. */
  public static final int CUSTOM = 9;

  /** Sort using term values as encoded Bytes.  Sort values are Byte and
   * lower values are at the front. */
  public static final int BYTE = 10;
  
  /** 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. */
  public static final int STRING_VAL = 11;
  
  // IMPLEMENTATION NOTE: the FieldCache.STRING_INDEX is in the same "namespace"
  // as the above static int values.  Any new values must not have the same value
  // as FieldCache.STRING_INDEX.

  /** Represents sorting by document score (relevance). */
  public static final SortField FIELD_SCORE = new SortField(null, SCORE);

  /** Represents sorting by document number (index order). */
  public static final SortField FIELD_DOC = new SortField(null, DOC);

  private String field;
  private int type;  // defaults to determining type dynamically
  private Locale locale;    // defaults to "natural order" (no Locale)
  boolean reverse = false;  // defaults to natural order
  private FieldCache.Parser parser;

  // Used for CUSTOM sort
  private FieldComparatorSource comparatorSource;

  /** 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 if
   *               <code>type is SCORE or DOC.
   * @param type   Type of values in the terms.
   */
  public SortField(String field, int 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 if
   *               <code>type 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, int type, boolean reverse) {
    initFieldType(field, type);
    this.reverse = reverse;
  }

  /** Creates a sort by terms in the given field, parsed
   * to numeric values using a custom {@link FieldCache.Parser}.
   * @param field  Name of field to sort by.  Must not be null.
   * @param parser Instance of a {@link FieldCache.Parser},
   *  which must subclass one of the existing numeric
   *  parsers from {@link FieldCache}. Sort type is inferred
   *  by testing which numeric parser the parser subclasses.
   * @throws IllegalArgumentException if the parser fails to
   *  subclass an existing numeric parser, or field is null
   */
  public SortField(String field, FieldCache.Parser parser) {
    this(field, parser, false);
  }

  /** Creates a sort, possibly in reverse, by terms in the given field, parsed
   * to numeric values using a custom {@link FieldCache.Parser}.
   * @param field  Name of field to sort by.  Must not be null.
   * @param parser Instance of a {@link FieldCache.Parser},
   *  which must subclass one of the existing numeric
   *  parsers from {@link FieldCache}. Sort type is inferred
   *  by testing which numeric parser the parser subclasses.
   * @param reverse True if natural order should be reversed.
   * @throws IllegalArgumentException if the parser fails to
   *  subclass an existing numeric parser, or field is null
   */
  public SortField(String field, FieldCache.Parser parser, boolean reverse) {
    if (parser instanceof FieldCache.IntParser) initFieldType(field, INT);
    else if (parser instanceof FieldCache.FloatParser) initFieldType(field, FLOAT);
    else if (parser instanceof FieldCache.ShortParser) initFieldType(field, SHORT);
    else if (parser instanceof FieldCache.ByteParser) initFieldType(field, BYTE);
    else if (parser instanceof FieldCache.LongParser) initFieldType(field, LONG);
    else if (parser instanceof FieldCache.DoubleParser) initFieldType(field, DOUBLE);
    else
      throw new IllegalArgumentException("Parser instance does not subclass existing numeric parser from FieldCache (got " + parser + ")");

    this.reverse = reverse;
    this.parser = parser;
  }

  /** Creates a sort by terms in the given field sorted
   * according to the given locale.
   * @param field  Name of field to sort by, cannot be <code>null.
   * @param locale Locale of values in the field.
   */
  public SortField (String field, Locale locale) {
    initFieldType(field, STRING);
    this.locale = locale;
  }

  /** Creates a sort, possibly in reverse, by terms in the given field sorted
   * according to the given locale.
   * @param field  Name of field to sort by, cannot be <code>null.
   * @param locale Locale of values in the field.
   */
  public SortField (String field, Locale locale, boolean reverse) {
    initFieldType(field, STRING);
    this.locale = locale;
    this.reverse = reverse;
  }

  /** Creates a sort with a custom comparison function.
   * @param field Name of field to sort by; cannot be <code>null.
   * @param comparator Returns a comparator for sorting hits.
   */
  public SortField(String field, FieldComparatorSource comparator) {
    initFieldType(field, 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.
   * @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, 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, int type) {
    this.type = type;
    if (field == null) {
      if (type != SCORE && type != DOC)
        throw new IllegalArgumentException("field can only be null when type is SCORE or DOC");
    } else {
      this.field = StringHelper.intern(field);
    }
  }

