pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / search / DocIdSetIterator.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/DocIdSetIterator.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/DocIdSetIterator.java
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+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;
+
+/**
+ * This abstract class defines methods to iterate over a set of non-decreasing
+ * doc ids. Note that this class assumes it iterates on doc Ids, and therefore
+ * {@link #NO_MORE_DOCS} is set to {@value #NO_MORE_DOCS} in order to be used as
+ * a sentinel object. Implementations of this class are expected to consider
+ * {@link Integer#MAX_VALUE} as an invalid value.
+ */
+public abstract class DocIdSetIterator {
+  
+  /**
+   * When returned by {@link #nextDoc()}, {@link #advance(int)} and
+   * {@link #docID()} it means there are no more docs in the iterator.
+   */
+  public static final int NO_MORE_DOCS = Integer.MAX_VALUE;
+
+  /**
+   * Returns the following:
+   * <ul>
+   * <li>-1 or {@link #NO_MORE_DOCS} if {@link #nextDoc()} or
+   * {@link #advance(int)} were not called yet.
+   * <li>{@link #NO_MORE_DOCS} if the iterator has exhausted.
+   * <li>Otherwise it should return the doc ID it is currently on.
+   * </ul>
+   * <p>
+   * 
+   * @since 2.9
+   */
+  public abstract int docID();
+
+  /**
+   * Advances to the next document in the set and returns the doc it is
+   * currently on, or {@link #NO_MORE_DOCS} if there are no more docs in the
+   * set.<br>
+   * 
+   * <b>NOTE:</b> after the iterator has exhausted you should not call this
+   * method, as it may result in unpredicted behavior.
+   * 
+   * @since 2.9
+   */
+  public abstract int nextDoc() throws IOException;
+
+  /**
+   * Advances to the first beyond (see NOTE below) the current whose document
+   * number is greater than or equal to <i>target</i>. Returns the current
+   * document number or {@link #NO_MORE_DOCS} if there are no more docs in the
+   * set.
+   * <p>
+   * Behaves as if written:
+   * 
+   * <pre>
+   * int advance(int target) {
+   *   int doc;
+   *   while ((doc = nextDoc()) &lt; target) {
+   *   }
+   *   return doc;
+   * }
+   * </pre>
+   * 
+   * Some implementations are considerably more efficient than that.
+   * <p>
+   * <b>NOTE:</b> when <code> target &le; current</code> implementations may opt
+   * not to advance beyond their current {@link #docID()}.
+   * <p>
+   * <b>NOTE:</b> this method may be called with {@link #NO_MORE_DOCS} for
+   * efficiency by some Scorers. If your implementation cannot efficiently
+   * determine that it should exhaust, it is recommended that you check for that
+   * value in each call to this method.
+   * <p>
+   * <b>NOTE:</b> after the iterator has exhausted you should not call this
+   * method, as it may result in unpredicted behavior.
+   * <p>
+   * 
+   * @since 2.9
+   */
+  public abstract int advance(int target) throws IOException;
+
+}