org.trypticon.luceneupgrader.lucene6.internal.lucene.index.IndexReaderContext Maven / Gradle / Ivy
/*
* 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.
*/
package org.trypticon.luceneupgrader.lucene6.internal.lucene.index;
import java.util.List;
/**
* A struct like class that represents a hierarchical relationship between
* {@link IndexReader} instances.
*/
public abstract class IndexReaderContext {
/** The reader context for this reader's immediate parent, or null if none */
public final CompositeReaderContext parent;
/** true if this context struct represents the top level reader within the hierarchical context */
public final boolean isTopLevel;
/** the doc base for this reader in the parent, 0 if parent is null */
public final int docBaseInParent;
/** the ord for this reader in the parent, 0 if parent is null */
public final int ordInParent;
// An object that uniquely identifies this context without referencing
// segments. The goal is to make it fine to have references to this
// identity object, even after the index reader has been closed
final Object identity = new Object();
IndexReaderContext(CompositeReaderContext parent, int ordInParent, int docBaseInParent) {
if (!(this instanceof CompositeReaderContext || this instanceof LeafReaderContext))
throw new Error("This class should never be extended by custom code!");
this.parent = parent;
this.docBaseInParent = docBaseInParent;
this.ordInParent = ordInParent;
this.isTopLevel = parent==null;
}
/** Expert: Return an {@link Object} that uniquely identifies this context.
* The returned object does neither reference this {@link IndexReaderContext}
* nor the wrapped {@link IndexReader}.
* @lucene.experimental */
public Object id() {
return identity;
}
/** Returns the {@link IndexReader}, this context represents. */
public abstract IndexReader reader();
/**
* Returns the context's leaves if this context is a top-level context.
* For convenience, if this is an {@link LeafReaderContext} this
* returns itself as the only leaf.
* Note: this is convenience method since leaves can always be obtained by
* walking the context tree using {@link #children()}.
* @throws UnsupportedOperationException if this is not a top-level context.
* @see #children()
*/
public abstract List leaves() throws UnsupportedOperationException;
/**
* Returns the context's children iff this context is a composite context
* otherwise null.
*/
public abstract List children();
}