--- /dev/null
+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.Serializable;
+import java.util.Arrays;
+
+
+/**
+ * Encapsulates sort criteria for returned hits.
+ *
+ * <p>The fields used to determine sort order must be carefully chosen.
+ * Documents must contain a single term in such a field,
+ * and the value of the term should indicate the document's relative position in
+ * a given sort order. The field must be indexed, but should not be tokenized,
+ * and does not need to be stored (unless you happen to want it back with the
+ * rest of your document data). In other words:
+ *
+ * <p><code>document.add (new Field ("byNumber", Integer.toString(x), Field.Store.NO, Field.Index.NOT_ANALYZED));</code></p>
+ *
+ *
+ * <p><h3>Valid Types of Values</h3>
+ *
+ * <p>There are four possible kinds of term values which may be put into
+ * sorting fields: Integers, Longs, Floats, or Strings. Unless
+ * {@link SortField SortField} objects are specified, the type of value
+ * in the field is determined by parsing the first term in the field.
+ *
+ * <p>Integer term values should contain only digits and an optional
+ * preceding negative sign. Values must be base 10 and in the range
+ * <code>Integer.MIN_VALUE</code> and <code>Integer.MAX_VALUE</code> inclusive.
+ * Documents which should appear first in the sort
+ * should have low value integers, later documents high values
+ * (i.e. the documents should be numbered <code>1..n</code> where
+ * <code>1</code> is the first and <code>n</code> the last).
+ *
+ * <p>Long term values should contain only digits and an optional
+ * preceding negative sign. Values must be base 10 and in the range
+ * <code>Long.MIN_VALUE</code> and <code>Long.MAX_VALUE</code> inclusive.
+ * Documents which should appear first in the sort
+ * should have low value integers, later documents high values.
+ *
+ * <p>Float term values should conform to values accepted by
+ * {@link Float Float.valueOf(String)} (except that <code>NaN</code>
+ * and <code>Infinity</code> are not supported).
+ * Documents which should appear first in the sort
+ * should have low values, later documents high values.
+ *
+ * <p>String term values can contain any valid String, but should
+ * not be tokenized. The values are sorted according to their
+ * {@link Comparable natural order}. Note that using this type
+ * of term value has higher memory requirements than the other
+ * two types.
+ *
+ * <p><h3>Object Reuse</h3>
+ *
+ * <p>One of these objects can be
+ * used multiple times and the sort order changed between usages.
+ *
+ * <p>This class is thread safe.
+ *
+ * <p><h3>Memory Usage</h3>
+ *
+ * <p>Sorting uses of caches of term values maintained by the
+ * internal HitQueue(s). The cache is static and contains an integer
+ * or float array of length <code>IndexReader.maxDoc()</code> for each field
+ * name for which a sort is performed. In other words, the size of the
+ * cache in bytes is:
+ *
+ * <p><code>4 * IndexReader.maxDoc() * (# of different fields actually used to sort)</code>
+ *
+ * <p>For String fields, the cache is larger: in addition to the
+ * above array, the value of every term in the field is kept in memory.
+ * If there are many unique terms in the field, this could
+ * be quite large.
+ *
+ * <p>Note that the size of the cache is not affected by how many
+ * fields are in the index and <i>might</i> be used to sort - only by
+ * the ones actually used to sort a result set.
+ *
+ * <p>Created: Feb 12, 2004 10:53:57 AM
+ *
+ * @since lucene 1.4
+ */
+public class Sort
+implements Serializable {
+
+ /**
+ * Represents sorting by computed relevance. Using this sort criteria returns
+ * the same results as calling
+ * {@link Searcher#search(Query,int) Searcher#search()}without a sort criteria,
+ * only with slightly more overhead.
+ */
+ public static final Sort RELEVANCE = new Sort();
+
+ /** Represents sorting by index order. */
+ public static final Sort INDEXORDER = new Sort(SortField.FIELD_DOC);
+
+ // internal representation of the sort criteria
+ SortField[] fields;
+
+ /**
+ * Sorts by computed relevance. This is the same sort criteria as calling
+ * {@link Searcher#search(Query,int) Searcher#search()}without a sort criteria,
+ * only with slightly more overhead.
+ */
+ public Sort() {
+ this(SortField.FIELD_SCORE);
+ }
+
+ /** Sorts by the criteria in the given SortField. */
+ public Sort(SortField field) {
+ setSort(field);
+ }
+
+ /** Sorts in succession by the criteria in each SortField. */
+ public Sort(SortField... fields) {
+ setSort(fields);
+ }
+
+ /** Sets the sort to the given criteria. */
+ public void setSort(SortField field) {
+ this.fields = new SortField[] { field };
+ }
+
+ /** Sets the sort to the given criteria in succession. */
+ public void setSort(SortField... fields) {
+ this.fields = fields;
+ }
+
+ /**
+ * Representation of the sort criteria.
+ * @return Array of SortField objects used in this sort criteria
+ */
+ public SortField[] getSort() {
+ return fields;
+ }
+
+ @Override
+ public String toString() {
+ StringBuilder buffer = new StringBuilder();
+
+ for (int i = 0; i < fields.length; i++) {
+ buffer.append(fields[i].toString());
+ if ((i+1) < fields.length)
+ buffer.append(',');
+ }
+
+ return buffer.toString();
+ }
+
+ /** Returns true if <code>o</code> is equal to this. */
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (!(o instanceof Sort)) return false;
+ final Sort other = (Sort)o;
+ return Arrays.equals(this.fields, other.fields);
+ }
+
+ /** Returns a hash code value for this object. */
+ @Override
+ public int hashCode() {
+ return 0x45aaf665 + Arrays.hashCode(fields);
+ }
+}
fnp / pylucene.git / blobdiff