  /** Returns the name of the field.  Could return <code>null
   * if the sort is by SCORE or DOC.
   * @return Name of field, possibly <code>null.
   */
  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 int getType() {
    return type;
  }

  /** Returns the Locale by which term values are interpreted.
   * May return <code>null if no Locale was specified.
   * @return Locale, or <code>null.
   */
  public Locale getLocale() {
    return locale;
  }

  /** Returns the instance of a {@link FieldCache} parser that fits to the given sort type.
   * May return <code>null if no parser was specified. Sorting is using the default parser then.
   * @return An instance of a {@link FieldCache} parser, or <code>null.
   */
  public FieldCache.Parser getParser() {
    return parser;
  }

  /** 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 BYTE:
        buffer.append("<byte: \"").append(field).append("\">");
        break;

      case SHORT:
        buffer.append("<short: \"").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;

      default:
        buffer.append("<???: \"").append(field).append("\">");
        break;
    }

    if (locale != null) buffer.append('(').append(locale).append(')');
    if (parser != null) buffer.append('(').append(parser).append(')');
    if (reverse) buffer.append('!');

    return buffer.toString();
  }

  /** Returns true if <code>o is equal to this.  If a
   *  {@link FieldComparatorSource} or {@link
   *  FieldCache.Parser} 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 (
      other.field == this.field // field is always interned
      && other.type == this.type
      && other.reverse == this.reverse
      && (other.locale == null ? this.locale == null : other.locale.equals(this.locale))
      && (other.comparatorSource == null ? this.comparatorSource == null : other.comparatorSource.equals(this.comparatorSource))
      && (other.parser == null ? this.parser == null : other.parser.equals(this.parser))
    );
  }

  /** Returns true if <code>o is equal to this.  If a
   *  {@link FieldComparatorSource} or {@link
   *  FieldCache.Parser} was provided, it must properly
   *  implement hashCode (unless a singleton is always
   *  used). */
  @Override
  public int hashCode() {
    int hash=type^0x346565dd + Boolean.valueOf(reverse).hashCode()^0xaf5998bb;
    if (field != null) hash += field.hashCode()^0xff5685dd;
    if (locale != null) hash += locale.hashCode()^0x08150815;
    if (comparatorSource != null) hash += comparatorSource.hashCode();
    if (parser != null) hash += parser.hashCode()^0x3aaf56ff;
    return hash;
  }

  // field must be interned after reading from stream
  private void readObject(java.io.ObjectInputStream in) throws java.io.IOException, ClassNotFoundException {
    in.defaultReadObject();
    if (field != null)
      field = StringHelper.intern(field);
  }

  /** 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) throws IOException {

    if (locale != null) {
      // TODO: it'd be nice to allow FieldCache.getStringIndex
      // to optionally accept a Locale so sorting could then use
      // the faster StringComparator impls
      return new FieldComparator.StringComparatorLocale(numHits, field, locale);
    }

    switch (type) {
    case SortField.SCORE:
      return new FieldComparator.RelevanceComparator(numHits);

    case SortField.DOC:
      return new FieldComparator.DocComparator(numHits);

    case SortField.INT:
      return new FieldComparator.IntComparator(numHits, field, parser);

    case SortField.FLOAT:
      return new FieldComparator.FloatComparator(numHits, field, parser);

    case SortField.LONG:
      return new FieldComparator.LongComparator(numHits, field, parser);

    case SortField.DOUBLE:
      return new FieldComparator.DoubleComparator(numHits, field, parser);

    case SortField.BYTE:
      return new FieldComparator.ByteComparator(numHits, field, parser);

    case SortField.SHORT:
      return new FieldComparator.ShortComparator(numHits, field, parser);

    case SortField.CUSTOM:
      assert comparatorSource != null;
      return comparatorSource.newComparator(field, numHits, sortPos, reverse);

    case SortField.STRING:
      return new FieldComparator.StringOrdValComparator(numHits, field, sortPos, reverse);

    case SortField.STRING_VAL:
      return new FieldComparator.StringValComparator(numHits, field);
        
    default:
      throw new IllegalStateException("Illegal sort type: " + type);
    }
  }
}

Other Lucene examples (source code examples)

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