package org.apache.lucene.facet.search;
import java.io.IOException;
/*
* 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.
*/
/**
* An interface for iterating over a "category list", i.e., the list of
* categories per document.
* <p>
* <b>NOTE:</b>
* <ul>
* <li>This class operates as a key to a Map. Appropriate implementation of
* <code>hashCode()</code> and <code>equals()</code> must be provided.
* <li>{@link #init()} must be called before you consume any categories, or call
* {@link #skipTo(int)}.
* <li>{@link #skipTo(int)} must be called before any calls to
* {@link #nextCategory()}.
* <li>{@link #nextCategory()} returns values < {@link Integer#MAX_VALUE}, so
* you can use it as a stop condition.
* </ul>
*
* @lucene.experimental
*/
public interface CategoryListIterator {
/**
* Initializes the iterator. This method must be called before any calls to
* {@link #skipTo(int)}, and its return value indicates whether there are
* any relevant documents for this iterator. If it returns false, any call
* to {@link #skipTo(int)} will return false as well.<br>
* <b>NOTE:</b> calling this method twice may result in skipping over
* documents for some implementations. Also, calling it again after all
* documents were consumed may yield unexpected behavior.
*/
public boolean init() throws IOException;
/**
* Skips forward to document docId. Returns true iff this document exists
* and has any categories. This method must be called before calling
* {@link #nextCategory()} for a particular document.<br>
* <b>NOTE:</b> Users should call this method with increasing docIds, and
* implementations can assume that this is the case.
*/
public boolean skipTo(int docId) throws IOException;
/**
* Returns the next category for the current document that is set through
* {@link #skipTo(int)}, or a number higher than {@link Integer#MAX_VALUE}.
* No assumptions can be made on the order of the categories.
*/
public long nextCategory() throws IOException;
}